CN116094612B - Tuning device for quantum communication system - Google Patents

Tuning device for quantum communication system Download PDF

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CN116094612B
CN116094612B CN202310374930.2A CN202310374930A CN116094612B CN 116094612 B CN116094612 B CN 116094612B CN 202310374930 A CN202310374930 A CN 202310374930A CN 116094612 B CN116094612 B CN 116094612B
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arm
interferometer
unequal
optical path
communication system
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CN116094612A (en
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张建
王其兵
陈柳平
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Guokaike Quantum Technology Beijing Co Ltd
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Guokaike Quantum Technology Beijing Co Ltd
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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
    • 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
    • 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
    • H04L9/0858—Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Optics & Photonics (AREA)
  • Optical Communication System (AREA)

Abstract

The present invention provides a tuning apparatus for a quantum communication system, the apparatus comprising: a light source arranged at the input end of the first unequal arm interferometer in the emitting end and used for outputting light pulses; the single photon detector is arranged at the output end of the second unequal arm interferometer in the receiving end and is used for detecting single photon counting; the right-angle prism is arranged on the light path of the short arm of the second unequal-arm interferometer and used for changing the light path in the short arm; and a controller configured to drive the right angle prism to move in response to the detected single photon count not reaching the interference threshold, to compensate for a difference between an optical path difference between two arms of the first unequal arm interferometer and an optical path difference between two arms of the second unequal arm interferometer by an amount of change in optical path generated in the right angle prism for the short arm by the movement. The invention improves the adaptability of the unequal-arm interferometer in the quantum communication system to the surrounding environment, thereby ensuring the stability of the interference effect of the unequal-arm interferometer in the quantum communication system.

Description

Tuning device for quantum communication system
Technical Field
The invention relates to the technical field of quantum communication, in particular to a tuning device for a quantum communication system.
Background
Currently, three coding modes of polarization coding, phase coding and time-phase coding are mainly adopted in a quantum communication system (such as a quantum key distribution system), wherein the phase coding and the time-phase coding both need to be coded and decoded by using different-arm interferometers. However, the interference effect of the unequal-arm interferometer is easily deteriorated by the surrounding environment (such as temperature, vibration, etc.), which may result in an increase in the error rate of the quantum communication system, and thus a significant decrease in the rate of the formation of the quantum communication system.
Therefore, improving the adaptability of the unequal arm interferometer to the surrounding environment to ensure the stability of the interference effect of the unequal arm interferometer is a problem to be solved.
Disclosure of Invention
The object of the present invention is to provide a tuning arrangement for a quantum communication system.
According to an aspect of the present invention, there is provided a tuning apparatus for a quantum communication system, the apparatus comprising: a light source arranged at the input end of the first unequal-arm interferometer in the emitting end of the quantum communication system and used for outputting light pulses; a single photon detector disposed at an output of a second unequal arm interferometer in a receiving end of the quantum communication system for detecting single photon counts from the light pulses; a right angle prism arranged on the optical path of the short arm of the second unequal arm interferometer in the receiving end of the quantum communication system for changing the optical path in the short arm; and a controller configured to drive the right angle prism to move in a direction perpendicular to an optical path of the short arm in response to the detected single photon count not reaching an interference threshold, to compensate a difference between an optical path difference between a long arm and a short arm of the first unequal arm interferometer and an optical path difference between a long arm and a short arm of the second unequal arm interferometer by an amount of change in the optical path generated in the right angle prism for the short arm by the movement until the detected single photon count reaches the interference threshold.
According to one embodiment of the invention, the light pulses are incident perpendicularly from the right angle face of the right angle prism along the short arm and exit via the inclined face of the right angle prism.
According to one embodiment of the invention, the first unequal arm interferometer is one of a spatial interferometer and a fiber optic interferometer, and the second unequal arm interferometer is a spatial interferometer.
According to one embodiment of the invention, the coding mode of the quantum communication system is based on one of phase coding and time phase coding.
According to another aspect of the present invention, there is also provided a tuning apparatus for a quantum communication system, the apparatus comprising: a light source arranged at the input end of the first unequal-arm interferometer in the emitting end of the quantum communication system and used for outputting light pulses; a single photon detector disposed at an output of a second unequal arm interferometer in a receiving end of the quantum communication system for detecting single photon counts from the light pulses; the right-angle prism is arranged on the optical path of the long arm of the second unequal-arm interferometer in the receiving end of the quantum communication system and is used for changing the optical path in the long arm; and a controller configured to drive the right angle prism to move in a direction perpendicular to an optical path of the long arm in response to the detected single photon count not reaching an interference threshold, to compensate a difference between an optical path difference between a long arm and a short arm of the first unequal arm interferometer and an optical path difference between a long arm and a short arm of the second unequal arm interferometer by an amount of change in the optical path generated in the right angle prism for the long arm by the movement until the detected single photon count reaches the interference threshold.
According to one embodiment of the invention, the light pulses are incident perpendicularly from the right angle face of the right angle prism along the long arm and exit via the inclined face of the right angle prism.
According to one embodiment of the invention, the first unequal arm interferometer is one of a spatial interferometer and a fiber optic interferometer, and the second unequal arm interferometer is a spatial interferometer.
According to one embodiment of the invention, the coding mode of the quantum communication system is based on one of phase coding and time phase coding.
According to another aspect of the present invention, there is also provided a tuning apparatus for a quantum communication system, the apparatus comprising: a light source arranged at the input end of the first unequal-arm interferometer in the emitting end of the quantum communication system and used for outputting light pulses; a single photon detector disposed at an output of a second unequal arm interferometer in a receiving end of the quantum communication system for detecting single photon counts from the light pulses; the right-angle prism is arranged on the light path of the short arm of the first unequal-arm interferometer in the transmitting end of the quantum communication system and is used for changing the light path in the short arm; and a controller configured to drive the right angle prism to move in a direction perpendicular to an optical path of the short arm in response to the detected single photon count not reaching an interference threshold, to compensate a difference between an optical path difference between a long arm and a short arm of the first unequal arm interferometer and an optical path difference between a long arm and a short arm of the second unequal arm interferometer by an amount of change in the optical path generated in the right angle prism for the short arm by the movement until the detected single photon count reaches the interference threshold.
According to one embodiment of the invention, the light pulses are incident perpendicularly from the right angle face of the right angle prism along the short arm and exit via the inclined face of the right angle prism.
According to one embodiment of the invention, the first unequal arm interferometer is a spatial interferometer and the second unequal arm interferometer is one of a spatial interferometer and a fiber optic interferometer.
According to one embodiment of the invention, the coding mode of the quantum communication system is based on one of phase coding and time phase coding.
According to another aspect of the present invention, there is also provided a tuning apparatus for a quantum communication system, the apparatus comprising: a light source arranged at the input end of the first unequal-arm interferometer in the emitting end of the quantum communication system and used for outputting light pulses; a single photon detector disposed at an output of a second unequal arm interferometer in a receiving end of the quantum communication system for detecting single photon counts from the light pulses; the right-angle prism is arranged on the optical path of the long arm of the first unequal-arm interferometer in the transmitting end of the quantum communication system and is used for changing the optical path in the long arm; and a controller configured to drive the right angle prism to move in a direction perpendicular to an optical path of the long arm in response to the detected single photon count not reaching an interference threshold, to compensate a difference between an optical path difference between a long arm and a short arm of the first unequal arm interferometer and an optical path difference between a long arm and a short arm of the second unequal arm interferometer by an amount of change in the optical path generated in the right angle prism for the long arm by the movement until the detected single photon count reaches the interference threshold.
According to one embodiment of the invention, the light pulses are incident perpendicularly from the right angle face of the right angle prism along the long arm and exit via the inclined face of the right angle prism.
According to one embodiment of the invention, the first unequal arm interferometer is a spatial interferometer and the second unequal arm interferometer is one of a spatial interferometer and a fiber optic interferometer.
According to one embodiment of the invention, the coding mode of the quantum communication system is based on one of phase coding and time phase coding.
The tuning device for the quantum communication system can improve the adaptability of the unequal-arm interferometer in the quantum communication system to the surrounding environment so as to ensure the stability of the interference effect of the unequal-arm interferometer in the quantum communication system.
Drawings
The above objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.
Fig. 1 is a schematic view illustrating an optical path of light passing through a right angle prism according to an exemplary embodiment of the present invention.
Fig. 2 shows a schematic diagram of a tuning arrangement for a quantum communication system according to an exemplary embodiment of the invention.
Fig. 3 shows another schematic diagram of a tuning arrangement for a quantum communication system according to an exemplary embodiment of the invention.
Fig. 4 shows another schematic diagram of a tuning arrangement for a quantum communication system according to an exemplary embodiment of the invention.
Fig. 5 shows another schematic diagram of a tuning arrangement for a quantum communication system according to an exemplary embodiment of the invention.
Detailed Description
In a quantum communication system based on phase encoding and time phase encoding, an optical encoding module of a transmitting end Alice and an optical decoding module of a receiving end Bob both comprise unequal-arm interferometers. In order to ensure that the quantum communication system described above achieves a sustained and stable optimal interference effect to ensure the stability of the system's code rate, it is necessary to have the unequal-arm interferometer M-Z included in the optical coding module of transmitting end Alice 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal-arm interferometer M-Z included in optical decoding module of receiving end Bob 2 Long arm L of (2) 3 And a short arm L 4 The optical path difference is always consistent in the whole, so that the increase of the error rate of the quantum communication system caused by the poor interference effect of the unequal-arm interferometer can be prevented.
The present invention is conceived to achieve fine adjustment of an optical path difference between a long arm and a short arm of an unequal arm interferometer by changing an optical path length in the long arm or the short arm of the unequal arm interferometer by a movement of a right angle prism provided on an optical path of the long arm or the short arm of the unequal arm interferometer, which fine adjustment can keep the optical path difference between the long arm and the short arm of the unequal arm interferometer included in a transmitting end consistent with the optical path difference between the long arm and the short arm of the unequal arm interferometer included in a receiving end as a whole to ensure stability of a system code rate.
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Referring to fig. 1, it can be seen that the optical path of light passing through the right angle Prism may be affected by the up-and-down movement of the right angle Prism in addition to the refractive index of the Prism. Therefore, in the case where the refractive index of the Prism is constant, the optical path of light passing through the right angle Prism can be dynamically changed by moving the right angle Prism. For example, when the right angle Prism is moved upward, the optical path of light in the right angle Prism can be lengthened; when the right angle Prism is moved downward, the optical path of light in the right angle Prism may become short.
In addition, as can be seen from fig. 1, although a part of light perpendicularly incident into the right angle Prism is dispersed, as long as the distance between the right angle Prism and the beam combiner provided at the output end of the unequal arm interferometer is sufficiently close, even if a part of light perpendicularly incident into the right angle Prism is dispersed, it is possible to ensure that most of the light passing through the right angle Prism reaches the output end of the unequal arm interferometer. In this case, the problem of the reduction in coupling efficiency at the output of the unequal-arm interferometer due to the dispersion of light can be minimized.
Hereinafter, an embodiment of the present invention will be described in detail with reference to fig. 2 to 5.
Referring to fig. 2 to 5, a tuning apparatus for a quantum communication system according to an exemplary embodiment of the present invention may include a light source Laser, a single photon detector SPD, a right angle Prism, and a controller (not shown).
In the tuning device shown in fig. 2, the light source Laser may be disposed in the quantum pass shown in fig. 2Inequality arm interferometer M-Z in transmitting terminal Alice of communication system 1 For outputting optical pulses; single photon detector SPD (SPD) can be arranged in unequal arm interferometer M-Z in receiving end Bob of quantum communication system shown in figure 2 2 For detecting single photon counts from the light pulses; right angle Prism may be provided in unequal arm interferometer M-Z in receiving end Bob of the quantum communication system shown in FIG. 2 2 Short arm L of (2) 4 For changing the short arm L 4 Is a light path in the optical fiber; the controller may be configured to drive the rectangular Prism along a direction perpendicular to the short arm L in response to the detected single photon count not reaching the interference threshold 4 To be directed to the short arm L in the right angle Prism by the movement 4 The resulting change in optical path length compensates for the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The difference between the optical path differences until the detected single photon count reaches the interference threshold.
In addition, in the tuning device shown in FIG. 2, the unequal arm interferometers M-Z 1 May be a spatial interferometer or a fiber optic interferometer, rather than an unequal arm interferometer M-Z 2 Is a spatial interferometer and the light pulse can follow the short arm L 4 Is perpendicularly incident from the right angle surface of the right angle Prism and is emitted through the inclined surface of the right angle Prism.
In one example, when the unequal arms interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 When the optical path difference between the two optical paths is increased along with the rising of the ambient temperature of the emitting end Alice, the controller can shorten the unequal arm interferometer M-Z by moving the right angle Prism downwards 2 Short arm L of (2) 4 To increase the optical path length of the unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 Optical path difference between them so that the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The optical path difference between them is kept consistent.
In another example, when the unequal arms interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 When the optical path difference between the two optical paths is reduced along with the decrease of the ambient temperature of the emitting end Alice, the controller can extend the unequal arm interferometer M-Z by moving the right angle Prism upwards 2 Short arm L of (2) 4 Reducing the optical path length of the unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 Optical path difference between them so that the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The optical path difference between them is kept consistent.
It can be seen that the tuning device shown in fig. 2 can promote the adaptability of the unequal-arm interferometer in the quantum communication system to the surrounding environment so as to ensure the stability of the interference effect of the unequal-arm interferometer in the quantum communication system.
In the tuning apparatus shown in fig. 3, a light source Laser may be disposed in an unequal-arm interferometer M-Z in the transmitting end Alice of the quantum communication system shown in fig. 3 1 For outputting optical pulses; single photon detector can be arranged in unequal arm interferometer M-Z in receiving end Bob of quantum communication system shown in figure 3 2 For detecting single photon counts from the light pulses; right angle Prism may be provided in unequal arm interferometer M-Z in receiving end Bob of the quantum communication system shown in FIG. 3 2 Long arm L of (2) 3 For changing the long arm L 3 Is a light path in the optical fiber; the controller may be configured to drive the rectangular Prism along a direction perpendicular to the long arm L in response to the detected single photon count not reaching the interference threshold 3 To be directed to the long arm L in the right angle Prism by the movement 3 The resulting change in optical path length compensates for the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The difference between the optical path differences until the detected single photon count reaches the interference threshold.
In addition, in the tuning device shown in fig. 3,inequality arm interferometer M-Z 1 May be a spatial interferometer or a fiber optic interferometer, rather than an unequal arm interferometer M-Z 2 Is a spatial interferometer and the light pulse can follow the long arm L 3 Is perpendicularly incident from the right angle surface of the right angle Prism and is emitted through the inclined surface of the right angle Prism.
In one example, when the unequal arms interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 When the optical path difference between the two optical paths is increased along with the rising of the ambient temperature of the emitting end Alice, the controller can prolong the unequal arm interferometer M-Z by moving the right angle Prism upwards 2 Long arm L of (2) 3 To increase the optical path length of the unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 Optical path difference between them so that the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The optical path difference between them is kept consistent.
In another example, when the unequal arms interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 When the optical path difference between the two optical paths is reduced along with the reduction of the ambient temperature of the emitting end Alice, the controller can shorten the unequal arm interferometer M-Z by moving the right angle Prism downwards 2 Long arm L of (2) 3 Reducing the optical path length of the unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 Optical path difference between them so that the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The optical path difference between them is kept consistent.
It can be seen that the tuning device shown in fig. 3 can also promote the adaptability of the unequal-arm interferometer in the quantum communication system to the surrounding environment so as to ensure the stability of the interference effect of the unequal-arm interferometer in the quantum communication system.
In the tuning apparatus shown in fig. 4, a light source Laser may be disposed in an unequal-arm interferometer M-Z in the transmitting end Alice of the quantum communication system shown in fig. 4 1 For outputting optical pulses; the single photon detector can be provided withInequality arm interferometer M-Z in receiving end Bob of quantum communication system shown in FIG. 4 2 For detecting single photon counts from the light pulses; right angle Prism may be provided in an inequality arm interferometer M-Z in the transmitting end Alice of the quantum communication system shown in FIG. 4 1 Short arm L of (2) 2 For changing the short arm L 2 Is a light path in the optical fiber; the controller may be configured to drive the rectangular Prism along a direction perpendicular to the short arm L in response to the detected single photon count not reaching the interference threshold 2 To be directed to the short arm L in the right angle Prism by the movement 2 The resulting change in optical path length compensates for the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The difference between the optical path differences until the detected single photon count reaches the interference threshold.
In addition, in the tuning device shown in FIG. 4, the unequal arm interferometers M-Z 1 Is a spatial interferometer, and the unequal arm interferometer M-Z 2 May be a spatial interferometer or a fiber optic interferometer, and the light pulses may follow the short arm L 2 Is perpendicularly incident from the right angle surface of the right angle Prism and is emitted through the inclined surface of the right angle Prism.
In one example, when the unequal arms interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 When the optical path difference between the two is increased along with the increase of the ambient temperature of the receiving end Bob, the controller can shorten the unequal arm interferometer M-Z by moving the right angle Prism downwards 1 Short arm L of (2) 2 To increase the optical path length of the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them so that the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The optical path difference between them is kept consistent.
In another example, when the unequal arms interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The optical path difference between the two is along with the circumference of the receiving end BobWhen the surrounding temperature decreases, the controller can extend the unequal arm interferometer M-Z by moving the right angle Prism upwards 1 Short arm L of (2) 2 Reducing the optical path length of the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them so that the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The optical path difference between them is kept consistent.
It can be seen that the tuning device shown in fig. 4 can also promote the adaptability of the unequal-arm interferometer in the quantum communication system to the surrounding environment so as to ensure the stability of the interference effect of the unequal-arm interferometer in the quantum communication system.
In the tuning apparatus shown in fig. 5, a light source Laser may be disposed in an unequal-arm interferometer M-Z in the transmitting end Alice of the quantum communication system shown in fig. 5 1 For outputting optical pulses; single photon detector can be arranged in unequal arm interferometer M-Z in receiving end Bob of quantum communication system shown in FIG. 5 2 For detecting single photon counts from the light pulses; right angle Prism may be provided in an inequality arm interferometer M-Z in the transmitting end Alice of the quantum communication system shown in FIG. 5 1 Long arm L of (2) 1 For changing the long arm L 1 Is a light path in the optical fiber; the controller may be configured to drive the rectangular Prism along a direction perpendicular to the long arm L in response to the detected single photon count not reaching the interference threshold 1 To be directed to the long arm L in the right angle Prism by the movement 1 The resulting change in optical path length compensates for the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The difference between the optical path differences until the detected single photon count reaches the interference threshold.
In addition, in the tuning device shown in FIG. 5, the unequal arm interferometers M-Z 1 Is a spatial interferometer, and the unequal arm interferometer M-Z 2 May be a spatial interferometer or a fiber optic interferometerThe instrument, and the light pulse can be along the long arm L 1 Is perpendicularly incident from the right angle surface of the right angle Prism and is emitted through the inclined surface of the right angle Prism.
In one example, when the unequal arms interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 When the optical path difference between the two is increased along with the increase of the ambient temperature of the receiving end Bob, the controller can extend the unequal-arm interferometer M-Z by moving the right-angle Prism upwards 1 Long arm L of (2) 1 To increase the optical path length of the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them so that the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The optical path difference between them is kept consistent.
In another example, when the unequal arms interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 When the optical path difference between the two is reduced along with the reduction of the ambient temperature of the receiving end Bob, the controller can shorten the unequal arm interferometer M-Z by moving the right angle Prism downwards 1 Long arm L of (2) 1 Reducing the optical path length of the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them so that the unequal arm interferometer M-Z 1 Long arm L of (2) 1 And a short arm L 2 Optical path difference between them and unequal arm interferometer M-Z 2 Long arm L of (2) 3 And a short arm L 4 The optical path difference between them is kept consistent.
It can be seen that the tuning device shown in fig. 5 can also improve the adaptability of the unequal-arm interferometer in the quantum communication system to the surrounding environment so as to ensure the stability of the interference effect of the unequal-arm interferometer in the quantum communication system.
While the present application has been shown and described with reference to the preferred embodiments, it will be understood by those skilled in the art that various modifications and changes may be made to these embodiments without departing from the spirit and scope of the present application as defined by the appended claims.

Claims (16)

1. A tuning apparatus for a quantum communication system, comprising:
a light source arranged at the input end of the first unequal-arm interferometer in the emitting end of the quantum communication system and used for outputting light pulses;
a single photon detector disposed at an output of a second unequal arm interferometer in a receiving end of the quantum communication system for detecting single photon counts from the light pulses;
a right angle prism arranged on the optical path of the short arm of the second unequal arm interferometer in the receiving end of the quantum communication system for changing the optical path in the short arm;
and a controller configured to drive the right angle prism to move in a direction perpendicular to an optical path of the short arm in response to the detected single photon count not reaching an interference threshold, to compensate a difference between an optical path difference between a long arm and a short arm of the first unequal arm interferometer and an optical path difference between a long arm and a short arm of the second unequal arm interferometer by an amount of change in the optical path generated in the right angle prism for the short arm by the movement until the detected single photon count reaches the interference threshold.
2. The apparatus of claim 1, wherein the light pulses are incident perpendicularly from a right angle face of the right angle prism along the short arm and exit via a bevel of the right angle prism.
3. The apparatus of claim 1, wherein the first unequal arm interferometer is one of a spatial interferometer and a fiber optic interferometer, and the second unequal arm interferometer is a spatial interferometer.
4. The apparatus of claim 1, wherein the quantum communication system is encoded based on one of phase encoding and time phase encoding.
5. A tuning apparatus for a quantum communication system, comprising:
a light source arranged at the input end of the first unequal-arm interferometer in the emitting end of the quantum communication system and used for outputting light pulses;
a single photon detector disposed at an output of a second unequal arm interferometer in a receiving end of the quantum communication system for detecting single photon counts from the light pulses;
the right-angle prism is arranged on the optical path of the long arm of the second unequal-arm interferometer in the receiving end of the quantum communication system and is used for changing the optical path in the long arm;
and a controller configured to drive the right angle prism to move in a direction perpendicular to an optical path of the long arm in response to the detected single photon count not reaching an interference threshold, to compensate a difference between an optical path difference between a long arm and a short arm of the first unequal arm interferometer and an optical path difference between a long arm and a short arm of the second unequal arm interferometer by an amount of change in the optical path generated in the right angle prism for the long arm by the movement until the detected single photon count reaches the interference threshold.
6. The apparatus of claim 5, wherein the light pulses are incident perpendicularly from a right angle face of the right angle prism along the long arm and exit via a bevel of the right angle prism.
7. The apparatus of claim 5, wherein the first unequal arm interferometer is one of a spatial interferometer and a fiber optic interferometer, and the second unequal arm interferometer is a spatial interferometer.
8. The apparatus of claim 5, wherein the quantum communication system is encoded based on one of phase encoding and time phase encoding.
9. A tuning apparatus for a quantum communication system, comprising:
a light source arranged at the input end of the first unequal-arm interferometer in the emitting end of the quantum communication system and used for outputting light pulses;
a single photon detector disposed at an output of a second unequal arm interferometer in a receiving end of the quantum communication system for detecting single photon counts from the light pulses;
the right-angle prism is arranged on the light path of the short arm of the first unequal-arm interferometer in the transmitting end of the quantum communication system and is used for changing the light path in the short arm;
and a controller configured to drive the right angle prism to move in a direction perpendicular to an optical path of the short arm in response to the detected single photon count not reaching an interference threshold, to compensate a difference between an optical path difference between a long arm and a short arm of the first unequal arm interferometer and an optical path difference between a long arm and a short arm of the second unequal arm interferometer by an amount of change in the optical path generated in the right angle prism for the short arm by the movement until the detected single photon count reaches the interference threshold.
10. The apparatus of claim 9, wherein the light pulses are incident perpendicularly from a right angle face of the right angle prism along the short arm and exit via a bevel of the right angle prism.
11. The apparatus of claim 9, wherein the first unequal arm interferometer is a spatial interferometer and the second unequal arm interferometer is one of a spatial interferometer and a fiber optic interferometer.
12. The apparatus of claim 9, wherein the quantum communication system is encoded based on one of phase encoding and time phase encoding.
13. A tuning apparatus for a quantum communication system, comprising:
a light source arranged at the input end of the first unequal-arm interferometer in the emitting end of the quantum communication system and used for outputting light pulses;
a single photon detector disposed at an output of a second unequal arm interferometer in a receiving end of the quantum communication system for detecting single photon counts from the light pulses;
the right-angle prism is arranged on the optical path of the long arm of the first unequal-arm interferometer in the transmitting end of the quantum communication system and is used for changing the optical path in the long arm;
and a controller configured to drive the right angle prism to move in a direction perpendicular to an optical path of the long arm in response to the detected single photon count not reaching an interference threshold, to compensate a difference between an optical path difference between a long arm and a short arm of the first unequal arm interferometer and an optical path difference between a long arm and a short arm of the second unequal arm interferometer by an amount of change in the optical path generated in the right angle prism for the long arm by the movement until the detected single photon count reaches the interference threshold.
14. The apparatus of claim 13, wherein the light pulses are incident perpendicularly from a right angle face of the right angle prism along the long arm and exit via a bevel of the right angle prism.
15. The apparatus of claim 13, wherein the first unequal arm interferometer is a spatial interferometer and the second unequal arm interferometer is one of a spatial interferometer and a fiber optic interferometer.
16. The apparatus of claim 13, wherein the quantum communication system is encoded based on one of phase encoding and time phase encoding.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH063107A (en) * 1992-06-24 1994-01-11 Nikon Corp Interferometer system
CN110132180A (en) * 2017-10-12 2019-08-16 安徽大学 Any angle mirror surface type laser mixes micro angle measurement system and measurement method certainly
CN216565158U (en) * 2022-04-11 2022-05-17 国开启科量子技术(北京)有限公司 Tuning device for unequal arm interferometer and quantum communication equipment
CN216959875U (en) * 2022-03-01 2022-07-12 国开启科量子技术(北京)有限公司 Tuning apparatus for quantum communication system
CN115629447A (en) * 2022-12-21 2023-01-20 北京中科国光量子科技有限公司 Four-in-one space light delay self-interferometer

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH063107A (en) * 1992-06-24 1994-01-11 Nikon Corp Interferometer system
CN110132180A (en) * 2017-10-12 2019-08-16 安徽大学 Any angle mirror surface type laser mixes micro angle measurement system and measurement method certainly
CN216959875U (en) * 2022-03-01 2022-07-12 国开启科量子技术(北京)有限公司 Tuning apparatus for quantum communication system
CN216565158U (en) * 2022-04-11 2022-05-17 国开启科量子技术(北京)有限公司 Tuning device for unequal arm interferometer and quantum communication equipment
CN115629447A (en) * 2022-12-21 2023-01-20 北京中科国光量子科技有限公司 Four-in-one space light delay self-interferometer

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