Quantum key distribution device capable of being configured with multiple protocols

Patent metadata

Field	Value
Publication number	US-11522689-B2
Application number	US-202217585494-A
Country	US
Kind code	B2
Filing date	Jan 26, 2022
Priority date	Feb 1, 2021
Publication date	Dec 6, 2022
Grant date	Dec 6, 2022

Abstract

The present invention relates to the field of quantum communication, especially a quantum key distribution device that can be configured with multiple protocols. It uses the simplified Faraday-Michelson interference ring in combination with the intensity modulator to perform timestamp encoding in a chopping manner. The phase modulation is completed with a Sagnac ring device composed of a single-polarization phase modulator, a polarization beam splitter and a Faraday rotator, so as to achieve the purpose of composite encoding and decoding, thus realizing a quantum key distribution device which can be configured with multiple protocols and multiple decoy state schemes. This device can be compatible with multiple protocols including BB84 protocol, the reference frame-independent protocol, the six-state protocol and SARG protocol and is characterized with polarization-independent phase modulation and low system complexity.

First claim

What is claimed is:

1. A quantum key distribution device capable of being configured with multiple protocols includes a sender, a receiver, and a communication channel used to connect the sender and the receiver, wherein the sender includes a sender-side main control board, a laser, a first intensity modulator, a sender Faraday-Michelson (F-M) interference ring, a synchronous laser, a second intensity modulator, a first circulator, an optical attenuator, a wavelength division multiplexer, and a phase encoder;
the sender-side main control board outputs electrical signals to the laser, wherein an output end of the laser is connected to an input end of the first intensity modulator, wherein the first intensity modulator is configured to modulate a quantum light outputted by the laser;
an output end of first intensity modulator is connected to the sender F-M interference ring, wherein the sender F-M interference ring is an unequal-arm F-M interference ring; after passing through the sender F-M interference ring, the quantum light is divided into front and rear bin pulses separated by a certain time, wherein the front and rear bin pulses comprise a front bin pulse and a rear bin pulse;
an output end of the sender F-M interference ring is connected to the second intensity modulator, and the sender F-M interference ring combines with the second intensity modulator to complete a Time-bin encoding of a timestamp;
an output end of second intensity modulator is connected to an input end of the first circulator, and one output end of the first circulator is connected to the phase encoder, wherein the phase encoder is configured for phase encoding of the quantum light; the other output end of the first circulator is connected to the optical attenuator configured to attenuate an intensity of the quantum light to a single-photon level;
the sender-side main control board outputs electrical signals to the synchronous laser, wherein an output end of the synchronous laser and an output end of the optical attenuator are both connected to an input end of the wavelength division multiplexer, wherein a synchronous light outputted by the synchronous laser and the quantum light outputted by the optical attenuator enter the same optical path through an coupling of the wavelength division multiplexer so as to enter the communication channel and be transmitted to the receiver;
the receiver includes a receiver-side main control board, a wavelength division demultiplexer, a first photoelectric tube, and a decoder;
the wavelength division demultiplexer is configured to demultiplex a light received by the receiver through the communication channel, separate the quantum light and the synchronous light, convert the synchronous light into an electrical signal through the first photoelectric tube, and generate a synchronous clock signal inputted to the receiver-side main control board, wherein the quantum light enters the decoder;
the decoder includes a second circulator, a receiver Sagnac ring, a third circulator, a receiver F-M interference ring, a first photon detector, and a second photon detector;
an input end of the second circulator receives the inputted quantum light, wherein one output end of the second circulator is connected to the receiver Sagnac ring, wherein the receiver Sagnac ring is configured for phase decoding, the other output end of the second circulator is connected to an input end of the third circulator, wherein one output end of the third circulator is connected to the receiver F-M interference ring, wherein the receiver F-M interference ring is configured for Time-bin decoding, wherein the other output end of the third circulator is connected to the second photon detector; an output end of the receiver F-M interference ring is connected to the first photon detector; and
the receiver-side main control board collects signals of the first photon detector and the second photon detector, and processes the signals in combination with the synchronous clock signal at the same time to obtain a secure key.

2. The quantum key distribution device capable of being configured with multiple protocols described in claim 1 , wherein the sender F-M interference ring includes a first beam splitter, a first Faraday rotator, and a second Faraday rotator, wherein the first beam splitter has four beam splitting arms, namely a first beam splitting aim, a second beam splitting arm, a third beam splitting arm, and a fourth beam splitting arm, wherein the third splitting arm and the fourth splitting arm have different arm lengths, and a port of the first splitting arm is connected to an output end of the first intensity modulator, and a port of the second splitting arm is connected to the second intensity modulator, and the third splitting arm and the fourth beam splitting arm are respectively connected to the first Faraday rotator and the second Faraday rotator;
the sender F-M interference ring has the same structure as the receiver F-M interference ring; and
the receiver F-M interference ring includes a second beam splitter, a third Faraday rotator and a fourth Faraday rotator, wherein the second beam splitter has four beam splitting arms, namely a fifth beam splitting arm, a sixth beam splitting arm, a seventh beam splitting arm, and an eighth beam splitting arm, wherein the seventh beam splitting arm and the eighth beam splitting arm have different arm lengths, wherein an port of the fifth beam splitting arm is connected to an output end of third circulator, a port of the sixth beam splitting arm is connected to the second photon detector, and the seventh beam splitting arm and the eighth beam splitting arm are respectively connected to the third Faraday rotator and the fourth Faraday rotator.

3. The quantum key distribution device capable of being configured with multiple protocols described in claim 1 , wherein a method of the Time-bin encoding of the timestamp includes that the second intensity modulator chops one of the front bin pulse and the rear bin pulse and allows the front and rear bin pulses to pass through at the same time.

4. The quantum key distribution device capable of being configured with multiple protocols described in claim 1 , wherein the phase encoder is a sender Sagnac ring, wherein the sender Sagnac ring includes a first single-polarization phase modulator, a first Faraday rotator, and a first polarization beam splitter; wherein the front bin pulse is divided into a first H component and a first V component after passing through the first polarization beam splitter, wherein the first H component is a transmitted light and the first V component is a reflected light, wherein after the transmitted first H component is phase-modulated by the first single-polarization phase modulator the transmitted first H component is rotated to a polarization direction of the first V component by the first Faraday rotator and returns to an original optical path, wherein after the first V component is rotated to a polarization direction of the component H by the first Faraday rotator, the first V component is phase-modulated through the first single-polarization phase modulator and returns to the original optical path; the rear bin pulse and the front bin pulse pass through the same optical path; the sender-side main control board transmits electrical signals to the first single-polarization phase modulator to modulate the quantum light to a specified phase;
the receiver Sagnac ring includes a second single-polarization phase modulator, a second Faraday rotator, and a second polarization beam splitter, wherein the front bin pulse is divided into a second H component and a second V component after passing through the second polarization beam splitter, wherein the second H component is a transmitted light, and the second V component is a reflected light, wherein the transmitte

Assignees

• Univ Nanjing Posts & Telecommunications

Inventors

• Wang Qin
• Jiang Qingqing
• Ding Huajian
• Zhang Chunhui
• Li Jian

Classifications

• H04B10/70

  Photonic quantum communication · CPC title

• G06N10/60

  Quantum algorithms, e.g. based on quantum optimisation, quantum Fourier or Hadamard transforms · CPC title

• H04L9/0858 Primary

  Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding · CPC title

• H04L69/18

  Multiprotocol handlers, e.g. single devices capable of handling multiple protocols · CPC title

• H04L9/0852 Primary

  Quantum cryptography (transmission systems employing electromagnetic waves other than radio waves, e.g. light, infrared H04B10/00; wavelength-division multiplex systems H04J14/02; WDM arrangements H04J14/03) · CPC title