Quantum communication time phase encoding device and method and key distribution system

Abstract

The invention discloses a quantum communication time phase encoding device and method and a key distribution system. The quantum communication time phase encoding device includes a first interferometer configured to receive an optical signal and generate a first signal and a second optical signal having a time difference, and a second interferometer configured to generate a third optical signal transmitted along the first optical path and a fourth optical signal transmitted along the second optical path based on the first signal, and generate a fifth optical signal transmitted along the firstoptical path and a sixth optical signal transmitted along the second optical path based on the second signal, wherein the first phase modulator of the first optical path and the second phase modulatorof the second optical path respectively increase or decrease a pi phase for one of the third optical signal and the fourth optical signal; or the pi phase is increased or decreased for one of the fifth optical signal and the sixth optical signal; and the first phase modulator in the first optical path and the second phase modulator in the second optical path increase or decrease pi phases for both of the third optical signal and the fourth optical signal, respectively; or the pi phase is increased or decreased for both the fifth optical signal and the sixth optical signal. For the quantum communication time phase encoding device and method, time phase encoding is realized by adding pi phases, and the encoding method is simple and convenient, and the phase modulation precision is high, andthe code forming rate is high.

Description

technical field [0001] The invention relates to the field of quantum secure communication, in particular to a time phase encoding device, encoding method and quantum key distribution system for quantum communication. Background technique [0002] Security technology is one of the cores of communication technology. Currently the most commonly used RSA encryption algorithm is not absolutely safe in theory. As an emerging technology developed on the basis of quantum mechanics, modern communication and modern cryptography, quantum secure communication is based on the basic principles of quantum mechanics and uses the "one-time pad" method to encrypt information. Unparalleled security advantages. [0003] The BB84 protocol is the most basic quantum key distribution protocol in the field of quantum secure communication. The BB84 protocol uses four polarization states of a single photon to encode. These four polarization states belong to two groups of conjugated groups. The two ...

AI Technical Summary

Problems solved by technology

First, under the current technical conditions, there is no single-photon light source required by the BB84 protocol with mature technology and large-scale commercial application. Usually, a weak coherent light source is used, but the quantum key distribution system using this light source will It is attacked by photon number separation, which reduces the security of the system

Second, the BB84 protocol uses the polarization state for encoding, which is easily affected by the polarization disturbance of the fiber, resulting in problems such as short transmission distance and high bit error rate.

[0008] Although this prior art can realize time phase encoding, it has the following technical problems: First, the phase modulator PM needs to be able to modulate four kinds of 0, π / 2, π, 3π / 2 between two coherent lights. Different phase differences make the encoding method more complicated

During the high-frequency phase modulation process, the switching of the phase modulator PM among four different voltages will lead to instability of the applied voltage, resulting in poor phase modulation accuracy and affecting the coding rate

Third, in order to ensure that the phase modulator PM is loaded with a relatively stable operating voltage to ensure phase modulation accuracy, a special phase modulation calibration device with a complex structure is required, which increases the complexity of the system structure

Fourth, the two channels of interference light generated by the encoding device need to be transmitted to the beam combiner through two different optical channels to synthesize one channel to generate encoded light, which also increases the complexity of the system structure

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