CN213879847U

CN213879847U - Multi-user double-field QKD network system based on orbital angular momentum

Info

Publication number: CN213879847U
Application number: CN202023259355.2U
Authority: CN
Inventors: 王鹏程; 胡敏; 郭邦红
Original assignee: South China Normal University
Current assignee: Guangdong Yukopod Technology Development Co ltd
Priority date: 2020-12-29
Filing date: 2020-12-29
Publication date: 2021-08-03
Anticipated expiration: 2030-12-29

Abstract

The utility model provides a multi-user double-field QKD network system based on orbital angular momentum, which comprises 3 Alice parties (sender) and 3 Bob parties (sender), two Arrayed Waveguide Gratings (AWG) and 3 measurement parties; the 3 Alice parties and the 3 Bob parties can realize the communication between any Alice and any Bob; the 6 transmitters are respectively connected with an Arrayed Waveguide Grating (AWG); the specific wavelength outlet of the Arrayed Waveguide Grating (AWG) is connected with a specified measuring party; the sender (Alice side and Bob side) sends the prepared single photons, the single photons reach the measuring end after passing through the Arrayed Waveguide Grating (AWG) to generate single photon interference, and then the single photons are measured to form code values. The utility model provides the high communication distance of no relay quantum key distribution, and can resist all attacks to the measuring terminal, strengthened the security of system.

Description

Multi-user double-field QKD network system based on orbital angular momentum

Technical Field

The utility model relates to a multi-user quantum communication field, concretely relates to three user's systems of two-field QKD based on orbital angular momentum.

Background

Quantum key distribution is an important technology for realizing symmetric key agreement between two communication parties based on quantum mechanics principle. In the case of the presence of an eavesdropper (Eve), the two communicating parties, i.e., Alice and Bob, can realize theoretically absolutely secure communication using the generated secret key in combination with the one-time pad protocol. The first quantum key distribution protocol was proposed by Bennett et al in 1984, referred to as the BB84 protocol, which presents various problems due to differences in real-world technological conditions and idealities. During the next decades, a great number of researchers have been proposing quantum key distribution protocols with greater security and greater transmission distances. In 2018, Lucamarini et al propose a double-field quantum key distribution protocol, namely TF-QKD (quaternary key distribution, QKD for short), that is, the double-field quantum key distribution protocol breaks through the theoretical limit of the quantum key distribution protocol transmission distance without quantum relay, and has the advantage of eliminating a side channel of a detection system. However, the original two-field QKD protocol implements point-to-point communication and employs phase encoding, with reference frame alignment issues. With the development of technology and the progress of society, it is obvious that the quantum secret communication between point-to-point users cannot meet the social requirements, the quantum secret communication between multiple users can well solve the problem, and the practical process of quantum secret communication is greatly promoted.

Orbital angular momentum was discovered and proposed by Allen et al in 1992, and photons have not only spin but also orbital angular momentum, which originates from the helical phase of light waves, and they have been found to have a phase structure

A light field of wherein

Is azimuthal, e.g. Laguerre Gaussian beam, with an average of each photon

The orbital angular momentum of (1), wherein is an arbitrary integer. Photon orbital angular momentum eigenstates mathematically form a complete set of orthogonal basis vectors, so that high-dimensional information coding can be realized by utilizing orbital angular momentum. States containing orbital angular momentum can be represented as

Wherein the content of the first and second substances,

showing the relative phase used for encoding, b_A，BE {0, pi } where 0 and pi represent 0 and 1 in the code, respectively.

For example, the sender and receiver generate coherent states

The above equation shows the photon state when the modulated beam value is 4.

Meng et al conducted some theoretical studies and simulations on TF-QKD using orbital angular momentum in 2020, but were limited to point-to-point quantum secure communication between single users, and did not consider multi-party quantum secure communication.

SUMMERY OF THE UTILITY MODEL

The utility model aims at overcoming the problem that prior art exists, provide a transmission distance length, transmission channel capacity are big, can be many ways of key distribution based on two field QKD systems of three users of orbit angular momentum. TF-QKD is the present newer quantum key distribution protocol, suitable for the quantum secret communication of long distance, and orbital angular momentum can be very big extension transmission channel capacity, has important effects to carrying on the high dimensional quantum key distribution. The utility model discloses combine advantage between them promptly to carry out quantum secret communication network's between the multi-user buildding, satisfy quantum secret communication's between the multi-user demand.

The orbital angular momentum was discovered and proposed by Allen et al in 1992 and is a new degree of freedom for photons. The orbital angular momentum has the property that any two values are in an orthogonal state in an infinite Hilbert space, so that the orbital angular momentum is applied to communication, and the channel capacity can be greatly expanded.

The double-field QKD is proposed in 2018 in order to break through the theoretical limit of the transmission distance of the traditional quantum key distribution protocol without quantum relay, and has the advantage of measuring equipment-independent quantum key distribution system, which is TF-QKD for short. The basic TF-QKD consists of two senders, namely Alice and Bob, and a measuring party, namely Charlie, and the communication method is as follows: 1. respectively and independently generating a single photon state with orbital angular momentum by Alice and Bob; 2. alice and Bob respectively send the prepared states to Charlie; 3. single-photon interference occurs on a BS beam splitter in front of Charlie in a single-photon state sent by Alice and Bob; 4. according to the response generated by the detection of the two OAM classifiers at the Charlie end, the original secret key can be obtained by the code forming rules Alice and Bob; 5. then both sides carry out post-processing procedures including monitoring and detection, error code analysis and privacy amplification. And finally generating a security key which can be communicated by Alice and Bob.

The OAM-TF-QKD measurement results are shown in Table 1 along with the corresponding code values.

TABLE 1 OAM-TF-QKD measurement results and corresponding code values

The present invention provides a multi-user system, in which any two users among a plurality of legitimate users can communicate. Specifically, what mainly states in the utility model is that three users distribute the quantum key mode to three users.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a multi-user double-field QKD network system based on orbital angular momentum comprises a first sender, a second sender, a third sender, a fourth sender, a fifth sender, a sixth sender, a first measuring party, a second measuring party and a third measuring party;

the grating structure also comprises two arrayed waveguide gratings, namely a first arrayed waveguide grating and a second arrayed waveguide grating; the first arrayed waveguide grating and the second arrayed waveguide grating are respectively provided with three input ports and three output ports; the three input ports of the second arrayed waveguide grating are respectively connected with a fourth sender, a fifth sender and a sixth sender; three output ports of the first arrayed waveguide grating and the second arrayed waveguide grating are respectively connected with a first measuring party, a second measuring party and a third measuring party.

The utility model discloses technical scheme can realize the communication between the different users according to the specific wavelength of negotiation between the different users.

Preferably, the first sender, the second sender, the third sender, the fourth sender, the fifth sender and the sixth sender are all single-photon sources.

Preferably, the first sender, the second sender, the third sender, the fourth sender, the fifth sender and the sixth sender each comprise a variable wavelength light source, an intensity modulator, a phase modulator, a random number generator and a spatial light modulator.

Preferably, the first measuring party, the second measuring party and the third measuring party each include one beam splitter BS and two OAM (Orbital Angular Momentum) classifiers, and one beam splitter BS is connected to each of the two OAM classifiers.

Preferably, a first output end of the first array waveguide grating is connected with the beam splitter BS of the first measuring party, a second output end of the first array waveguide grating is connected with the beam splitter BS of the second measuring party, and a third output end of the first array waveguide grating is connected with the beam splitter BS of the third measuring party; the first output end of the second array waveguide grating is connected with the beam splitter BS of the first measuring party, the second output end of the second array waveguide grating is connected with the beam splitter BS of the second measuring party, and the third output end of the second array waveguide grating is connected with the beam splitter BS of the third measuring party.

Preferably, both parties of the communication select light of the same wavelength for communication before performing communication.

Compared with the prior art, the beneficial effects of the utility model are that:

1. the utility model discloses a agreement is based on TF-QKD, TF-QKD has included the advantage that all measuring equipment do not have the relation quantum key distribution, can resist all attacks to measuring equipment.

2. The utility model discloses utilized the photon that has orbital angular momentum as the carrier of information, need not calibrate with reference system, simplified system's complexity, improved secret key speed.

3. The orbital angular momentum state has the characteristic of infinite dimension, so that the invention has strong expansion capability, can be conveniently combined with a multiplexing/separating device of the orbital angular momentum, greatly improves the channel capacity and expands the user side.

4. The utility model has simple structure, easy realization and low economic cost; the method can be used for a multi-user system, breaks through the limit of the distribution distance of the quantum key without relay in theory, and has longer transmission distance than the traditional quantum key distribution protocol.

Drawings

FIG. 1 is a block diagram of a first sender, Alice1, according to the present invention;

FIG. 2 is a block diagram of a second sender Alice2 in accordance with the present invention;

FIG. 3 is a block diagram of a third sender Alice3 according to the present invention;

FIG. 4 is a block diagram of a fourth sender Bob1 according to the invention;

FIG. 5 is a block diagram of a fifth sender Bob2 according to the present invention;

FIG. 6 is a block diagram of a sixth sender Bob3 according to the invention;

FIG. 7 is a diagram of the structure of Det1 of the first measuring party according to the present invention;

FIG. 8 is a diagram of the structure of Det2 of the second measuring party according to the present invention;

FIG. 9 is a diagram of the structure of Det3 of the third measuring party according to the present invention;

fig. 10 is an overall structural view of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to specific embodiments and the accompanying drawings, but the scope of the present invention is not limited to the embodiments.

Example 1:

first, both parties that need to communicate before communication starts select communication light wavelengths, and both parties should select light of the same wavelength to load information. The light of both communication parties reaches the same detector through the wavelength division router to carry out communication. Therefore, in order to facilitate multi-party communication, the two communication parties adopt the variable wavelength laser, and multi-party communication can be realized.

As shown in fig. 10, a two-field QKD three-user system based on orbital angular momentum includes six transmitters (Alice1, Alice2, Alice3, Bob1, Bob2, Bob3), three measuring parties (Det1, Det2, Det3), and two Arrayed Waveguide Gratings (AWG).

Specifically, the first sender, the second sender, the third sender, the fourth sender, the fifth sender and the sixth sender are all single photon sources.

Because a single photon source is difficult to obtain, as shown in fig. 1, 2, 3, 4, 5 and 6, the single photon source is a probabilistic single photon source and consists of a variable wavelength light source, an intensity modulator, a random number generator, a phase modulator and a spatial light modulator. Single photons are generated by a variable wavelength light source, then the single photons are modulated by an intensity modulator and a phase modulator under the control of a random number generator, and the modulated single photons are sent to a spatial light modulator for information loading of orbital angular momentum.

As shown in fig. 7, 8 and 9, the first measuring party, the second measuring party and the third measuring party are specifically composed of a beam splitter BS and two detectors, when the first sender, namely Alice1, and the fourth sender, namely Bob1, arrive at the first measuring party BS, single photon interference occurs in the input light at the BS, and according to the interference result, the light arrives at the D0 detector from the left or arrives at the D1 detector from the right, and the corresponding detectors are triggered to respond. Judging whether bit flipping is needed according to which detector responses, and judging whether bit flipping is needed according to which detector responses; the right detector response, does not need to be bit flipped. The particular bit value is determined based on the response of the particular detector. The rules for coding are as described in table 1 above.

As shown in fig. 10, a two-field QKD three-user system based on orbital angular momentum realizes quantum key distribution by the following specific steps:

the method comprises the following steps: preparation work: the two parties needing to communicate define the communication optical wavelength, and the two parties need to adopt the light with the same wavelength for communication;

step two: preparing information to be measured: two sending ends, namely Alice and Bob, respectively modulate photons to be sent, randomly load intensity and phase information, and then send the intensity and phase information to the array waveguide grating;

step three: sending information to be tested: the array waveguide grating transmits the received light to a corresponding measuring end for measurement according to different wavelengths of the received light;

step four: measurement: single photons coming out of the arrayed waveguide grating enter a corresponding measuring end, single photon interference occurs on a beam splitter BS, different responses can occur to a detector according to information loaded by two communication parties, and the measuring end can publish the response condition of the detector;

step five: forming an original code: forming an original code according to an initially agreed double-field QKD coding mode;

step six: eavesdropping detection: estimating the error rate according to partial original keys disclosed by two communication parties, namely an Alice party and a Bob party, comparing the error rate with the range of a theoretical error rate value, if the error rate exceeds a credible range, terminating the protocol in the current round, and restarting;

step seven: and (3) data post-processing: and the Bob side performs data post-processing on the generated original key, and the steps of data negotiation, privacy enhancement and the like are included, so that the secure key is finally obtained.

The Bob side sometimes needs to perform bit flipping according to different probe response conditions. For example, when the detector D0 responds, a bit flip is required, i.e., 0 becomes 1 and 1 becomes 0.

It should be noted that the Alice side described herein may be any Alice, that is, Alice1, Alice2, and Alice3, and similarly, the Bob side may also be any Bob, that is, Bob1, Bob2, and Bob 3. The utility model discloses can realize the communication between three users.

Variations and modifications to the above-described embodiments may occur to those skilled in the art, which fall within the scope and spirit of the above description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A multi-user double-field QKD network system based on orbital angular momentum is characterized by comprising a first sender, a second sender, a third sender, a fourth sender, a fifth sender, a sixth sender, a first measurer, a second measurer and a third measurer;

2. The multi-user dual-field QKD network system based on orbital angular momentum of claim 1, wherein said first, second, third, fourth, fifth and sixth senders are all single photon sources.

3. The multi-user dual-field QKD network system based on orbital angular momentum of claim 2, wherein said first, second, third, fourth, fifth and sixth transmitters each comprise a variable wavelength optical source, an intensity modulator, a phase modulator, a random number generator and a spatial light modulator connected in sequence.

4. The multi-user dual-field QKD network system based on orbital angular momentum of claim 1, wherein the first, second and third measuring parties each comprise a beam splitter BS and two OAM classifiers, one beam splitter BS being connected to each of the two OAM classifiers.

5. The orbital-angular-momentum-based multi-user two-field QKD network system according to claim 1, wherein both communicating parties select the same wavelength of light for communication before communicating.

6. The multi-user dual-field QKD network system based on orbital angular momentum of claim 1, wherein a first output of the first arrayed waveguide grating is connected to the beam splitter BS of the first measuring party, a second output is connected to the beam splitter BS of the second measuring party, and a third output is connected to the beam splitter BS of the third measuring party; the first output end of the second array waveguide grating is connected with the beam splitter BS of the first measuring party, the second output end of the second array waveguide grating is connected with the beam splitter BS of the second measuring party, and the third output end of the second array waveguide grating is connected with the beam splitter BS of the third measuring party.