CN115412231A - Target evaluation light pulse generation method, device and equipment - Google Patents

Target evaluation light pulse generation method, device and equipment Download PDF

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Publication number
CN115412231A
CN115412231A CN202110587046.8A CN202110587046A CN115412231A CN 115412231 A CN115412231 A CN 115412231A CN 202110587046 A CN202110587046 A CN 202110587046A CN 115412231 A CN115412231 A CN 115412231A
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light
state
sequence
quantum
target
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马龑
汤艳琳
许穆岚
刘仁德
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Quantumctek Co Ltd
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Quantumctek Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
    • H04L9/0852—Quantum cryptography
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/508—Pulse generation, e.g. generation of solitons
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/70—Photonic quantum communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
    • H04L9/0819—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s)

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  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
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  • Electromagnetism (AREA)
  • Computer Security & Cryptography (AREA)
  • Optics & Photonics (AREA)
  • Theoretical Computer Science (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
  • Optical Communication System (AREA)

Abstract

The invention discloses a method, a device and equipment for generating target evaluation light pulses, which are used for a quantum key distribution system and comprise the following steps: generating light pulses constituting a first light emission sequence; modulating the light pulses comprising the first emission sequence to generate light pulses comprising a second emission sequence, wherein the light pulses in the second emission sequence have different encoding states; and performing extinction on the light pulses with the non-target coding state in the second light-emitting sequence and retaining the light pulses with the target coding state according to the evaluation requirement to generate target evaluation light pulses constituting a third light-emitting sequence. The invention can obtain more accurate state parameters of the optical pulse signals in each coding state under the condition of not changing the normal working state of the light source module of the quantum key distribution system so as to meet the requirement of evaluation.

Description

Target evaluation light pulse generation method, device and equipment
Technical Field
The invention relates to the field of quantum secret communication, in particular to a method, a device and equipment for generating target evaluation light pulse for a quantum key distribution system.
Background
Quantum Key Distribution (QKD) technology has received much attention because it can produce a perfectly consistent unconditionally secure Key between two communicating parties. Since the BB84 proposal was proposed in 1984, various theoretical schemes are perfected day by day, and the technology is gradually mature and goes to practical application. The quantum key distribution is fundamentally different from a classical key system in that a single photon or an entangled photon pair is adopted as a carrier of a key, and the three fundamental principles of quantum mechanics (namely, heisenberg inaccuracy principle, measurement collapse theory and quantum unclonable law) ensure that the process is not eavesdroppable and not decipherable, so that a safer key system is provided.
At present, because a single photon source technology cannot meet practical requirements, a light source scheme adopted by a practical quantum key distribution system is to strongly attenuate a coherent light source to obtain weak coherent light. However, the weak coherent light contains multi-photon components with a certain probability, so that an eavesdropper can carry out an attack of separating photon numbers, and the security coding rate of the eavesdropper is greatly limited. Against this background, a decoy-state BB84 quantum key distribution protocol has been proposed to defend against attacks. Specifically, the influence of the channel and the eavesdropper on the light pulse is monitored by randomly doping some decoy light of different intensities in the signal light emitted by the laser. In conjunction with the decoy state technique, the rate of composition of the BB84 protocol is nearly the same as the protocol using an ideal single photon source, even with a weak coherent light source. Thus, the decoy-state BB84 quantum key distribution protocol is widely adopted in laboratory and engineering practice.
A quantum key distribution system based on BB84 quantum key distribution protocol of decoy state comprises a light source module and a modulation module, wherein the light source module emits light signals, and the modulation module performs quantum state modulation and intensity modulation (namely, decoy state modulation) on the emitted light signals, wherein the quantum state modulation enables four different quantum states to be contained in phase or polarization, namely, the phase state (time phase state) or the polarization state, and can be represented by two random numbers; wherein the intensity modulation is such that a plurality of different intensities, such as a typical signal state, a decoy state and a vacuum state, are included in the intensity, and the three different intensities are generally set according to a certain proportion, such as 6. Taking the polarization encoding method and the decoy state ratio of 6. The polarization states H, V, P and N respectively represent that the optical signals emitted by the light source part at the transmitting end of the quantum key distribution system are optical signals corresponding to four polarization states prepared by randomly selecting a right angle basis (H, V) and a diagonal basis (P, N).
With the development of quantum key distribution technology, the importance of evaluating the actual safety of the quantum key distribution technology is increasingly highlighted. When performing indiscriminate quantum evaluation on random states of each code of a quantum key distribution system, a light source part at an emitting end of the quantum key distribution system is generally required to emit light in a specific state, for example, only signal state light is emitted, and relevant physical quantity measurement is performed, for example, state parameters such as wavelength, amplitude, time sequence and the like of the light in the specific state are measured, while other unspecific states avoid interference or errors caused during measurement by not emitting light. Specifically, an external evaluation software sends out a specific state light instruction, and a light source part of a transmitting end of the quantum key distribution system outputs specific state light required for evaluation according to the received instruction.
Fig. 2 shows a timing diagram of the light emitting sequence and modulation output by the light source module at the transmitting end of the quantum key distribution system when extracting specific state light (e.g., signal state light S or polarized state light H) required for evaluation in the prior art. Specifically, the process of extracting the specific state light required for evaluation in the prior art mainly includes the following steps (the order of step S3 and step S4 may be interchanged):
step S1: the evaluation software sends out an instruction that the evaluation target is a specific state light (specific code);
step S2: the light source module at the transmitting end of the quantum key distribution system only emits light at a specific state (specific coding) position and does not emit light at other non-specific state positions according to the random coding, so that a light emitting sequence is formed; or the light source module can emit periodic light in a specific state;
and step S3: modulating the light pulse of the light-emitting sequence into a corresponding signal state, decoy state or vacuum state by a decoy state modulation module, namely modulating the intensity of the light pulse;
and step S4: modulating the light-emitting sequence modulated in the step 3 into a corresponding polarization state or phase state through a quantum state modulation module, namely performing quantum state modulation on the light pulse;
step S5: and outputting the specific state light pulse after decoy state modulation and quantum state modulation for evaluation.
Note that the solid line boxes shown in fig. 2 represent light pulses in a specific state (e.g., polarization state H or signal state S) required for evaluation, while the dashed line boxes represent light pulses (e.g., polarization states V, P, N, or decoy state D and vacuum state V) required for non-evaluation.
However, in the normal working stage, the light emitting mode of the light source module of the quantum key distribution system is a true random sequence (i.e., random light pulse based on random number control), and the intensity modulation and the quantum state modulation are both realized by external modulation; without loss of generality, the light source module may emit periodic light. Fig. 3 is a schematic diagram showing a comparison between the light-emitting sequence output by the light source module in the normal operation stage of the quantum key distribution system and the light-emitting sequence output by the light source module in the evaluation stage of the prior art. As shown in fig. 3, the light emitting sequence of the light source module in the evaluation phase of the prior art is not consistent with the truly random (including periodic) light emitting sequence in the normal operation phase of the system. Specifically, the prior art changes the state of the light source module in the normal operation stage, so that the light emitting sequence of the output light source does not emit light in the undesired state position (as shown by the position indicated by the dashed line in fig. 3). The state parameters (such as wavelength, amplitude, timing, etc.) of the light source are usually closely related to the light emitting sequence, and if the duty ratios of the light pulse signals with different encoding states (such as four polarization states of H, V, P, N) are different, the state parameters of the respective light emitting sequences may be different. Therefore, the light emitting manner in the prior art (i.e. only emitting light at a specific state position required for evaluation) may cause that the measurement result may deviate from the real operating state of the quantum key distribution system, and especially when evaluating the mode consistency (e.g. wavelength mode, time mode, etc.) of each encoding state, the different duty ratios cause that the light emitting sequences of the light sources are different, so that the measurement results of the state parameters of the optical pulse signals of each encoding state are different due to the influence of different light emitting sequences, the consistency of the encoding state itself cannot be reflected, and finally, the misjudgment on the security of the quantum key distribution system may be caused.
Disclosure of Invention
In order to solve the above problems, the present invention provides a method, an apparatus, and a device for generating target evaluation optical pulses for a quantum key distribution system, which can obtain more accurate state parameters of optical pulse signals in each encoding state without changing the operating state of a light source module at a transmitting end of the quantum key distribution system, so as to meet the requirements of evaluation.
The embodiment of the invention provides a method for generating target evaluation light pulses, which is used for a quantum key distribution system and comprises the following steps: generating light pulses constituting a first light emission sequence; modulating the light pulses comprising the first light emission sequence to generate light pulses comprising a second light emission sequence, wherein the light pulses in the second light emission sequence have different encoding states; and performing extinction on the light pulses with the non-target coding state in the second light-emitting sequence and retaining the light pulses with the target coding state according to the evaluation requirement to generate target evaluation light pulses constituting a third light-emitting sequence.
Further, the encoded states include at least one of quantum states and intensity states.
Further, the method also includes at least one of quantum state modulating and intensity modulating the light pulses in the first light emission sequence to generate the second light emission sequence, wherein the quantum state modulating includes polarization quantum state modulating, time phase quantum state modulating, or phase quantum state modulating the light pulses in the first light emission sequence.
Further, the method further comprises: quantum state modulating and/or intensity modulating the light pulses in the first emission sequence to generate the second emission sequence, wherein the light pulses in the second emission sequence have different quantum states and/or intensity states; and quenching the light pulses in the second light-emitting sequence having non-target quantum states and/or intensity states and retaining the light pulses having target quantum states and/or intensity states according to the evaluation requirement to generate the target evaluation light pulses.
Further, the method further comprises: quantum state modulating the light pulses in the first light emission sequence to generate the second light emission sequence when the evaluation requirement indicates that the target evaluation light pulse is a light pulse having a target quantum state, wherein the light pulses in the second light emission sequence have different quantum states; and modulating, by the intensity modulation, light pulses in the second light emission sequence having the target quantum state to have a preset intensity state, and modulating light pulses in the second light emission sequence having a non-target quantum state to have a non-preset intensity state, wherein the non-preset intensity state is an extinction state.
Further, the method further comprises: when the evaluation requirement indicates that a target evaluation light pulse is a light pulse having a target intensity state, intensity modulating the light pulses in the first light emission sequence to generate the second light emission sequence, wherein the light pulses in the second light emission sequence have different intensity states; modulating light pulses in the second light-emitting sequence having a target intensity state to have preset time quantum states and modulating light pulses in the second light-emitting sequence having a non-target intensity state to have non-preset time quantum states by the time phase quantum state modulation; and performing extinction on the optical pulse with the non-preset time quantum state through an optical attenuator so as to retain the optical pulse with the preset time quantum state.
Further, the method further comprises: when the evaluation requirement indicates that a target evaluation light pulse is a light pulse having a target intensity state, intensity modulating the light pulses in the first light emission sequence to generate the second light emission sequence, wherein the light pulses in the second light emission sequence have different intensity states; modulating light pulses in the second light-emitting sequence with the target intensity state to have a preset polarization quantum state by the polarization quantum state modulation, and modulating light pulses in the second light-emitting sequence with a non-target intensity state to have a non-preset polarization quantum state; and retaining the light pulses with the preset polarization quantum states through a polarization filter, and performing extinction on the light pulses with the non-preset polarization quantum states.
The embodiment of the invention also provides a device for generating target evaluation light pulse, which is used for a quantum key distribution system and comprises: the light source module is used for emitting light pulses forming a first light emitting sequence; a modulation module for modulating the light pulses in the first light emission sequence to generate light pulses constituting a second light emission sequence, wherein the light pulses in the second light emission sequence have different encoding states; the extinction module is used for carrying out extinction on the optical pulses with the non-target coding state in the second light-emitting sequence according to the evaluation requirement and reserving the optical pulses with the target coding state so as to generate target evaluation optical pulses forming a third light-emitting sequence; and the control module is used for sending control signals to the light source module, the modulation module and the extinction module so as to drive the light source module, the modulation module and the extinction module to cooperatively work.
Further, the encoded states include at least one of quantum states and intensity states.
Further, the modulation module includes a quantum state modulation unit and/or a decoy state modulation unit, which are respectively configured to perform quantum state modulation and/or intensity modulation on the light pulses in the first light-emitting sequence to generate the second light-emitting sequence, where the light pulses in the second light-emitting sequence have different quantum states and/or intensity states; and the extinction module is an optical extraction modulator and is used for carrying out extinction on the optical pulse with the non-target quantum state and/or the intensity state in the second light-emitting sequence according to the evaluation requirement and retaining the optical pulse with the target quantum state and/or the intensity state so as to generate the target evaluation optical pulse.
Further, the modulation module includes a quantum state modulation unit, configured to perform quantum state modulation on the light pulses in the first light-emitting sequence to generate the second light-emitting sequence, where the light pulses in the second light-emitting sequence have different quantum states; and the extinction module comprises a decoy state modulation unit which is used for modulating the light pulse with the target quantum state in the second light-emitting sequence into a preset intensity state and modulating the light pulse with the non-target quantum state in the second light-emitting sequence into a non-preset intensity state, wherein the non-preset intensity state is an extinction state.
Further, the modulation module comprises a decoy state modulation unit for performing intensity modulation on the light pulses in the first light emitting sequence to generate the second light emitting sequence, wherein the light pulses in the second light emitting sequence have different intensity states; and the extinction module comprises a time phase quantum state modulation unit which is used for modulating the optical pulse with the target intensity state in the second light-emitting sequence into a preset time quantum state, and modulating the optical pulse with the non-target intensity state in the second light-emitting sequence into a non-preset time quantum state, wherein the extinction module further comprises an optical attenuator which is used for carrying out extinction on the optical pulse with the non-preset time quantum state, so that the optical pulse with the preset time quantum state is reserved.
Further, the modulation module comprises a decoy state modulation unit for performing intensity modulation on the light pulses in the first light emitting sequence to generate the second light emitting sequence, wherein the light pulses in the second light emitting sequence have different intensity states; and the extinction module comprises a polarization quantum state modulation unit which is used for modulating the light pulse with the target intensity state in the second light-emitting sequence into a preset polarization quantum state, and modulating the light pulse with the non-target intensity state in the second light-emitting sequence into a non-preset polarization quantum state, wherein the extinction module further comprises a polarization filter which is used for retaining the light pulse with the preset polarization quantum state and carrying out extinction on the light pulse with the non-preset polarization quantum state.
Embodiments of the present invention also provide an optical pulse transmitting apparatus for a quantum key distribution system, the apparatus including the apparatus for generating a target evaluation optical pulse according to any one of the embodiments.
The invention has the advantages that: the method, the device and the equipment for generating the target evaluation light pulse for the quantum key distribution system can extract the light in a specific state required by evaluation through the light extraction modulation device without changing the normal working state of the light source module during evaluation, and eliminate other light which is not required by evaluation, so that the evaluation result can better and accurately reflect the state parameters (such as wavelength, amplitude, time sequence and the like) of the light pulse signal in each coding state, and the safety evaluation result of the quantum key distribution system in a real working state is obtained.
Drawings
The technical solution and other advantages of the present invention will become apparent from the following detailed description of specific embodiments of the present invention, which is to be read in connection with the accompanying drawings.
Fig. 1 shows a table of an exemplary light-emitting encoding manner of a quantum key distribution system based on a BB84 quantum key distribution protocol in a decoy state.
Fig. 2 shows a timing diagram of the light emission sequence and modulation of the light source module output of an exemplary prior art optical quantum key distribution system at a particular state required for extraction evaluation.
Fig. 3 is a schematic diagram showing a comparison between the light emitting sequence output by the light source module in the normal operation stage of the quantum key distribution system and the light emitting sequence output by the light source module in the evaluation stage of the prior art.
Fig. 4 shows a schematic structural diagram of an apparatus for generating a target evaluation light pulse for a quantum key distribution system according to an embodiment of the present invention.
Fig. 5 is a schematic structural diagram illustrating a first specific embodiment of the apparatus for generating a target evaluation light pulse for a quantum key distribution system according to the present invention.
Fig. 6 is a schematic structural diagram illustrating a second specific embodiment of the apparatus for generating target evaluation light pulses for a quantum key distribution system according to the present invention.
Fig. 7 shows a schematic structural diagram of a third specific embodiment of the apparatus for generating a target evaluation light pulse for a quantum key distribution system provided by the present invention.
Fig. 8 is a schematic flow chart illustrating a method for generating target evaluation light pulses for a quantum key distribution system according to an embodiment of the present invention.
Fig. 9 is a timing chart showing modulation voltages corresponding to a light emission sequence when the pumping modulator multiplexes the decoy state modulation unit to pump a specific quantum state light pulse as a light pulse required for evaluation according to the embodiment of the present invention.
Fig. 10 is a timing chart showing modulation voltages corresponding to a light emission sequence when the pumping modulator multiplexes the quantum state modulation units to pump a specific decoy state light pulse as a light pulse required for evaluation according to the embodiment of the present invention.
Fig. 11 is a timing chart showing modulation voltages corresponding to a light emission sequence when the pumping modulator multiplexes the quantum state modulation unit to pump a specific decoy state light pulse as a light pulse required for evaluation according to another embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It should be apparent that the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terms "first," "second," "third," and the like in the description and in the claims, as well as in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the objects so described are interchangeable under appropriate circumstances. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. Some of the block diagrams shown in the figures are functional entities and do not necessarily correspond to physically or logically separate entities. These functional entities may be implemented in the form of software, or in one or more hardware circuits or integrated circuits, or in different networks and/or processor devices and/or microcontroller devices.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.
The present invention will be described in more detail with reference to the accompanying drawings and detailed description thereof, so that the objects, features and advantages thereof will be more clearly understood.
Fig. 4 shows a schematic structural diagram of an apparatus 100 for generating target evaluation light pulses for a quantum key distribution system according to an embodiment of the present invention. As shown in fig. 4, the apparatus 100 comprises a light source module 10 for emitting light pulses constituting a first light emission sequence; a modulation module 20 for modulating the light pulses in the first light emission sequence to generate light pulses constituting a second light emission sequence, wherein the light pulses in the second light emission sequence have different encoding states; the extinction module 40 is used for carrying out extinction on the optical pulses with the non-target coding state in the second light-emitting sequence according to the evaluation requirement and reserving the optical pulses with the target coding state so as to generate target evaluation optical pulses forming a third light-emitting sequence; and a control module 30, configured to send a control signal to the light source module 10, the modulation module 20, and the light extinction module 40 to drive the light source module 10, the modulation module 20, and the light extinction module 40 to cooperatively work.
Specifically, the basic operation principle of the apparatus 100 for generating a target evaluation light pulse includes: when the device 100 receives an evaluation requirement of evaluation software, the control module 30 outputs a control signal according to the evaluation requirement to drive the light source module 10 to output light pulses constituting a first light emitting sequence in a random light mode, and the control module 30 drives the modulation module 20 to perform quantum state and/or intensity modulation on the light pulses of the first light emitting sequence to generate light pulses constituting a second light emitting sequence with different quantum states and/or intensity states; subsequently, the control module 30 outputs a control signal to drive the extinction module 40 to perform extinction on the light pulses with the non-target quantum states and/or intensity states in the second light-emitting sequence and retain the light pulses with the target quantum states and/or intensity states according to the evaluation requirement, so as to generate target evaluation light pulses constituting a third light-emitting sequence; wherein, the sending of the control signal from the control module 30 to the light source module 10, the modulation module 20, and the extinction module 40 further includes: and outputting a control signal to the light source module 10, the modulation module 20 and the light extinction module 40 according to the evaluation requirement, so that the light source module 10, the modulation module 20 and the light extinction module 40 can cooperatively work.
In the device 100 disclosed in the present invention, the extinction module 40 is an optical extraction modulator 40 capable of implementing extinction. The extraction modulator 40 may be an electro-optic modulator or other type of modulator (e.g., an intensity modulator IM or Sagnac interferometer based intensity modulation module) disposed outside the transmit side light source section 50 of the quantum key distribution system as shown in fig. 5, or may be a multiplexing of the modulation modules 20 inside the transmit side light source section 50 as shown in fig. 6 and 7. The pumping modulator 40 adjusts the amplitude, phase, polarization, etc. of the optical pulse according to the encoding driving, and especially the amplitude modulation (i.e. intensity modulation) can realize the extinction and retention operation of the optical pulse without affecting the characteristics of the optical pulse itself.
Fig. 5 is a schematic structural diagram illustrating a first specific embodiment of the apparatus 100 for generating target evaluation light pulses for a quantum key distribution system according to the present invention. In this embodiment, the apparatus 100 includes a light source section 50 at the transmitting end of the quantum key distribution system and an extraction modulator 40 connected thereto. The transmitting end light source part 50 comprises a light source module 10, a modulation module 20 connected with the light source module 10, and a control module 30 connected with the light source module 10 and the modulation module 20, wherein the modulation module 20 comprises a decoy state modulation unit 21 and/or a quantum state modulation unit 22.
In this embodiment, when the apparatus 100 receives an evaluation requirement of evaluation software, the control module 30 outputs a control signal according to the evaluation requirement to control the light source module 10 to output the light pulses constituting the first light emitting sequence in a random light mode, and outputs the light pulses to the modulation module 20 for quantum state and/or intensity modulation, the decoy-state modulation unit 21 and/or the quantum-state modulation unit 22 in the modulation module 20 keep the random modulation mode unchanged, and the pumping modulator 40 receives the light pulses constituting the second light emitting sequence after quantum state and/or intensity modulation output by the modulation module 20, and performs a quenching operation on the light pulses constituting the second light emitting sequence according to the control signal output by the control module 30 to generate target evaluation light pulses constituting a third light emitting sequence. Therefore, under the condition of not changing the normal working state of the light source module 10, more accurate state parameters of the light pulse in the target coding state can be obtained, and the requirement of evaluation is met.
The pumping modulator 40 may also receive an evaluation requirement according to a control device (not shown in the figure) disposed outside the quantum key distribution system, or the pumping modulator 40 itself may have a control unit, which may receive the evaluation requirement from evaluation software and perform an extinction operation on the quantum state and/or intensity modulated optical pulse. It should be noted that the light extraction modulator 40 and the related control device need to be clock-synchronized with the light source module 10, the modulation module 20, and the control module 30.
Fig. 6 shows a schematic structural diagram of a second specific embodiment of the apparatus 100 for generating target evaluation light pulses for a quantum key distribution system according to the present invention. In this embodiment, the apparatus 100 is the light source part 50 at the transmitting end of the quantum key distribution system shown in fig. 5, and the light extraction modulator 40 is a multiplexing of the quantum state modulation units 22 in the modulation module 20, where the quantum state modulation units 22 are time phase quantum state modulation units or polarization quantum state modulation units. As shown in fig. 6, when measuring the state of light of different intensities (decoy states), the light source module 10 outputs a light pulse in a random light mode, and performs a light extraction operation using the quantum state modulation unit 22 as the light extraction modulator 40 while keeping the random modulation mode of the decoy state modulation unit 21 in the modulation module 20 unchanged.
Fig. 7 shows a schematic structural diagram of a third specific embodiment of the apparatus 100 for generating target evaluation light pulses for a quantum key distribution system provided in the present invention. In this embodiment, the apparatus 100 is the light source part 50 at the transmitting end of the quantum key distribution system shown in fig. 5, and the light extraction modulator 40 is a multiplex of the decoy state modulation unit 21 in the modulation module 20. As shown in fig. 7, when measuring the state of light with different phases or polarization quantum states (for example, H-polarized light in fig. 1), the light source module 10 outputs in a random light mode, while keeping the random modulation mode of the quantum state modulation unit 22 in the modulation module 20 unchanged, and performs the light pumping operation with the decoy state modulation unit 21 as the light pumping modulator 40.
The apparatus 100 (i.e., the transmitting-side light source section 50) shown in fig. 6 and 7 can obtain more accurate state parameters of the light pulses of the target encoding state without changing the normal operating state of the light source module 10, and meet the requirements of evaluation; meanwhile, an additional active light extraction modulator is not needed, and only an existing active modulation module in a multiplexing system is needed, for example, for polarization quantum state modulation, an additional passive polarization filter device can be used for assistance; for the time phase quantum state modulation, the attenuator on the interference arm corresponding to the non-preset time state can be used for assisting, and then the light extraction can be realized.
Fig. 8 is a schematic flow chart of a target evaluation light pulse generation method according to an embodiment of the present invention. The method comprises the following steps: s10, generating light pulses forming a first light emitting sequence; s11, modulating the light pulses forming the first light-emitting sequence to generate light pulses forming a second light-emitting sequence, wherein the light pulses in the second light-emitting sequence have different coding states; and S12, performing extinction on the light pulses with the non-target coding states in the second light-emitting sequence according to the evaluation requirement, and reserving the light pulses with the target coding states to generate target evaluation light pulses forming a third light-emitting sequence.
Specifically, referring to fig. 4 to 8 together, in step S10, the control module 30 outputs a driving signal according to the light emitting state instruction of the evaluation software to control the light source module 10 to output the light pulses constituting the first light emitting sequence, which is consistent with the state of normal operation of the quantum key distribution system (for example, in a random light mode), and the light source module 10 does not change the state parameters (such as timing, wavelength, amplitude, etc.) of the output light pulses.
In step S11, the control module 30 outputs a signal to the modulation module 20 according to the received evaluation requirement, so that the modulation module 20 performs at least one of quantum state modulation and intensity modulation on the light pulses in the first light emitting sequence to generate the second light emitting sequence, where the quantum state modulation includes polarization quantum state modulation, time phase quantum state modulation, or phase quantum state modulation on the light pulses in the first light emitting sequence.
In step S12, the control module 30 outputs a signal to the light extraction modulator 40 according to the received evaluation requirement, and the light extraction modulator 40 performs extinction on the light pulse with the non-target coding state in the second light-emitting sequence and retains the light pulse with the target coding state to generate a target evaluation light pulse constituting a third light-emitting sequence.
In a further embodiment, when the light extraction modulator 40 is an external electro-optical modulator of a quantum key distribution system as shown in fig. 5 or another type of modulator, step S11 further includes that the modulation module 20 performs quantum state modulation and/or intensity modulation on the light pulses in the first light-emitting sequence to generate the second light-emitting sequence, where the light pulses in the second light-emitting sequence have different quantum states and/or intensity states. Specifically, the quantum state modulation and intensity modulation modes are kept consistent with the state of normal operation of the quantum key distribution system, for example, the quantum state modulation unit 22 and the decoy state modulation unit 21 operate in the random modulation mode without changing the modulation characteristic parameters (i.e., without changing the voltage of the driving voltage sequence, etc.). Based on this, step S12 further includes outputting a signal to the light extraction modulator 40 according to the evaluation requirement received by the control module 30, where the light extraction modulator 40 performs extinction on the light pulse with the non-target quantum state and/or intensity state in the second light-emitting sequence and retains the light pulse with the target quantum state and/or intensity state to generate the target evaluation light pulse constituting the third light-emitting sequence. Therefore, under the condition of not changing the normal working state of the light source module 10, more accurate state parameters of the light pulse in the target coding state can be obtained, and the requirement of evaluation is met.
When the quantum state modulation unit 22 works in the random modulation mode, the control module 30 outputs 4 random different signals to the quantum state modulation unit 22 of the modulation module 20, so that the quantum state modulation unit 22 generates 4 different random pulse voltages, and the voltages act on the optical pulse sequence output by the light source module 10 to generate quantum state signals with 4 different polarizations or phases. When the spoof state modulating unit 21 works in the random modulation mode, the control module 30 outputs 3 random different signals to the spoof state modulating unit 21 of the modulating module 20, so that the spoof state modulating unit 21 generates 3 different random pulse voltages, which act on the light pulse sequence output by the light source module 10 to generate signals (spoof state signals) with 3 different intensities, i.e., a signal state, a spoof state, and a vacuum state.
It should be understood that the number of random different signals output by the control module 30 matches the number of quantum states and the number of decoy states, and the 4 kinds and 3 kinds are merely exemplary and not limited. In addition, the control module 30 can also control the quantum state modulation unit 22 and the decoy state modulation unit 21 to operate in a non-random modulation mode (i.e., voltage of the driving voltage sequence needs to be changed, etc.) to output the optical pulse in a specific state. Specifically, the control module 30 outputs a specific signal (for example, outputs an extinction modulation signal corresponding to the modulation signal) to the decoy state modulation unit 21 or the quantum state modulation unit 22 of the modulation module 20 according to the evaluation requirement, so that the decoy state modulation unit 21 or the quantum state modulation unit 22 generates a specific pulse voltage, and the voltage acts on the optical pulse sequence to generate a signal with a specific quantum state or intensity state.
In a further embodiment, when the optical pumping modulator 40 is multiplexing of the modulation module 20 inside the quantum key distribution system as shown in fig. 6 or fig. 7, that is, when the optical pumping modulator 40 is multiplexing the decoy state modulation unit 21 or the quantum state modulation unit 22 in the modulation module 20 (that is, the quantum state modulation unit 22 is a time phase quantum state modulation unit or a polarization quantum state modulation unit), steps S11 and S12 further include:
quantum state modulating the light pulses in the first light emission sequence to generate the second light emission sequence when the evaluation requirement indicates that the target evaluation light pulse is a light pulse having a target quantum state, wherein the light pulses in the second light emission sequence have different quantum states; and modulating, by the intensity modulation, light pulses in the second light emission sequence having the target quantum state to have a preset intensity state, and modulating light pulses in the second light emission sequence having a non-target quantum state to have a non-preset intensity state, wherein the non-preset intensity state is an extinction state.
When the evaluation requirement indicates that a target evaluation light pulse is a light pulse having a target intensity state, intensity modulating the light pulses in the first light emission sequence to generate the second light emission sequence, wherein the light pulses in the second light emission sequence have different intensity states; modulating the light pulses in the second light-emitting sequence with the target intensity state to have a preset polarization quantum state and modulating the light pulses in the second light-emitting sequence with the non-target intensity state to have a non-preset polarization quantum state by the polarization quantum state modulation; and retaining the light pulses with the preset polarization quantum states through a polarization filter, and performing extinction on the light pulses with the non-preset polarization quantum states.
When the evaluation requirement indicates that a target evaluation light pulse is a light pulse having a target intensity state, intensity modulating the light pulses in the first light emission sequence to generate the second light emission sequence, wherein the light pulses in the second light emission sequence have different intensity states; modulating light pulses in the second light-emitting sequence having a target intensity state to have a preset time quantum state and modulating light pulses in the second light-emitting sequence having a non-target intensity state to have a non-preset time quantum state by the time phase quantum state modulation; and performing extinction on the optical pulse with the non-preset time quantum state through an optical attenuator so as to retain the optical pulse with the preset time quantum state.
The process of extracting different quantum state or decoy state optical pulses as optical pulses required for evaluation when the optical extraction modulator multiplexes modulation modules inside the quantum key distribution system will be described in detail below with reference to fig. 9 to 11.
Fig. 9 is a timing chart showing modulation voltages corresponding to a light emission sequence when the pumping modulator multiplexes the decoy state modulation unit to pump an H-polarized state light pulse as a light pulse required for evaluation according to the embodiment of the present invention.
Referring to fig. 7 and fig. 9, when the light pulse required for evaluation is a specific quantum state light pulse, such as an H polarized light pulse of a polarization system, the light source module 10 is first kept to output a light pulse sequence in a random light mode, and the random modulation state of the quantum state modulation unit 22 in the modulation module 20 is unchanged, that is, 4 random different signals are output to the quantum state modulation unit 22 by the control module 30, so that the quantum state modulation unit 22 generates 4 different random pulse voltages, that is, V polarized light pulses 0 、V π 、V π/2 、V 3π/2 Voltages respectively applied to the optical pulse train output by the light source module 10 to generate an optical pulse train having quantum state signals with 4 different polarizations, wherein the voltages respectively corresponding to the H, V, P, and N polarization states are V 0 、V π 、V π/2 、V 3π/2 A voltage. Next, the H-polarization optical pulse modulated by the quantum state modulation unit 22 is modulated into a light-holding state when the decoy state modulation (i.e., intensity modulation) is performed by the decoy state modulation unit 21; and other polarized light pulses except the light pulse in the H polarization state modulate the extinction state with the minimum light intensity when the trick state is modulated. Therefore, specific H polarized light pulse can be reserved, and other polarized light pulses can be eliminated.
According to the modulation condition (i.e., pulse voltage sequence, etc.) of the quantum state modulation unit 22, the control module 30 generates a corresponding extinction modulation signal and outputs the extinction modulation signal to the decoy state modulation unit 21 to generate two decoy state modulation voltages, where the two modulation voltages respectively act on the H-polarized light pulse and the non-H-polarized light pulse in the optical pulse sequence modulated by the quantum state modulation unit 22 to generate a light emitting sequence with two optical pulse intensities, and the two optical pulse intensities are respectively set to be in "bright" and "extinction" intensity states. Note that the specific intensities of "bright" and "dark" are not limited herein. Preferably, the "light" state has a light intensity close to the maximum light intensity, and the "light extinction" state has a light intensity close to zero.
It should be understood that, similarly, if the pumping modulator 40 multiplexes the decoy state modulation unit 21 to pump the phase state light pulse as the light pulse required for evaluation, the quantum state modulation unit 22 needs to generate 4 different random pulse voltages to act on the light pulse sequences output by the light source module 10 respectively, so as to generate a light pulse sequence with 4 quantum state signals with different phases, and the phase state light pulse required for evaluation, which is modulated by the quantum state modulation unit 22, modulates the reserved state of light when decoy state modulation (i.e. intensity modulation) is performed by the decoy state modulation unit 21; and other phase state light pulses except the quantum state light pulse required for evaluation modulate the extinction state of the minimum light intensity when the deception state is modulated. The specific modulation mode is similar to the above-mentioned extraction of the H-polarized light pulse as the light pulse required for evaluation, and is not described herein again.
Fig. 10 shows a timing chart of modulation voltages corresponding to a light emission sequence when the pumping modulator multiplexes the quantum state modulation unit, which is a time phase quantum state modulation unit, to pump a D decoy state light pulse as a light pulse necessary for evaluation.
Referring to fig. 6 and 10 together, when the light pulse required for evaluation is a light pulse with a specific intensity (decoy state), such as a D-decoy state light pulse, the light source module 10 is first kept to output a light pulse sequence in a random light mode, and the random modulation state of the decoy state modulation unit 21 in the modulation module 20 is unchanged, that is, 3 random different signals are output to the decoy state modulation unit 21 by the control module 30, so that the decoy state modulation unit 21 generates 3 different random pulse voltages, which respectively act on the light pulse sequence output by the light source module 10 to generate signals (decoy state signals) with 3 different intensities, that is, a signal state, a decoy state and a vacuum state, which are respectively denoted by S, D and V in fig. 10. Next, when the D decoy state light pulse modulated by the decoy state modulation unit 21 is subjected to quantum state modulation by the time phase quantum state modulation unit 22, a first time state (denoted as "reserved") is modulated; while other light pulses than the D-decoy state light pulse modulate other temporal states than the first temporal state (denoted as "extinction").
Specifically, as shown in fig. 10, when the D decoy-state light pulse modulated by the decoy-state modulation unit 21 is quantum-state modulated by the time-phase quantum-state modulation unit 22, the T0 time state is modulated; and other light pulses except the D decoy state light pulse modulate other T1 time states. Then, the extinction of the T1 time state is realized by the improvement of the attenuation value of the Variable Optical Attenuator (VOA) on the corresponding path of the unequal arm interferometer through which the T1 time state passes in the time phase quantum state modulation unit 22.
Similar to the above-mentioned multiplexed decoy state modulation unit 21, according to the modulation condition (i.e. pulse voltage sequence, etc.) of the decoy state modulation unit 21, the control module 30 generates a corresponding extinction modulation signal and outputs the extinction modulation signal to the time phase quantum state modulation unit 22 to generate two time phase quantum state modulation voltages, where the two modulation voltages respectively act on the D decoy state optical pulse and the non-D decoy state optical pulse in the optical pulse sequence modulated by the decoy state modulation unit 21 to correspondingly generate a light emitting sequence of optical pulses having T0 time state and T1 time state.
Fig. 11 is a timing chart showing modulation voltages corresponding to a light emission sequence when the pumping modulator multiplexes the quantum state modulation unit to pump the D decoy state light pulse as the light pulse required for evaluation, according to another embodiment of the present invention, wherein the quantum state modulation unit is a polarization quantum state modulation unit.
Referring to fig. 6 and fig. 11 together, when the light pulse required for evaluation is a light pulse with a specific intensity (spoofing state), such as a D-spoofing state light pulse, the light source module 10 is first kept to output a light pulse sequence in a random light mode, and the random modulation state of the spoofing state modulation unit 21 in the modulation module 20 is unchanged, that is, 3 random different signals are output to the spoofing state modulation unit 21 by the control module 30, so that the spoofing state modulation unit 21 generates 3 different random pulse voltages, which respectively act on the light pulse sequence output by the light source module 10 to generate signals (spoofing state signals) with 3 different intensities, that is, a signal state, a spoofing state and a vacuum state, which are respectively represented by S, D and V in fig. 11. Next, the D decoy-state light pulse modulated by the decoy-state modulation unit 21 is modulated into a first polarization state (denoted as "reserved") when the polarization quantum state modulation is performed by the polarization quantum state modulation unit 22; while light pulses other than the D-decoy state light pulses modulate other polarization states other than the first polarization state (identified as "extinction").
Specifically, when the D decoy state light pulse modulated by the decoy state modulation unit 21 is quantum-state modulated by the polarization quantum-state modulation unit 22, the H polarization state is modulated; and the light pulses other than the D decoy state light pulse modulate other polarization states different from the H polarization state, for example, the V polarization state. Then, the other polarization states are extinguished through an additionally arranged passive polarization filter device. For example, the polarization filter device is a Polarization Beam Splitter (PBS) configured such that the H polarization state is transmitted and retained, and other polarization states (e.g., the V polarization state) are not transmitted and extinguished.
It should be understood that when the polarization quantum state modulation unit 22 performs quantum state modulation, the polarization state other than the H polarization state can be modulated as the "reserved" polarization state, and at the same time, the polarization filtering device (e.g., PBS) needs to be adjusted in the subsequent optical path to match the "reserved" polarization state and to extinguish the corresponding polarization state other than the "reserved" polarization state. Meanwhile, the selection of the reserved polarization state does not influence the safety evaluation result.
Similar to the above-mentioned multiplexed spoofed state modulation unit 21, according to the modulation condition (i.e. pulse voltage sequence, etc.) of the spoofed state modulation unit 21, the control module 30 generates a corresponding extinction modulation signal and outputs the extinction modulation signal to the polarization quantum state modulation unit 22 to generate two polarization quantum state modulation voltages (for example, corresponding to the H polarization state and the V polarization state, respectively), which are respectively applied to the D spoofed state light pulse and the non-D spoofed state light pulse in the light pulse sequence modulated by the spoofed state modulation unit 21 to correspondingly generate a light emitting sequence of light pulses with the H polarization state and the V polarization state.
It should be understood that the "extinction" identified in fig. 9-11 is such that this light pulse is not present, while the "hold" is such that this light pulse is output; and the quantum state or decoy state, identified by the dashed box, represents that the light pulse in this quantum state or decoy state will be extinguished in a subsequent step.
The light extraction is not limited to extracting a certain state independently through the method, the measured light state can be measured according to any combination of codes, and the true reliability of the measurement result can be proved.
The method for generating the light in the specific state can also be used for a calibration feedback stage, such as a polarization feedback stage, of the quantum key distribution system, and only light in a certain specific state needs to be emitted.
It should be noted that although the pumping modulator is the modulation module of the multiplexing quantum key distribution system itself, the random control signal and the corresponding modulation voltage applied to the modulation module may not be the same as the normal operation stage of the quantum key distribution system, and at this time, it is necessary to configure appropriate values so as to achieve a higher extinction ratio for states other than the specific state. For example, in normal operation, the decoy state modulation unit modulates three different intensities of a signal state, a decoy state and a vacuum state according to a ratio of 6. Meanwhile, the system complexity and the evaluation complexity can be reduced by multiplexing the existing quantum state modulation unit and decoy state modulation unit of the system.
Specifically, if the optical pulse in the substate needs to be measured, the dummy state modulation unit is multiplexed to extinguish the optical pulse in the other state than the measured substate. If the decoy state light pulse needs to be detected, the quantum state modulation unit is multiplexed, so that the light pulses in other states except the detected decoy state are extinguished. For the time phase coding system, when multiplexing the time phase quantum state modulation unit, a certain time state is modulated first, and then the time state in the time phase quantum state modulation unit is utilized to realize extinction through VOA attenuation on an inner path of an interferometer. For the polarization coding system, when the polarization quantum state modulation unit is multiplexed, a certain polarization state is modulated firstly, then the polarization state is reserved through an additional passive polarization filter device, and the rest polarization states are not penetrated and are extinguished.
In another embodiment, there is provided an optical pulse transmitting apparatus for a quantum key distribution system, the apparatus including the above-described apparatus for generating a target evaluation optical pulse.
As can be seen from the above, in the prior art, since the light-emitting sequence of the light source in the evaluation stage and the truly random (including periodic) light-emitting sequence in the normal working stage of the system may have a difference and cannot represent a real working state, the measurement result of the state parameters (such as wavelength, amplitude, timing sequence, etc.) of the light pulses in each encoding state cannot accurately reflect the real working state of the object to be measured, and thus, the safety of the quantum key distribution system may be misjudged easily. In contrast, according to the method, the device and the transmitting equipment for generating the evaluation light pulse, provided by the invention, during evaluation, light emitted by the light source module of the quantum key distribution system is always consistent with the state of the system during normal work; meanwhile, light not required for evaluation is eliminated by the light extraction modulator, and light in a specific state required for evaluation is retained, thereby generating light in a specific state required for evaluation. The pumping modulator hardly brings extra influence to the measured parameters (such as time sequence, wavelength, amplitude and the like) of the measured object (such as the optical pulse in each coding state), so that the measured object can be better and accurately reflected by the evaluation result, and the safety evaluation result in a real working state is obtained.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database or other medium used in the embodiments provided herein can include non-volatile and/or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), rambus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
The above detailed description is given to the method, apparatus, and device for generating target evaluation light pulses for a quantum key distribution system according to the embodiments of the present invention, and specific examples are applied herein to explain the principles and embodiments of the present invention, and the description of the above embodiments is only used to help understanding the technical solutions and core ideas of the present invention; those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications or substitutions do not depart from the spirit and scope of the present invention in its embodiments.

Claims (14)

1. A method for generating target evaluation light pulse, which is used for a quantum key distribution system, is characterized by comprising the following steps:
generating light pulses constituting a first light emission sequence;
modulating the light pulses comprising the first light emission sequence to generate light pulses comprising a second light emission sequence, wherein the light pulses in the second light emission sequence have different encoding states; and
and performing extinction on the light pulses with the non-target coding state in the second light-emitting sequence and keeping the light pulses with the target coding state according to the evaluation requirement to generate target evaluation light pulses forming a third light-emitting sequence.
2. The method of generating a target evaluation light pulse according to claim 1, wherein the encoding state includes at least one of a quantum state and an intensity state.
3. The method of generating target evaluation light pulses of claim 1 further comprising at least one of quantum state modulating and intensity modulating the light pulses in the first light emission sequence to generate the second light emission sequence, wherein the quantum state modulating comprises polarization quantum state modulating, time phase quantum state modulating, or phase quantum state modulating the light pulses in the first light emission sequence.
4. The method of generating an objective evaluation light pulse according to claim 3, further comprising:
quantum state modulating and/or intensity modulating the light pulses in the first light emission sequence to generate the second light emission sequence, wherein the light pulses in the second light emission sequence have different quantum states and/or intensity states; and
quenching the light pulses in the second light emission sequence having non-target quantum states and/or intensity states and retaining the light pulses having target quantum states and/or intensity states according to the evaluation requirement to generate the target evaluation light pulses.
5. The method of generating a target evaluation light pulse according to claim 3, further comprising:
quantum state modulating the light pulses in the first light emission sequence to generate the second light emission sequence when the evaluation requirement indicates that the target evaluation light pulse is a light pulse having a target quantum state, wherein the light pulses in the second light emission sequence have different quantum states; and
modulating, by the intensity modulation, light pulses in the second light emission sequence having the target quantum state to have a preset intensity state, and modulating light pulses in the second light emission sequence having a non-target quantum state to have a non-preset intensity state, wherein the non-preset intensity state is an extinction state.
6. The method of generating a target evaluation light pulse according to claim 3, further comprising:
when the evaluation requirement indicates that a target evaluation light pulse is a light pulse having a target intensity state, intensity modulating the light pulses in the first light emission sequence to generate the second light emission sequence, wherein the light pulses in the second light emission sequence have different intensity states;
modulating light pulses in the second light-emitting sequence having a target intensity state to have a preset time quantum state and modulating light pulses in the second light-emitting sequence having a non-target intensity state to have a non-preset time quantum state by the time phase quantum state modulation; and
and performing extinction on the optical pulse with the non-preset time quantum state through an optical attenuator so as to retain the optical pulse with the preset time quantum state.
7. The method of generating an objective evaluation light pulse according to claim 3, further comprising:
when the evaluation requirement indicates that a target evaluation light pulse is a light pulse having a target intensity state, intensity modulating the light pulses in the first lighting sequence to generate the second lighting sequence, wherein the light pulses in the second lighting sequence have different intensity states;
modulating the light pulses in the second light-emitting sequence with the target intensity state to have a preset polarization quantum state and modulating the light pulses in the second light-emitting sequence with the non-target intensity state to have a non-preset polarization quantum state by the polarization quantum state modulation; and
the light pulses with the preset polarization quantum states are retained by a polarization filter, and the light pulses with the non-preset polarization quantum states are subjected to extinction.
8. An apparatus for generating target evaluation light pulses for use in a quantum key distribution system, comprising:
the light source module is used for emitting light pulses forming a first light emitting sequence;
a modulation module for modulating the light pulses in the first light emission sequence to generate light pulses constituting a second light emission sequence, wherein the light pulses in the second light emission sequence have different encoding states; and
the extinction module is used for carrying out extinction on the optical pulses with the non-target coding state in the second light-emitting sequence according to the evaluation requirement and reserving the optical pulses with the target coding state so as to generate target evaluation optical pulses forming a third light-emitting sequence; and
and the control module is used for sending control signals to the light source module, the modulation module and the extinction module so as to drive the light source module, the modulation module and the extinction module to cooperatively work.
9. The apparatus for generating a target evaluation light pulse according to claim 8, wherein the encoding state includes at least one of a quantum state and an intensity state.
10. The apparatus for generating a target evaluation light pulse according to claim 8, wherein the modulation module comprises a quantum state modulation unit and/or a decoy state modulation unit for quantum state modulating and/or intensity modulating the light pulses in the first light emitting sequence to generate the second light emitting sequence, respectively, wherein the light pulses in the second light emitting sequence have different quantum states and/or intensity states; and
the extinction module is an optical extraction modulator and is used for carrying out extinction on the optical pulses with the non-target quantum states and/or the intensity states in the second light-emitting sequence according to the evaluation requirement and retaining the optical pulses with the target quantum states and/or the intensity states so as to generate the target evaluation optical pulses.
11. The apparatus for generating target evaluation light pulses of claim 8 wherein the modulation module comprises a quantum state modulation unit for quantum state modulating the light pulses in the first light emission sequence to generate the second light emission sequence, wherein the light pulses in the second light emission sequence have different quantum states; and
the extinction module comprises a decoy state modulation unit which is used for modulating the light pulse with the target quantum state in the second light-emitting sequence into a preset intensity state and modulating the light pulse with the non-target quantum state in the second light-emitting sequence into a non-preset intensity state, wherein the non-preset intensity state is an extinction state.
12. The apparatus for generating target evaluation light pulses of claim 8, wherein the modulation module comprises a decoy state modulation unit for intensity modulating the light pulses in the first light emission sequence to generate the second light emission sequence, wherein the light pulses in the second light emission sequence have different intensity states; and
the extinction module comprises a time phase quantum state modulation unit, and is configured to modulate a light pulse with a target intensity state in the second light-emitting sequence into a preset time quantum state, and modulate a light pulse with a non-target intensity state in the second light-emitting sequence into a non-preset time quantum state, wherein the extinction module further comprises an optical attenuator, and is configured to perform extinction on the light pulse with the non-preset time quantum state, so as to retain the light pulse with the preset time quantum state.
13. The apparatus for generating target evaluation light pulses of claim 8 wherein the modulation module comprises a decoy state modulation unit for intensity modulating the light pulses in the first light emission sequence to generate the second light emission sequence, wherein the light pulses in the second light emission sequence have different intensity states; and
the extinction module comprises a polarization quantum state modulation unit, which is used for modulating the light pulse with the target intensity state in the second light-emitting sequence into a preset polarization quantum state, and modulating the light pulse with the non-target intensity state in the second light-emitting sequence into a non-preset polarization quantum state, wherein the extinction module further comprises a polarization filter, which is used for retaining the light pulse with the preset polarization quantum state and carrying out extinction on the light pulse with the non-preset polarization quantum state.
14. An optical pulse transmission apparatus for a quantum key distribution system, characterized in that the apparatus comprises the apparatus for generating an object evaluation optical pulse according to any one of claims 8 to 13.
CN202110587046.8A 2021-05-27 2021-05-27 Target evaluation light pulse generation method, device and equipment Pending CN115412231A (en)

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