CN109818740B

CN109818740B - Method for distributing and accessing uplink continuous variable quantum key by using wavelength division multiplexer

Info

Publication number: CN109818740B
Application number: CN201910066340.7A
Authority: CN
Inventors: 张一辰; 黄韵頔; 赵一甲; 王翔宇; 喻松
Original assignee: Beijing University of Posts and Telecommunications
Current assignee: Beijing University of Posts and Telecommunications
Priority date: 2019-01-24
Filing date: 2019-01-24
Publication date: 2020-06-19
Anticipated expiration: 2039-01-24
Also published as: CN109818740A

Abstract

The invention provides an uplink continuous variable quantum key distribution access network method using a wavelength division multiplexer. In the scheme, a user side generates an uplink continuous variable quantum signal by using a continuous variable quantum key distribution sending end, the continuous variable quantum signal is transmitted to a time delay control module through an optical fiber and then enters a wavelength division multiplexer, the output is transmitted to a terminal continuous variable quantum key distribution receiving end through the optical fiber, and the continuous variable quantum key distribution receiving end measures the continuous variable quantum signal by utilizing homodyne detection or heterodyne detection and carries out a key extraction step so as to extract a key. The scheme realizes the continuous variable quantum key distribution access network of the multi-user end, and has the characteristics of high code rate, low cost, easy realization and the like. Lays a foundation for the construction of large-scale practical quantum networks.

Description

Method for distributing and accessing uplink continuous variable quantum key by using wavelength division multiplexer

Technical Field

The invention relates to the field of continuous variable quantum key distribution, in particular to an uplink continuous variable quantum key distribution access network method using a wavelength division multiplexer.

Background

The proof of the security of the continuous variable quantum key distribution theory lays a foundation for the application of the continuous variable quantum key distribution technology. At present, a plurality of countries develop continuous variable quantum key distribution experiments, and the continuous variable quantum key distribution technology is rapidly stepping into the application stage. The access network is an important place in network construction as a connection between a backbone network and a user terminal. The wavelength division multiplexing technology can enable signals with different wavelengths to be transmitted simultaneously in a single optical fiber, can greatly improve the transmission quantity of the optical fiber, and is an important technology in the next generation optical network. The quantum access network technology based on the discrete variable protocol still has the problems that the cost of the detector is high, the detection efficiency is low under the room temperature condition, and the like, and the large-scale application is not facilitated. Therefore, there is still a need for an access network method that can distribute quantum keys to users.

Disclosure of Invention

The invention discloses a method for distributing and accessing an uplink continuous variable quantum key by using a wavelength division multiplexer, which avoids using a single photon detector, realizes the distribution of the quantum key to a user by using all components with high commercialization degree, greatly reduces the construction cost of the quantum access network, and improves the feasibility of large-scale quantum network construction.

The invention comprises four steps:

step 1: the n continuous variable quantum key distribution transmitting ends respectively generate continuous variable quantum signals with n wavelengths.

Step 2: the n paths of continuous variable quantum signals and the local oscillator light respectively pass through the time delay control module to calibrate the time for the continuous variable quantum signals to reach the optical branching device;

and step 3: and outputting the n paths of calibrated continuous variable quantum signal light and local oscillator light into one path of signal through a wavelength division multiplexer, and transmitting the one path of signal to a continuous variable quantum key distribution receiving terminal through an optical fiber.

And 4, step 4: and the continuous variable quantum key distribution receiving end detects the continuous variable quantum signal and extracts the key. The technical points of step 1 are specifically described as follows:

the n continuous variable quantum communication transmitting terminals respectively use lasers with wavelengths of lambda 1 to lambda n, the wavelengths of lambda 1 to lambda n are different, and the wavelengths of lambda 1 to lambda n range from 1528.77nm to 1560.61 nm.

The n continuous variable quantum communication transmitting ends firstly prepare pulse signals through a laser or the laser and an intensity modulator, then divide the pulse signals into signal light and local oscillator light through a beam splitter, wherein the signal light modulates quantum states through the intensity modulator and a phase modulator, attenuates the quantum signals through an attenuator to prepare continuous variable quantum signal pulses, and then is optically coupled with the local oscillator through a polarization combiner and transmitted to a time delay control module.

The technical points of step 2 are specifically described as follows:

the continuous variable quantum key distribution transmitting end generates a continuous variable quantum signal and local oscillator light, and the continuous variable quantum signal and the local oscillator light are transmitted to the delay control module through the optical fiber, wherein the delay control module is a delay line. The n time delay modules change the time for the continuous variable quantum signals to enter the wavelength division multiplexing by adjusting the time delay, and the wavelength division multiplexing device is ensured to have no overlapping of n paths of continuous variable quantum signals.

The technical points of step 4 are specifically described as follows:

and the continuous variable quantum communication receiving end detects the continuous variable quantum signals in a homodyne detection or heterodyne detection mode, and performs a key extraction step to obtain the key.

The invention provides a deployment method of a plurality of continuous variable quantum key distribution transmitting terminals and a continuous variable quantum key distribution receiving terminal, and realizes a many-to-one quantum access network structure. The invention uses mature commercial components and detectors with high detection efficiency to realize an access network structure with high code rate, low cost and easy implementation. Lays a foundation for the construction of large-scale practical quantum networks.

Drawings

FIG. 1 is a simplified schematic diagram of a transmitting end of continuous variable quantum key distribution

FIG. 2 is a schematic structural diagram of the present invention

Detailed Description

Specific embodiments of the present invention are described below with reference to the accompanying drawings:

referring to fig. 2, a method for distributing an access network using an upstream continuous variable quantum key of an optical splitter includes the following steps:

1. the access network adopts an uplink structure, namely n user terminals send keys to one continuous variable quantum key distribution receiving terminal through the continuous variable quantum key distribution sending terminal.

And 2, n continuous variable quantum key distribution transmitting ends respectively select lasers with wavelengths of lambda 1 to lambda n, wherein the wavelengths of lambda 1 to lambda n are different, and the wavelength selection range of the wavelengths of lambda 1 to lambda n is 1528.77nm to 1560.61 nm.

N continuous variable quantum key distributing and transmitting ends, referring to fig. 1, the continuous variable quantum key distributing and transmitting ends firstly prepare pulse signals through a laser or the laser and an intensity modulator, then divide the pulse signals into signal light and local oscillator light through a beam splitter, wherein the signal light modulates quantum states through the intensity modulator and a phase modulator, attenuates the quantum signals through an attenuator to prepare continuous variable quantum signal pulses, and then is optically coupled with the local oscillator light through a polarization combiner and transmitted to a time delay control module.

4. The continuous variable quantum signals prepared by the continuous variable quantum key distribution sending terminal pass through the delay module, wherein the delay module is a delay line in the example, and the delay module enables n paths of continuous variable quantum signals to respectively enter the optical splitter without overlapping by adjusting the time delay of the continuous variable quantum signals.

5. And the continuous variable quantum signal pulse passing through the time delay module is transmitted to the optical splitter through the optical fiber, and the output signal of the optical splitter is transmitted to a continuous variable quantum key distribution receiving end through one optical fiber.

6. And the continuous variable quantum communication receiving end detects the continuous variable quantum signals in a homodyne detection or heterodyne detection mode, and performs a key extraction step to obtain the key.

It can be seen from the above examples that the method for uplink distribution of the continuous variable quantum key provided by the invention can realize a many-to-one uplink quantum access network structure under the conditions of avoiding using a single photon detector and room temperature. The feasibility of quantum network construction is greatly improved.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the protective enclosure of the present invention should be defined by the appended claims.

Claims

1. A method for distributing and accessing an access network by using an uplink continuous variable quantum key of a wavelength division multiplexer is characterized in that: the method comprises the following steps:

step 1: the n continuous variable quantum key distribution transmitting ends respectively generate continuous variable quantum signals with n wavelengths;

the step 1 comprises the following steps:

step 1 a: n continuous variable quantum communication transmitting ends prepare pulse signals through a laser or the laser and an intensity modulator, and then the pulse signals are divided into signal light and local oscillator light through a beam splitter;

step 1 b: the signal light modulates the quantum state through an intensity modulator and a phase modulator, and attenuates the quantum signal light into a continuous variable quantum signal through an attenuator;

step 1 c: the continuous variable quantum signal is optically coupled with a local oscillator through a polarization combiner and is sent to a time delay control module;

step 2: the n paths of continuous variable quantum signals and the local oscillator light respectively pass through the time delay control module to calibrate the time of the continuous variable quantum signals and the local oscillator light reaching the wavelength division multiplexer;

and step 3: outputting the n paths of calibrated continuous variable quantum signal light and local oscillator light into one path of signal through a wavelength division multiplexer, and transmitting the one path of signal to a continuous variable quantum key distribution receiving terminal through an optical fiber;

and 4, step 4: and the continuous variable quantum key distribution receiving end detects the continuous variable quantum signal and extracts the key.

2. The method according to claim 1, wherein in step 1, the n sending terminals for continuous variable quantum key distribution use lasers with wavelengths λ 1 to λ n, the wavelengths λ 1 to λ n are different, and the wavelengths λ 1 to λ n range from 1528.77nm to 1560.61 nm.

3. The method according to claim 1, wherein the continuous variable quantum signal and the local oscillation light generated by the transmitting end of the continuous variable quantum key distribution are transmitted to the delay control module through an optical fiber.

4. The method according to claim 1, wherein the delay control module in step 2 is a delay line, and the wavelength division multiplexer is configured to ensure that n continuous variable quantum signals enter the delay line without overlapping by adjusting the delay module.

5. The method according to claim 1, wherein in step 4, the continuous variable quantum distribution receiving end detects the continuous variable quantum signal by homodyne detection or heterodyne detection, and performs the key extraction step to extract the key.