Dynamic user quantum communication system and method based on polarization selection

Abstract

The invention discloses a dynamic user quantum communication system based on polarization selection. The dynamic user quantum communication system comprises a transmitting end Alice and a plurality of receiving end users Bob, the sending end Alice is connected with the first receiving end Bob1; the plurality of receiving ends are connected in sequence; the sending end Alice is used for sending a phase-modulated pulse signal to the first receiving end Bob1 or any one of the plurality of receiving ends Bob; and after any receiving end Bob receiving the pulse signal receives the pulse signal, the pulse signal is subjected to phase modulation, polarization compensation and reflection optical fiber delay, and then the pulse signal returns to the Alice end along the original path for detection. According to the invention, users can be increased or replaced through the cooperation of the N (N > = 2) optical switches in the system, the optical paths are adjusted through the N (N > = 2) optical switches, one-to-one, one-to-many and random selection of receiving ends can be realized, the whole network does not need to be reconfigured, the complexity and cost of system adjustment are reduced, and the robustness of the quantum network is improved.

Description

Technical Field

[0001] The present invention relates to the field of quantum communication and quantum network, and in particular to a dynamic user quantum communication system and method based on polarization selection. Background Art

[0002] Quantum communication is an emerging technology that uses the principles of quantum mechanics to transmit information. Compared with traditional communication methods, quantum communication has higher security, especially in preventing eavesdropping and information leakage. Quantum Key Distribution (QKD) is the most representative technology in quantum communication and quantum network applications. It ensures the security of key transmission through the uncertainty principle in quantum mechanics.

[0003] Quantum communication is the process of transmitting quantum signals along fixed paths, which can be optical fibers, free space (such as satellite-to-ground communications), or other media capable of carrying quantum states. In quantum communication, quantum states (such as quantum bits) are transmitted along these fixed paths, and information is usually loaded by phase, polarization, and other optical degrees of freedom modulation to achieve encryption or transmission of information. How to achieve efficient and flexible quantum information transmission in a complex network environment has become an important research direction. Traditional quantum communication systems usually use fixed paths for information transmission. Although this method is simple, it lacks flexibility and cannot meet the needs of dynamic communication with free switching of multiple users.

[0004] Therefore, it is necessary to improve the existing technology and propose a quantum communication system and method based on phase coding and polarization selection of users, which reduces the complexity and cost of system adjustment. Summary of the invention

[0005] In order to solve the above technical problems, a quantum communication system and method based on phase-coded polarization selective users are proposed, which reduces the complexity and cost of system adjustment.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A dynamic user quantum communication system based on polarization selection includes a transmitting end Alice and multiple receiving end users Bob, wherein the multiple receiving ends Bob are respectively a first receiving end Bob1, a second receiving end Bob2, a third receiving end Bob3, ..., an Nth receiving end Bobn, wherein;

[0008] The transmitting end Alice is connected to the first receiving end Bob1; the first receiving end Bob1, the second receiving end Bob2, the third receiving end Bob3, ..., the Nth receiving end Bobn are connected in sequence;

[0009] The transmitting end Alice is used to send a phase-modulated pulse signal to the first receiving end Bob1 or any one of the multiple receiving ends Bob;

[0010] After receiving the pulse signal, any receiving end Bob performs phase modulation, polarization compensation, and reflection fiber delay on the pulse signal, and then the pulse signal returns to Alice along the original path for detection.

[0011] Preferably, the receiving end Bob comprises a first optical switch and a second off switch, wherein the first optical switch and the second off switch each comprise three paths.

[0012] The three paths of the first optical switch are: a first path, a second path and a third path;

[0013] The three paths of the second switch are respectively: a fourth path, a fifth path and a sixth path.

[0014] Preferably, the sending end Alice is connected to the receiving end Bob through the first path of the first switch of any receiving end Bob; the first switch of any receiving end Bob is connected to the second switch, and the sixth path of the second switch of the previous receiving end Bob is connected to the first switch of its next adjacent receiving end Bob.

[0015] Preferably, the pulse signal of the transmitting end Alice enters the first receiving end Bob1 through the first path connection of the first optical switch;

[0016] Or the pulse signal of the transmitting end Alice is connected to the second optical switch of the first receiving end Bob1 through the third path of the first optical switch, and the sixth path of the second optical switch of the first receiving end Bob1 is connected to the first path of the first optical switch of the second receiving end Bob2 to enter the second receiving end Bob2;

[0017] Or the pulse signal of the transmitting end Alice passes through the above path through the third path of the first optical switch of the second receiving end Bob2 and is connected to the second optical switch of the second receiving end Bob2, and the sixth path of the second optical switch of the second receiving end Bob2 is connected to the first path of the first optical switch of the third receiving end Bob3 and enters the third receiving end Bob3;

[0018] By analogy, the pulse signal from the transmitting end Alice enters through the Nth receiving end Bobn.

[0019] Preferably, any receiving end Bob comprises a first optical switch, a circulator, a Faraday rotator, a Sagnac ring device, a second optical switch, an optical fiber delay line and a Faraday mirror;

[0020] The first path of the first optical switch is connected to the transmitting end Alice;

[0021] The second path of the first optical switch is sequentially connected to a circulator, a Faraday rotator, and a Sagnac ring device;

[0022] The circulator is further connected to the second optical switch via a fourth path of the second optical switch;

[0023] The third path of the first optical switch is connected to the second switch;

[0024] The second switch is connected in sequence to the optical fiber delay line and the Faraday mirror through a fifth path;

[0025] The sixth path of the second switch is connected to the first path of the first optical switch of the next adjacent receiving end Bob.

[0026] Preferably, the Sagnac loop device is used to perform Bob-end phase modulation on the pulse signal.

[0027] Preferably, the Faraday rotator is used to compensate for the polarization change introduced by the Sagnac ring device.

[0028] Preferably, the optical fiber delay line is used to delay the pulse signal to prevent the pulse reflected back by the Faraday mirror from colliding with the next pulse signal being transmitted.

[0029] Preferably, the Sagnac ring device comprises a beam splitter, a phase modulator and a Faraday rotator, and the beam splitter, the phase modulator and the Faraday rotator are connected in sequence in a ring shape.

[0030] A dynamic user quantum communication method based on polarization selection, which applies the above-mentioned dynamic user quantum communication system based on polarization selection, has the following steps:

[0031] Step S1: the transmitting end Alice sends a phase modulated pulse signal;

[0032] The pulse signal enters the receiving Bob in two ways:

[0033] First way:

[0034] Step S2-1: the pulse signal enters the first receiving end Bob1 through the first optical switch of the first receiving end Bob1, and then enters the second path of the first receiving end Bob1;

[0035] Step S2-2: In the second path, the pulse signal enters the Faraday rotator through the circulator, and then performs phase modulation on Bob's end through the ring device to obtain key information;

[0036] Step S2-3: After the key information comes out of the Sagnac ring device, it enters the Faraday rotator to compensate for the polarization change caused by the Sagnac ring device, and then enters the fourth path of the second optical switch through the circulator;

[0037] Step S2-4: Entering the fifth path of the second optical switch from the fourth path;

[0038] Step S2-5: In the fifth path, the key information enters the optical fiber delay line, is reflected back to the optical fiber delay line through the Faraday mirror, and returns to Alice's end along the original path for detection;

[0039] Second way:

[0040] Step S3-1: The pulse signal enters the first receiving end Bob1 through the first optical switch of the first receiving end Bob1, passes through the third path of the first receiving end Bob1, and then connects to the second optical switch of the first receiving end Bob1 and enters the sixth path of the second optical switch;

[0041] Step S3-2: The pulse signal enters the first switch of the second receiving end Bob2 from the first receiving end Bob1 through the sixth path.

[0042] Beneficial technical effects of the present invention: The present invention sets a first optical switch and a second optical switch in the system, and can add or replace users through the cooperation of N (N≥2) optical switches. By adjusting the optical path through N (N≥2) switches, 1-to-1, 1-to-many, and arbitrary selection of receiving ends can be easily achieved without reconfiguring the entire network, thereby reducing the complexity and cost of system adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is an overall structural block diagram of a dynamic user quantum communication system based on polarization selection according to the present invention;

[0044] Figure 2 A schematic diagram of the structure of a Sagnac ring device of a dynamic user quantum communication system based on polarization selection in the present invention;

[0045] Figure 3 The present invention is a flowchart of the steps of a dynamic user quantum communication method based on polarization selection. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments, but the scope of protection claimed in the present invention is not limited to the following specific embodiments.

[0047] like Figure 1As shown, a dynamic user quantum communication system based on polarization selection includes a transmitting end Alice and multiple receiving end users Bob, the multiple receiving ends Bob are respectively a first receiving end Bob1, a second receiving end Bob2, a third receiving end Bob3, ..., an Nth receiving end Bobn, wherein;

[0048] The transmitting end Alice is connected to the first receiving end Bob1 through an optical fiber; the first receiving end Bob1, the second receiving end Bob2, the third receiving end Bob3, ..., the Nth receiving end Bobn are sequentially connected through the optical fiber;

[0049] The transmitting end Alice is used to send a phase-modulated pulse signal and send it to the first receiving end Bob1 or any one of the multiple receiving ends Bob;

[0050] After receiving the pulse signal, any receiving end Bob will perform phase modulation, polarization compensation, and reflection fiber delay on the pulse signal, and then return the processed pulse signal along the original path to Alice for detection.

[0051] Specifically, the detailed connection relationship between the sender Alice and any receiver Bob is as follows:

[0052] The receiving end Bob includes a first optical switch 101 and a second switch 105, wherein the first optical switch 101 and the second switch 105 each include three paths.

[0053] The three paths of the first optical switch 101 are: a first path 1, a second path 2 and a third path 3;

[0054] The three paths of the second switch 105 are respectively: a fourth path 4 , a fifth path 5 and a sixth path 6 .

[0055] The sending end Alice is connected to the receiving end Bob through the first path 1 of the first switch 101 of any receiving end Bob; the first switch 101 of any receiving end Bob is connected to the second switch 105, and the sixth path 6 of the second switch 105 of the previous receiving end Bob is connected to the first switch 101 of its next adjacent receiving end Bob.

[0056] After the pulse signal of the transmitting end Alice enters the receiving end Bob, it is connected to the first receiving end Bob1 through the first path 1 of the first optical switch 101 of the receiving end Bob;

[0057] Or the pulse signal of the transmitting end Alice is connected to the second optical switch 105 of the first receiving end Bob1 through the third path 3 of the first optical switch 101, and the sixth path 6 of the second optical switch 105 of the first receiving end Bob1 is connected to the first path 1 of the first optical switch 101 of the second receiving end Bob2 to enter the second receiving end Bob2;

[0058] Or the pulse signal of the transmitting end Alice is connected to the second optical switch 105 of the second receiving end Bob2 through the third path 3 of the first optical switch 101 of the second receiving end Bob2, and the sixth path 6 of the second optical switch 105 of the second receiving end Bob2 is connected to the first path 1 of the first optical switch 101 of the third receiving end Bob3 to enter the third receiving end Bob3;

[0059] By analogy, the pulse signal of the transmitting end Alice enters the Nth receiving end Bobn.

[0060] Specifically, the internal structure and connection relationship of any receiving end Bob are as follows:

[0061] Any receiving end Bob includes a first optical switch 101, a circulator 102, a Faraday rotator 103, a Sagnac ring device 104, a second optical switch 105, an optical fiber delay line 106 and a Faraday mirror 107;

[0062] The first path 1 of the first optical switch 101 is connected to the transmitting end Alice;

[0063] The second path 2 of the first optical switch 101 is sequentially connected to the circulator 102, the Faraday rotator 103, and the Sagnac ring device 104;

[0064] The circulator 102 is further connected to the second optical switch 105 via a fourth path 4 of the second optical switch 105;

[0065] The third path 3 of the first optical switch 101 is connected to the second switch 105;

[0066] The second switch 105 is connected to the optical fiber delay line 106 and the Faraday mirror 107 in sequence through the fifth path 5;

[0067] The sixth path 6 of the second switch 105 is connected to the first path 1 of the first optical switch 101 of the next adjacent receiving end Bob.

[0068] The functions of each device are as follows:

[0069] The Sagnac ring device 104 is used to perform phase modulation on the pulse signal entering Bob's end;

[0070] The Faraday rotator 103 is used to compensate for the polarization change introduced by the Sagnac ring device 104;

[0071] The optical fiber delay line 106 is used to delay the pulse signal to prevent the pulse signal reflected by the Faraday mirror 103 from colliding with the next pulse signal being transmitted.

[0072] Specifically, the Sagnac ring device 104 includes a beam splitter 201, a phase modulator 202 and a Faraday rotator 203, and the beam splitter 201, the phase modulator 202 and the Faraday rotator 203 are connected in sequence in a ring shape.

[0073] For ease of understanding, we describe two situations: the sender Alice communicates with the receiver Bob1, and the sender Alice communicates with the receiver Bob2.

[0074] Communication situation 1: The sender Alice communicates with the receiver Bob1:

[0075] First, part of the phase-modulated pulse signal generated by the transmitting end Alice is transmitted to Bob1. After the pulse signal enters the first optical switch 101 through the first path, it is connected to the second path 2 through the port of the first optical switch 101; after the pulse signal passes through the circulator 102, it first enters the Faraday rotator 103, and then passes through the Sagnac ring device 104 to perform phase modulation on the Bob end. At this time, the pulse signal has the phase modulation information of both Alice and Bob1, that is, the pulse signal at this time contains key information. At this time, the pulse signal containing the key information comes out of the Sagnac ring device 104, enters the Faraday rotator 103 to compensate for the polarization change caused by the Sagnac ring device, and then passes through the circulator 102 to the fourth path 4. At this time, because the communication user selected by Alice is Bob1, the pulse signal enters the second optical switch 105 through the fourth path 4, and then accesses the fifth path 5 through the port of the second optical switch 105. After entering path 5, the pulse signal first passes through the optical fiber delay line 106, then is reflected by the Faraday mirror 107 and passes through the optical fiber delay line 106 again, and finally the pulse signal returns to Alice along the original path for detection.

[0076] The general process of the pulse signal carrying the key information returning along the original path is as follows:

[0077] The pulse signal enters the fourth path 4 through the second optical switch 105; after passing through the circulator 102, it goes to the second path 2. The pulse signal then returns to Alice's end through the first path 1 of the first optical switch 101 and is detected at Alice's end.

[0078] The pulse signal is detected at Alice's end using an existing quantum communication detection method, which is not the gist of the present invention and will not be described in detail.

[0079] Communication situation 12: The sender Alice communicates with the receiver Bob2:

[0080] First, part of the phase-modulated pulse signal generated by the transmitter Alice is transmitted to Bob1. After the pulse signal reaches the first optical switch 101, it is connected to the third path 3 through the port of the first optical switch 101. The third path 3 is connected to the sixth path 6 of the second optical switch 105, and is connected to the first path 1 of the first switch 101 of Bob2 through the sixth path 6. The pulse signal enters Bob2 through the first path 1 of the first switch 101 of Bob2. Similarly, as with the communication between Alice and Bob1, the pulse signal is connected to the second path 2 through the port of the first optical switch 101 of Bob2. After passing through the circulator 102 of Bob2, the pulse signal first enters the Faraday rotator 103 of Bob2, and then is phase modulated at the Bob end through the Sagnac ring device 104 of Bob2. At this time, the pulse signal has the phase modulation information of both Alice and Bob2, that is, the key information. At this time, after the pulse signal comes out of Bob2's Sagnac ring device 104, it enters Bob2's Faraday rotator 103 to compensate for the polarization change caused by passing through Bob2's Sagnac ring device, and then passes through Bob2's circulator 102 to reach the fourth path 4. It enters the second switch 105 through the fourth path 4, and then enters the fifth path 5 through the second switch 105; after entering path 5, the pulse signal first passes through Bob2's optical fiber delay line 106, and then is reflected by Bob2's Faraday mirror 107 and passes through the optical fiber delay line 106 again, and the pulse signal returns to Alice's end along the original path for detection.

[0081] A dynamic user quantum communication method based on polarization selection, the method steps are as follows:

[0082] Step S1: the transmitting end Alice sends a phase modulated pulse signal;

[0083] The pulse signal enters the receiving end Bob through the following two ways;

[0084] First way:

[0085] Step S2-1: The pulse signal enters the first receiving end Bob1 through the first path 1 of the first switch 101, and enters the second path 2 of the first switch 101 of the receiving end Bob1;

[0086] Step S2-2: In the second path 2, the pulse signal enters the Faraday rotator 103 through the circulator 102, and then undergoes phase modulation at the Bob end through the ring device 104 to obtain the key information;

[0087] Step S2-3: After the key information comes out of the Sagnac ring device 104, it enters the Faraday rotator 103 to compensate for the polarization change caused by the Sagnac ring device 104, and then enters the fourth path 4 of the second optical switch 105 through the circulator 102;

[0088] Step S2-4: Entering the fifth path 5 of the second optical switch 105 from the fourth path 4;

[0089] Step S2-5: In the fifth path 5, the key information enters the optical fiber delay line 106, is reflected back to the optical fiber delay line 106 through the Faraday mirror 107, and returns to Alice's end along the original path for detection.

[0090] Second way:

[0091] Step S3-1: The pulse signal enters the third path 3 of the first receiving end Bob1 through the first switch 101 of the first receiving end Bob1 and then enters the sixth path 6 of the first receiving end Bob1 through the second optical switch 105 of the first receiving end Bob1;

[0092] Step S3-2: The pulse signal enters the first switch 101 of the second receiving end Bob2 from the sixth path 6 of the first receiving end Bob1, and then enters the second path 2 of the first switch 101 of the second receiving end Bob2 to implement the same signal processing operation as the first method above.

[0093] Similarly, through the second method, the pulse signal can enter the Nth receiving end Bobn.

[0094] The present invention sets a first optical switch and a second optical switch in the system. Through the cooperation of the two optical switches, users can be added or replaced. By adjusting the optical path through the two optical switches, one-to-one and one-to-many can be easily achieved, and any selection of the receiving end can be achieved without reconfiguring the entire network, thereby reducing the complexity and cost of system adjustment.

[0095] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the invention.

Claims

1. A dynamic user quantum communication system based on polarization selection, characterized in that: It includes a sending end Alice and multiple receiving end users Bob, the multiple receiving ends Bob are respectively a first receiving end Bob1, a second receiving end Bob2, a third receiving end Bob3, ..., an Nth receiving end Bobn, wherein; The transmitting end Alice is connected to the first receiving end Bob1; the first receiving end Bob1, the second receiving end Bob2, the third receiving end Bob3, ..., the Nth receiving end Bobn are connected in sequence; The transmitting end Alice is used to send a phase-modulated pulse signal to the first receiving end Bob1 or any one of the multiple receiving ends Bob; After receiving the pulse signal, any receiving end Bob performs phase modulation, polarization compensation, and reflection fiber delay on the pulse signal, and then the pulse signal returns to Alice along the original path for detection.

2. A dynamic user quantum communication system based on polarization selection as claimed in claim 1, characterized in that: The receiving end Bob includes a first optical switch and a second optical switch, wherein the first optical switch and the second optical switch each include three paths. The three paths of the first optical switch are: a first path, a second path and a third path; The three paths of the second switch are respectively: a fourth path, a fifth path and a sixth path.

3. A dynamic user quantum communication system based on polarization selection as claimed in claim 2, characterized in that: The transmitting end Alice is connected to the receiving end Bob through the first path of the first switch of any receiving end Bob; the first switch of any receiving end Bob is connected to the second switch, and the sixth path of the second switch of the previous receiving end Bob is connected to the first switch of its next adjacent receiving end Bob.

4. A dynamic user quantum communication system based on polarization selection as claimed in claim 3, characterized in that: The pulse signal of the transmitting end Alice enters the first receiving end Bob1 through the first path connection of the first optical switch; Or the pulse signal of the transmitting end Alice is connected to the second optical switch of the first receiving end Bob1 through the third path of the first optical switch, and the sixth path of the second optical switch of the first receiving end Bob1 is connected to the first path of the first optical switch of the second receiving end Bob2 to enter the second receiving end Bob2; Or the pulse signal of the transmitting end Alice passes through the above path through the third path of the first optical switch of the second receiving end Bob2 and is connected to the second optical switch of the second receiving end Bob2, and the sixth path of the second optical switch of the second receiving end Bob2 is connected to the first path of the first optical switch of the third receiving end Bob3 and enters the third receiving end Bob3; By analogy, the pulse signal from the transmitting end Alice enters through the Nth receiving end Bobn.

5. A dynamic user quantum communication system based on polarization selection as claimed in claim 4, characterized in that: Any receiving end Bob includes a first optical switch, a circulator, a Faraday rotator, a Sagnac ring device, a second optical switch, an optical fiber delay line and a Faraday mirror; The first path of the first optical switch is connected to the transmitting end Alice; The second path of the first optical switch is sequentially connected to a circulator, a Faraday rotator, and a Sagnac ring device; The circulator is further connected to the second optical switch via a fourth path of the second optical switch; The third path of the first optical switch is connected to the second switch; The second switch is connected in sequence to the optical fiber delay line and the Faraday mirror through a fifth path; The sixth path of the second switch is connected to the first path of the first optical switch of the next adjacent receiving end Bob.

6. A dynamic user quantum communication system based on polarization selection as claimed in claim 5, characterized in that: The Sagnac loop device is used to perform phase modulation on the pulse signal at the Bob end.

7. A dynamic user quantum communication system based on polarization selection as claimed in claim 6, characterized in that: The Faraday rotator is used to compensate for the polarization change introduced by the Sagnac ring device.

8. A dynamic user quantum communication system based on polarization selection as claimed in claim 7, characterized in that: The optical fiber delay line is used to delay the pulse signal to prevent the pulse reflected by the Faraday mirror from colliding with the next pulse signal being transmitted.

9. A dynamic user quantum communication system based on polarization selection as claimed in claim 8, characterized in that: The Sagnac ring device comprises a beam splitter, a phase modulator and a Faraday rotator, and the beam splitter, the phase modulator and the Faraday rotator are connected in sequence in a ring shape.

10. A method for dynamic user quantum communication based on polarization selection, using a dynamic user quantum communication system based on polarization selection as claimed in any one of claims 1 to 9, characterized in that: The steps of this method are as follows: Step S1: the transmitting end Alice sends a phase modulated pulse signal; The pulse signal enters the receiving Bob in two ways: First way: Step S2-1: the pulse signal enters the first receiving end Bob1 through the first optical switch of the first receiving end Bob1, and then enters the second path of the first receiving end Bob1; Step S2-2: In the second path, the pulse signal enters the Faraday rotator through the circulator, and then performs phase modulation on Bob's end through the ring device to obtain key information; Step S2-3: After the key information comes out of the Sagnac ring device, it enters the Faraday rotator to compensate for the polarization change caused by the Sagnac ring device, and then enters the fourth path of the second optical switch through the circulator; Step S2-4: Entering the fifth path of the second optical switch from the fourth path; Step S2-5: In the fifth path, the key information enters the optical fiber delay line, is reflected back to the optical fiber delay line through the Faraday mirror, and returns to Alice's end along the original path for detection; Second way: Step S3-1: The pulse signal enters the first receiving end Bob1 through the first optical switch of the first receiving end Bob1, passes through the third path of the first receiving end Bob1, and then connects to the second optical switch of the first receiving end Bob1 and enters the sixth path of the second optical switch; Step S3-2: The pulse signal enters the first switch of the second receiving end Bob2 from the first receiving end Bob1 through the sixth path.

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