CN108365955A - A kind of device-independent high channel capacity quantum communication system and method - Google Patents

Abstract

The invention belongs to the technical field of information processing, and discloses a device-independent high-channel-capacity quantum communication system and method. The communication method adopts a super-entangled state under multiple degrees of freedom as a quantum carrier, establishes a device-independent super-entangled quantum communication model, and performs Dense encoding; by calculating the amount of information that can be transmitted by each particle, and comparing it with the amount of information in other protocols, the channel capacity is verified; at the same time, the invention discloses a device-independent high-channel-capacity quantum communication system. The present invention completes the distribution of a two-bit device-independent key by distributing two particles, and the quantum efficiency reaches 1; if an ordinary entangled state such as a Bell state is used as a quantum carrier, only one device-independent key can be completed by distributing two particles distribution, the quantum efficiency is only 0.5.

Description

A device-independent high channel capacity quantum communication system and method

technical field

The invention belongs to the technical field of information processing, and in particular relates to a device-independent high channel capacity quantum communication system and method.

Background technique

At present, the existing technologies commonly used in the industry are as follows:

In order to promote the practical application of quantum communication, security and channel capacity improvement under the premise of security are two key issues that need to be solved urgently. In previous studies, the security of quantum communication is guaranteed by the principle of quantum mechanics, and both the quantum state preparation source and the measurement equipment are assumed to be perfect by default. However, under realistic conditions, it is difficult to achieve perfect preparation of source and measurement equipment. Therefore, there may be various security risks in the actual quantum communication system. Aiming at the imperfection of the device, there have been many attack schemes leading to the leakage of secret information, such as "time displacement attack", "dead time attack" and "bright light blinding attack" and so on. That is to say, quantum communication protocols that are absolutely safe in theory may be very insecure in practice. Therefore, under the premise that the equipment cannot be trusted, the study of a secure quantum communication protocol is the first step that must be taken to promote the practical application of quantum communication and ensure security. In addition, under the premise that the device cannot be trusted, the actual channel capacity will be greatly reduced. If the channel capacity in communication is too low, it will not be possible to truly implement a practical quantum-safe communication protocol. Therefore, it is of theoretical significance and practical value to study quantum communication protocols that are safe and have high capacity under the condition of untrustworthy equipment. At present, the theoretical and technical research on quantum communication under the premise of untrustworthy equipment mainly focuses on the following five aspects: research on quantum secure communication independent of equipment, and shielding side channel attack vulnerabilities caused by untrustworthy preparation sources and measurement equipment. The research on quantum secure communication independent of measurement equipment only shields the vulnerability of side channel attacks caused by untrustworthy measurement equipment. An untrusted third party measures the entanglement state of the particles sent by both communication parties and announces the results. The communication parties generate keys by judging the relevance of their input data, thereby removing the detector side channel loopholes. However, it is impossible to shield the vulnerability of side-channel attacks caused by untrustworthy preparation sources, and only the decoy state method can be used to avoid the security problems caused by non-ideal light sources. Research on semi-device-independent quantum key distribution, which assumes that neither the preparation source nor the measurement device can be trusted, but requires the communication party to prepare a quantum system with known Hilbert space dimensions. The research on unilateral device-independent quantum key distribution mainly studies the use of EPR-steering inequality violation judgment to shield the side-channel attack vulnerability caused by the untrustworthy measuring device of one party under the premise that only one of the communication devices is untrustworthy. However, none of the above studies on quantum secure communication under the premise of untrustworthy equipment has not considered a problem that is indispensable in any communication: the problem of coding efficiency has not been considered. Under the premise of untrustworthy equipment, the actual channel capacity will be greatly reduced. , if the channel capacity in communication is too low, a practical quantum-safe communication protocol cannot be truly realized.

In summary, the problems in the prior art are:

The prior art is very insecure in actual communication. Most of the existing technologies do not consider the potential security risks caused by untrustworthy devices. Even if a few technologies consider the factors of untrustworthy devices, they have not yet considered the problem of low coding efficiency caused by untrustworthy devices.

Therefore, the prior art is safe in theory, but not safe in practice, and the efficiency is not high.

The difficulty and significance of solving the above technical problems:

The present invention can prevent (shield) information leakage caused by untrustworthy preparation source equipment or measurement equipment (controlled or provided by eavesdroppers), and resist common side channel attack vulnerabilities, such as "time displacement attack" and "dead time attack" And "strong light blinding attack", etc., provide safe and reliable communication; at the same time, it also improves the channel capacity of device-independent quantum communication. Taking key distribution as an example, the quantum efficiency is doubled. At present, the theoretical value of the quantum efficiency can only reach 0.5 at the highest when using the existing technology for key distribution, but the theoretical value of the quantum efficiency can reach 1 at the highest in the technology proposed by the present invention.

Contents of the invention

Aiming at the problems existing in the prior art, the present invention provides a device-independent quantum communication system and method with high channel capacity.

The present invention is achieved in this way, a device-independent high-channel-capacity quantum communication method, comprising:

Establish a quantum communication model independent of the quantum state preparation source: in the worst case, the quantum density of state function model of the entangled state is prepared by an eavesdropper; then when designing a quantum protocol under the described quantum state density function description model, according to Bell's inequality The violation of the principle eliminates the non-entangled state, retains the super-entangled state, and communicates based on the super-entangled state. According to the principle of monogamous entanglement and not exceeding the speed of light, the eavesdropper cannot obtain any secret information by controlling the preparation source;

Establish a device-independent quantum communication model: the device-independent includes preparation-source-independent and measurement-equipment-independent; only analyze whether the statistical probability relationship between measurement input and output results violates the Bell-type inequality, and use this as a consideration in quantum communication whether With the judgment condition of the eavesdropper, a quantum communication model independent of the measurement equipment is constructed; the quantum state distributed to the user for communication is in the maximum entangled state, and according to the monogamous principle of entanglement and the principle of not exceeding the speed of light, the eavesdropper no matter It is impossible to obtain the secret information of legal users through the measuring equipment by any means;

Establish a device-independent high-channel-capacity quantum communication model: use multi-degree-of-freedom super-entangled states as quantum carriers, and establish a device-independent super-entangled quantum communication model for dense encoding.

Further, the establishment of a quantum communication model independent of the quantum state preparation source includes:

Assume that the entangled state is prepared by the eavesdropper Eve and then distributed to the sender and receiver for the next communication; the eavesdropper Eve does not prepare a perfect super-entangled Bell state in order to obtain as much secret information as possible from the sender and receiver ;On the contrary, the eavesdropper Eve prepares a mixed state of super-entangled state and non-entangled state, confuses the sending end and the receiving end so that he does not find his eavesdropping behavior, and obtains the secret information of the sending end and the receiving end;

The super-entangled Bell state prepared by the eavesdropper Eve is represented by the following density function model:

The density function model indicates that the state prepared by the eavesdropper Eve is a super-entangled state and a mixed state of the non-entangled state I/4, the super-entangled state in the mixed state The visibility of the unentangled state I/4 is p, and the visibility of the non-entangled state I/4 is 1–p;

According to the monogamous principle of entanglement, if the eavesdropper Eve prepares an entangled state, it will not be able to obtain any secret information of the sender and receiver; and if the eavesdropper Eve prepares a non-entangled state, it will obtain part of the secret information of the sender and receiver;

When analyzing the impact of various noises in the channel, the sending end and the receiving end accept the original convert to

If the non-entangled state is eliminated according to the violation principle of Bell's inequality, and the super-entangled state is retained, and the communication is based on the super-entangled state, the eavesdropper Eve cannot obtain any information between the sender and receiver secret information.

Further, the establishment of a device-independent quantum communication model includes:

If the eavesdropper Eve sends A particle to the sender and B particle to the receiver; the sender and the receiver randomly select the measurement input x and y∈{0,1} to measure their respective particles, where x=0 means Z first ^S -based measurement and then Z ^P -based measurement, x=1 means Z ^S- based measurement first and then X ^P -based measurement; where y=0 means Z S-based measurement first and then X ^P -based measurement base measurement, y=1 means Z ^S base measurement first and then base measurement;

The measurement results of the sending end and the receiving end are denoted as a and b∈{0l,0u,1l,1u} respectively;

Define the CHSH inequality

P(a ₀ ＝b ₀ )+P(a ₀ ＝b ₁ )+P(a ₁ ＝b ₀ )+P(a ₁ ≠b ₁ )≤3, where

P(a _j =b _k )=P(a=b=0l|x=j,y=k)+P(a=b=0u|x=j,y=k)

+P(a=b=11|x=j, y=k)+P(a=b=1u|x=j, y=k).

The sending end and the receiving end select some particles to calculate the conditional probability P(a,b|x,y), and judge whether the CHSH inequality is violated. If it is violated, it means that the particles distributed by the eavesdropper Eve to the sending end and the receiving end are in a super-entangled state.

Further, the original is a super-entangled Bell state under a polarization state degree of freedom and a path mode degree of freedom;

where |0> and |1> represent the horizontal polarization state and vertical polarization state of the photon respectively; the subscripts A and B represent the two photons in the super-entangled state respectively; l and u represent the different path modes of the photon A and B; The subscript P represents the degree of freedom of the polarization state, and the subscript S represents the degree of freedom of the path mode; an ultraviolet optical pump pulse passing through a barium borate β crystal BBO will generate interrelated photon pairs in the mode u; after reflection, it passes through the The crystal, in turn, will generate interrelated photon pairs in mode l;

For a two-photon superentangled Bell state quantum system with polarization state degree of freedom and path mode degree of freedom, there are 16 Bell states, expressed as:

where |Θ> _P represents one of the four Bell states under the polarization state of freedom:

where |Ξ> _S represents one of the four Bell states under the path mode degree of freedom:

Using CHBSA to distinguish 16 kinds of super-entangled Bell states;

The two non-orthogonal measurement bases under the degree of polarization state freedom are selected as: Z ^P ＝{|0>,|1>} and

The two non-orthogonal measurement bases for path mode degrees of freedom are selected as: Z ^S ＝{|l>,|u>} and

Super-entangled state with two degrees of freedom of polarization state and path mode

hour,

Eve prepares the quantum state:

in Indicates that the state prepared by Eve is a super-entangled state and a mixed state of the non-entangled state I/4, in which the super-entangled state The visibility of is p, and the visibility of the non-entangled state I/4 is 1-p.

Another object of the present invention is to provide a key distribution method of the device-independent high channel capacity quantum communication method, the key distribution method comprising:

Eve sends A particle to the sending end, B particle to the receiving end; the sending end and the receiving end respectively randomly select the measurement input x and y∈{0,1} to measure their respective particles, where x=0 means Z ^S basis Measurement and then Z ^P basis measurement, x=1 means first Z ^S basis measurement and then X ^P basis measurement; where y=0 means first Z ^S basis measurement and then base measurement, y=1 means Z ^S base measurement first and then Base measurement; the measurement results of the sending end and the receiving end are respectively expressed as a and b∈{0l,0u,1l,1u};

Define the CHSH inequality

P(a ₀ ＝b ₀ )+P(a ₀ ＝b ₁ )+P(a ₁ ＝b ₀ )+P(a ₁ ≠b ₁ )≤3, where

P(a _j =b _k )=P(a=b=0l|x=j,y=k)+P(a=b=0u|x=j,y=k)

+P(a=b=1l|x=j,y=k)+P(a=b=1u|x=j,y=k);

The sending end and the receiving end select some particles to calculate the conditional probability P(a,b|x,y), and judge whether the CHSH inequality is violated. If it is violated, it means that the particles distributed by Eve to the sending end and the receiving end are in a super-entangled state; based on a In the super-entangled state, the sender and the receiver share a two-digit security key 0l, 0u, 1l or 1u.

Another object of the present invention is to provide a computer program for implementing the device-independent high channel capacity quantum communication method.

Another object of the present invention is to provide an information processing terminal carrying the computer program.

Another object of the present invention is to provide a computer-readable storage medium, including instructions, which, when run on a computer, cause the computer to execute the device-independent high-channel-capacity quantum communication method

Another object of the present invention is to provide a device-independent high channel capacity quantum communication system, including:

A quantum communication model unit that has nothing to do with the quantum state preparation source is used to prepare a quantum density of state function model of an entangled state by an eavesdropper in the worst case; then when designing a quantum protocol under the described quantum state density function description model, according to Bell inequality violates the principle of eliminating non-entangled states, retaining super-entangled states, and communicating based on super-entangled states, based on the monogamy of entanglement and the principle of not exceeding the speed of light, so that eavesdroppers cannot obtain any secret information by controlling the preparation source;

A quantum communication model unit that has nothing to do with the device, the device has nothing to do with the preparation source and the measurement device has nothing to do; it is used to only analyze whether the statistical probability relationship between the measurement input and output results violates the Bell class inequality, and use it as a consideration for quantum communication Whether there is an eavesdropper in the judgment condition, construct a quantum communication model that has nothing to do with the measurement equipment; make the quantum state distributed to the user for communication in the maximum entangled state, and according to the monogamous principle of entanglement and the principle of not exceeding the speed of light, make the eavesdropping No matter what method is used, the user cannot obtain the secret information of the legal user through the measuring equipment;

The device-independent high-channel-capacity quantum communication model unit is used to use the super-entangled state under multiple degrees of freedom as a quantum carrier to establish a device-independent super-entangled quantum communication model for dense encoding.

Another object of the present invention is to provide an information processing terminal equipped with the device-independent high channel capacity quantum communication system.

In summary, the advantages and positive effects of the present invention are:

The present invention can prevent (shield) information leakage caused by untrustworthy preparation source equipment or measurement equipment (controlled or provided by eavesdroppers), and resist common side channel attack vulnerabilities, such as "time displacement attack" and "dead time attack" And "strong light blinding attack", etc., provide safe and reliable communication; at the same time, it also improves the channel capacity of device-independent quantum communication. Taking key distribution as an example, the quantum efficiency is doubled. Most of the existing quantum communication technologies have the problem of information leakage caused by untrustworthy preparation source equipment or measurement equipment. Even a few technologies have proposed some methods to prevent information leakage caused by untrustworthy preparation source equipment or measurement equipment. The channel capacity cannot be guaranteed, mainly because they have not considered that untrustworthy equipment is also a major cause of channel capacity reduction. At present, the theoretical value of the quantum efficiency can only reach 0.5 at the highest when using the existing technology for key distribution, but the theoretical value of the quantum efficiency can reach 1 at the highest in the technology proposed by the present invention.

Aiming at the problem of how to improve the channel capacity (quantum efficiency) of device-independent quantum communication, the present invention adopts a super-entangled state under multiple degrees of freedom as a quantum carrier, establishes a device-independent super-entangled quantum communication model, and realizes dense coding. By calculating the amount of information that can be transmitted by each particle and comparing it with the amount of information in other protocols, it is proved that the method proposed by the present invention can achieve higher channel capacity (quantum efficiency). The present invention completes the distribution of two device-independent keys by distributing two particles, and the quantum efficiency reaches 1. If an ordinary entangled state such as the Bell state |φ ⁺ > _AB is used as the quantum carrier, only one device-independent key can be distributed by distributing two particles, and the quantum efficiency is only 0.5.

In the case that the eavesdropper controls or provides the preparation source equipment, the invention performs mathematical modeling or mathematical description on the super-entangled Bell state prepared by the preparation source, aiming at the untrustworthy problem of the preparation source of the quantum state (especially entangled state, super-entangled state) , proposed to construct the worst-case scenario—an entangled quantum state density function description model prepared by an eavesdropper, and then design a quantum communication protocol based on this model, and analyze the security of quantum communication to ensure that the eavesdropper cannot control the prepared source. Obtain secret information.

Description of drawings

FIG. 1 is a schematic structural diagram of a device-independent high-channel-capacity quantum communication system provided by an embodiment of the present invention.

In the figure: 1. The quantum communication model unit independent of the quantum state preparation source; 2. The quantum communication model unit independent of the device; 3. The high channel capacity quantum communication model unit independent of the device.

Fig. 2 is a flowchart of a device-independent high-capacity quantum communication method provided by an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The prior art is very insecure in actual communication. Most of the existing technologies do not consider the potential security risks caused by untrustworthy devices. Even if a few technologies consider the factors of untrustworthy devices, they have not yet considered the problem of low coding efficiency caused by untrustworthy devices.

As shown in Figure 1, the device-independent high channel capacity quantum communication system provided by the embodiment of the present invention includes:

The quantum communication model unit 1 independent of the quantum state preparation source is used to prepare the quantum density of state function model of the entangled state by the eavesdropper in the worst case; then when designing the quantum protocol under the described quantum state density function description model, Eliminate the non-entangled state according to the violation principle of Bell's inequality, keep the super-entangled state, and communicate based on the super-entangled state, and make it impossible for eavesdroppers to obtain any secret information by controlling the preparation source according to the monogamous and non-superluminal principle of entanglement;

Device-independent quantum communication model unit 2, the device-independent includes preparation-source-independent and measurement-equipment-independent; it is used to only analyze whether the statistical probability relationship between the measurement input and output results violates the Bell-like inequality, and use this as a consideration for quantum The judgment condition of whether there is an eavesdropper in the communication, constructs a quantum communication model independent of the measurement equipment; makes the quantum state distributed to the user for communication in the maximum entangled state, and according to the monogamous principle of entanglement and the principle of not exceeding the speed of light, so that Eavesdroppers cannot obtain the secret information of legitimate users through measuring equipment no matter what means they use;

The device-independent high-channel-capacity quantum communication model unit 3 is used to use the super-entangled state under multiple degrees of freedom as the quantum carrier, and establish a device-independent super-entangled quantum communication model for dense encoding.

The present invention will be further described below in conjunction with specific analysis.

As shown in Figure 2, the device-independent high-capacity quantum communication method provided by the embodiment of the present invention includes:

Establish a quantum communication model independent of the quantum state preparation source: in the worst case, the quantum density of state function model of the entangled state is prepared by an eavesdropper; then when designing a quantum protocol under the described quantum state density function description model, according to Bell's inequality The violation of the principle eliminates the non-entangled state, retains the super-entangled state, and communicates based on the super-entangled state. According to the principle of monogamous entanglement and not exceeding the speed of light, the eavesdropper cannot obtain any secret information by controlling the preparation source;

Establish a device-independent quantum communication model: the device-independent includes preparation-source-independent and measurement-equipment-independent; only analyze whether the statistical probability relationship between measurement input and output results violates the Bell-type inequality, and use this as a consideration in quantum communication whether With the judgment condition of the eavesdropper, a quantum communication model independent of the measurement equipment is constructed; the quantum state distributed to the user for communication is in the maximum entangled state, and according to the monogamous principle of entanglement and the principle of not exceeding the speed of light, the eavesdropper no matter It is impossible to obtain the secret information of legal users through the measuring equipment by any means;

Establish a device-independent high-channel-capacity quantum communication model: use multi-degree-of-freedom super-entangled states as quantum carriers, and establish a device-independent super-entangled quantum communication model for dense encoding.

(1) Establish a quantum communication model independent of the quantum state preparation source, the functional principle:

Aiming at the untrustworthy problem of quantum state (especially entangled state) preparation source, it is proposed to construct the worst case-the quantum state density function description model of entangled state prepared by an eavesdropper, and then design a quantum communication protocol under this model, and analyze the quantum The security of communication ensures that eavesdroppers cannot obtain secret information by controlling the preparation source.

Super-entangled Bell states with one polarization state degree of freedom and path mode degree of freedom For example, assuming that the entangled state is prepared by the eavesdropper Eve and then distributed to the sender (Alice) and the receiver (Bob) for the next communication, then in order for Eve to obtain as much secret information as possible from the sender and receiver, Eve will not prepare a perfect super-entangled Bell state. On the contrary, Eve will try to prepare a mixed state of super-entangled state and non-entangled state, which can confuse the sending end and the receiving end to prevent them from discovering their eavesdropping behavior. Help yourself to the secret information on the sending and receiving ends. Then the present invention can represent the super-entangled Bell state that Eve may prepare with the following density function model:

The density function indicates that the state prepared by Eve is a super-entangled state and a mixed state of the non-entangled state I/4, the super-entangled state in the mixed state The visibility of is p, and the visibility of the non-entangled state I/4 is 1-p. According to the monogamous principle of entanglement, if Eve prepares an entangled state (including a super-entangled state), then he will not be able to obtain any secret information of the sender and receiver, and if Eve prepares a non-entangled state, then he can obtain the secret information of the sender and receiver. Part of the secret information on the terminal. For the sending end and the receiving end, they can accept the original The state becomes the state due to the influence of the noise If the present invention eliminates non-entangled states in communication based on the violation principle of Bell’s inequality, retains super-entangled states, and communicates based on super-entangled states, then Eve will not be able to obtain the sending end and receiving any confidential information on the terminal.

It can be seen that if the quantum carrier used for communication is described as a quantum density of state function model prepared by an eavesdropper (in the worst case), then when designing a quantum protocol, the non-entangled state is eliminated according to the violation principle of Bell's inequality, and the remaining Super-entangled state, and communication based on super-entangled state, based on the principle of monogamous entanglement and no faster than the speed of light, can ensure that eavesdroppers cannot obtain any secret information by controlling the preparation source.

(2) Establish a quantum communication model independent of equipment (including independent of preparation source and independent of measurement equipment), functional principle:

On the basis of preparation source-independence, the problem of untrustworthiness of measurement equipment is shielded, a device-independent (including preparation source-independent and measurement equipment-independent) quantum communication model is established, and the internal implementation and operation details of the measurement equipment are not considered (that is, the measurement equipment is treated as a black box). box), and only observe whether the statistical probability relationship between the measurement input and output results violates the Bell-type inequality, and use this as a judgment condition to consider whether there is an eavesdropper in the quantum communication, and build a quantum communication model that is independent of the measurement equipment. Ensure that the quantum state distributed to users for communication is in the maximum entanglement state (non-local relationship), so that according to the principle of monogamous entanglement and the principle of not exceeding the speed of light, eavesdroppers cannot obtain legal data through measuring equipment no matter what means they use. User's confidential information.

Eve sends the A particle to the sender, and the B particle to the receiver. The sending end and the receiving end randomly select the measurement input x and y∈{0,1} to measure their respective particles, where x=0 means that the Z ^S basis is measured first and then the Z ^P basis is measured, and x=1 means that the Z ^S basis is measured first Then X ^P base measurement; where y=0 means first Z ^S base measurement and then base measurement, y=1 means Z ^S base measurement first and then base measurement. The measurement results at the transmitter and receiver are denoted as a and b∈{0l,0u,1l,1u}, respectively.

Define the CHSH inequality

P(a ₀ ＝b ₀ )+P(a ₀ ＝b ₁ )+P(a ₁ ＝b ₀ )+P(a ₁ ≠b ₁ )≤3, where

P(a _j =b _k )=P(a=b=0l|x=j,y=k)+P(a=b=0u|x=j,y=k)

+P(a=b=11|x=j, y=k)+P(a=b=1u|x=j, y=k).

The sender and receiver select some particles to calculate the conditional probability P(a,b|x,y), and judge whether the CHSH inequality is violated. If it is violated, it means that the particles distributed by Eve to the sender and receiver are in a super-entangled state.

(3) Establish a device-independent high channel capacity quantum communication model.

Aiming at how to improve the channel capacity (quantum efficiency) of device-independent quantum communication, a super-entangled state with multiple degrees of freedom is used as the quantum carrier, and a device-independent super-entangled quantum communication model is established to realize dense coding. By calculating the amount of information that can be transmitted by each particle and comparing it with the amount of information in other protocols, it is proved that the method proposed by the present invention can achieve higher channel capacity (quantum efficiency).

On the basis of establishing a quantum communication model independent of the quantum state preparation source and a quantum communication model independent of the device (including preparation source independent and measurement device independent), the sending end and the receiving end are based on a super-entangled state, and can share two bit security key 0l, 0u, 1l or 1u. Obviously, in the above key distribution process, if the particle used for CHSH inequality detection is removed, the two-bit device-independent key distribution is completed by distributing two particles, and the quantum efficiency reaches 1. If an ordinary entangled state such as the Bell state |φ ⁺ > _AB is used as the quantum carrier, only one device-independent key can be distributed by distributing two particles, and the quantum efficiency is only 0.5.

In the device-independent high-capacity quantum communication method provided by the embodiment of the present invention, super-entanglement is a state of entanglement in multiple degrees of freedom at the same time. Photons have multiple quantum degrees of freedom, and each quantum degree of freedom may define a qubit under suitable conditions. In theory, these different degrees of freedom can also form entanglement, which is the so-called super-entanglement. For example, the two degrees of freedom of a certain photon can be entangled with the two degrees of freedom of another photon at the same time, so that one photon can be used as two qubits.

The super-entangled Bell state with one polarization state degree of freedom and path mode degree of freedom can be described as:

where |0> and |1> denote the horizontal polarization state and vertical polarization state of the photon, respectively. The subscripts A and B denote the two photons in the super-entangled state, respectively. l and u represent the different path patterns of photons A and B. The subscript P indicates the degree of freedom of the polarization state, and the subscript S indicates the degree of freedom of the path mode. A UV optical pump pulse passing through a barium borate beta crystal (BBO) produces correlated photon pairs in mode u; a second reflection through the crystal produces correlated photon pairs in mode l.

For a two-photon superentangled Bell state quantum system with polarization state degree of freedom and path mode degree of freedom, there are 16 Bell states, which can be expressed as:

where |Θ> _P represents one of the four Bell states under the polarization state of freedom:

where |Ξ> _S represents one of the four Bell states under the path mode degree of freedom:

Using CHBSA, 16 super-entangled Bell states can be completely distinguished.

Two non-orthogonal measurement bases under polarization state of freedom can be selected as: Z ^P ={|0>,|1>} and Two non-orthogonal measurement bases under path mode degrees of freedom can be selected as: Z ^S ={|l>,|u>} and

Super-entangled state with two degrees of freedom of polarization state and path mode as an example. Eve prepares the quantum state:

in Indicates that the state prepared by Eve is a super-entangled state (i.e. non-local relation) and a non-entangled state I/4 (i.e. local relation), in which super-entangled state The visibility of is p, and the visibility of the non-entangled state I/4 is 1-p.

The present invention will be further described below in combination with key distribution as an example.

The present invention takes key distribution as an example to explain the process of using super-entangled state for communication under the condition of device-independence, and proves that the channel capacity (quantum efficiency) is effectively improved. Eve sends the A particle to the sender, and the B particle to the receiver. The sending end and the receiving end randomly select the measurement input x and y∈{0,1} to measure their respective particles, where x=0 means that the Z ^S basis is measured first and then the Z ^P basis is measured, and x=1 means that the Z ^S basis is measured first Then X ^P base measurement; where y=0 means first Z ^S base measurement and then base measurement, y=1 means Z ^S base measurement first and then base measurement. The measurement results at the transmitter and receiver are denoted as a and b∈{0l,0u,1l,1u}, respectively.

Define the CHSH inequality

P(a ₀ ＝b ₀ )+P(a ₀ ＝b ₁ )+P(a ₁ ＝b ₀ )+P(a ₁ ≠b ₁ )≤3, where

P(a _j =b _k )=P(a=b=0l|x=j,y=k)+P(a=b=0u|x=j,y=k)

+P(a=b=11|x=j, y=k)+P(a=b=1u|x=j, y=k).

The sender and receiver select some particles to calculate the conditional probability P(a,b|x,y), and judge whether the CHSH inequality is violated. If it is violated, it means that the particles distributed by Eve to the sender and receiver are in a super-entangled state. At this time, based on a hyper-entangled state, the sender and receiver can share the two-bit security key 0l, 0u, 1l or 1u.

The present invention proves that by adopting the above-mentioned communication mode, using the super-entangled state to distribute the device-independent key can obtain higher quantum efficiency than the ordinary entangled state. Obviously, in the above key distribution process, if the particles used for CHSH inequality detection are removed, the present invention completes the distribution of two-bit device-independent keys by distributing two particles, and the quantum efficiency reaches 1. If an ordinary entangled state such as the Bell state |φ ⁺ > _AB is used as the quantum carrier, only one device-independent key can be distributed by distributing two particles, and the quantum efficiency is only 0.5.

In the above embodiments, all or part of them may be implemented by software, hardware, firmware or any combination thereof. When implemented wholly or partly in the form of a computer program product, said computer program product comprises one or more computer instructions. When the computer program instructions are loaded or executed on the computer, the processes or functions according to the embodiments of the present invention will be generated in whole or in part. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website, computer, server or data center Transmission to another website site, computer, server or data center by wired (eg coaxial cable, fiber optic, digital subscriber line (DSL) or wireless (eg infrared, wireless, microwave, etc.)). The computer-readable storage medium may be any available medium that can be accessed by a computer, or a data storage device such as a server or a data center integrated with one or more available media. The available medium may be a magnetic medium (for example, a floppy disk, a hard disk, or a magnetic tape), an optical medium (for example, DVD), or a semiconductor medium (for example, a Solid State Disk (SSD)).

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (9)

1. a device-independent high channel capacity quantum communication method, characterized in that, the device-independent high channel capacity quantum communication method comprises: Establish a quantum communication model independent of the quantum state preparation source: in the worst case, the quantum density of state function model of the entangled state is prepared by an eavesdropper; then when designing a quantum protocol under the described quantum state density function description model, according to Bell's inequality The violation of the principle eliminates the non-entangled state, retains the super-entangled state, and communicates based on the super-entangled state. According to the principle of monogamous entanglement and not exceeding the speed of light, the eavesdropper cannot obtain any secret information by controlling the preparation source; Establish a device-independent quantum communication model: the device-independent includes preparation-source-independent and measurement-equipment-independent; only analyze whether the statistical probability relationship between measurement input and output results violates the Bell-type inequality, and use this as a consideration in quantum communication whether With the judgment condition of the eavesdropper, a quantum communication model independent of the measurement equipment is constructed; the quantum state distributed to the user for communication is in the maximum entangled state, and according to the monogamous principle of entanglement and the principle of not exceeding the speed of light, the eavesdropper no matter It is impossible to obtain the secret information of legal users through the measuring equipment by any means; Establish a device-independent high-channel-capacity quantum communication model: use multi-degree-of-freedom super-entangled states as quantum carriers, and establish a device-independent super-entangled quantum communication model for dense encoding. 2. the device-independent high channel capacity quantum communication method as claimed in claim 1, is characterized in that, in the quantum communication model that described setting up has nothing to do with quantum state preparation source, comprise: suppose that this entangled state is prepared by eavesdropper Eve and then Then distribute it to the sending end and the receiving end for the next communication; the eavesdropper Eve does not prepare a perfect super-entangled Bell state in order to obtain as much secret information as possible from the sending end and the receiving end; on the contrary, the eavesdropper Eve prepares a super-entangled Bell state. The mixed state of entangled state and non-entangled state confuses the sender and receiver so that they will not discover their eavesdropping behavior, and obtain the secret information of the sender and receiver; The super-entangled Bell state prepared by the eavesdropper Eve is represented by the following density function model: The density function model indicates that the state prepared by the eavesdropper Eve is a super-entangled state and a mixed state of the non-entangled state I/4, the super-entangled state in the mixed state The visibility of the unentangled state I/4 is p, and the visibility of the non-entangled state I/4 is 1–p; According to the monogamous principle of entanglement, if the eavesdropper Eve prepares an entangled state, it will not be able to obtain any secret information of the sender and receiver; and if the eavesdropper Eve prepares a non-entangled state, it will obtain part of the secret information of the sender and receiver; When analyzing the impact of various noises in the channel, the sending end and the receiving end accept the original convert to If the non-entangled state is eliminated according to the violation principle of Bell's inequality, and the super-entangled state is retained, and the communication is based on the super-entangled state, the eavesdropper Eve cannot obtain any information between the sender and receiver secret information. 3. the equipment-independent high channel capacity quantum communication method as claimed in claim 1, is characterized in that, described establishment has nothing to do with equipment quantum communication model, comprises: If the eavesdropper Eve sends A particle to the sender and B particle to the receiver; the sender and the receiver randomly select the measurement input x and y∈{0,1} to measure their respective particles, where x=0 means Z first ^S -based measurement and then Z ^P -based measurement, x=1 means Z ^S- based measurement first and then X ^P -based measurement; where y=0 means Z S-based measurement first and then X ^P -based measurement base measurement, y=1 means Z ^S base measurement first and then base measurement; The measurement results of the sending end and the receiving end are denoted as a and b∈{0l,0u,1l,1u} respectively; Define the CHSH inequality P(a ₀ ＝b ₀ )+P(a ₀ ＝b ₁ )+P(a ₁ ＝b ₀ )+P(a ₁ ≠b ₁ )≤3, where P(a _j =b _k )=P(a=b=0l|x=j,y=k)+P(a=b=0u|x=j,y=k)+P(a=b=1l |x=j, y=k)+P(a=b=1u|x=j, y=k); The sending end and the receiving end select some particles to calculate the conditional probability P(a,b|x,y), and judge whether the CHSH inequality is violated. If it is violated, it means that the particles distributed by the eavesdropper Eve to the sending end and the receiving end are in a super-entangled state. 4. A key distribution method of the device-independent high channel capacity quantum communication method as claimed in claim 1, wherein the key distribution method comprises: Eve sends A particle to the sending end, B particle to the receiving end; the sending end and the receiving end respectively randomly select the measurement input x and y∈{0,1} to measure their respective particles, where x=0 means Z ^S basis Measurement and then Z ^P basis measurement, x=1 means first Z ^S basis measurement and then X ^P basis measurement; where y=0 means first Z ^S basis measurement and then base measurement, y=1 means Z ^S base measurement first and then Base measurement; the measurement results of the sending end and the receiving end are respectively expressed as a and b∈{0l,0u,1l,1u}; Define the CHSH inequality P(a ₀ ＝b ₀ )+P(a ₀ ＝b ₁ )+P(a ₁ ＝b ₀ )+P(a ₁ ≠b ₁ )≤3, where P(a _j =b _k )=P(a=b=0l|x=j,y=k)+P(a=b=0u|x=j,y=k)+P(a=b=1l |x=j, y=k)+P(a=b=1u|x=j, y=k); The sending end and the receiving end select some particles to calculate the conditional probability P(a,b|x,y), and judge whether the CHSH inequality is violated. If it is violated, it means that the particles distributed by Eve to the sending end and the receiving end are in a super-entangled state; based on a In the super-entangled state, the sender and the receiver share a two-digit security key 0l, 0u, 1l or 1u. 5. A computer program for realizing the device-independent high channel capacity quantum communication method according to any one of claims 1-4. 6. An information processing terminal carrying the computer program according to claim 5. 7. A computer-readable storage medium, comprising an instruction, when it is run on a computer, it causes the computer to perform the device-independent high-channel-capacity quantum communication method as claimed in any one of claims 1-4 8. A device-independent high channel capacity quantum communication system of the device-independent high channel capacity quantum communication method as claimed in claim 1, wherein the device-independent high channel capacity quantum communication system comprises: A quantum communication model unit that has nothing to do with the quantum state preparation source is used to prepare a quantum density of state function model of an entangled state by an eavesdropper in the worst case; then when designing a quantum protocol under the described quantum state density function description model, according to Bell inequality violates the principle of eliminating non-entangled states, retaining super-entangled states, and communicating based on super-entangled states, based on the monogamy of entanglement and the principle of not exceeding the speed of light, so that eavesdroppers cannot obtain any secret information by controlling the preparation source; A quantum communication model unit that has nothing to do with the device, the device has nothing to do with the preparation source and the measurement device has nothing to do; it is used to only analyze whether the statistical probability relationship between the measurement input and output results violates the Bell class inequality, and use it as a consideration for quantum communication Whether there is an eavesdropper in the judgment condition, construct a quantum communication model that has nothing to do with the measurement equipment; make the quantum state distributed to the user for communication in the maximum entangled state, and according to the monogamous principle of entanglement and the principle of not exceeding the speed of light, make the eavesdropping No matter what method is used, the user cannot obtain the secret information of the legal user through the measuring equipment; The device-independent high-channel-capacity quantum communication model unit is used to use the super-entangled state under multiple degrees of freedom as a quantum carrier to establish a device-independent super-entangled quantum communication model for dense encoding. 9. An information processing terminal equipped with a device-independent high channel capacity quantum communication system according to claim 8.