A quantum key distribution device and method integrating transceiver

Abstract

This invention discloses an integrated quantum key distribution device and method, which serves as both a transmitter and a receiver. As a transmitter, an optical injection locking device generates a group of optical pulses, which, after passing through an optical attenuator, are input to an unequal-arm Mach-Zehnder interferometer to obtain the quantum states of the corresponding basis vectors, and then input to a quantum channel. As a receiver, quantum states are received from the quantum channel. For Z-based quantum states, the output is sent to a third single-photon detector for decoding after passing through an optical beamsplitter; for X-based or Y-based quantum states, the output is sent to the unequal-arm Mach-Zehnder interferometer after passing through an optical beamsplitter, and then to a first and second single-photon detector for decoding. This invention eliminates the need for external modulation, enabling quantum state preparation and measurement within a single device using only one interferometer. This reduces the complexity of the quantum key distribution system, improves its compactness, and facilitates practical application.

Description

Technical Field

[0001] This invention relates to the field of quantum cryptography, and in particular to an integrated quantum key distribution device and method. Background Technology

[0002] Quantum key distribution (QKD) allows users to communicate with information-theoretic security, whose unconditional security is guaranteed by the principles of quantum mechanics. It has become a strong candidate for addressing the threat posed by quantum computers to many existing encryption protocols based on complexity theory.

[0003] Current QKD devices mainly fall into three categories in terms of preparation and measurement: The first category involves the sender preparing the quantum state and the receiver measuring it; the second category involves one user preparing the quantum state and measuring it upon its return, while the other user only encodes the quantum state, such as the plug-and-play QKD scheme; the third category involves both communicating parties preparing quantum states and sending them to an untrusted third-party user for measurement, such as the MDI-QKD and TF-QKD schemes. In these schemes, the user's device often only has the function of sending or receiving, and cannot simultaneously prepare and measure quantum states. Requiring users to simultaneously prepare and measure quantum states in a single QKD device is not easy, partly because the transmitter and receiver require different devices, and partly because the basis selection during active encoding and decoding is random, making it impossible to complete decoding simultaneously with encoding.

[0004] Existing devices capable of simultaneously encoding and decoding optical qubits generally deploy separate transmitter and receiver modules on the communication side. Although some schemes can perform encoding and decoding simultaneously in a single device—for example, CN110932857A discloses a fully symmetric quantum key distribution device capable of transmitting and receiving keys, which is a fully symmetric quantum key distribution device capable of transmitting and receiving keys composed of two interferometers; CN114629563A discloses a polarization multiplexing quantum key distribution device and an all-time, all-pass quantum key distribution network, specifically a polarization multiplexing quantum key distribution device and an all-time, all-pass quantum key distribution network based on a bidirectional phase modulation module; and CN115883089A discloses a polarization-selective phase modulation interferometer, a quantum key distribution device, a system, and a network, specifically a quantum key distribution device, system, and network based on a polarization-selective phase modulation interferometer—these schemes typically rely on interferometers with complex principles and structures or introduce additional optical components, leading to increased complexity and cost of the QKD system and potentially introducing additional insertion loss. Meanwhile, the above-mentioned solutions generally use intensity modulators (IM) and phase modulators (PM), which are expensive, bulky, and require high drive voltages, which undoubtedly further limits the practical application of QKD. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide an integrated quantum key distribution device and method that can achieve simultaneous encoding and decoding in a single device without external modulation and using only an unequal-arm Mach-Zehnder interferometer.

[0006] Technical solution: The quantum key distribution device integrating transmission and reception described in this invention includes: an optical injection locking device, an optical attenuator, a third optical beam splitter, an unequal-arm Mach-Zehnder interferometer, and first to third single-photon detectors;

[0007] The quantum key distribution device serves as both a transmitter and a receiver.

[0008] When the quantum key distribution device is used as the transmitter, the optical injection locking device generates a group of optical pulses, which are then input into the unequal-arm Mach-Zehnder interferometer after passing through an optical attenuator to obtain the quantum state of the corresponding basis vector, and then input into the quantum channel.

[0009] When the quantum key distribution device acts as a receiver, it receives quantum states from the quantum channel. For Z-based quantum states, the state is output to the third single-photon detector after passing through the third optical beam splitter for decoding. For X-based or Y-based quantum states, the state is output to the unequal-arm Mach-Zehnder interferometer after passing through the third optical beam splitter, and then output to the first and second single-photon detectors for decoding.

[0010] Furthermore, the quantum key distribution device also includes a second circulator;

[0011] When the quantum key distribution device is used as the transmitter, the light pulse group output by the light injection locking device enters from the first port of the second circulator and exits from the second port, entering the unequal-arm Mach-Zehnder interferometer.

[0012] When the quantum key distribution device acts as a receiver, one optical pulse output from the unequal-arm Mach-Zehnder interferometer enters from the second port of the second circulator and exits from the third port, reaching the first single-photon detector; the other optical pulse output from the unequal-arm Mach-Zehnder interferometer reaches the second single-photon detector.

[0013] Furthermore, the quantum key distribution device also includes a third circulator;

[0014] When the quantum key distribution device acts as a receiver, the quantum state enters from the first port and exits from the second port of the third circulator, and is output to the third optical beam splitter. The third optical beam splitter performs passive basis selection based on the splitting ratio and outputs to the third single-photon detector and the unequal-arm Mach-Zehnder interferometer, respectively.

[0015] Furthermore, the optical pulse is phase-shifted by the fiber stretcher after passing through the long arm of the unequal-arm Mach-Zehnder interferometer. , for or The light pulse passes directly through the short arm of the unequal-arm Mach-Zehnder interferometer.

[0016] When long arm At the same time, the quantum key distribution device serves as the transmitter to prepare and transmit the quantum states of Z-based and Y-based quantum states, and simultaneously serves as the receiver to receive and measure the quantum states of Z-based and X-based quantum states;

[0017] When long arm At the same time, the quantum key distribution device acts as a transmitter to prepare and send quantum states based on Z and X, and simultaneously acts as a receiver to receive and measure quantum states based on Z and Y.

[0018] Furthermore, each user holds one of the aforementioned quantum key distribution devices. When 2n users distribute quantum keys simultaneously, their respective quantum key distribution devices are connected in sequence to form a ring quantum key distribution network.

[0019] 2n users are numbered as follows ;

[0020] Odd-numbered users set the fiber stretcher to apply phase. Even-numbered users set the fiber stretcher to apply phase. ;

[0021] Alternatively, odd-numbered users can set the fiber stretcher to apply phase. Even-numbered users set the fiber stretcher to apply phase. .

[0022] Furthermore, the optical injection locking device includes a master laser, a slave laser, and a first circulator;

[0023] The seed light generated by the main laser enters from the first port and exits from the second port of the first circulator, and is injected into the slave laser for optical injection locking and direct phase modulation, generating a group of three optical pulses, wherein the relative phase of the first two optical pulses is... The relative phase of the latter two light pulses is The phases of different light pulse groups are random.

[0024] Furthermore, after the optical pulse group passes through an unequal-arm Mach-Zehnder interferometer, the intensity and relative phase of the first two optical pulses are determined by... , and Control, the intensity of the third light pulse is random; by adjusting , and Prepare the quantum states of the corresponding basis vectors.

[0025] The quantum key distribution method integrating transceiver described in this invention, when the quantum key distribution device is used as the transmitter, generates a group of optical pulses through an optical injection locking device. After the optical pulse group passes through an optical attenuator, it is input into an unequal-arm Mach-Zehnder interferometer to obtain the quantum state of the corresponding basis vector, and the quantum state is sent to the quantum channel.

[0026] When the quantum key distribution device acts as a receiver, it receives quantum states from the quantum channel. For Z-based quantum states, the state is output to the third single-photon detector after passing through the third optical beam splitter for decoding. For X-based or Y-based quantum states, the state is output to the unequal-arm Mach-Zehnder interferometer after passing through the third optical beam splitter, and then output to the first and second single-photon detectors for decoding.

[0027] The computer-readable storage medium of the present invention stores a computer program, which, when executed by a processor, implements the integrated quantum key distribution method.

[0028] The computer program product of the present invention includes a computer program that, when executed by a processor, implements the integrated quantum key distribution method according to the present invention.

[0029] Beneficial effects: Compared with the prior art, the advantages of the present invention are: (1) The present invention only requires one set of devices to prepare and measure quantum states simultaneously, realizing the integration of transmission and reception; (2) The present invention only uses one of the most commonly used unequal-arm Mach-Zehnder interferometers, reducing the complexity of the QKD system; (3) The present invention uses optical injection locking, direct phase modulation, and coherent interference to replace the phase modulator and intensity modulator, avoiding the introduction of external modulators, which improves the compactness of the QKD system and is conducive to the practical application of the QKD system; (4) The present invention can be applied to simultaneous bidirectional quantum key distribution by two users and ring quantum key distribution networks by multiple users. When there are two users holding a transceiver integrated quantum key distribution device that does not require external modulation, simultaneous bidirectional quantum key distribution can be performed, which makes the key generation rate twice that of the traditional transceiver separation device, and can perform unidirectional quantum key distribution as needed; The present invention can also be extended to the application scenario of multiple users forming a ring quantum key distribution network, thus improving the flexibility and practicality of the QKD system. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the quantum key distribution device of the present invention.

[0031] Figure 2 This is a schematic diagram of the device used for simultaneous bidirectional quantum key distribution to two users in this embodiment.

[0032] Figure 3 This is a schematic diagram of a ring quantum key distribution network structure for multi-user use in this embodiment. Detailed Implementation

[0033] The quantum key distribution device designed in this scheme, which requires no external modulation, can simultaneously encode and decode, that is, it can act as both a transmitter and a receiver. It uses only one unequal-arm Mach-Zehnder interferometer and does not require a phase modulator or intensity modulator. It can implement the BB84 protocol for timestamp phase encoding and passive decoding.

[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0035] like Figure 1 As shown, the integrated quantum key distribution device includes a master laser (Laser1), a slave laser (Laser2), an optical attenuator (ATT), an unequal-arm Mach-Zehnder interferometer (AMZI), a third optical beam splitter (BS3), a first circulator (CIR1), a second circulator (CIR2), a third circulator (CIR3), a first single-photon detector (D1), a second single-photon detector (D2), and a third single-photon detector (D3). The unequal-arm Mach-Zehnder interferometer (AMZI) includes an optical fiber stretcher (FS), a first optical beam splitter (BS1), and a second optical beam splitter (BS2). In this embodiment, for multi-port devices (such as circulators, unequal-arm Mach-Zehnder interferometers, and optical beam splitters), each port is identified by a number in the accompanying drawings. Figure 1 Taking the first circulator CIR1 as an example, the numbers 1, 2, and 3 marked around it correspond to port 1, port 2, and port 3 of the device, respectively.

[0036] Both the master laser (Laser1) and the slave laser (Laser2) are distributed feedback (DFB) lasers. The master laser (Laser1) includes an internal isolator, while the slave laser (Laser2) does not. The master laser (Laser1), the slave laser (Laser2), and the first circulator (CIR1) constitute an optical injection-locked (OIL) device. The first optical beamsplitter (BS1) and the second optical beamsplitter (BS2) in the unequal-arm Mach-Zehnder interferometer (AMZI) are connected to form a long arm and a short arm, with an optical fiber stretcher (FS) attached to the long arm.

[0037] The main laser Laser1 is connected to port 1 of the first circulator CIR1, and the secondary laser Laser2 is connected to port 2 of the first circulator CIR1. One end of the optical attenuator ATT is connected to port 3 of the first circulator CIR1, and the other end is connected to port 1 of the second circulator CIR2. The first single-photon detector D1 is connected to port 3 of the second circulator CIR2.

[0038] Port 1 of the unequal-arm Mach-Zehnder interferometer AMZI is connected to port 2 of the second circulator CIR2. Port 2 of the unequal-arm Mach-Zehnder interferometer AMZI is connected to the second single-photon detector D2. Port 3 of the unequal-arm Mach-Zehnder interferometer AMZI is left unused. Port 4 of the unequal-arm Mach-Zehnder interferometer AMZI is connected to port 1 of the third optical beamsplitter BS3. Port 2 of the third optical beamsplitter BS3 is connected to the third single-photon detector D3. Port 3 of the third optical beamsplitter BS3 is used as the transmitting port. Port 4 of the third optical beamsplitter BS3 is connected to port 2 of the third circulator CIR3. Port 1 of the third circulator CIR3 is used as the receiving port. Port 3 of the third circulator CIR3 is left unused.

[0039] (a) A quantum key distribution device integrating transceiver functions as the transmitter

[0040] When the integrated quantum key distribution device is used as the transmitter, the process of preparing and transmitting the quantum state is as follows: The seed light generated by the main laser Laser1 enters from port 1 and exits from port 2 of the circulator CIR1, and is injected into the secondary laser Laser2 for optical injection locking. Direct phase modulation technology is used, that is, a certain time-width amplitude perturbation is introduced into the electrical drive signal of the main laser Laser1, ultimately generating pulse groups (three pulses per group) with precisely controlled relative phases, wherein the relative phases of the first two pulses are... The relative phase of the last two pulses is The phases of different pulse groups are random; the generated pulse groups enter from port 2 and exit from port 3 of the circulator CIR1, are attenuated to a single-photon level by the optical attenuator ATT, then enter from port 1 and exit from port 2 of the circulator CIR2, and then enter from port 1 and exit from port 4 of the unequal-arm Mach-Zehnder interferometer AMZI. The pulses passing through the long arm are then subjected to the force of the fiber stretcher FS. Phase, for or After passing through the short arm, it passes directly, ultimately generating three pulses within one logic bit. The intensity and relative phase of the first two pulses can be determined by... , , Control, the intensity of the third pulse is random; by adjusting , , The signal state and decoy state of the corresponding basis vector can be prepared, avoiding the use of phase modulator and intensity modulator; the 4-port output signal state and decoy state of the unequal arm Mach-Zehnder interferometer AMZI are input from port 1 and output from port 3 of the optical beam splitter BS3 and output to the quantum channel.

[0041] Specifically, the use of phase modulators and intensity modulators can be avoided through the above process. The first two pulses can be represented as early arrival timestamps and late arrival timestamps. The above conclusion can be derived from the following derivation process.

[0042] The three light pulses in the light pulse group (each group consisting of three pulses) generated using optical injection locking and direct phase modulation are respectively used... , , The three coherent states are represented as follows: Used to indicate the first light pulse in the next light pulse group. The amplitude represents the coherent state. This indicates the initial phase of the optical pulse group. Indicates the initial phase of the next light pulse group, all of which are in The upper part follows a uniform distribution. Indicates the initial angular frequency. Indicates time.

[0043]

[0044]

[0045]

[0046]

[0047] After passing through AMZI's short arm, we can obtain:

[0048]

[0049]

[0050]

[0051]

[0052] After passing through AMZI's long arm, we can obtain:

[0053]

[0054]

[0055]

[0056]

[0057] in , , , This indicates that the four optical pulses obtained after passing through the AMZI short arm correspond to... , , , , , , , This indicates that the four light pulses obtained after passing through the AMZI long arm correspond to the same four light pulses. , , , . and Interference generates early arrival timestamps , and Interference generates late arrival timestamps , and Interference produces an additional pulse It can be expressed as the following formula:

[0058]

[0059]

[0060]

[0061] By calculating the amplitude and phase separately, we can obtain:

[0062]

[0063]

[0064] in , These represent the amplitude and phase of the earliest arrival timestamp, respectively. , These represent the amplitude and phase of the later arriving timestamp, respectively. , These represent the amplitude and phase of the additional pulse, respectively.

[0065] The phase difference between the early and late arrival timestamps is The phase difference between the late arrival timestamp and the additional pulse is The intensity can be obtained by squared the amplitude. Then, by controlling... , , This allows modulation of the intensity and relative phase of early and late arrival timestamps, with the intensity of the additional pulses generated by the interference being random, and the relative phase with the late arrival timestamp also being random. This scheme can be applied to the decoy-state BB84 protocol QKD based on timestamp phase coding. When for At that time, the device can modulate the signal state and decoy state of the Z-based system, and the signal state of the Y-based system; when for At that time, the device can modulate the signal state and decoy state of the Z-based system, and the signal state of the X-based system. for or At that time, the corresponding quantum state needs to be modulated. and The values ​​set are not the same, and they are summarized in Table 1.

[0066] Table 1. Quantum states and corresponding values ​​of the BB84 protocol based on timestamp phase encoding. , , The value that needs to be set

[0067]

[0068] This device can modulate multiple decoy states based on the Z-base, requiring only the setting of appropriate parameters. or This makes the strength of early or late arrival timestamps approach zero. Table 1 only lists the values ​​when... for or At that time, each has a method for modulating the Z-based decoy state. and The setup method.

[0069] When a user holding the quantum key distribution device needs to prepare the Z-based and decoy states and the Y-based signal states of the timestamp phase coding scheme to implement the BB84 protocol, the fiber stretcher FS needs to be set to apply... Phase, and set appropriate and When users need to prepare Z-based and decoy states and X-based signal states of a timestamp phase coding scheme to implement the BB84 protocol, the fiber stretcher FS needs to be set to apply... Phase, and set appropriate and Finally, the quantum state is output to the quantum channel via the optical beam splitter BS3.

[0070] (ii) A quantum key distribution device integrating transceiver functions as the receiving end

[0071] The integrated transceiver quantum key distribution device (QKDD) employs passive decoding as the receiver. The third circulator (CIR3) isolates the quantum signal transmitted by the local QKDD from the four-port output of the optical beamsplitter (BS3), preventing the quantum signal from reaching unintended receivers and guiding quantum signals transmitted by other user QKDDs into the local QKDD for decoding. The third optical beamsplitter (BS3) is used for passive basis selection, and its splitting ratio needs to be adjusted according to the basis selection probability at the transmitter.

[0072] When receiving Z-based and Y-based quantum key distribution signals from another user's quantum key distribution device, for Z-based decoding, the quantum state is directly output from port 2 of BS3, detected by the single-photon detector D3, and then decoded by measuring the arrival time using a timer. If the measurement result is early arrival, the decoded value is bit 0; if the measurement result is late arrival, the decoded value is bit 1; if the measurement result is both early and late arrival, the bit is randomly assigned either 0 or 1. For Y-based decoding, the user needs to set the fiber stretcher FS to apply... The phase, quantum state, is output from port 1 of BS3 to the unequal-arm Mach-Zehnder interferometer AMZI, where it is delayed by one pulse period and applied by the fiber stretcher FS after passing through the long arm. The phase of the short arm passes directly through, creating three time windows in the time domain. Only pulses carrying phase information that arrive simultaneously at the optical beamsplitter BS1 within the middle time window will interfere. Finally, the outputs from ports 1 and 2 of the unequal-arm Mach-Zehnder interferometer AMZI reach single-photon detectors D1 and D2, respectively, for BB84 state measurements. The results can be derived as follows:

[0073]

[0074] Early arrival timestamp and late arrival timestamp are represented as follows: and After a delay of one pulse cycle, it is represented as and , For the pulse period, the relative phase between the early arrival timestamp and the late arrival timestamp of the Y-basis is represented as: , for or Considering that interference only occurs when optical pulses arrive simultaneously at the first optical beam splitter BS1 within the middle time window, and interference does not occur in other cases, only the interferometric term is retained. When the optical pulse arrives at the detector port, it can be represented as:

[0075]

[0076]

[0077] The response probabilities for the corresponding single-photon detectors D1 and D2 are as follows:

[0078]

[0079]

[0080] Based on this result, the decoding rules can be obtained: if the detection result is that D1 responds and D2 does not respond, then the value is decoded as bit 0; if the detection result is that D1 does not respond and D2 responds, then the value is decoded as bit 1; if the detection result is that both D1 and D2 respond, then the value is randomly assigned as bit 0 or 1.

[0081] When receiving Z-based and X-based quantum key distribution from another user's quantum key distribution device, the Z-based decoding is the same as described above; for X-based decoding, the user needs to set the fiber stretcher FS to apply a 0-phase condition, and the relative phase between the early arrival timestamp and the late arrival timestamp of the X-based condition should be 0 or... Except for the application of a 0-phase state by the fiber stretcher FS after passing through the long arm, it is the same as Y-based decoding.

[0082] The decoding rules are summarized in Table 2. The phase value set for the fiber stretcher FS of another user's quantum key distribution device. The phase value set for the fiber stretcher FS of the local quantum key distribution device. When the fiber stretcher FS is set to apply... ( At phase 1, the quantum key distribution device prepares and sends quantum states of Z-based and Y-based (Z-based and X-based) quantum states, and simultaneously receives and measures quantum states of Z-based and X-based (Z-based and Y-based) quantum states. Preparation and measurement are performed simultaneously and share a single unequal-arm Mach-Zehnder interferometer AMZI.

[0083] Table 2 and corresponding Required values ​​and decoding rules

[0084]

[0085] (iii) Simultaneous bidirectional quantum key distribution between two users

[0086] Reference Figure 2 There are two users, Alice and Bob, who possess transceiver integrated quantum key distribution devices that do not require external modulators. To distinguish between Alice's and Bob's devices, identical components are labeled differently. In summary, Alice's quantum key distribution device includes an optical injection locking (OIL) device and an optical attenuator (ATT). Aunequal-arm Mach-Zehnder interferometer AMZI A BS optical beam splitter A Circulators CIR2 and CIR3, single-photon detectors D1, D2, and D3, AMZI A Includes fiber optic stretcher FS A Bob's quantum key distribution device includes an optical injection locking (OIL) device and an optical attenuator (ATT). B unequal-arm Mach-Zehnder interferometer AMZI B BS optical beam splitter B Circulators CIR5 and CIR6, single-photon detectors D4, D5, and D6, AMZI B Includes fiber optic stretcher FS B Alice and Bob are performing simultaneous bidirectional quantum key distribution based on the BB84 protocol. Alice needs to use the fiber stretcher FS. A applied Set as ( (Phase ), Bob correspondingly needs to adjust the fiber stretcher FS. B applied Set as ( Phase.

[0087] When the fiber optic stretcher FS A Set to apply Phase, and fiber stretcher FS B Set to apply In terms of phase, Alice prepares Z-based and Y-based quantum states for quantum key distribution, while Bob passively decodes the quantum states sent by Alice. Simultaneously, Bob can also prepare Z-based and X-based quantum states for quantum key distribution, and Alice can passively decode the quantum states sent by Bob, thus achieving simultaneous bidirectional quantum key distribution. Conversely, Alice can also use the fiber stretcher FS... A Set to apply Phase is used to prepare and measure quantum states, but to achieve simultaneous bidirectional quantum key distribution, Bob needs to stretch the fiber optic cable FS. B Set to apply Phase.

[0088] This quantum key distribution device can also perform one-to-one quantum key distribution, i.e., Alice is the transmitter and Bob is the receiver, or Bob is the transmitter and Alice is the receiver.

[0089] (iv) Multi-user ring quantum key distribution network

[0090] Reference Figure 3 There are multiple users possessing integrated transceiver quantum key distribution devices that do not require external modulation, forming a ring quantum key distribution network. Each user acts as both a transmitter and a receiver, and adjacent users perform one-to-one quantum key distribution using the BB84 protocol. The users are numbered as follows: , For positive integers, users Set the fiber optic stretcher FS to apply Phase.

[0091] When the fiber optic stretcher FS of odd-numbered users is set to apply Phase, even-numbered user's fiber stretcher FS is set to apply In phase, odd-numbered users, acting as transmitters, prepare Z- and Y-base signals and send them to the next even-numbered user. As receivers, they passively decode the Z- and X-base signals sent by the previous even-numbered user. Conversely, even-numbered users, acting as transmitters, prepare Z- and X-base signals and send them to the next odd-numbered user. They passively decode the Z- and Y-base signals sent by the previous odd-numbered user. Phase is used to prepare and measure quantum states, but even-numbered users need to set the fiber stretcher FS to apply phase. Phase.

[0092] In summary, the transceiver integrated quantum key distribution device of this invention utilizes optical injection locking and direct phase modulation techniques, along with a QKD scheme that replaces phase and intensity modulators with coherent interference, reducing the complexity of the QKD system and facilitating the practical application and integration of quantum key distribution systems. This invention cleverly introduces an fiber stretcher FS, which allows for switching the phase applied by the fiber stretcher FS on the long arm of the unequal-arm Mach-Zehnder interferometer (AMZI). , Two state preparation methods for the BB84 timestamp phase encoding protocol are achieved by adjusting the phase setting of the master laser: Z-based and Y-based, and Z-based and X-based. Furthermore, decoding can be performed simultaneously with quantum state preparation using the phase applied by the fiber stretcher FS. For example, when the fiber stretcher FS is set to apply... The phase can be measured simultaneously with the preparation of Z-based and Y-based phases, thereby achieving integrated transmission and reception, and realizing the BB84 protocol based on timestamp phase encoding and passive decoding using only one interferometer.

[0093] Furthermore, the quantum key distribution device of this invention can be applied to simultaneous bidirectional QKD for two users, as well as to multi-user ring quantum key distribution networks. Moreover, it is not only applicable to the BB84 protocol, but can also be extended to other QKD protocols, such as the coherent single-path (COW) protocol.

[0094] Example 2

[0095] The quantum key distribution method integrating transceiver described in this invention, when the quantum key distribution device is used as the transmitter, generates a group of optical pulses through an optical injection locking device. After the optical pulse group passes through an optical attenuator, it is input into an unequal-arm Mach-Zehnder interferometer to obtain the quantum state of the corresponding basis vector, and the quantum state is sent to the quantum channel.

[0096] When the quantum key distribution device acts as a receiver, it receives quantum states from the quantum channel. For Z-based quantum states, the state is output to the third single-photon detector after passing through the third optical beam splitter for decoding. For X-based or Y-based quantum states, the state is output to the unequal-arm Mach-Zehnder interferometer after passing through the third optical beam splitter, and then output to the first and second single-photon detectors for decoding.

[0097] Example 3

[0098] The computer-readable storage medium of the present invention stores a computer program, which, when executed by a processor, implements the integrated quantum key distribution method.

[0099] The computer-readable storage medium may include RAM, ROM, EEPROM, CD-ROM or other optical disc storage devices, magnetic disk storage devices or other magnetic storage devices, flash memory or any other medium that can be used to store program code in the form of instructions or data structures and is accessible by a computer.

[0100] The processor is used to execute a computer program stored in memory to implement the various steps in the methods described in the above embodiments.

[0101] Example 4

[0102] The computer program product of the present invention includes a computer program that, when executed by a processor, implements the integrated quantum key distribution method according to the present invention.

[0103] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial results of the present invention. It should be understood that this embodiment is only introduced as an example of a QKD device composed of optical fiber components. For example, the method used in the specific embodiments of the present invention is also applicable to other on-chip QKD devices or free space QKD devices, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A transceiver integrated quantum key distribution apparatus characterized by comprising: The quantum key distribution device comprises: a light injection locking device, a light attenuator, a third light beam splitter, an unequal arm Mach-Zehnder interferometer, and first to third single-photon detectors; The quantum key distribution device simultaneously serves as a transmitting end and a receiving end. When the quantum key distribution device serves as the transmitting end, the light injection locking device generates a group of light pulses which are input to the unequal arm Mach-Zehnder interferometer after passing through the light attenuator to obtain quantum states corresponding to base vectors, and then are input to a quantum channel. When the quantum key distribution device serves as the receiving end, quantum states are received from the quantum channel, for quantum states of the Z base, after passing through the third light beam splitter, are output to the third single-photon detector for decoding; for quantum states of the X base or the Y base, after passing through the third light beam splitter, are output to the unequal arm Mach-Zehnder interferometer, and then are output to the first single-photon detector and the second single-photon detector for decoding. The group of light pulses comprises three light pulses, wherein the relative phase of the first two light pulses is , and the relative phase of the last two light pulses is ; The light pulse group passes through a Mach-Zehnder interferometer with unequal arms, the intensity and relative phase of the first two light pulses are controlled by 、 and , and the intensity of the third light pulse is random; the quantum state of the corresponding base vector is prepared by adjusting 、 and ; The light pulse passing through the long arm of the unequal arm Mach-Zehnder interferometer is phase applied by a fiber stretcher , To Or The light pulse passing through the short arm of the unequal arm Mach-Zehnder interferometer is directly passed; When the long arm of the The quantum key distribution device prepares and sends quantum states of Z basis and Y basis as a transmitting end, and receives and measures quantum states of Z basis and X basis as a receiving end. When the long arm of the The quantum key distribution device prepares and sends quantum states of Z basis and X basis as a transmitting end, and receives and measures quantum states of Z basis and Y basis as a receiving end.

2. The transceiver integrated QKD apparatus according to claim 1, wherein The quantum key distribution device further comprises a second circulator. When the quantum key distribution device serves as the transmitting end, the group of light pulses output by the light injection locking device enter the unequal arm Mach-Zehnder interferometer from the first port of the second circulator and exit from the second port. When the quantum key distribution device serves as the receiving end, one of the light pulses output by the unequal arm Mach-Zehnder interferometer enters the first single-photon detector from the second port of the second circulator and exits from the third port; the other light pulse output by the unequal arm Mach-Zehnder interferometer reaches the second single-photon detector.

3. The transceiver integrated QKD apparatus according to claim 1, wherein The quantum key distribution device further comprises a third circulator. When the quantum key distribution device serves as the receiving end, the quantum states enter the third light beam splitter from the first port of the third circulator and exit from the second port; the third light beam splitter passively selects the base according to the splitting ratio and outputs to the third single-photon detector and the unequal arm Mach-Zehnder interferometer, respectively.

4. The transceiver integrated QKD apparatus according to claim 1, wherein Each user holds one quantum key distribution device, and when 2n users simultaneously perform quantum key distribution, the quantum key distribution devices held by the users are connected in sequence to form a ring-shaped quantum key distribution network. 2n users are numbered respectively as ; Odd numbered users have the fiber stretcher set to apply phase , even numbered users have the fiber stretcher set to apply phase ; Alternatively, odd numbered users set the fiber stretcher to apply a phase of 0, and even numbered users set the fiber stretcher to apply a phase of π / 2.

5. The transceiver integrated QKD apparatus according to claim 1, wherein The light injection locking device comprises a master laser, a slave laser, and a first circulator. The seed light generated by the master laser enters the slave laser from the first port of the first circulator and exits from the second port, and the light injection locking and direct phase modulation are performed on the seed light to generate a group of light pulses comprising three light pulses, and the phases of different groups of light pulses are random.

6. A transceiver integrated quantum key distribution method based on the device of claim 1, wherein When the quantum key distribution device serves as the transmitting end, a group of light pulses are generated by the light injection locking device, the group of light pulses are input to the unequal arm Mach-Zehnder interferometer after passing through the light attenuator to obtain quantum states corresponding to base vectors, and the quantum states are sent to a quantum channel; When the quantum key distribution device serves as the receiving end, quantum states are received from the quantum channel, for quantum states of the Z base, after passing through the third light beam splitter, are output to the third single-photon detector for decoding; for quantum states of the X base or the Y base, after passing through the third light beam splitter, are output to the unequal arm Mach-Zehnder interferometer, and then are output to the first single-photon detector and the second single-photon detector for decoding.

7. A computer-readable storage medium storing a computer program, wherein the computer program comprises the following steps of: receiving a request for a resource from a client; determining whether the client is authorized to access the resource; and if the client is authorized to access the resource, providing the resource to the client. The computer program is executed by a processor to implement the transceiving integrated quantum key distribution method according to claim 6.

8. A computer program product comprising a computer program, characterized in that, The computer program is executed by a processor to implement the transceiving integrated quantum key distribution method according to claim 6.

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