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CN112925145A - Diamond optical cavity-based state conversion system and method for frequency seamless connection - Google Patents

Diamond optical cavity-based state conversion system and method for frequency seamless connection Download PDF

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CN112925145A
CN112925145A CN202110127123.1A CN202110127123A CN112925145A CN 112925145 A CN112925145 A CN 112925145A CN 202110127123 A CN202110127123 A CN 202110127123A CN 112925145 A CN112925145 A CN 112925145A
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郝赫
李贵兰
高红卫
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Beijing Institute of Radio Measurement
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Abstract

The invention relates to a state conversion system and a state conversion method for seamless connection of frequencies based on a diamond optical cavity, wherein the state conversion system comprises at least one quantum node, and each quantum node comprises a diamond optical cavity structure; the device also comprises a first excitation device, a second excitation device and a third excitation device which respectively act on the light cavity structure of each diamond; seamless conversion of any quantum node from a spin state to a mechanical state or from the mechanical state to the spin state is completed by using the first excitation light emitted by the first excitation device and the second excitation light emitted by the second excitation device; and the seamless conversion of any quantum node from the mechanical state to the optical state or from the optical state to the mechanical state is completed by using third excitation light emitted by a third excitation device. The invention is based on the structure of the diamond optical cavity, realizes the frequency seamless connection conversion from the spin state, the mechanical state to the optical state by taking the mechanical state as a medium, and has positive promotion effect on the large-scale and solid state development of the quantum network.

Description

Diamond optical cavity-based state conversion system and method for frequency seamless connection
Technical Field
The invention relates to the technical field of quantum information, in particular to a diamond optical cavity-based state conversion system and method for seamless frequency connection.
Background
In recent years, the rapid development of quantum information technology, whether quantum communication or quantum computing, relies on the establishment of a large-scale quantum network and the high-fidelity, low-loss and long-distance transmission of information in the network. The carrier of quantum information can be in various forms such as photon, phonon, electron spin and the like, the photon is suitable for being used as a carrier for long-distance information transmission, and the phonon and the electron spin are suitable for being used as a carrier for information storage. In a large-scale quantum network, information transmission among different quantum carriers is realized, namely, conversion among different quantum states is realized on a physical layer, and the method is an important link for large-scale construction of the quantum network. However, at present, state conversion is realized among different quantum information carriers, and the requirement of frequency matching needs to be met, which greatly limits the development and cross application of quantum information carriers in quantum networks.
At present, a solid-state quantum information carrier represented by electron spin of a nitrogen vacancy diamond color center has great advantages in the aspects of quantum information storage and operation, and how to connect the solid-state quantum information carrier with a quantum channel of the existing communication waveband to construct an all-solid-state quantum network is a bottleneck in the technical field of quantum information and industrial development. The technology is restricted by the frequency mismatch between the electron spin and the photon in the communication waveband, and two commonly used solutions are provided at present, one is a scheme based on the frequency conversion of the electro-optical effect or the crystal optics, and the frequency detuning between the spin and the photon is compensated by introducing the nonlinear optical effect. However, the realization of the method still has strict resonance requirements on photon frequency and emission frequency of the solid-state quantum information carrier, and is not suitable for application of different solid-state quantum information carriers in a large-scale network. The other method is based on a state conversion mode of the optical force cavity structure, realizes conversion between a photon state and a spin state of any frequency by means of a mechanical vibration mode of the optical force micro-cavity structure, and overcomes the difficulty of frequency matching. However, in system implementation, frequency matching between the mechanical mode of the optical cavity structure and the solid-state spin state needs to be satisfied, and the scheme has a certain gap from state conversion of a real arbitrary frequency, so that realization of quantum network scale is limited.
Therefore, it is a necessary trend to propose a state transition scheme in which the frequencies between the spin state and the photon state are seamlessly connected.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a state conversion system and method based on frequency seamless connection of a diamond optical cavity, aiming at the defects of the prior art, so that the conversion of a spin state and a photon state is independent of frequency characteristics, the interaction and conversion of the spin state and photons with any frequency are realized, the frequency seamless connection conversion from the spin state, a mechanical state to an optical state is realized, and the system and method have positive propulsion effect on the large-scale and solid state development of a quantum network.
The technical scheme for solving the technical problems is as follows:
a state conversion system of frequency seamless connection based on a diamond optical cavity comprises at least one quantum node, wherein each quantum node comprises a diamond optical cavity structure;
the device also comprises a first excitation device, a second excitation device and a third excitation device which respectively act on the light cavity structure of each diamond;
the first excitation device is used for respectively providing first excitation light for each diamond optical cavity structure, the second excitation device is used for respectively providing second excitation light for each diamond optical cavity structure, and the third excitation device is used for respectively providing third excitation light for each diamond optical cavity structure;
for any one diamond optical cavity structure, the optical cavity structure is used for completing the seamless conversion of the corresponding quantum node from the spin state to the mechanical state or the seamless conversion from the mechanical state to the spin state under the combined action of the corresponding first excitation light and the corresponding second excitation light; and the quantum node is used for completing the seamless transition of the corresponding quantum node from the mechanical state to the optical state or from the optical state to the mechanical state under the action of the corresponding third exciting light.
The state conversion system based on the frequency seamless connection of the diamond optical cavity has the advantages that: the whole system comprises at least one quantum node containing a diamond optical cavity structure, and is provided with a first excitation device for respectively emitting first excitation light to each diamond optical cavity structure, a second excitation device for respectively emitting second excitation light to each diamond optical cavity structure, and a third excitation device for respectively emitting third excitation light to each diamond optical cavity structure; in any quantum node, three quantum states of an optical state, a mechanical state and a spin state exist, and the conversion of the spin state of any quantum node to the mechanical state of any frequency is realized by utilizing the first excitation device and the second excitation device under the combined action of the first excitation light and the second excitation light; then the first excitation device and the second excitation device are closed, and the third excitation device is utilized to realize the seamless conversion of the mechanical state of any quantum node to the optical state of any frequency under the action of third excitation light; or, for any quantum node, the third excitation device is utilized to realize the seamless conversion of the optical state of any quantum node to the mechanical state of any frequency under the action of the third excitation light; then, the first excitation device and the second excitation device are utilized to realize the conversion of the mechanical state of any quantum node to the spin state of any frequency under the combined action of the first excitation light and the second excitation light; because the system relates to the same mechanical mode, two conversion processes related under two different conditions occur successively, the frequency seamless connection of state conversion among an optical state, a mechanical state and a self-spinning state in any single quantum node by taking the mechanical state as a medium is realized, and meanwhile, when a plurality of quantum nodes exist, the system is also beneficial to the state conversion in the plurality of quantum nodes and realizes the frequency seamless connection of state conversion among the plurality of quantum nodes;
the state conversion system based on the diamond optical cavity and frequency seamless connection can enable the conversion of the spin state and the photon state to be independent of frequency characteristics based on the diamond optical cavity structure, achieves the interaction and conversion of the spin state and photons with any frequency, realizes the frequency seamless connection conversion from the spin state and the mechanical state to the optical state, and has positive promotion effect on the large-scale and solid state development of a quantum network.
On the basis of the technical scheme, the invention also has the following improvements:
further: in any quantum node, the diamond optical force cavity structure comprises a diamond optical force cavity of which the surface is inlaid with a nitrogen vacancy color center, and the nitrogen vacancy color center comprises a three-level structure containing two transition channels;
in any quantum node, the first excitation device is specifically configured to provide first excitation light to one of the transition channels of the three-level structure in the nitrogen vacancy color center according to a first preset excitation duration; the second excitation device is specifically configured to provide second excitation light to another transition channel of the corresponding three-level structure according to the first preset excitation duration while the first excitation device provides the first excitation light to one transition channel of the three-level structure; the third excitation device is specifically configured to provide third excitation light for the diamond optical power cavity on the corresponding diamond optical power cavity structure according to a second preset excitation duration after the first excitation device provides the first excitation light and the second excitation device provides the second excitation light;
in any quantum node, the nitrogen vacancy color center is specifically used for completing the conversion of the corresponding quantum node from the spin state to the mechanical state of any frequency or from the mechanical state to the spin state of any frequency under the simultaneous action of the corresponding first excitation light and the corresponding second excitation light according to the first preset excitation time length; the diamond optical power cavity is specifically used for completing conversion from a mechanical state to an optical state with any frequency or from the optical state to the mechanical state with any frequency under the action of corresponding third exciting light according to second preset exciting time duration.
The beneficial effects of the further technical scheme are as follows: in the diamond optical force cavity structure of any single quantum node, the frequency seamless connection between quantum states is realized through two physical processes, one is phonon-assisted spin state conversion, and the other is optical force interaction;
when the initial quantum state of the quantum node is a spin state, then the first physical process involves the conversion of the spin state and a mechanical state; selecting three energy levels of a nitrogen vacancy color center to form a three-energy-level structure, wherein the three-energy-level structure comprises two transition channels, and using first exciting light emitted by a first exciting device for excitation of one transition channel to cooperate with a mechanical vibration mode, wherein the frequency and the draw ratio frequency of the first exciting light are respectively omega1And Ω1Frequency of mechanical mode and the ratio frequency ωmAnd Ωm(ii) a Simultaneously using a second excitation light emitted by a second excitation device for excitation of another transition channel, wherein the frequency and the pull ratio frequency of the second excitation light are respectively omega2And Ω2By adjusting the frequency of the two beams of exciting light, the two beams of light can ensure the driving time of the first preset excitation duration, the two transition channels can be ensured to keep consistent detuning amount, and the ratio frequency is more than { omega1,Ω2,ΩmThe three-level structure can be equivalent to a two-level transition system, and the mechanical state acts on the two-level system to realize the conversion of the nitrogen vacancy color center spin state and form the conversion of the mechanical state and the spin state; because the frequencies of the first excitation light and the second excitation light can be changed arbitrarily, excitation conditions meeting the conditions are always found for the mechanical state with any frequency, and further seamless conversion from the spin state in any single quantum node to the mechanical state with any frequency can be realized;
a second physical process, subsequent to the first physical process, involving a conversion between a mechanical state and an optical state; in the diamond optical power cavity structure with any single quantum node, after the conversion from the spin state to the mechanical state is realized, the first excitation device and the second excitation device are closed, the third excitation device is used for exciting the diamond optical power cavity, optical vibration can be generated, the optical mode causes mechanical vibration of the optical power cavity through radiation pressure, and therefore an optical mode and a mechanical mode in the quantum node are excited; because the optical mode and the mechanical mode are interacted through radiation pressure, the mechanical mode can be interacted with the optical mode with any frequency, and the frequency seamless connection of the optical mode and the mechanical mode is realized;
when the initial quantum state of the quantum node is an optical state, the first physical process relates to the conversion between the optical state and the mechanical state, and the second physical process relates to the conversion between the mechanical state and the spin state, which is the inverse process of the two physical processes in the former case;
the two physical processes under the two conditions occur in succession and both involve the same mechanical mode, so that the mechanical mode is used as an intermediate medium to connect the optical state and the spin state to interact, and the frequency seamless connection in a single quantum node is realized;
wherein, the Hamiltonian of the interaction within a single quantum node can be expressed as:
Figure BDA0002924455000000051
HEis the Hamiltonian in a single quantum node, a represents the optical state, b represents the mechanical state, S represents the spin state, G is the equivalent optical state-mechanical state interaction strength, eta is the equivalent mechanical state-spin state interaction strength, h is the Planck constant, a+、b+And S+Respectively, optical state, mechanical state, spin state.
Further: each diamond optical cavity is of a microdisk structure made of single crystal diamond materials.
The beneficial effects of the further technical scheme are as follows: the material and the microdisk structure can simultaneously support an optical mode with the wavelength of 1552nm and mechanical vibration with the frequency of 39MHz, can be used as a host of a nitrogen vacancy color center, and can cause the change of the energy level of the nitrogen vacancy color center due to the mechanical pressure of the material and the microdisk structure, thereby being convenient for realizing the subsequent state conversion of seamless connection.
Further: the first preset excitation time length is pi/2 eta, and the second preset excitation time length is pi/2G;
wherein eta is the equivalent mechanical state-spin state interaction strength, and G is the equivalent photon state-mechanical state interaction strength.
The beneficial effects of the further technical scheme are as follows: through the first excitation duration, the excitation condition meeting the condition can be effectively ensured to be found, the consistent detuning quantity of the two transition channels is ensured, and further the seamless conversion from the spin state in any single quantum node to the mechanical state with any frequency or the seamless conversion from the mechanical state to the spin state with any frequency can be realized; through the second excitation time, the mechanical vibration of the optical cavity caused by radiation pressure can be effectively ensured, so that an optical mode and a mechanical mode in the quantum node are excited, and further, the frequency seamless connection of a mechanical state and an optical state or the frequency seamless connection of the optical state and the mechanical state in a single quantum node is realized. It should be noted that the process of internal state transition of a single quantum node in the present invention is reversible.
Further: when the number of the quantum nodes is more than 1, the state conversion system based on the frequency seamless connection of the diamond optical cavity further comprises a micro-nano optical fiber coupled between every two connected quantum nodes;
the micro-nano optical fiber is used for providing an information transmission channel for optical state conversion between every two connected quantum nodes, and the seamless conversion of the optical state between every two connected quantum nodes is completed according to preset transmission duration.
The beneficial effects of the further technical scheme are as follows: when the number of quantum nodes is greater than 1, the state transition not only relates to the state transition inside a single quantum node, but also relates to the state transition between every two connected quantum nodes; each two connected quantum nodes are connected in a coupling mode through a micro-nano optical fiber, specifically evanescent wave coupling connection, and the micro-nano optical fiber can be used as a transmission channel of an optical state between the two connected quantum nodes; because any single quantum can be seamlessly converted into an optical state from a spin state, seamless conversion between the optical state of one quantum node and the optical state of the other quantum node can be realized through the micro-nano optical fiber between every two connected quantum nodes; then, because the state conversion in any single quantum node is reversible, the state conversion in another quantum node can be realized through the corresponding inverse process of the third exciting light, the first exciting light and the second exciting light;
by the coupling connection of the micro-nano optical fibers, the state conversion of frequency seamless connection between any two or more connected quantum nodes can be realized, and the scale and solid state development of the quantum network is promoted effectively.
Further: the preset transmission duration is
Figure BDA0002924455000000071
Wherein g is the optical state-fiber coupling coefficient.
The beneficial effects of the further technical scheme are as follows: through the preset transmission duration, seamless transition of optical states between any two connected quantum nodes can be effectively ensured.
According to another aspect of the present invention, there is also provided a state transition method for frequency seamless connection based on a diamond optical cavity, where the state transition method using the state transition system for frequency seamless connection based on a diamond optical cavity in the present invention includes the following steps:
step 1A: for any quantum node, a first excitation device is used for emitting first excitation light, a second excitation device is used for emitting second excitation light, the first excitation light and the second excitation light act on the corresponding diamond optical cavity structure simultaneously, and seamless conversion of the corresponding quantum node from a self-spinning state to a mechanical state is completed;
step 2A: closing the first excitation device and the second excitation device, emitting third excitation light by using a third excitation device, and acting the third excitation light on the corresponding diamond optical cavity structure to complete seamless conversion of the corresponding quantum node from a mechanical state to an optical state;
or,
step 1B: for any quantum node, the third excitation device is utilized to emit third excitation light, and the third excitation light acts on the corresponding diamond optical cavity structure to complete seamless conversion of the corresponding quantum node from an optical state to a mechanical state;
and step 2B: and closing the third excitation device, utilizing the first excitation device to emit first excitation light, utilizing the second excitation device to emit second excitation light, and simultaneously acting the first excitation light and the second excitation light on the corresponding diamond optical cavity structure to complete the seamless conversion of the corresponding quantum node from the mechanical state to the spin state.
The state conversion method based on the frequency seamless connection of the diamond optical cavity has the advantages that: based on the diamond optical cavity-based state conversion system with seamless frequency connection, three quantum states of an optical state, a mechanical state and a spin state exist in any quantum node, and the conversion of the spin state of any quantum node to the mechanical state of any frequency is realized under the combined action of the first excitation light and the second excitation light by utilizing the first excitation device and the second excitation device; then the first excitation device and the second excitation device are closed, and the third excitation device is utilized to realize the seamless conversion of the mechanical state of any quantum node to the optical state of any frequency under the action of third excitation light; or, for any quantum node, the third excitation device is utilized to realize the seamless conversion of the optical state of any quantum node to the mechanical state of any frequency under the action of the third excitation light; then, the first excitation device and the second excitation device are utilized to realize the conversion of the mechanical state of any quantum node to the spin state of any frequency under the combined action of the first excitation light and the second excitation light; the system realizes seamless connection of the frequency of state conversion among optical state, mechanical state and spin state in a single quantum node by taking the mechanical state as a medium because the system relates to the same mechanical mode and two conversion processes related under two different conditions occur in succession; meanwhile, when a plurality of quantum nodes exist, the state conversion in the plurality of quantum nodes is facilitated, and the frequency seamless connection of the state conversion among the plurality of quantum nodes is realized; the step 1B to the step 2B are the reverse process of the step 1A to the step 2A;
the state conversion method based on the frequency seamless connection of the diamond optical cavity, disclosed by the invention, is based on the diamond optical cavity structure, can ensure that the conversion of the spin state and the photon state does not depend on the frequency characteristic, the interaction and conversion of the spin state and photons with any frequency are realized, the frequency seamless connection conversion from the spin state and the mechanical state to the optical state is realized, and the method has a positive propulsion effect on the large-scale and solid state development of a quantum network.
On the basis of the technical scheme, the method further comprises the following improvements:
further: in any quantum node, the diamond optical cavity structure comprises a diamond optical cavity with a nitrogen vacancy color center embedded on the surface;
said step 1A comprises:
step 1a 1: for any quantum node, selecting three energy levels to form a three-energy-level structure containing two transition channels on a nitrogen vacancy color center of a diamond optical power cavity structure;
step 1a 2: the first excitation light is used for emitting first excitation light, the second excitation light is used for emitting second excitation light, the first excitation light acts on one transition channel of the three-level structure corresponding to the nitrogen vacancy color center according to a first preset excitation duration, the second excitation light simultaneously acts on the other transition channel of the three-level structure corresponding to the nitrogen vacancy color center, detuning of the two transition channels corresponding to the nitrogen vacancy color center is kept consistent, and conversion of the corresponding quantum node from a spin state to a mechanical state with any frequency is completed;
the step 2A specifically comprises the following steps:
closing the first excitation device and the second excitation device, emitting third excitation light by using the third excitation device, acting the third excitation light on the diamond optical cavity of the corresponding diamond optical cavity structure according to a second preset excitation time length, and completing the conversion of the corresponding quantum node from a mechanical state to an optical state with any frequency in a radiation pressure coupling mode;
or,
the step 1B specifically comprises the following steps:
for any quantum node, the third excitation device is used for emitting third excitation light, the third excitation light acts on the corresponding diamond optical cavity structure according to the second preset excitation duration, and the seamless conversion of the corresponding quantum node from the optical state to the mechanical state is completed in the radiation pressure coupling mode;
the step 2B comprises the following steps:
step 2B 1: turning off the third excitation device; for any quantum node, selecting three energy levels to form a three-energy-level structure containing two transition channels on a nitrogen vacancy color center of a diamond optical power cavity structure;
step 2B 2: and the first excitation device is used for emitting first excitation light, the second excitation device is used for emitting second excitation light, the first excitation light acts on one transition channel of the three-level structure corresponding to the nitrogen vacancy color center according to the first preset excitation duration, the second excitation light simultaneously acts on the other transition channel of the three-level structure corresponding to the nitrogen vacancy color center, the detuning of the two transition channels corresponding to the nitrogen vacancy color center is kept consistent, and the seamless conversion of the corresponding quantum node from the mechanical state to the spin state is completed.
The beneficial effects of the further technical scheme are as follows: in the diamond optical force cavity structure of any single quantum node, the frequency seamless connection between quantum states is realized through two physical processes, one is phonon-assisted spin state conversion, and the other is optical force interaction; when the initial quantum state of the quantum node is a spin state, a first physical process involves the conversion of the spin state and a mechanical state, and a second physical process involves the conversion of the mechanical state and an optical state; when the initial quantum state of the quantum node is an optical state, the first physical process involves the conversion between the optical state and the mechanical state, and the second physical process involves the conversion between the mechanical state and the spin state, which is the inverse process of the two physical processes in the former case; in both cases, the two physical processes occur sequentially, and since the same mechanical mode is involved, the mechanical mode will serve as an intermediate medium to link the optical state and the spin state, thereby realizing frequency seamless connection in a single quantum node.
Further: the first preset excitation time length is pi/2 eta, and the second preset excitation time length is pi/2G;
wherein eta is the equivalent mechanical state-spin state interaction strength, and G is the equivalent photon state-mechanical state interaction strength.
The beneficial effects of the further technical scheme are as follows: through the first excitation duration, the excitation condition meeting the condition can be effectively ensured to be found, the consistent detuning quantity of the two transition channels is ensured, and further the seamless conversion from the spin state in any single quantum node to the mechanical state with any frequency or the seamless conversion from the mechanical state to the spin state with any frequency can be realized; through the second excitation time, the mechanical vibration of the optical cavity caused by radiation pressure can be effectively ensured, so that an optical mode and a mechanical mode in the quantum node are excited, and further, the frequency seamless connection of a mechanical state and an optical state or the frequency seamless connection of the optical state and the mechanical state in a single quantum node is realized.
Further: when the number of the quantum nodes is more than 1, every two connected quantum nodes are connected through micro-nano optical fiber coupling;
then the step 1a1 is specifically:
selecting any quantum node as an initial quantum node, and selecting three energy levels to form a three-level structure containing two transition channels on a nitrogen vacancy color center corresponding to the initial quantum node;
the step 1a2 specifically includes:
utilizing the first excitation device to emit first excitation light and the second excitation device to emit second excitation light, simultaneously acting the first excitation light and the second excitation light on one transition channel of the three-level structure corresponding to the nitrogen vacancy color center on the initial quantum node according to the first preset excitation duration, simultaneously acting the second excitation light on the other transition channel of the three-level structure corresponding to the nitrogen vacancy color center on the initial quantum node, and enabling the detuning of the two transition channels corresponding to the nitrogen vacancy color center on the initial quantum node to be consistent, so that the conversion of the initial quantum node from a spin state to a mechanical state with any frequency is completed;
the step 2A further specifically includes:
closing the first excitation device and the second excitation device, emitting third excitation light by using the third excitation device, acting the third excitation light on the diamond optical cavity on the initial quantum node according to the second preset excitation duration, and completing the conversion of the initial quantum node from a mechanical state to an optical state with any frequency by adopting the radiation pressure coupling mode;
further comprising, after the step 2A:
and step 3: obtaining a target quantum node set corresponding to the initial quantum node according to all quantum nodes connected with the initial quantum node;
and 4, step 4: selecting any target quantum node in a target quantum node set, and completing conversion from the optical state of the initial quantum node to the optical state of the selected target quantum node by utilizing the micro-nano optical fiber between the initial quantum node and the selected target quantum node in an evanescent wave coupling mode according to preset transmission time;
and 5: according to the same method from the step 1B to the step 2B2, completing the seamless conversion of the selected target quantum nodes from the mechanical state to the spin state and the state conversion between each target quantum node and the initial quantum node;
step 6: traversing each target quantum node in the target quantum node set corresponding to the initial quantum node, and completing the seamless conversion of each target quantum node from a mechanical state to a self-spinning state and the state conversion between each target quantum node and the initial quantum node according to the methods from the step 4 to the step 5.
The beneficial effects of the further technical scheme are as follows: when the number of quantum nodes is greater than 1, the state transition not only relates to the state transition inside a single quantum node, but also relates to the state transition between every two connected quantum nodes; each two connected quantum nodes are connected in a coupling mode through a micro-nano optical fiber, specifically evanescent wave coupling connection, and the micro-nano optical fiber can be used as a transmission channel of an optical state between the two connected quantum nodes; because any single quantum can be seamlessly converted into an optical state from a spin state, seamless conversion between the optical state of one quantum node and the optical state of the other quantum node can be realized through the micro-nano optical fiber between every two connected quantum nodes; then, because the state conversion in any single quantum node is reversible, any single quantum node is selected as an initial quantum node, and the conversion from the spin state to the optical state in the initial quantum node is realized according to the method from the step 1A1 and the step 1A2 to the step 2A; then all quantum nodes connected with the initial quantum node are used as a target quantum node set, and for any target quantum node in the set, seamless conversion from the optical state in any target quantum node to the spin state is realized according to the process (the reverse process of the steps 1A to 2A) described in the steps 4 to 6, and meanwhile, state conversion between the initial quantum node and the target quantum node is also realized; then traversing each target quantum node in the target quantum node set, and realizing seamless conversion from the optical state in each target quantum node to a self-spinning state and state conversion between the initial quantum node and each target quantum node;
the steps realize the state conversion of frequency seamless connection among all the connected quantum nodes in the whole system, and effectively help to promote the large-scale and solid-state development of the quantum network.
Further: the preset transmission duration is
Figure BDA0002924455000000131
Wherein g is the optical state-fiber coupling coefficient.
The beneficial effects of the further technical scheme are as follows: through the preset transmission duration, seamless transition of optical states between any two connected quantum nodes can be effectively ensured.
Drawings
Fig. 1 is a schematic structural diagram of a frequency seamless connection state transition system based on a diamond optical cavity according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of another frequency-seamless-connection state transition system based on a diamond optical cavity according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of the three-level structure and excitation of nitrogen vacancy color centers in accordance with an embodiment of the present invention;
fig. 4 and fig. 5 are schematic flow charts of a frequency seamless connection state transition system based on a diamond optical cavity according to a second embodiment of the present invention;
fig. 6 is a schematic flow chart of another frequency seamless connection state transition system based on a diamond optical cavity according to a second embodiment of the present invention.
Detailed Description
The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.
The present invention will be described with reference to the accompanying drawings.
First embodiment, as shown in fig. 1, a frequency-seamless-connected state transition system based on a diamond optical cavity includes at least one quantum node, wherein each quantum node includes a diamond optical cavity structure;
the device also comprises a first excitation device, a second excitation device and a third excitation device which respectively act on the light cavity structure of each diamond;
the first excitation device is used for respectively providing first excitation light for each diamond optical cavity structure, the second excitation device is used for respectively providing second excitation light for each diamond optical cavity structure, and the third excitation device is used for respectively providing third excitation light for each diamond optical cavity structure;
for any one diamond optical cavity structure, the optical cavity structure is used for completing the seamless conversion of the corresponding quantum node from the spin state to the mechanical state or the seamless conversion from the mechanical state to the spin state under the combined action of the corresponding first excitation light and the corresponding second excitation light; and the quantum node is used for completing the seamless transition of the corresponding quantum node from the mechanical state to the optical state or from the optical state to the mechanical state under the action of the corresponding third exciting light.
The whole system comprises at least one quantum node containing a diamond optical cavity structure, and is provided with a first excitation device for respectively emitting first excitation light to each diamond optical cavity structure, a second excitation device for respectively emitting second excitation light to each diamond optical cavity structure, and a third excitation device for respectively emitting third excitation light to each diamond optical cavity structure; in any quantum node, three quantum states of an optical state, a mechanical state and a spin state exist, and the conversion of the spin state of any quantum node to the mechanical state of any frequency is realized by utilizing the first excitation device and the second excitation device under the combined action of the first excitation light and the second excitation light; then the first excitation device and the second excitation device are closed, and the third excitation device is utilized to realize the seamless conversion of the mechanical state of any quantum node to the optical state of any frequency under the action of third excitation light; or, for any quantum node, the third excitation device is utilized to realize the seamless conversion of the optical state of any quantum node to the mechanical state of any frequency under the action of the third excitation light; then, the first excitation device and the second excitation device are utilized to realize the conversion of the mechanical state of any quantum node to the spin state of any frequency under the combined action of the first excitation light and the second excitation light; because the system relates to the same mechanical mode, two conversion processes related under two different conditions occur successively, the frequency seamless connection of state conversion among an optical state, a mechanical state and a self-spinning state in a single quantum node by taking the mechanical state as a medium is realized, and meanwhile, when a plurality of quantum nodes exist, the system is also beneficial to the state conversion in the plurality of quantum nodes and realizes the frequency seamless connection of state conversion among the plurality of quantum nodes;
the state conversion system based on the diamond optical cavity and frequency seamless connection in the embodiment is based on a diamond optical cavity structure, so that the conversion of a spin state and a photon state is independent of frequency characteristics, the interaction and conversion of the spin state and photons with any frequency are realized, the frequency seamless connection conversion from the spin state and a mechanical state to an optical state is realized, and the system has a positive propulsion effect on the large-scale and solid-state development of a quantum network.
Preferably, in any one quantum node, the diamond optical force cavity structure comprises a diamond optical force cavity with a nitrogen vacancy color center inlaid on the surface, and the nitrogen vacancy color center comprises a three-level structure containing two transition channels;
in any quantum node, the first excitation device is specifically configured to provide first excitation light to one of the transition channels of the three-level structure in the nitrogen vacancy color center according to a first preset excitation duration; the second excitation device is specifically configured to provide second excitation light to another transition channel of the corresponding three-level structure according to the first preset excitation duration while the first excitation device provides the first excitation light to one transition channel of the three-level structure; the third excitation device is specifically configured to provide third excitation light for the diamond optical power cavity on the corresponding diamond optical power cavity structure according to a second preset excitation duration after the first excitation device provides the first excitation light and the second excitation device provides the second excitation light;
in any quantum node, the nitrogen vacancy color center is specifically used for completing the conversion of the corresponding quantum node from the spin state to the mechanical state of any frequency or from the mechanical state to the spin state of any frequency under the simultaneous action of the corresponding first excitation light and the corresponding second excitation light according to the first preset excitation time length; the diamond optical power cavity is specifically used for completing conversion from a mechanical state to an optical state with any frequency or from the optical state to the mechanical state with any frequency under the action of corresponding third exciting light according to second preset exciting time duration.
In the diamond optical cavity structure of any single quantum node, the frequency seamless connection between the quantum states is realized through two physical processes which occur sequentially, and the two physical processes both relate to the same mechanical mode, so that the mechanical mode is used as an intermediate medium to realize the interaction between the optical state and the self-spinning state, and the frequency seamless connection in the single quantum node is realized;
wherein, the Hamiltonian of the interaction within a single quantum node can be expressed as:
Figure BDA0002924455000000151
HEis the Hamiltonian in a single quantum node, a represents the optical state, b represents the mechanical state, S represents the spin state, G is the equivalent optical state-mechanical state interaction strength, eta is the equivalent mechanical state-spin state interaction strength, h is the Planck constant, a+、b+And S+Respectively, optical state, mechanical state, spin state.
Preferably, when the number of the quantum nodes is greater than 1, the state conversion system based on the frequency seamless connection of the diamond optical cavity further comprises a micro-nano optical fiber coupled between every two connected quantum nodes;
the micro-nano optical fiber is used for providing an information transmission channel for optical state conversion between every two connected quantum nodes, and the seamless conversion of the optical state between every two connected quantum nodes is completed according to preset transmission duration.
When the number of quantum nodes is greater than 1, the state transition not only relates to the state transition inside a single quantum node, but also relates to the state transition between every two connected quantum nodes; each two connected quantum nodes are connected in a coupling mode through a micro-nano optical fiber, specifically evanescent wave coupling connection, and the micro-nano optical fiber can be used as a transmission channel of an optical state between the two connected quantum nodes; because any single quantum can be seamlessly converted into an optical state from a spin state, seamless conversion between the optical state of one quantum node and the optical state of the other quantum node can be realized through the micro-nano optical fiber between every two connected quantum nodes; then, because the state conversion in any single quantum node is reversible, the state conversion in another quantum node can be realized through the corresponding inverse process of the third excitation light, the first excitation light and the second excitation light; the state conversion of frequency seamless connection between any two or more connected quantum nodes can be realized, and the large-scale and solid-state development of the quantum sub-network is promoted effectively.
Specifically, as shown in fig. 2, the fiber comprises two quantum nodes with a distance of 6.6 meters and a length of unidirectionally transmitting nano-fiber 6, each quantum node is composed of a single crystal diamond disk, and Si is used in this embodiment3N4The material is prepared, the radius R of a disc is 2.5 mu m, the height h is 940nm, and the micro-disc designed in this way supports the vibration frequency wmA mechanical vibration mode of 38.84MHz and an optical whispering gallery mode with a wavelength λ 1542nm, which are used in the present embodiment as the mechanical state and the optical state, respectively. The surface of the microdisk is embedded with nitrogen vacancy color centers, the internal energy levels are rich, and three of the energy levels are selected to form an Λ energy level, as shown in figure 3, wherein the spin ground state m in the nitrogen vacancy color centerss＝-1，msWith +1 as the ground state 13 and metastable state 14, respectively, of a three-level system2The state serves as excited state 15 of the three-level system. Each quantum node is driven by three lasers 3 (or 9), 4 (or 10) and 5 (or 11), and the third excitation light 3 (or 9) excites an optical mode (i.e., optical state) and a mechanical mode (i.e., mechanical state) of the microdisk. The three-level system has two transition channels, wherein the transition channels 14-13 are formed by the mechanical vibration 12 and the first excitation light 4 (or10) And jointly exciting the transition channels 15-13 by the second exciting light 5(11), and adjusting the frequencies of the two exciting lights to ensure that the two transition channels keep equal detuning amount.
The micro-nano optical fiber 6 for unidirectional transmission is made of a material with the refractive index n of 2.143, has a square cross section and the size of 800nm multiplied by 800nm, and the whispering gallery mode of the micro-disc and the mode in the optical fiber can be coupled through evanescent waves so as to carry out remote transmission.
In the second embodiment, as shown in fig. 4 and fig. 5, a method for switching states of a frequency seamless connection based on a diamond optical cavity, which uses a system for switching states of a frequency seamless connection based on a diamond optical cavity in the first embodiment to perform state switching, includes the following steps:
S1A: for any quantum node, a first excitation device is used for emitting first excitation light, a second excitation device is used for emitting second excitation light, the first excitation light and the second excitation light act on the corresponding diamond optical cavity structure simultaneously, and seamless conversion of the corresponding quantum node from a self-spinning state to a mechanical state is completed;
S2A: closing the first excitation device and the second excitation device, emitting third excitation light by using a third excitation device, and acting the third excitation light on the corresponding diamond optical cavity structure to complete seamless conversion of the corresponding quantum node from a mechanical state to an optical state;
or,
S1B: for any quantum node, the third excitation device is utilized to emit third excitation light, and the third excitation light acts on the corresponding diamond optical cavity structure to complete seamless conversion of the corresponding quantum node from an optical state to a mechanical state;
S2B: and closing the third excitation device, utilizing the first excitation device to emit first excitation light, utilizing the second excitation device to emit second excitation light, and simultaneously acting the first excitation light and the second excitation light on the corresponding diamond optical cavity structure to complete the seamless conversion of the corresponding quantum node from the mechanical state to the spin state.
Based on the state conversion system based on the diamond optical cavity in the first embodiment and with seamless frequency connection, in any quantum node, there are three quantum states, namely an optical state, a mechanical state and a spin state, and the conversion of the spin state to the mechanical state with any frequency is realized under the combined action of the first excitation device and the second excitation device corresponding to each diamond optical cavity structure; then, a first excitation device and a second excitation device corresponding to each diamond optical cavity structure are closed, and a third excitation device corresponding to each diamond optical cavity structure is utilized to realize seamless conversion from a mechanical state to an optical state with any frequency under the action of third excitation light; or, for any quantum node, the third excitation device is utilized to realize the seamless conversion of the optical state of any quantum node to the mechanical state of any frequency under the action of the third excitation light; then, the first excitation device and the second excitation device are utilized to realize the conversion of the mechanical state of any quantum node to the spin state of any frequency under the combined action of the first excitation light and the second excitation light; the process realizes the frequency seamless connection of state conversion among the optical state, the mechanical state and the self-spinning state in a single quantum node, and is also beneficial to the state conversion in a plurality of quantum nodes when a plurality of quantum nodes exist, so that the frequency seamless connection of the state conversion among a plurality of quantum nodes is realized;
the state conversion method based on the frequency seamless connection of the diamond optical cavity in the embodiment is based on the diamond optical cavity structure, so that the conversion of the spin state and the photon state is independent of the frequency characteristic, the interaction and conversion of the spin state and photons with any frequency are realized, the frequency seamless connection conversion from the spin state and the mechanical state to the optical state is realized, and the method has a positive propulsion effect on the large-scale and solid-state development of a quantum network.
It should be noted that S1B to S2B are the reverse process of S1A to S2A.
Preferably, in any one quantum node, the diamond optical cavity structure comprises a diamond optical cavity with a nitrogen vacancy color center inlaid on the surface;
S1A includes:
S1A 1: for any quantum node, selecting three energy levels to form a three-energy-level structure containing two transition channels on a nitrogen vacancy color center of a diamond optical power cavity structure;
S1A 2: the first excitation light is used for emitting first excitation light, the second excitation light is used for emitting second excitation light, the first excitation light acts on one transition channel of the three-level structure corresponding to the nitrogen vacancy color center according to a first preset excitation duration, the second excitation light simultaneously acts on the other transition channel of the three-level structure corresponding to the nitrogen vacancy color center, detuning of the two transition channels corresponding to the nitrogen vacancy color center is kept consistent, and conversion of the corresponding quantum node from a spin state to a mechanical state with any frequency is completed;
S2A specifically is:
closing the first excitation device and the second excitation device, emitting third excitation light by using the third excitation device, acting the third excitation light on the diamond optical cavity of the corresponding diamond optical cavity structure according to a second preset excitation time length, and completing the conversion of the corresponding quantum node from a mechanical state to an optical state with any frequency in a radiation pressure coupling mode;
or,
S1B specifically is:
for any quantum node, the third excitation device is used for emitting third excitation light, the third excitation light acts on the corresponding diamond optical cavity structure according to the second preset excitation duration, and the seamless conversion of the corresponding quantum node from the optical state to the mechanical state is completed in the radiation pressure coupling mode;
S2B includes:
S2B 1: turning off the third excitation device; for any quantum node, selecting three energy levels to form a three-energy-level structure containing two transition channels on a nitrogen vacancy color center of a diamond optical power cavity structure;
S2B 2: and the first excitation device is used for emitting first excitation light, the second excitation device is used for emitting second excitation light, the first excitation light acts on one transition channel of the three-level structure corresponding to the nitrogen vacancy color center according to the first preset excitation duration, the second excitation light simultaneously acts on the other transition channel of the three-level structure corresponding to the nitrogen vacancy color center, the detuning of the two transition channels corresponding to the nitrogen vacancy color center is kept consistent, and the seamless conversion of the corresponding quantum node from the mechanical state to the spin state is completed.
In the diamond optical force cavity structure of any single quantum node, the frequency seamless connection between quantum states is realized through two physical processes, one is phonon-assisted spin state conversion, and the other is optical force interaction; when the initial quantum state of the quantum node is a spin state, a first physical process involves the conversion of the spin state and a mechanical state, and a second physical process involves the conversion of the mechanical state and an optical state; when the initial quantum state of the quantum node is an optical state, the first physical process involves the conversion between the optical state and the mechanical state, and the second physical process involves the conversion between the mechanical state and the spin state, which is the inverse process of the two physical processes in the former case; in both cases, the two physical processes occur sequentially, and since the same mechanical mode is involved, the mechanical mode will serve as an intermediate medium to link the optical state and the spin state, thereby realizing frequency seamless connection in a single quantum node.
Preferably, when the number of the quantum nodes is more than 1, every two connected quantum nodes are connected through micro-nano optical fiber coupling;
then S1a1 is specifically:
selecting any quantum node as an initial quantum node, and selecting three energy levels to form a three-level structure containing two transition channels on a nitrogen vacancy color center corresponding to the initial quantum node;
s1a2 specifically is:
utilizing the first excitation device to emit first excitation light and the second excitation device to emit second excitation light, simultaneously acting the first excitation light and the second excitation light on one transition channel of the three-level structure corresponding to the nitrogen vacancy color center on the initial quantum node according to the first preset excitation duration, simultaneously acting the second excitation light on the other transition channel of the three-level structure corresponding to the nitrogen vacancy color center on the initial quantum node, and enabling the detuning of the two transition channels corresponding to the nitrogen vacancy color center on the initial quantum node to be consistent, so that the conversion of the initial quantum node from a spin state to a mechanical state with any frequency is completed;
S2A is also specifically:
closing the first excitation device and the second excitation device, emitting third excitation light by using the third excitation device, acting the third excitation light on the diamond optical cavity on the initial quantum node according to the second preset excitation duration, and completing the conversion of the initial quantum node from a mechanical state to an optical state with any frequency by adopting the radiation pressure coupling mode;
S2A is followed by:
s3: obtaining a target quantum node set corresponding to the initial quantum node according to all quantum nodes connected with the initial quantum node;
s4: selecting any target quantum node in a target quantum node set, and completing conversion from the optical state of the initial quantum node to the optical state of the selected target quantum node by utilizing the micro-nano optical fiber between the initial quantum node and the selected target quantum node in an evanescent wave coupling mode according to preset transmission time;
s5: according to the same method of S1B-S2B 2, seamless conversion of the selected target quantum nodes from a mechanical state to a spinning state and state conversion between each target quantum node and the initial quantum node are completed;
s6: traversing each target quantum node in the target quantum node set corresponding to the initial quantum node, and completing the seamless conversion of each target quantum node from a mechanical state to a spin state and the state conversion between each target quantum node and the initial quantum node according to the methods from S4 to S5.
When the number of quantum nodes is greater than 1, the state transition not only relates to the state transition inside a single quantum node, but also relates to the state transition between every two connected quantum nodes; each two connected quantum nodes are connected in a coupling mode through a micro-nano optical fiber, specifically evanescent wave coupling connection, and the micro-nano optical fiber can be used as a transmission channel of an optical state between the two connected quantum nodes; because any single quantum can be seamlessly converted into an optical state from a spin state, seamless conversion between the optical state of one quantum node and the optical state of the other quantum node can be realized through the micro-nano optical fiber between every two connected quantum nodes; then, as the state conversion in any single quantum node is reversible, any single quantum node is selected as an initial quantum node, and the conversion from the spin state to the optical state in the initial quantum node is realized according to the methods of S1A1 and S1A 2-S2A; then all quantum nodes connected with the initial quantum node are used as a target quantum node set, and for any target quantum node in the set, the seamless conversion from the optical state to the spin state in any target quantum node is realized according to the process from S4 to S6 (the process is the reverse process from S1A to 2A), and meanwhile, the state conversion between the initial quantum node and the target quantum node is also realized; then traversing each target quantum node in the target quantum node set, and realizing seamless conversion from the optical state in each target quantum node to a self-spinning state and state conversion between the initial quantum node and each target quantum node;
the steps realize the state conversion of frequency seamless connection among all the connected quantum nodes in the whole system, and effectively help to promote the large-scale and solid-state development of the quantum network.
Specifically, based on the state transition systems shown in fig. 2 and 3, two physical interactions are involved in each quantum node, one is the interaction of the mechanical mode and the spin, and the interaction size is η, and the interaction of the mechanical mode and the microdisk whispering gallery mode, and the interaction size is G. The interaction size of the whispering gallery modes and the evanescent wave of the fiber is g.
As shown in fig. 6, the state transition method between two connected quantum nodes is implemented as follows:
the first step is as follows: the default system initial state is a spin state in a first quantum node (the first node is also an initial quantum node), at this time, a first exciting light 4 and a second exciting light 5 are turned on, the driving time is controlled to be a first preset exciting time duration pi/2 eta, and the conversion from the spin state to the mechanical state is completed;
the second step is that: closing the first exciting light 4 and the second exciting light 5, and opening the third exciting light 3 for a second preset excitation duration pi/2G to complete the conversion from the mechanical state to the optical state of the microdisk;
the third step: the third exciting light 3 is turned off to complete the conversion and transmission between the optical state of the microdisk and the micro-nano optical fiber through the evanescent state, and the process lasts for the preset transmission time length
Figure BDA0002924455000000221
This time ensures that the optical state from the first quantum node is transmitted via the nanofiber exactly to the second quantum node;
the fourth step: turning on a third exciting light 9 for driving the second quantum node to complete the transfer of the optical state to the mechanical state of the second quantum node, wherein the duration time is also a second preset excitation duration pi/2G;
the fifth step: the second excitation light 9 is turned off, and the first excitation light 10 and the second excitation light 11 of the second quantum node are turned on, so that the conversion of the mechanical state of the second quantum node to the spin state is completed. At this point, the transition of the spin state in the first quantum node to the spin state of the second quantum node is completed.
The frequency of all optical modes and mechanical modes of the microdisk can be arbitrarily selected in the whole process, and the scheme has the scheme of spin-mechanical mode, mechanical mode-optical mode interaction and indiscriminate frequency selectivity of conversion.
Details of the embodiment are not described in detail in the first embodiment and the specific descriptions in fig. 1 to 3, which are not repeated herein.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (10)

1. A state conversion system of frequency seamless connection based on a diamond optical cavity is characterized by comprising at least one quantum node, wherein each quantum node comprises a diamond optical cavity structure;
the device also comprises a first excitation device, a second excitation device and a third excitation device which are respectively acted on the light cavity structure of each diamond;
the first excitation device is used for respectively providing first excitation light for each diamond optical cavity structure, the second excitation device is used for respectively providing second excitation light for each diamond optical cavity structure, and the third excitation device is used for respectively providing third excitation light for each diamond optical cavity structure;
for any one diamond optical cavity structure, the optical cavity structure is used for completing the seamless conversion of the corresponding quantum node from the spin state to the mechanical state or the seamless conversion from the mechanical state to the spin state under the combined action of the corresponding first excitation light and the corresponding second excitation light; and the quantum node is used for completing the seamless transition of the corresponding quantum node from the mechanical state to the optical state or from the optical state to the mechanical state under the action of the corresponding third exciting light.
2. The diamond optical cavity based frequency seamless connected state transition system according to claim 1, wherein in any one quantum node, the diamond optical cavity structure comprises a diamond optical cavity with a nitrogen vacancy color center inlaid on the surface, and the nitrogen vacancy color center comprises a three-level structure comprising two transition channels;
in any quantum node, the first excitation device is specifically configured to provide first excitation light to one of the transition channels of the three-level structure in the nitrogen vacancy color center according to a first preset excitation duration; the second excitation device is specifically configured to provide second excitation light to another transition channel of the corresponding three-level structure according to the first preset excitation duration while the first excitation device provides the first excitation light to one transition channel of the three-level structure; the third excitation device is specifically configured to provide third excitation light for the diamond optical power cavity on the corresponding diamond optical power cavity structure according to a second preset excitation duration after the first excitation device provides the first excitation light and the second excitation device provides the second excitation light;
in any quantum node, the nitrogen vacancy color center is specifically used for completing the conversion of the corresponding quantum node from the spin state to the mechanical state of any frequency or from the mechanical state to the spin state of any frequency under the simultaneous action of the corresponding first excitation light and the corresponding second excitation light according to the first preset excitation time length; the diamond optical power cavity is specifically used for completing conversion from a mechanical state to an optical state with any frequency or from the optical state to the mechanical state with any frequency under the action of corresponding third exciting light according to second preset exciting time duration.
3. The diamond optical cavity based frequency seamless connected state transition system of claim 2, wherein the first preset excitation duration is pi/2 η, and the second preset excitation duration is pi/2G;
wherein eta is the equivalent mechanical state-spin state interaction strength, and G is the equivalent photon state-mechanical state interaction strength.
4. The diamond optical cavity-based state transition system for frequency seamless connection according to claim 2, wherein when the number of the quantum nodes is greater than 1, the diamond optical cavity-based state transition system for frequency seamless connection further comprises micro-nano optical fibers coupled between every two connected quantum nodes;
the micro-nano optical fiber is used for providing an information transmission channel for optical state conversion between every two connected quantum nodes, and the seamless conversion of the optical state between every two connected quantum nodes is completed according to preset transmission duration.
5. The diamond optical cavity based frequency seamless connection state transition system according to claim 4, wherein the preset transmission duration is
Figure FDA0002924454990000021
Wherein g is the optical state-fiber coupling coefficient.
6. A state transition method of frequency seamless connection based on a diamond optical cavity is characterized in that the state transition is carried out by adopting the state transition system of the frequency seamless connection based on the diamond optical cavity, which is disclosed by any one of claims 1 to 5, and the method comprises the following steps:
step 1A: for any quantum node, a first excitation device is used for emitting first excitation light, a second excitation device is used for emitting second excitation light, the first excitation light and the second excitation light act on the corresponding diamond optical cavity structure simultaneously, and seamless conversion of the corresponding quantum node from a self-spinning state to a mechanical state is completed;
step 2A: closing the first excitation device and the second excitation device, emitting third excitation light by using a third excitation device, and acting the third excitation light on the corresponding diamond optical cavity structure to complete seamless conversion of the corresponding quantum node from a mechanical state to an optical state;
or,
step 1B: for any quantum node, the third excitation device is utilized to emit third excitation light, and the third excitation light acts on the corresponding diamond optical cavity structure to complete seamless conversion of the corresponding quantum node from an optical state to a mechanical state;
and step 2B: and closing the third excitation device, utilizing the first excitation device to emit first excitation light, utilizing the second excitation device to emit second excitation light, and simultaneously acting the first excitation light and the second excitation light on the corresponding diamond optical cavity structure to complete the seamless conversion of the corresponding quantum node from the mechanical state to the spin state.
7. The method for state transition of seamless connection of frequency based on diamond optical cavity of claim 6, wherein in any quantum node, the diamond optical cavity structure comprises a diamond optical cavity with a nitrogen vacancy color center inlaid on the surface;
said step 1A comprises:
step 1a 1: for any quantum node, selecting three energy levels to form a three-energy-level structure containing two transition channels on a nitrogen vacancy color center of a diamond optical power cavity structure;
step 1a 2: the first excitation light is used for emitting first excitation light, the second excitation light is used for emitting second excitation light, the first excitation light acts on one transition channel of the three-level structure corresponding to the nitrogen vacancy color center according to a first preset excitation duration, the second excitation light simultaneously acts on the other transition channel of the three-level structure corresponding to the nitrogen vacancy color center, detuning of the two transition channels corresponding to the nitrogen vacancy color center is kept consistent, and conversion of the corresponding quantum node from a spin state to a mechanical state with any frequency is completed;
the step 2A specifically comprises the following steps:
closing the first excitation device and the second excitation device, emitting third excitation light by using the third excitation device, acting the third excitation light on the diamond optical cavity of the corresponding diamond optical cavity structure according to a second preset excitation time length, and completing the conversion of the corresponding quantum node from a mechanical state to an optical state with any frequency in a radiation pressure coupling mode;
or,
the step 1B specifically comprises the following steps:
for any quantum node, the third excitation device is used for emitting third excitation light, the third excitation light acts on the corresponding diamond optical cavity structure according to the second preset excitation duration, and the seamless conversion of the corresponding quantum node from the optical state to the mechanical state is completed in the radiation pressure coupling mode;
the step 2B comprises the following steps:
step 2B 1: turning off the third excitation device; for any quantum node, selecting three energy levels to form a three-energy-level structure containing two transition channels on a nitrogen vacancy color center of a diamond optical power cavity structure;
step 2B 2: and the first excitation device is used for emitting first excitation light, the second excitation device is used for emitting second excitation light, the first excitation light acts on one transition channel of the three-level structure corresponding to the nitrogen vacancy color center according to the first preset excitation duration, the second excitation light simultaneously acts on the other transition channel of the three-level structure corresponding to the nitrogen vacancy color center, the detuning of the two transition channels corresponding to the nitrogen vacancy color center is kept consistent, and the seamless conversion of the corresponding quantum node from the mechanical state to the spin state is completed.
8. The method of claim 7, wherein the first predetermined excitation duration is pi/2 η, and the second predetermined excitation duration is pi/2G;
wherein eta is the equivalent mechanical state-spin state interaction strength, and G is the equivalent photon state-mechanical state interaction strength.
9. The state transition method of seamless connection of frequency based on diamond optical cavity of claim 7, when the number of quantum nodes is greater than 1, every two connected quantum nodes are coupled and connected through micro-nano optical fiber;
then the step 1a1 is specifically:
selecting any quantum node as an initial quantum node, and selecting three energy levels to form a three-level structure containing two transition channels on a nitrogen vacancy color center corresponding to the initial quantum node;
the step 1a2 specifically includes:
utilizing the first excitation device to emit first excitation light and the second excitation device to emit second excitation light, simultaneously acting the first excitation light and the second excitation light on one transition channel of the three-level structure corresponding to the nitrogen vacancy color center on the initial quantum node according to the first preset excitation duration, simultaneously acting the second excitation light on the other transition channel of the three-level structure corresponding to the nitrogen vacancy color center on the initial quantum node, and enabling the detuning of the two transition channels corresponding to the nitrogen vacancy color center on the initial quantum node to be consistent, so that the conversion of the initial quantum node from a spin state to a mechanical state with any frequency is completed;
the step 2A further specifically includes:
closing the first excitation device and the second excitation device, emitting third excitation light by using the third excitation device, acting the third excitation light on the diamond optical cavity on the initial quantum node according to the second preset excitation duration, and completing the conversion of the initial quantum node from a mechanical state to an optical state with any frequency by adopting the radiation pressure coupling mode;
further comprising, after the step 2A:
and step 3: obtaining a target quantum node set corresponding to the initial quantum node according to all quantum nodes connected with the initial quantum node;
and 4, step 4: selecting any target quantum node in a target quantum node set, and completing conversion from the optical state of the initial quantum node to the optical state of the selected target quantum node by utilizing the micro-nano optical fiber between the initial quantum node and the selected target quantum node in an evanescent wave coupling mode according to preset transmission time;
and 5: according to the same method from the step 1B to the step 2B2, completing the seamless conversion of the selected target quantum nodes from the mechanical state to the spin state and the state conversion between each target quantum node and the initial quantum node;
step 6: traversing each target quantum node in the target quantum node set corresponding to the initial quantum node, and completing the seamless conversion of each target quantum node from a mechanical state to a self-spinning state and the state conversion between each target quantum node and the initial quantum node according to the methods from the step 4 to the step 5.
10. The diamond optical cavity based frequency seamless connection state transition system according to claim 9, wherein the preset transmission duration is
Figure FDA0002924454990000061
Wherein g is the optical state-fiber coupling coefficient.
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