WO2023016534A1 - 用于单光子探测器的门控装置和量子通信设备 - Google Patents

用于单光子探测器的门控装置和量子通信设备 Download PDF

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WO2023016534A1
WO2023016534A1 PCT/CN2022/111947 CN2022111947W WO2023016534A1 WO 2023016534 A1 WO2023016534 A1 WO 2023016534A1 CN 2022111947 W CN2022111947 W CN 2022111947W WO 2023016534 A1 WO2023016534 A1 WO 2023016534A1
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periodic gating
quantum communication
gating signal
communication system
periodic
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PCT/CN2022/111947
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French (fr)
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陈柳平
范永胜
王其兵
万相奎
李南
金振阳
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国开启科量子技术(北京)有限公司
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    • 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

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  • the invention relates to the technical field of quantum communication, in particular to a gate control device for a single photon detector and quantum communication equipment.
  • the quantum communication system it is mainly used to apply a periodic gating signal to the single photon detector as shown in FIG. 5B to open the gate of the single photon detector to detect the light pulse transmitted in the quantum communication system.
  • this way of applying the gating signal leads to a high repetition rate due to the use of a single periodic gating signal, which increases the dark count and post-pulse count in the single-photon detector, which will cause the quantum communication system to be in the coding state.
  • the error rate in the process increases, thereby reducing the coding rate of the system.
  • the present invention provides a gate control device and a quantum communication device for a single photon detector.
  • a gating device for a single photon detector, the gating device comprising: a system synchronization unit configured to obtain a periodic gating signal synchronized with a clock of a quantum communication system; A clock distributor configured to divide the periodic gating signal into two identical periodic gating signals; a delayer configured to control one of the two periodic gating signals The signal is delayed, so that one of the two periodic gating signals is different from the other periodic gating signal by a predetermined duration in time, wherein the predetermined duration is for The optical path difference between the long arm and the short arm of the unequal arm interferometer for phase encoding in a quantum communication system; and a logic OR gate configured to pair a delayed periodic gated signal with an undelayed Another way of periodic gating signal is ORed to generate a periodic gating signal sequence synchronized with the clock of the quantum communication system, and the gating signals in each gating signal sequence are spaced from each other by a pre
  • a quantum communication device includes the aforementioned gate control device for a single photon detector.
  • the gating device and quantum communication equipment for single photon detectors provided by the present invention can effectively reduce the high-frequency periodical gating signal caused by the use of high-repetition-frequency periodic gating signals for single-photon detectors in quantum communication systems.
  • the dark counting and post-pulse counting can greatly reduce the error rate of the quantum communication system in the coding process.
  • the gating device and quantum communication equipment for single photon detectors provided by the present invention can also significantly reduce the number of single photon detectors and polarization beam splitters used in quantum communication systems, which can not only greatly reduce System implementation cost, but also to avoid the insertion loss caused by the use of additional polarization beam splitter.
  • FIG. 1A shows a schematic diagram of a gating device for a single photon detector according to an exemplary embodiment of the present invention.
  • FIG. 1B shows a schematic diagram of the signal timing sequence of the working process of the gate control device for a single photon detector according to an exemplary embodiment of the present invention.
  • FIG. 2A shows another schematic diagram of a gating device for a single photon detector according to an exemplary embodiment of the present invention.
  • FIG. 2B shows another schematic diagram of signal timing of the working process of the gate control device for a single photon detector according to an exemplary embodiment of the present invention.
  • FIG. 3A shows a schematic diagram of a narrow pulse generating unit in a gating device for a single photon detector according to an exemplary embodiment of the present invention.
  • FIG. 3B shows a schematic diagram of the signal sequence of the working process of the narrow pulse generating unit in the gate control device for a single photon detector according to an exemplary embodiment of the present invention.
  • FIG. 4 shows a schematic diagram of a system synchronization unit in a gating device for a single photon detector according to an exemplary embodiment of the present invention.
  • Fig. 5A shows a schematic diagram of a quantum communication system based on time-phase encoding in the related art.
  • Fig. 5B shows a schematic diagram of applying a gating signal to the single photon detector in the quantum communication system shown in Fig. 5A to detect the time code carried by the light pulse using the related technology.
  • Fig. 6A shows a schematic diagram of a quantum communication system based on time-phase encoding according to an exemplary embodiment of the present invention.
  • Fig. 6B shows the application of a gating signal to the single-photon detector in the quantum communication system shown in Fig. 6A using the gating device for a single-photon detector according to an exemplary embodiment of the present invention to detect the Schematic diagram of time encoding.
  • FIG. 7 is a schematic diagram showing a comparison between a periodic gating signal output using a correlation technique and a periodic gating signal sequence output using a gating device for a single photon detector according to an exemplary embodiment of the present invention.
  • FIG. 1A shows a schematic diagram of a gating device for a single photon detector according to an exemplary embodiment of the present invention.
  • FIG. 1B shows a schematic diagram of the signal timing sequence of the working process of the gate control device for a single photon detector according to an exemplary embodiment of the present invention.
  • a gating device for a single photon detector may at least include a system synchronization unit 101 , a clock distributor 102 , a delayer 103 and a logical OR gate 104 .
  • the system synchronization unit 101 can be configured to obtain a periodic gating signal 1010 synchronized with the clock of the quantum communication system (that is, the clock of the encoded signal of the quantum communication system); the clock distributor 102 can be configured to divide the periodic gating signal 1010 into the same two-way periodic gating signal 1011 and 1012; The gating signal 1011 is subjected to delay processing, so that one of the two periodic gating signals 1011 and 1012 has a time difference between the one periodic gating signal 1011 and the other periodic gating signal 1012 by a predetermined duration ⁇ t 1 .
  • the predetermined duration ⁇ t 1 may be the optical path difference between the long arm and the short arm of the unequal arm interferometer used for phase encoding in the quantum communication system; the logical OR gate 104 may be configured to compare the delayed One path of periodic gating signal 1013 and another path of non-delayed periodic gating signal 1012 are ORed to generate a periodic gating signal sequence 1014 synchronized with the clock of the quantum communication system, and each of the gating signal sequences
  • the gating signals are spaced from each other by a predetermined duration ⁇ t 1 such that the single photon detector in the quantum communication system opens the gate of the single photon detector in response to a received light pulse (in other words, makes the single photon detector in the quantum communication system Photon detectors operate in Geiger mode for received light pulses). This minimizes dark counts and post-pulse counts in single-photon detectors in quantum communication systems due to unnecessary repetitive gating signals.
  • the quantum communication system may be a quantum communication system based on time-phase encoding, or a quantum communication system based on phase encoding.
  • a quantum communication system based on time-phase encoding using the periodic gating signal sequence 1014 output by the gating device shown in FIG. Opening the gate of the single-photon detector by the coded light pulse can also enable the single-photon detector to open the gate of the single-photon detector for the light pulse carrying the phase code received in the quantum communication system, and can also make the The single-photon detector can open the gate of the single-photon detector for the time-encoded light pulse and the phase-encoded light pulse received in the quantum communication system.
  • each of the periodic gating signal sequences 1014 shown in FIG. 1B includes 2 gating signals spaced apart from each other by a predetermined duration ⁇ t 1 , the present invention is not limited thereto, As needed, more devices than those shown in Figure 1A (such as, but not limited to, more clock distributors, delayers, and OR gates, etc.) can be used to make the periodic gating signal sequence
  • Each of the gating signal sequences includes more gating signals than the gating signals of each gating signal sequence in the periodic gating signal sequence 1014 shown in FIG. 1B , which can not only significantly reduce the The number of single-photon detectors and polarization beam splitters used in the system can greatly reduce the cost of system implementation, and can also avoid the insertion loss caused by the use of additional polarization beam splitters.
  • FIG. 2A shows another schematic diagram of a gating device for a single photon detector according to an exemplary embodiment of the present invention.
  • FIG. 2B shows another schematic diagram of signal timing of the working process of the gate control device for a single photon detector according to an exemplary embodiment of the present invention.
  • the gating device shown in Figure 2A can also include a narrow pulse generation unit in addition to the system synchronization unit 101, clock distributor 102, delayer 103 and logical OR gate 104 shown in Figure 1A 105 , the narrow pulse generation unit 105 may be disposed between the system synchronization unit 101 and the clock distributor 102 , and may be configured to narrow the pulse width of the periodic gating signal 1014 . In the case that the pulse width of the gating signal exceeds the system threshold, this enables the pulse width of the gating signal generated by the above-mentioned gating device to meet the working requirements of the quantum communication system for single photon detectors in Geiger mode.
  • the implementation of the narrow pulse generating unit 105 will be described in detail below with reference to FIGS. 3A and 3B .
  • FIG. 3A shows a schematic diagram of a narrow pulse generating unit 105 in a gating device for a single photon detector according to an exemplary embodiment of the present invention.
  • FIG. 3B shows a schematic diagram of signal timing of the working process of the narrow pulse generating unit 105 in the gate control device for a single photon detector according to an exemplary embodiment of the present invention.
  • the narrow pulse generating unit 105 shown in FIG. 3A may include a clock distributor 106 , a delayer 107 and a logical AND gate 108 .
  • the clock distributor 106 can be configured to divide the periodic gating signal 1010 into the same two-way periodic gating signals 1016 and 1017; the delayer 107 can be configured as Delay processing is performed on one of the periodic gating signals 1016 in the two periodic gating signals 1016 and 1017, so that the periodic gating signal 1016 of the two periodic gating signals 1016 and 1017 is different from the other periodic gating signal 1016
  • the gate control signal 1017 differs in time by a predetermined duration ⁇ t 2 , and the predetermined duration ⁇ t 2 is less than the pulse width of the periodic gate control signal;
  • the logic AND gate 108 can be configured to control the delayed one-way periodic gate An AND operation is performed on the signal 1018 and another undelayed periodic gating signal 1017 to narrow the pulse width of the periodic gating signal.
  • FIG. 3A shows a schematic diagram of the narrow pulse generating unit 105 in the gating device for a single photon detector according to an exemplary embodiment of the present invention
  • the present invention is not limited thereto, and other devices or a combination of other devices to implement the narrow pulse generating unit 105.
  • the components in the narrow pulse generating unit 105 may be more or less than those shown in FIG. 3A .
  • system synchronization unit 101 The implementation of the system synchronization unit 101 will be described in detail below with reference to FIG. 4 .
  • FIG. 4 shows a schematic diagram of a system synchronization unit 101 in a gating device for a single photon detector according to an exemplary embodiment of the present invention.
  • a system synchronization unit 101 in a gating device for a single photon detector may include a synchronization photodetection unit 109 and a phase-locked loop 110 .
  • the synchronization light detection unit 109 can be configured to convert the received synchronization light of the quantum communication system (that is, the synchronization light emitted synchronously with the optical pulse in the encoded signal) into a synchronization electrical signal to obtain the clock 1009 of the quantum communication system;
  • the phase-locked loop 110 can be configured to phase-lock and frequency-multiply the synchronous electrical signal to obtain a periodic gating signal 1010 synchronized with the clock 1009 of the quantum communication system.
  • the system synchronization unit 101 shown in FIG. Sex gating signal so that the low frequency signal is converted into high frequency signal.
  • FIG. 4 shows a schematic diagram of a system synchronization unit 101 in a gating device for a single photon detector according to an exemplary embodiment of the present invention
  • the present invention is not limited thereto, and other devices may also be used or a combination of other devices to implement the system synchronization unit 101.
  • the devices in the system synchronization unit 101 may be more or less than those shown in FIG. 4 .
  • Fig. 5A shows a schematic diagram of a quantum communication system based on time-phase encoding in the related art.
  • a quantum communication system based on time-phase encoding may include an Alice end and a Bob end.
  • the light pulse sent from Alice end can reach one of the single photon detectors D 0 , D 1 , D 2 and D 3 in Bob end, wherein, through the unequal arm interferometer
  • the paths ( L 2 , L 4 ) and (L 1 , L 3 ) provided by MZ 1 and MZ 2 will not cause optical interference for the light pulses reaching Bob, and the paths ( Light pulses of L 1 , L 4 ) and (L 2 , L 3 ) arriving at Bob's end will produce light phenomena.
  • Alice and Bob can modulate the phases of the phase modulators PM 1 and PM 2 to make the intensity of the interfering optical pulses vary with the phase difference, thereby implementing phase encoding.
  • the Alice end and the Bob end can also adjust the time of the light pulse, so as to realize time encoding.
  • the optical pulses carrying the phase encoding can be randomly assigned to one of the single photon detectors D0 and D1 in the Bob end for detection, and the optical pulses carrying the time encoding can be randomly assigned to the Bob end Detection is performed in one of the single photon detectors D2 and D3 .
  • FIG. 5B shows a schematic diagram of applying a gate signal to the single-photon detectors D 2 and D 3 in the quantum communication system shown in FIG. 5A to detect the time code carried by the light pulse using related techniques.
  • Fig. 6A shows a schematic diagram of a quantum communication system based on time-phase encoding according to an exemplary embodiment of the present invention.
  • the quantum communication system based on time-phase encoding shown in FIG. 6A may include an Alice end and a Bob end.
  • the optical pulse emitted from Alice’s end can reach one of the single-photon detectors D 0 , D 1 and D 2 at Bob’s end, wherein, via the unequal arm interferometer MZ 1 and The optical pulses from the paths (L 2 , L 4 ) and (L 1 , L 3 ) provided by MZ 2 to Bob’s end will not undergo optical interference, and the paths (L 1 , L 4 ) and (L 2 , L 3 ) light pulses arriving at the Bob end will produce light phenomena.
  • Alice and Bob can modulate the phases of the phase modulators PM 1 and PM 2 to make the intensity of the interfering optical pulses vary with the phase difference, thereby implementing phase encoding.
  • the Alice end and the Bob end can also adjust the time of the light pulse, so as to realize time encoding.
  • the optical pulses carrying the phase encoding can be randomly assigned to one of the single photon detectors D 0 and D 1 in the Bob end for detection, and the optical pulses carrying the time encoding can be It is directly assigned to a single single photon detector D2 in the Bob end for detection.
  • FIG. 6B shows the application of a gating signal to the single-photon detector D2 in the quantum communication system shown in FIG. 6A using the gating device 100 for a single-photon detector according to an exemplary embodiment of the present invention Schematic representation of time encoding carried by probe light pulses.
  • the quantum communication system shown in FIG. 6A only uses A single single-photon detector D2 is used to detect the time code carried by the light pulse, which can not only reduce the number of single-photon detectors used in the quantum communication system, reduce the cost of system implementation, but also avoid the use of
  • the insertion loss caused by the polarized beam splitter BS is about 3dB under normal circumstances.
  • FIG. 6A and FIG. 6B respectively illustrate the use of the gating device 100 for a single photon detector according to an exemplary embodiment of the present invention to detect the time code carried by the light pulse via a single single photon detector D2 example, but this example is only illustrative, and the present invention is not limited thereto.
  • the gating device 100 for a single photon detector according to an exemplary embodiment of the present invention can also be used to pass through a single A photon detector is used to detect the phase encoding carried by the light pulse, and even a suitable modification can be made on the gating device 100 for a single photon detector according to an exemplary embodiment of the present invention, for example, by making the The gating device out includes more devices (such as, but not limited to, including more clock distributors, more delays, or more logical OR gates) to enable Each of the periodic gating signal sequences 1014 output by the gating device 100 for a single-photon detector includes more than two gating signals, so that a single single-photon detector can both detect light pulses The phase code carried by the light pulse can also be detected by the time code carried by the light pulse.
  • FIG. 7 shows a comparison of a periodic gating signal 1000 output using a related technique and a periodic gating signal sequence 1014 output using a gating device 100 for a single photon detector according to an exemplary embodiment of the present invention.
  • the periodic gating signal sequence 1014 outputted using the gating device 100 for a single photon detector according to an exemplary embodiment of the present invention has A lower repetition rate, which can reduce the dark count and post-pulse count caused by the high repetition rate of the single photon detector in the quantum communication system during high-frequency operation, thereby reducing the quantum communication system to a large extent.
  • the error rate in the coding process is not limited to the following abbreviations:
  • the present invention also provides a quantum communication device (such as the Bob end shown in FIG.
  • Dark counting and post-pulse counting caused by the use of high-repetition-frequency periodic gating signals during high-frequency operation can greatly reduce the error rate of quantum communication systems in the coding process.
  • it can also Significantly reduce the number of single-photon detectors and polarization beam splitters used in quantum communication systems to reduce the system implementation cost while avoiding the interpolation caused by the use of an additional polarization beam splitter BS (as shown in Fig. 5A). damage.

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Abstract

本发明提供用于单光子探测器的门控装置和量子通信设备，所述门控装置包括：系统同步单元，被配置为获取与量子通信系统的时钟同步的周期性门控信号；时钟分配器，被配置为将周期性门控信号分成两路周期性门控信号；延时器，被配置为对两路周期性门控信号中的一路周期性门控信号进行延时处理，使得一路周期性门控信号与另一路周期性门控信号在时间上相差预定持续时间；以及逻辑或门，被配置为对延时后的一路周期性门控信号和未延时的另一路周期性门控信号进行或操作，以产生与量子通信系统的时钟同步的周期性门控信号序列。

Description

用于单光子探测器的门控装置和量子通信设备 技术领域
本发明涉及量子通信技术领域，尤其涉及用于单光子探测器的门控装置和量子通信设备。
背景技术
目前，在量子通信系统中，主要采用向单光子探测器施加如图5B所示的周期性门控信号来打开单光子探测器的门控以对在量子通信系统中传输的光脉冲进行探测。然而，这种施加门控信号的方式会因使用单一的周期性门控信号而导致高重复频率进而使得单光子探测器中的暗计数和后脉冲计数增加，这会导致量子通信系统在成码过程中的错误率增加，进而降低系统的成码率。
发明内容
为解决上述问题，本发明提供了用于单光子探测器的门控装置和量子通信设备。
根据本发明的一方面，提供一种用于单光子探测器的门控装置，所述门控装置包括：系统同步单元，被配置为获取与量子通信系统的时钟同步的周期性门控信号；时钟分配器，被配置为将所述周期性门控信号分成相同的两路周期性门控信号；延时器，被配置为对所述两路周期性门控信号中的一路周期性门控信号进行延时处理，使得所述两路周期性门控信号中的一路周期性门控信号与另一路周期性门控信号在时间上相差预定持续时间，其中，所述预定持续时间为用于在量子通信系统中进行相位编码的不等臂干涉仪的长臂与短臂之间的光程差；以及逻辑或门，被配置为对延时后的一路周期性门控信号和未延时的另一路周期性门控信号进行或操作，以产生与量子通信系统的时钟同步的周期性门控信号序列，每个门控信号序列中的门控信号以预定持续时间彼此间隔，以使量子通信系统中的单光子探测器针对接收到的光脉冲而打开所述单光子探测器的门控。
根据本发明的另一方面，提供一种量子通信设备，所述量子通信设备包括如前所述的用于单光子探测器的门控装置。
本发明提供的用于单光子探测器的门控装置和量子通信设备能够有效地减少量子通信系统中的单光子探测器在高频运行过程中因使用高重复频率的周期性门控信号而引起的暗计数和后脉冲计数，从而在很大程度上减少了量子通信系统在成码过程中的错误率。另外，本发明提供的用于单光子探测器的门控装置和量子通信设备还显著地减少了量子通信系统中所使用的单光子探测器和偏振分束器的数量，这样不仅能够大幅度降低系统实现成本，而且还能够避免因使用额外的偏振分束器而引起的插损。
附图说明
通过下面结合附图进行的描述，本发明的上述目的和特点将会变得更加清楚。
图1A示出了根据本发明的示例性实施例的用于单光子探测器的门控装置的示意图。
图1B示出了根据本发明的示例性实施例的用于单光子探测器的门控装置的工作过程的信号时序示意图。
图2A示出了根据本发明的示例性实施例的用于单光子探测器的门控装置的另一示意图。
图2B示出了根据本发明的示例性实施例的用于单光子探测器的门控装置的工作过程的另一信号时序示意图。
图3A示出了根据本发明的示例性实施例的用于单光子探测器的门控装置中的窄脉冲产生单元的示意图。
图3B示出了根据本发明的示例性实施例的用于单光子探测器的门控装置中的窄脉冲产生单元的工作过程的信号时序示意图。
图4示出了根据本发明的示例性实施例的用于单光子探测器的门控装置中的系统同步单元的示意图。
图5A示出了相关技术中的基于时间相位编码的量子通信系统的示意图。
图5B示出了使用相关技术向图5A示出的量子通信系统中的单光子探测器施加门控信号以探测光脉冲携带的时间编码的示意图。
图6A示出了根据本发明的示例性实施例的基于时间相位编码的量子通信系统的示意图。
图6B示出了使用根据本发明的示例性实施例的用于单光子探测器的门控装置向图6A所示的量子通信系统中的单光子探测器施加门控信号以探测光脉冲携带的时间编码的示意图。
图7示出了使用相关技术输出的周期性门控信号和使用根据本发明的示例性实施例的用于单光子探测器的门控装置输出的周期性门控信号序列的对比的示意图。
具体实施方式
下面，将参照附图来详细说明本发明的实施例。
图1A示出了根据本发明的示例性实施例的用于单光子探测器的门控装置的示意图。图1B示出了根据本发明的示例性实施例的用于单光子探测器的门控装置的工作过程的信号时序示意图。
参照图1A和图1B，根据本发明的示例性实施例的用于单光子探测器的门控装置至少可包括系统同步单元101、时钟分配器102、延时器103和逻辑或门104。
在图1A示出的门控装置中，系统同步单元101可被配置为获取与量子通信系统的时钟(即，量子通信系统的编码信号的时钟)同步的周期性门控信号1010；时钟分配器102可被配置为将周期性门控信号1010分成相同的两路周期性门控信号1011和1012；延时器103可被配置为对两路周期性门控信号1011和1012中的一路周期性门控信号1011进行延时处理，使得两路周期性门控信号1011和1012中的一路周期性门控信号1011与另一路周期性门控信号1012在时间上相差预定持续时间△t 1，该预定持续时间△t 1可为用于 在量子通信系统中进行相位编码的不等臂干涉仪的长臂与短臂之间的光程差；逻辑或门104可被配置为对延时后的一路周期性门控信号1013和未延时的另一路周期性门控信号1012进行或操作，以产生与量子通信系统的时钟同步的周期性门控信号序列1014，每个门控信号序列中的门控信号以预定持续时间△t 1彼此间隔，以使量子通信系统中的单光子探测器针对接收到的光脉冲而打开该单光子探测器的门控(换言之，使量子通信系统中的单光子探测器针对接收到的光脉冲而工作于盖革模式下)。这样可最大限度地减少量子通信系统中的单光子探测器因不必要的重复门控信号而产生的暗计数和后脉冲计数。
在图1A示出的门控装置中，量子通信系统可以是基于时间相位编码的量子通信系统，也可以是基于相位编码的量子通信系统。作为示例，在基于时间相位编码的量子通信系统中，使用图1A示出的门控装置输出的周期性门控信号序列1014可使得单光子探测器能够针对在量子通信系统中接收到的携带时间编码的光脉冲而打开单光子探测器的门控，也可使得单光子探测器能够针对在量子通信系统中接收到的携带相位编码的光脉冲而打开单光子探测器的门控，还可使得单光子探测器能够针对在量子通信系统中接收到的携带时间编码的光脉冲和携带相位编码的光脉冲而打开单光子探测器的门控。
应当理解，尽管图1B中示出的周期性门控信号序列1014中的每个门控信号序列包括以预定持续时间△t 1彼此间隔的2个门控信号，但是本发明并不限于此，根据需要，可使用比如图1A所示的器件更多的器件(诸如，但不限于，可使用更多的时钟分配器、延时器和逻辑或门等)来使得周期性门控信号序列中的每个门控信号序列包括比如图1B所示的周期性门控信号序列1014中的每个门控信号序列的门控信号更多的门控信号，这样不仅能够显著地减少在量子通信系统中所使用的单光子探测器和偏振分束器的数量，大幅度降低系统实现成本，而且还能够避免因使用额外的偏振分束器而引起的插损。
图2A示出了根据本发明的示例性实施例的用于单光子探测器的门控装置的另一示意图。图2B示出了根据本发明的示例性实施例的用于单光子探测器的门控装置的工作过程的另一信号时序示意图。
参照图2A和2B，图2A示出的门控装置除了包括图1A示出的系统同步单元101、时钟分配器102、延时器103和逻辑或门104之外，还可包括窄脉冲产生单元105，窄脉冲产生单元105可设置在系统同步单元101与时钟分配器102之间，并且可被配置为使周期性门控信号1014的脉冲宽度变窄。在门控信号的脉冲宽度超出系统阈值的情况下，这样可使得经由上述门控装置产生的门控信号的脉冲宽度能够满足量子通信系统针对单光子探测器在盖革模式下的工作要求。
下面将参照图3A和图3B来详细地描述窄脉冲产生单元105的实施。
图3A示出了根据本发明的示例性实施例的用于单光子探测器的门控装置中的窄脉冲产生单元105的示意图。图3B示出了根据本发明的示例性实施例的用于单光子探测器的门控装置中的窄脉冲产生单元105的工作过程的信号时序示意图。
参照图3A和3B，图3A示出的窄脉冲产生单元105可包括时钟分配器106、延时器107和逻辑与门108。
在图3A示出的窄脉冲产生单元105中，时钟分配器106可被配置为将周期性门控信号1010分成相同的两路周期性门控信号1016和1017；延时器107可被配置为对两路周期性门控信号1016和1017中的一路周期性门控信号1016进行延时处理，使得两路周期性门控信号1016和1017中的一路周期性门控信号1016与另一路周期性门控信号1017在时间上相差预定持续时间△t 2，该预定持续时间△t 2小于周期性门控信号的脉冲宽度；逻辑与门108可被配置为对延时后的一路周期性门控信号1018和未延时的另一路周期性门控信号1017进行与操作，以使周期性门控信号的脉冲宽度变窄。
应当理解，尽管图3A示出了根据本发明的示例性实施例的用于单光子探测器的门控装置中的窄脉冲产生单元105的示意图，但是本发明并不限于此，也可采用其他器件或其他器件组合来实现窄脉冲产生单元105。窄脉冲产生单元105中的器件可比图3A示出的器件多，也可比图3A示出的器件少。
下面将参照图4来详细地描述系统同步单元101的实施。
图4示出了根据本发明的示例性实施例的用于单光子探测器的门控装置中的系统同步单元101的示意图。
参照图4，根据本发明的示例性实施例的用于单光子探测器的门控装置中的系统同步单元101可包括同步光探测单元109和锁相环110。
在图4示出的系统同步单元101中，同步光探测单元109可被配置为将接收到的量子通信系统的同步光(即，与编码信号中的光脉冲同步发出的同步光)转换为同步电信号，以获取量子通信系统的时钟1009；锁相环110可被配置为对同步电信号进行锁相和倍频，以获取与量子通信系统的时钟1009同步的周期性门控信号1010。作为示例，在同步光为低频光的情况下，可通过图4示出的系统同步单元101将例如，但不限于，频率为100kHz的同步电信号转换为例如，但不限于，频率为125MHz周期性门控信号，以使得低频信号转换为高频信号。
应当理解，尽管图4示出了根据本发明的示例性实施例的用于单光子探测器的门控装置中的系统同步单元101的示意图，但是本发明并不限于此，也可采用其他器件或其他器件组合来实现系统同步单元101。系统同步单元101中的器件可比图4示出的器件多，也可比图4示出的器件少。
图5A示出了相关技术中的基于时间相位编码的量子通信系统的示意图。
参照图5A，在相关技术中，基于时间相位编码的量子通信系统可包括Alice端和Bob端。在图5A示出的量子通信系统中，从Alice端发出的光脉冲可到达Bob端的单光子探测器D 0、D 1、D 2和D 3中的一者，其中，经由不等臂干涉仪M-Z 1和M-Z 2提供的路径(L 2，L 4)和(L 1，L 3)到达Bob端的光脉冲不 会发生光干涉现象，经由不等臂干涉仪M-Z 1和M-Z 2提供的路径(L 1，L 4)和(L 2，L 3)到达Bob端的光脉冲会发生光现象。Alice端和Bob端可通过调制相位调制器PM 1和PM 2的相位来使得发生干涉的光脉冲的强度随着相位差的不同而发生变化，从而实现相位编码。除此之外，Alice端和Bob端还可对光脉冲进行时间上的调整，从而实现时间编码。
在相关技术中，携带相位编码的光脉冲可随机地分配至Bob端中的单光子探测器D 0和D 1中的一者中进行探测，携带时间编码的光脉冲可随机地分配至Bob端中的单光子探测器D 2和D 3中的一者中进行探测。作为示例，图5B示出了使用相关技术分别向图5A示出的量子通信系统中的单光子探测器D 2和D 3施加门控信号以探测光脉冲携带的时间编码的示意图。
图6A示出了根据本发明的示例性实施例的基于时间相位编码的量子通信系统的示意图。
参照图6A，图6A示出的基于时间相位编码的量子通信系统可包括Alice端和Bob端。在图6A示出的量子通信系统中，从Alice端发出的光脉冲可到达Bob端的单光子探测器D 0、D 1和D 2中的一者，其中，经由不等臂干涉仪M-Z 1和M-Z 2提供的路径(L 2，L 4)和(L 1，L 3)到达Bob端的光脉冲不会发生光干涉现象，经由不等臂干涉仪M-Z 1和M-Z 2提供的路径(L 1，L 4)和(L 2，L 3)到达Bob端的光脉冲会发生光现象。Alice端和Bob端可通过调制相位调制器PM 1和PM 2的相位来使得发生干涉的光脉冲的强度随着相位差的不同而发生变化，从而实现相位编码。除此之外，Alice端和Bob端也可对光脉冲进行时间上的调整，从而实现时间编码。
在图6A示出的量子通信系统中，携带相位编码的光脉冲可随机地分配至Bob端中的单光子探测器D 0和D 1中的一者中进行探测，携带时间编码的光脉冲可直接地分配至Bob端中的单个单光子探测器D 2中进行探测。作为示例，图6B示出了使用根据本发明的示例性实施例的用于单光子探测器的门控装 置100向图6A示出的量子通信系统中的单光子探测器D 2施加门控信号以探测光脉冲携带的时间编码的示意图。
可以看出，相比于图5A示出的量子通信系统，通过使用根据本发明的示例性实施例的用于单光子探测器的门控装置100，图6A示出的量子通信系统仅使用了单个单光子探测器D 2来探测光脉冲携带的时间编码，这样不仅能够减少量子通信系统中所使用的单光子探测器的数量，降低系统实现成本，而且还能够避免因使用如图5A所示的偏振分束器BS而引起的插损，该插损在通常情况下约为3dB。
应当理解，尽管图6A和图6B分别示出了使用根据本发明的示例性实施例的用于单光子探测器的门控装置100经由单个单光子探测器D 2来探测光脉冲携带的时间编码的示例，但是该示例仅仅是示意性的，本发明并不限于此，例如，根据需要，也可使用根据本发明的示例性实施例的用于单光子探测器的门控装置100经由单个单光子探测器来探测光脉冲携带的相位编码，甚至还可在根据本发明的示例性实施例的用于单光子探测器的门控装置100上进行适当的变型，例如，可通过使图1A示出的门控装置包括更多的器件(诸如，但不限于，包括更多的时钟分配器，更多的延时器，或者更多的逻辑或门)来使根据本发明的示例性实施例的用于单光子探测器的门控装置100输出的周期性门控信号序列1014中的每个门控信号序列包括2个以上的门控信号，以使单个单光子探测器既能够探测光脉冲携带的相位编码，也能够探测光脉冲携带的时间编码。
图7示出了使用相关技术输出的周期性门控信号1000和使用根据本发明的示例性实施例的用于单光子探测器的门控装置100输出的周期性门控信号序列1014的对比的示意图。
可以看出，相比于使用相关技术输出的周期性门控信号1000，使用根据本发明的示例性实施例的用于单光子探测器的门控装置100输出的周期性门控信号序列1014具有更低的重复频率，这样可减少量子通信系统中的单光子 探测器在高频运行过程中因高重复频率而引起的暗计数和后脉冲计数，从而在很大程度上减少了量子通信系统在成码过程中的错误率。
相应地，本发明还提供了一种包括上述用于单光子探测器的门控装置的量子通信设备(诸如，图6A所示的Bob端)，以减少量子通信系统中的单光子探测器在高频运行过程中因使用高重复频率的周期性门控信号而引起的暗计数和后脉冲计数，这样可在很大程度上减少量子通信系统在成码过程中的错误率，另外，还可显著地减少量子通信系统中所使用的单光子探测器和偏振分束器的数量，以降低系统实现成本，同时避免因使用额外的偏振分束器BS(如图5A所示)而引起的插损。
尽管已参照优选实施例表示和描述了本申请，但本领域技术人员应该理解，在不脱离由权利要求限定的本申请的精神和范围的情况下，可以对这些实施例进行各种修改和变换。

Claims (6)

  1. 一种用于单光子探测器的门控装置，其特征在于，所述门控装置包括：
    系统同步单元，被配置为获取与量子通信系统的时钟同步的周期性门控信号；
    时钟分配器，被配置为将所述周期性门控信号分成相同的两路周期性门控信号；
    延时器，被配置为对所述两路周期性门控信号中的一路周期性门控信号进行延时处理，使得所述两路周期性门控信号中的一路周期性门控信号与另一路周期性门控信号在时间上相差预定持续时间，其中，所述预定持续时间为用于在量子通信系统中进行相位编码的不等臂干涉仪的长臂与短臂之间的光程差；以及
    逻辑或门，被配置为对延时后的一路周期性门控信号和未延时的另一路周期性门控信号进行或操作，以产生与量子通信系统的时钟同步的周期性门控信号序列，每个门控信号序列中的门控信号以所述预定持续时间彼此间隔，以使量子通信系统中的单光子探测器针对接收到的光脉冲而打开所述单光子探测器的门控。
  2. 根据权利要求1所述的门控装置，其特征在于，所述量子通信系统为基于时间相位编码的量子通信系统或基于相位编码的量子通信系统。
  3. 根据权利要求1所述的门控装置，其特征在于，所述门控装置还包括：
    窄脉冲产生单元，设置在所述系统同步单元与所述时钟分配器之间，并且被配置为使所述周期性门控信号的脉冲宽度变窄。
  4. 根据权利要求3所述的门控装置，其特征在于，所述窄脉冲产生单元包括：
    另一时钟分配器，被配置为将所述周期性门控信号分成相同的另外两路周期性门控信号；
    另一延时器，被配置为对所述另外两路周期性门控信号中的一路周期性门控信号进行延时处理，使得所述另外两路周期性门控信号中的一路周期性门控信号与另一路周期性门控信号在时间上相差另一预定持续时间，其中，所述另一预定持续时间小于所述周期性门控信号的脉冲宽度；以及
    逻辑与门，被配置为对延时后的一路周期性门控信号和未延时的另一路 周期性门控信号进行与操作，以使所述周期性门控信号的脉冲宽度变窄。
  5. 根据权利要求1所述的门控装置，其特征在于，所述系统同步单元包括：
    同步光探测单元，被配置为将接收到的量子通信系统的同步光转换为同步电信号，以获取量子通信系统的时钟；以及
    锁相环，被配置为对所述同步电信号进行锁相和倍频，以获取与量子通信系统的时钟同步的周期性门控信号。
  6. 一种量子通信设备，其特征在于，所述量子通信设备包括权利要求1至5中任意一项所述的用于单光子探测器的门控装置。
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