Multi-polarization-state solid-state quantum storage device and method

Abstract

The invention discloses a multi-polarization-state solid-state quantum storage device which comprises a laser generation module, a pump light modulation module, a storage light modulation module and a quantum storage module. The invention further discloses a multi-polarization-state solid-state quantum storage method which is realized based on the multi-polarization-state solid-state quantum storage device. The invention discloses a multi-polarization-state solid-state quantum storage device and method, and the device achieves the storage of multi-polarization-state signal light through the storage of signal light in a specified polarization state through a quantum storage module, and carrying out the polarization state conversion of signal light in a non-specified polarization state, and then carrying out the storage of the signal light. The method is applied to quantum parallel computing and quantum network scale application.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum storage and quantum computing, and in particular to a multi-polarization solid-state quantum storage device and method. Background Art

[0002] Quantum Key Distribution (QKD) is an unconditionally secure communication method based on the principles of physics. Currently, the main challenge facing quantum communication is to achieve long-distance quantum communication.

[0003] Quantum computing (QC) is gradually emerging as a new computing model. It follows the laws of quantum mechanics to control quantum information units for computing. It is a new computing model that can break through the bottleneck of classical computing power. Photons are the natural carriers of quantum communication. However, due to insurmountable channel losses, the transmission distance of photons is very limited. For this reason, people have proposed quantum relay schemes based on quantum memory and quantum entanglement exchange, which are key technologies for quantum computing and quantum networks.

[0004] At present, the more commonly used solid-state quantum memory is based on rare earth doped ions. However, most rare earth doped crystals have anisotropic absorption characteristics. A single crystal can only store a specific polarization state, but cannot store photons encoded with arbitrary polarization. Polarization is the most convenient and stable degree of freedom for photons to carry information. Due to the anisotropic absorption characteristics of crystals, existing solid-state quantum storage solutions all pre-select input photons with a single polarization state and can only store a single polarization state. Summary of the invention

[0005] In order to solve the problem that the existing solid-state quantum storage solution can only realize single polarization state storage, the present invention provides a multi-polarization state solid-state quantum storage device and method.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A multi-polarization solid-state quantum storage device, comprising a laser generation module, a pump light modulation module, a storage light modulation module and a quantum storage module;

[0008] The laser generating module is used to generate a continuously tunable multi-frequency continuous laser;

[0009] The pump light modulation module is used to modulate the multi-frequency continuous laser according to the frequency interval of the quantum storage module to obtain the pump light required by the quantum storage module;

[0010] The storage light modulation module is used to modulate the multi-frequency continuous laser according to the frequency interval of the quantum storage module to obtain the signal light to be stored;

[0011] The quantum storage module is used to receive pump light and signal light to be stored, and to store signal light in a specified polarization state, and to store signal light in a non-specified polarization state after polarization state conversion, thereby realizing storage of signal light in multiple polarization states.

[0012] In the above scheme, the signal light of the designated polarization state is stored by the quantum storage module, and the signal light of the non-designated polarization state is stored after the polarization state conversion, thereby realizing the storage of the signal light of multiple polarization states.

[0013] Preferably, the laser generation module comprises a laser, a polarizer and a beam splitter;

[0014] The laser is used to generate a continuously tunable multi-frequency continuous laser;

[0015] The polarizer is used to modulate the polarization state of the continuous laser light generated by the laser;

[0016] The beam splitter is used to split the continuous laser beam into two paths, one of which is input into the pump light modulation module, and the other is input into the storage light modulation module.

[0017] Preferably, the pump light modulation module includes a first acousto-optic modulator and an intensity modulator;

[0018] The first acousto-optic modulator is used to modulate the multi-frequency continuous laser according to the frequency interval of the quantum storage module to obtain the pump light required by the quantum storage module;

[0019] The intensity modulator is used to modulate the intensity of the pump light.

[0020] Preferably, the storage optical modulation module includes a second acousto-optic modulator, an attenuator and a polarization controller;

[0021] The second acousto-optic modulator is used to modulate the multi-frequency continuous laser according to the frequency interval of the quantum storage module to obtain the signal light to be stored;

[0022] The attenuator is used to attenuate the signal light to be stored to a single photon level;

[0023] The polarization controller is used to modulate the polarization state of the signal light to be stored.

[0024] Preferably, the quantum storage module comprises a first rare earth doped crystal, a first polarization rotator, a second rare earth doped crystal, a second polarization rotator and a polarization analyzer;

[0025] The first rare earth doped crystal is used to store and release signal light of a specified polarization state;

[0026] The first polarization rotator is used to convert the polarization state of the signal light output by the first rare-earth-doped crystal;

[0027] The second rare earth doped crystal is used to store and release the signal light of the specified polarization state after passing through the first polarization rotator;

[0028] The second polarization rotator is used to convert the polarization state of the signal light output by the second rare-earth-doped crystal;

[0029] The polarization analyzer is used to detect and analyze the polarization state of the signal light passing through the second polarization rotator.

[0030] Preferably, the first polarization rotator and the second polarization rotator are matched half-wave plates.

[0031] Preferably, the quantum storage module further comprises a phase plate for compensating the phase difference of the signal light output by the second rare-earth-doped crystal.

[0032] Preferably, a lens is further included to focus the pump light output by the pump light modulation module and the signal light to be stored output by the storage light modulation module into the quantum storage module.

[0033] Preferably, in the optical path arrangement, the pump light reaches the solid-state quantum memory earlier than the signal light to be stored.

[0034] A multi-polarization state solid-state quantum storage method is implemented based on the multi-polarization state solid-state quantum storage device, comprising the following steps:

[0035] S1: Generates continuously tunable multi-frequency continuous laser;

[0036] S2: Pump light modulation and storage light modulation are performed on the multi-frequency continuous laser according to the frequency interval of the quantum storage module, and the pump light and the signal light to be stored are correspondingly obtained;

[0037] S3: The quantum storage module receives the pump light and the signal light to be stored, and stores the signal light of the specified polarization state, and converts the polarization state of the signal light of the non-specified polarization state before storing it, so as to realize the storage of the signal light of multiple polarization states.

[0038] Beneficial technical effects of the present invention:

[0039] The present invention provides a multi-polarization state solid-state quantum storage device and method, which stores signal light of a specified polarization state through a quantum storage module, and stores signal light of a non-specified polarization state after polarization state conversion, thereby realizing the storage of signal light of multiple polarization states. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of module connection of the present invention;

[0041] Figure 2 It is a flowchart of the implementation steps of the technical solution of the present invention;

[0042] Among them: 1. laser generation module; 11. laser; 12. polarizer; 13. beam splitter; 2. pump light modulation module; 21. first acousto-optic modulator; 22. intensity modulator; 3. storage light modulation module; 31. second acousto-optic modulator; 32. attenuator; 33. polarization controller; 4. quantum storage module; 41. first rare earth-doped crystal; 42. first polarization rotator; 43. second rare earth-doped crystal; 44. second polarization rotator; 45. polarization analyzer; 46. phase plate; 5. lens. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments, but the scope of protection claimed in the present invention is not limited to the following specific embodiments.

[0044] Example 1

[0045] like Figure 1 As shown, a multi-polarization solid-state quantum storage device includes a laser generation module 1, a pump light modulation module 2, a storage light modulation module 3 and a quantum storage module 4;

[0046] The laser generating module 1 is used to generate a continuously tunable multi-frequency continuous laser;

[0047] The pump light modulation module 2 is used to modulate the multi-frequency continuous laser according to the frequency interval of the quantum storage module 4 to obtain the pump light required by the quantum storage module 4;

[0048] The storage light modulation module 3 is used to modulate the multi-frequency continuous laser according to the frequency interval of the quantum storage module 4 to obtain the signal light to be stored;

[0049] The quantum storage module 4 is used to receive pump light and signal light to be stored, and to store signal light of a specified polarization state, and to store signal light of a non-specified polarization state after polarization state conversion, thereby realizing storage of signal light of multiple polarization states.

[0050] In the specific implementation process, the quantum storage module 4 is used to store the signal light of the designated polarization state, and the signal light of the non-designated polarization state is stored after the polarization state conversion, thereby realizing the storage of the signal light of multiple polarization states.

[0051] Example 2

[0052] More specifically, the laser generating module 1 includes a laser 11, a polarizer 12 and a beam splitter 13;

[0053] The laser 11 is used to generate a continuously tunable multi-frequency continuous laser;

[0054] The polarizer 12 is used to modulate the polarization state of the continuous laser light generated by the laser 11;

[0055] The beam splitter 13 is used to split the continuous laser beam into two paths, one of which is input into the pump light modulation module 2 and the other is input into the storage light modulation module 3 .

[0056] In this embodiment, the continuous laser light is modulated into a polarization state of 45 degrees of H+V by the polarizer 12, providing the polarization state of two components for the pump light.

[0057] More specifically, the pump light modulation module 2 includes a first acousto-optic modulator 21 and an intensity modulator 22;

[0058] The first acousto-optic modulator 21 is used to modulate the multi-frequency continuous laser according to the frequency interval of the quantum storage module 4 to obtain the pump light required by the quantum storage module 4;

[0059] The intensity modulator 22 is used to modulate the intensity of the pump light to ensure that its intensity can manipulate the energy level of the rare earth doped crystal.

[0060] In the specific implementation process, an acousto-optic modulator with suitable center frequency parameters is selected as the first acousto-optic modulator 21, which is used to modulate the continuous laser with continuously tunable multi-frequency into a periodic pulse pair in the time domain, and its energy spectrum corresponds to the frequency comb structure of one period of the solid-state quantum memory, so that the pump light can efficiently operate the energy level of the solid-state quantum memory.

[0061] More specifically, the storage optical modulation module 3 includes a second acousto-optic modulator 31, an attenuator 32 and a polarization controller 33;

[0062] The second acousto-optic modulator 31 is used to modulate the multi-frequency continuous laser according to the frequency interval of the quantum storage module 4 to obtain the signal light to be stored;

[0063] The attenuator 32 is used to attenuate the signal light to be stored to a single photon level (0.8 photons per pulse on average);

[0064] The polarization controller 33 is used to modulate the polarization state of the signal light to be stored.

[0065] In the specific implementation process, the polarization state of the signal light to be stored is modulated into the desired polarization state by the polarization controller 33. The polarization state can be represented by the Jones vector. The relationship between the H component and the V component of the polarization state can be clearly seen by the Jones vector:

[0066]

[0067] More specifically, the quantum storage module 4 includes a first rare earth doped crystal 41, a first polarization rotator 42, a second rare earth doped crystal 43, a second polarization rotator 44 and a polarization analyzer 45;

[0068] The first rare earth doped crystal 41 is used to store and release the signal light of the specified polarization state;

[0069] In this embodiment, the specified polarization state is a horizontal polarization state;

[0070] The first polarization rotator 42 is used to convert the polarization state of the signal light output by the first rare-earth doped crystal 41;

[0071] The second rare earth doped crystal 43 is used to store and release the signal light of the specified polarization state after passing through the first polarization rotator 42;

[0072] The second polarization rotator 44 is used to convert the polarization state of the signal light output by the second rare-earth doped crystal 43;

[0073] The polarization analyzer 45 is used to detect and analyze the polarization state of the signal light passing through the second polarization rotator 44 .

[0074] In this embodiment, the first rare earth doped crystal 41 and the second rare earth doped crystal 43 strongly absorb the horizontal polarization component of photons, but do not absorb other polarization states. Other polarization states can be approximately regarded as passing through the rare earth doped crystals without loss.

[0075] The vertical polarization component of the signal light to be stored is converted into a horizontal polarization component by the first polarization rotator 42, so as to be absorbed and stored by the second rare earth doped crystal 43, and the horizontal polarization component released after storage by the first rare earth doped crystal 41 is converted into a vertical polarization component, which passes through the second rare earth doped crystal 43 without loss. At this time, the polarization state of the photon released after storage can be expressed as:

[0076]

[0077] The signal light after storage release is converted into the original polarization state by the second polarization rotator 44 .

[0078] More specifically, the first polarization rotator 42 and the second polarization rotator 44 are matched half-wave plates.

[0079] In a specific implementation process, the angle between the fast axis of the half-wave plate serving as the second polarization rotator 44 and the x-axis is θ=45°, and its Jones matrix can be expressed as:

[0080]

[0081] After passing through the half-wave plate, the stored and released photons return to their original polarization state:

[0082]

[0083] More specifically, the quantum storage module 4 further includes a phase plate 46 for compensating the phase difference of the signal light output by the second rare-earth doped crystal 43 .

[0084] More specifically, a lens 5 is also included, which is used to focus the pump light output by the pump light modulation module 2 and the signal light to be stored output by the storage light modulation module 3 into the quantum storage module 4 .

[0085] More specifically, in terms of optical path setting, the pump light is allowed to reach the solid-state quantum memory earlier than the signal light to be stored.

[0086] In the specific implementation process, quantum storage based on rare earth doped crystals utilizes the principle of photon echo. Photon echo is caused by the inhomogeneous broadening of rare earth doped crystal media. Specifically, when a photon is incident on a two-level atomic ensemble, the photon will be absorbed by the atomic ensemble. If all atoms are in phase at a certain moment, due to coherence, the atomic ensemble will re-emit the absorbed photon, achieving the process of quantum storage and emission.

[0087] Example 3

[0088] like Figure 2 As shown, a multi-polarization state solid-state quantum storage method is implemented based on the multi-polarization state solid-state quantum storage device, comprising the following steps:

[0089] S1: Generates continuously tunable multi-frequency continuous laser;

[0090] S2: performing pump light modulation and storage light modulation on the multi-frequency continuous laser according to the frequency interval of the quantum storage module 4, and correspondingly obtaining the pump light and the signal light to be stored;

[0091] S3: The quantum storage module 4 receives the pump light and the signal light to be stored, and stores the signal light of the designated polarization state, and stores the signal light of the non-designated polarization state after polarization state conversion, so as to realize the storage of the signal light of multiple polarization states.

[0092] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A multi-polarization solid-state quantum storage device, characterized in that: It includes a laser generation module, a pump light modulation module, a storage light modulation module and a quantum storage module; The laser generating module is used to generate a continuously tunable multi-frequency continuous laser; The pump light modulation module is used to modulate the multi-frequency continuous laser according to the frequency interval of the quantum storage module to obtain the pump light required by the quantum storage module; The storage light modulation module is used to modulate the multi-frequency continuous laser according to the frequency interval of the quantum storage module to obtain the signal light to be stored; The quantum storage module is used to receive pump light and signal light to be stored, and to store signal light in a specified polarization state, and to store signal light in a non-specified polarization state after polarization state conversion, thereby realizing storage of signal light in multiple polarization states.

2. A multi-polarization solid-state quantum storage device according to claim 1, characterized in that: The laser generation module includes a laser, a polarizer and a beam splitter; The laser is used to generate a continuously tunable multi-frequency continuous laser; The polarizer is used to modulate the polarization state of the continuous laser light generated by the laser; The beam splitter is used to split the continuous laser beam into two paths, one of which is input into the pump light modulation module, and the other is input into the storage light modulation module.

3. The multi-polarization solid-state quantum storage device according to claim 1, characterized in that: The pump light modulation module includes a first acousto-optic modulator and an intensity modulator; The first acousto-optic modulator is used to modulate the multi-frequency continuous laser according to the frequency interval of the quantum storage module to obtain the pump light required by the quantum storage module; The intensity modulator is used to modulate the intensity of the pump light.

4. The multi-polarization solid-state quantum storage device according to claim 1, characterized in that: The storage light modulation module includes a second acousto-optic modulator, an attenuator and a polarization controller; The second acousto-optic modulator is used to modulate the multi-frequency continuous laser according to the frequency interval of the quantum storage module to obtain the signal light to be stored; The attenuator is used to attenuate the signal light to be stored to a single photon level; The polarization controller is used to modulate the polarization state of the signal light to be stored.

5. The multi-polarization solid-state quantum storage device according to claim 1, characterized in that: The quantum storage module includes a first rare earth doped crystal, a first polarization rotator, a second rare earth doped crystal, a second polarization rotator and a polarization analyzer; The first rare earth doped crystal is used to store and release signal light of a specified polarization state; The first polarization rotator is used to convert the polarization state of the signal light output by the first rare-earth-doped crystal; The second rare earth doped crystal is used to store and release the signal light of the specified polarization state after passing through the first polarization rotator; The second polarization rotator is used to convert the polarization state of the signal light output by the second rare-earth-doped crystal; The polarization analyzer is used to detect and analyze the polarization state of the signal light passing through the second polarization rotator.

6. The multi-polarization solid-state quantum storage device according to claim 5, characterized in that: The first polarization rotator and the second polarization rotator are half-wave plates arranged in a matching manner.

7. The multi-polarization solid-state quantum storage device according to claim 1, characterized in that: The quantum storage module also includes a phase plate for compensating the phase difference of the signal light output by the second rare-earth doped crystal.

8. The multi-polarization solid-state quantum storage device according to claim 1, characterized in that: It also includes a lens for focusing the pump light output by the pump light modulation module and the signal light to be stored output by the storage light modulation module into the quantum storage module.

9. The multi-polarization solid-state quantum storage device according to claim 8, characterized in that: In terms of optical path setting, the pump light reaches the solid-state quantum memory earlier than the signal light to be stored.

10. A multi-polarization solid-state quantum storage method, characterized in that: The following steps are involved: S1: Generates continuously tunable multi-frequency continuous laser; S2: According to the frequency interval of the quantum storage module, the multi-frequency continuous laser is pumped and stored, and the pump light and the signal light to be stored are obtained accordingly; S3: The quantum storage module receives the pump light and the signal light to be stored, and stores the signal light of the specified polarization state, and converts the polarization state of the signal light of the non-specified polarization state before storing it, so as to realize the storage of the signal light of multiple polarization states.

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