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Phase-differential quantum key allocation and allocating system

A key distribution system and key distribution technology, applied in a one-way, fast phase difference quantum key distribution method and system, in the field of stability, can solve the problem of easy to receive external environment interference, limit transmission distance, poor stability, etc. problem, to achieve the effect of fast quantum key distribution, high communication security, and avoidance of theft

Inactive Publication Date: 2009-12-30
SOUTH CHINA NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The phase difference system uses two pulses in time for phase encoding at the transmitting end, and uses the response results of two detectors for decoding at the receiving end, thus saving the phase modulator at the receiving end, reducing the insertion loss of the line and greatly The transmission efficiency is improved; however, this system is extremely susceptible to interference from the external environment when phase modulation is performed at the transmitter end and interference detection at the receiver end, and the stability is poor
Although the currently developed optical waveguide integration technology can avoid these factors to a certain extent, its process is complicated and expensive.
Therefore, in practice, if the phase or polarization state of a single photon is used for encoding and decoding, due to the imperfection of the device and the influence of environmental factors (such as temperature, vibration, etc.), the state of the photon is inconsistent at the transmitting end and the receiving end, which leads to inability Correct modulation and demodulation of quantum information
At the same time, the inherent insertion loss in the device and the optical path limits the transmission distance, and the structural characteristics of the key distribution system directly affect the transmission rate of the quantum code

Method used

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  • Phase-differential quantum key allocation and allocating system
  • Phase-differential quantum key allocation and allocating system
  • Phase-differential quantum key allocation and allocating system

Examples

Experimental program
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Embodiment 1

[0050] Such as figure 1 The signal modulation transmitting end 1' shown in the figure uses the intensity modulator 12' to modulate the laser light emitted by the continuous laser source 11' into coherent pulsed light with an equal time interval of Δt, and then enters the four-port polarization beam splitter 16' into horizontal and vertical beam splitters. Two beams of polarized light. One of the beams of light directly enters the phase modulator 18', and the other beam of light passes through the Faraday rotating mirror 17', the polarization plane is rotated by 90 degrees, and then enters the phase modulator 18' from the other end, and the distance between the optical fiber 19' is designed so that the two The light beams simultaneously reach the phase modulator 18'. Since the two beams travel the same optical path, they are recombined at the port of the polarizing beam splitter 16'. Therefore, according to the phase modulation information {0, π}, a random quantum code is out...

Embodiment 2

[0055] Such as figure 2 The signal modulation transmitting end 1 shown directly uses the intensity modulator 12 to modulate the laser light emitted by the continuous laser light source 11 into coherent pulsed light with an equal time interval of Δt, and enters the phase modulator 14 after being controlled by the polarizer 13 . After loading the phase modulation information {0, π}, it is attenuated to the single quantum state μ=0.1 by the optical attenuator 15 . This method has a simple structure, less components, low price and good stability. The receiving end of the system is exactly the same as that in Embodiment 1.

[0056] Optical path such as Figure 5 As shown, at the transmitting end, Alice performs random phase modulation on each pulse with 0 or π, and when the specified phase is 0, it means the code "0", and when the phase is π, it means the code "1". The signal is transmitted to the receiving end through the optical fiber 10. At the receiving end, Bob uses a dete...

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Abstract

The invention manages to provide a stable and fast differential quantum key distribution method and system thereof. At transmitting end, with a continuous laser source, the quantum codes are prepared using two approaches: 1) using the beam-splitting, polarization-independent and phase-stabilizing approach to prepare the stable quantum code; 2) using polarization approach to directly prepare stable quantum code. At receiving end,differential phase-Faraday-Micheal test approach is used to directly receive the quantum information.

Description

technical field [0001] The invention relates to the field of special equipment for quantum secure communication in the field of communication, in particular to a one-way, stable and fast phase difference quantum key distribution method and system thereof. technical background [0002] Quantum secure communication is currently proven to be the only absolutely secure communication method. Using single photon as an information carrier to transmit quantum information bits, its security is guaranteed by the uncertainty principle in quantum mechanics and the no-cloning theorem of unknown quantum states. This absolutely safe quantum cryptography will be first applied in military, national security and other fields, and will become a new battlefield for scientists from all over the world. [0003] In the existing quantum secure communication system, according to the encoding and decoding methods, there are three encoding methods: polarization encoding / polarization detection, phase ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L9/08
Inventor 赵峰路铁群王发强廖常俊刘颂豪
Owner SOUTH CHINA NORMAL UNIVERSITY