HD-QKD system based on polarization modulation time coding

A technology of polarization modulation and time coding, applied in transmission systems, digital transmission systems, and key distribution, which can solve the problems of positive correlation between complexity and dimension, constraints on high-dimensional time coding QKD systems, and increased complexity of X-based vector measurement devices , to achieve the effect of improving measurement efficiency

Pending Publication Date: 2018-09-14
RUBAN QUANTUM TECH CO LTD
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Problems solved by technology

[0020] Defects of existing schemes: In the measurement system of high-dimensional time encoding, the measurement of Z base vector is the same as that of common qubit encoding (two-dimensional); but the complexity of X base vector measurement device is greatly increased, and its complexity Positively related to dimension
In addition to the consideration of cost and system stability, there is also an obvious defect in the high-dimensional X-based vector measurement system. The measurement efficiency of the above-mentioned X-based vector measurement device is inversely proportional to the dimension, which is 1 / d (this value does not include the loss and photodetector efficiency), higher dimensional encoding means lower detection efficiency, which obviously restricts the practical application of high-dimensional time-encoded QKD systems

Method used

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  • HD-QKD system based on polarization modulation time coding
  • HD-QKD system based on polarization modulation time coding

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Embodiment 1

[0162] see Figure 11 In this embodiment, the modulation of the base vector and the decoy state adopts an internal modulation method, which is completed by a polarization pulse group generating device, including:

[0163] 1. Use Figure 6 The polarized pulse group generating device shown generates a polarized pulse group;

[0164] 2. Through internal modulation, the output pulse group completes the modulation of the base vector and the decoy state (see below);

[0165] 3. The modulated pulse group sequence is transmitted to the measurement end through optical fiber;

[0166] 4. The pulse group sequence is first split by the beam splitter BS, and its transmission and reflection ratios are just the probability ratio of Z and X base vector modulation;

[0167] 5. The transmission pulse enters the Z base vector measuring device; preferably, the Z base vector measuring device selects one of the structures shown in Figure 7;

[0168] 6. The reflected pulse enters the X base vect...

Embodiment 2

[0175] see Figure 14 , compared with embodiment 1, this embodiment realizes the modulation of the decoy state through the form of external modulation; short pulse drive voltage V 0 To achieve, but through an external modulator to achieve.

[0176] Preferably, the decoy state modulation means is an intensity modulator;

[0177] Preferably, the decoy state modulation device is an intensity modulation device composed of a beam splitter and a phase modulator, such as Figure 15 As shown; the pulse is incident through port 1 of the balanced beam splitter (BS), and the pulse with the required intensity can be obtained through interference at port 2 of the BS by adjusting the modulation phase of the phase modulator (PM).

[0178] The rest of the device and the steps are the same as in Example 1.

Embodiment 3

[0180] see Figure 5 , compared with Embodiment 2, the modulation of the base vector in this embodiment is also performed in the form of external modulation; Figure 6 The driving voltage of the light injected into the polarized pulse group generating device is as follows Figure 16 As shown; the device generates polarization-modulated pulse groups: pulses with the same intensity in four time intervals, and the phase of each pulse is the same.

[0181] The base vector modulation device consists of Figure 15 The shown intensity modulation device and phase modulator are composed;

[0182] The decoy state modulation device is Figure 15 structure shown.

[0183] The rest of the device and the steps are the same as in Example 1.

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Abstract

The invention discloses an HD-QKD system based on polarization modulation time coding, comprising: the transmitting end generates a polarization modulated optical pulse group based on light injection,then obtains a coded optical pulse group via a base vector modulation and a decoy state modulation, and sends the encoded optical pulse group to the receiving end after being attenuated; and the receiving end respectively uses the Z-based vector detecting module and the X-based vector detecting module to perform detection after splitting the coded optical pulse group from the transmitting end. The HD-QKD system provided by the invention adopts polarization modulation time coding and corresponding measuring devices, and further improves the measurement efficiency.

Description

technical field [0001] The invention relates to the technical field of quantum communication, in particular to a high-dimensional quantum key distribution system based on polarization modulation time coding. Background technique [0002] With the development of quantum information theory and technology, quantum computers will be available soon. Traditional public key systems based on computational complexity will no longer be secure. People have known for a long time that symmetric encryption is used, and the one-time pad encryption system is safe from the perspective of information theory. This kind of security is not based on similar premises such as computational complexity, so it will not be affected by quantum computers. But this kind of symmetric encryption system needs to carry out secure real-time long-distance key distribution, which is difficult to do in the classical system. The emergence of quantum key distribution system (QKD) solves the security problem in th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L9/08
CPCH04L9/0858
Inventor 富尧朱伟
Owner RUBAN QUANTUM TECH CO LTD
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