Predictive quantum secure direct communication method and system based on compression state superposition

Abstract

The invention discloses a method and a system for indicating quantum secure direct communication based on compression state superposition, and belongs to the technical field of quantum communication. The method comprises the following steps: generating signal state photons by using a compressed state superposed indication single photon source, and generating a photon sequence SA through random coding; an information sender selects a part of photons as first-round safety detection photons, randomly selects a measuring machine for measurement, and publishes a measurement base and a measurement result; the information receiver performs a first round of safety detection; if the first round of security detection is passed, the information sender extracts the remaining photons, selects one part to carry out random coding, and carries out information coding on the other part to generate a photon sequence SB; the information receiver receives and stores the photon sequence SB; the information receiver extracts the security detection photons to perform a second round of security detection; and if the second round of security detection is passed, the information receiver extracts residual information coding photons from the photon sequence SB and deduces the information sent by the information sender according to the residual information coding photons.

Description

Technical Field

[0001] The present invention belongs to the field of quantum communication technology, and in particular relates to a method and system for predictive quantum secure direct communication based on compressed state superposition. Background Art

[0002] Quantum secure direct communication (QSDC) is an important branch of quantum secure communication. It can directly transmit secret information in a quantum channel without the need to generate a key in advance. In 2000, Long Guilu and others proposed the first quantum secure direct communication scheme - the efficient QSDC scheme. Deng Fuguo and others proposed a two-step QSDC scheme based on EPR entangled pairs and a one-time pad QSDC scheme based on single photons in 2003 and 2004, respectively. The one-time pad QSDC scheme based on single photons and the two-step QSDC scheme based on entanglement were experimentally verified in 2016 and 2017, respectively. In 2021, the first QSDC network protocol experiment involving 15 users was completed. In 2022, Long Guilu and others achieved quantum secure direct communication on the order of hundreds of kilometers. Among the existing QSDC protocols, the two-step QSDC protocol based on entanglement is easier to promote and has developed into a quantum direct dialogue protocol. The QSDC protocol based on single photons is easier to implement than the QSDC protocol based on entanglement.

[0003] While QSDC has proven secure under ideal conditions, actual quantum communication systems often exhibit some flaws. In particular, there are currently no perfect single-photon sources, and practical light sources, such as weakly coherent light sources, can generate vacuum states and multiphoton events. Vacuum states reduce the photon reception rate, affecting information transmission efficiency, while multiphoton events can leak information, impacting secure information capacity and communication distance. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method and system for predicted quantum secure direct communication based on squeezed state superposition, which solves the problems in the existing technology.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for predicting quantum secure direct communication based on squeezed state superposition, comprising the following steps:

[0007] A series of signal state photons are generated using a predicted single photon source of squeezed state superposition, and a photon sequence S is generated by random coding. A ;

[0008] The information sender stores the photon sequence S A , and select a portion of photons as the first round of security detection photons, randomly select a measurement basis to measure single photons, and publish the measurement basis and measurement results;

[0009] The information receiver conducts the first round of security testing based on the single-photon measurement base and measurement results published by the information sender;

[0010] If the first round of security check passes, the information sender extracts the remaining photons, selects a part as the second round of security check photons for random encoding, and the other part for information encoding to generate the photon sequence S B and sent to the information recipient;

[0011] Information receiving and storing photon sequence S B ; The information sender publishes the photon sequence S B The position and random operation of the second round of security detection photons; the information receiver extracts the security detection photons for the second round of security detection;

[0012] If the second round of security check passes, the information receiver will receive the photon sequence S B The remaining information-encoded photons are extracted, the information-encoded photons are measured using the prepared basis, and decoded by comparing with the initial state to infer the information sent by the sender.

[0013] Further, generate a photon sequence S A The process is:

[0014] The information receiver interacts a compressed state and a coherent state through a crossed Kerr medium, measures the output coherent state, and generates a photon odd superposition state and a photon even superposition state according to the measurement results; the photon odd superposition state is input into the beam splitter, and the photons at one output end of the beam splitter are detected, and the photons at the other output end are used as signal light pulses; when the detector detects the photon signal, the output at the other end is randomly encoded and sent to the information sender through the quantum channel; the information receiver repeats the above operation to generate a photon sequence S A ;

[0015] The photon odd superposition state is input into the beam splitter to generate a dual-mode output state. The dual-mode output state is a pair of entangled photon pairs, and the two photons of the photon pair are distributed in the prediction path and the signal path.

[0016] Furthermore, when generating the photon sequence S A During the random encoding process, the random encoding operation includes any of the following four encoding operations:

[0017] U0=|H> <H|+|V><V|

[0018] U1=|V> <H|-|H><V|

[0019]

[0020] Where U0, U1, U2, and U3 represent four encoding operations respectively. The single-photon preparation basis generated by the U0 and U1 operations is recorded as the Z basis, and the single photon is described as: {|H>, |V>}; the single-photon preparation basis generated by the U2 and U3 operations is recorded as the X basis, and the single photon is described as: Among them, H and V represent the two polarization states of the photon, H represents the horizontal polarization of the photon, V represents the vertical polarization, |+> and |-> represent the diagonal polarization state and the anti-diagonal polarization state.

[0021] Furthermore, the specific steps of the first round of security testing include:

[0022] S31, the information receiver obtains the photon positions and measurement basis of the first round of security detection published by the information sender; extracts the corresponding photons of the first round of security detection for measurement, and publishes the measurement results;

[0023] S32, the information sender compares the measurement result with the prepared initial quantum state; if the measurement result is the same as the initial quantum state, it is correct; otherwise, it indicates that an error has occurred;

[0024] S33, the information sender calculates the error rate based on the comparison results of all the first round of security detection photons. If the error rate does not exceed the set threshold, the first round of security detection is passed; when the error rate exceeds the preset threshold, it means that the photon sequence S A The transmission process is not secure; at this point, both parties need to terminate the communication.

[0025] Furthermore, the specific process of the second round of safety testing is as follows:

[0026] S51 The information receiver obtains the photon position and coding information of the second round of security detection published by the information sender; extracts the corresponding photon of the second round of security detection for measurement, and publishes the measurement result;

[0027] S52, the information receiver determines the security of the second transmission by comparing the random coding analysis error rate with the information sender; calculates the comparison error rate of all second-round security detection photons. If the error rate does not exceed the set second threshold, the second round of security detection passes; otherwise, it fails and the communication is terminated.

[0028] Furthermore, in the process of measuring the information-encoded photons using the prepared basis and decoding them by comparing with the initial state:

[0029] If the prepared basis is the Z basis, the Z basis is selected to perform the decoding operation on the extracted second-round security detection photons:

[0030] Z=|H> <H|+|V><V|

[0031] If the prepared basis is X basis, then select X basis to perform decoding operation on the extracted second round security detection photons:

[0032]

[0033] A quantum secure direct communication system based on compressed state superposition, comprising:

[0034] Photon sequence S A Generation module: Use the predicted single photon source of squeezed state superposition to generate a series of signal state photons, and generate the photon sequence S through random coding A ;

[0035] Measurement module: The information sender stores the photon sequence S A , and select a portion of photons as the first round of security detection photons, randomly select a measuring machine to measure the single photons, and publish the measurement basis and measurement results;

[0036] First round detection module: The information receiver performs the first round of security detection based on the single-photon measurement basis and measurement results published by the information sender;

[0037] Photon sequence S B Generation module: If the first round of security detection passes, the information sender extracts the remaining photons, selects a part as the second round of security detection photons for random encoding, and the other part for information encoding to generate the photon sequence S B and sent to the information recipient;

[0038] Second round of detection module: the information receiver stores the photon sequence S B ; The information sender publishes the photon sequence S B The position and random operation of the second round of security detection photons; the information receiver extracts the security detection photons for the second round of security detection;

[0039] And, decoding inference module: If the second round of security detection is passed, the information receiver will receive the information from the photon sequence S B The remaining information-encoded photons are extracted, the information-encoded photons are measured using the prepared basis, and decoded by comparing with the initial state to infer the information sent by the sender.

[0040] A computer storage medium stores a readable program, which, when executed by a processor, can execute the aforementioned predicted quantum secure direct communication method based on compressed state superposition.

[0041] An electronic device comprising: a processor, a memory, a communication interface, and a communication bus, wherein the processor, the memory, and the communication interface communicate with each other via the communication bus;

[0042] The memory is used to store at least one executable instruction, and the executable instruction enables the processor to perform operations corresponding to the above-mentioned predicted quantum secure direct communication method based on squeezed state superposition.

[0043] A computer program product includes computer instructions, wherein the computer instructions instruct a computing device to perform operations corresponding to the aforementioned method for predicting quantum secure direct communication based on squeezed state superposition.

[0044] Beneficial effects of the present invention:

[0045] The present invention uses a predicted single-photon source based on squeezed state superposition to replace the weak coherent light source used in previous technologies, fundamentally reducing the probability of the light source generating a vacuum state and multiple photons, increasing the emission probability of predicted single photons, significantly improving the information capacity, greatly expanding the communication distance, and providing a strong guarantee for the efficient and stable information transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0047] Figure 1 This is a flow chart of the quantum secure direct communication method of the present invention;

[0048] Figure 2 This is a structural diagram of the present invention's foreshadowing single-photon source based on squeezed state superposition;

[0049] Figure 3 This is a block diagram of the structural principle of quantum secure direct communication of the present invention;

[0050] Figure 4 This is a schematic diagram of the principle of the quantum secure direct communication method of the present invention. DETAILED DESCRIPTION

[0051] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0052] Example 1

[0053] like Figure 3As shown in the figure, quantum secure direct communication generally involves two participants, namely the information receiver Bob and the information sender Alice, who exchange information through a quantum channel.

[0054] like Figure 1 and Figure 4 As shown, a method for predicting quantum secure direct communication based on squeezed state superposition includes the following steps:

[0055] S1, using the predicted single photon source of squeezed state superposition to generate a series of signal state photons, and generating the photon sequence S by random coding A ;

[0056] like Figure 2 As shown, the predicted single-photon source based on squeezed-state superposition includes a crossed Kerr medium, a beam splitter, and a photon detector. The input squeezed state and the coherent state first interact in the crossed Kerr medium. A homodyne measurement is then used to measure the output coherent state. Finally, appropriate post-selection operations are performed to extract the odd-number superposition state and the even-number superposition state. The beam splitter uses one photon from the resulting entangled superposition state for detection and the other photon as a signal photon for encoding. If the detector responds during this process, it indicates that a signal photon was also generated, thus forming a predicted single-photon source.

[0057] The information receiver Bob interacts a compressed state with a coherent state through a crossed Kerr medium, measures the output coherent state, and generates a photon odd superposition state and a photon even superposition state according to the measurement results. The photon odd superposition state is input into the beam splitter BS, and the photons at one output end of the beam splitter BS are detected, and the photons at the other output end are used as signal light pulses. When the detector detects the photon signal, the output at the other end is randomly encoded and sent to the information sender Alice through the quantum channel. The information receiver repeats the above operation to generate a photon sequence S A .

[0058] The odd superposition state of photons is input into the beam splitter BS, generating a dual-mode output state. The dual-mode output state is essentially a pair of entangled photons, and the two photons of the photon pair are distributed in two different paths, namely the herald path and the signal path.

[0059] In this embodiment, it is assumed that a total of n+m+l signal state photons are generated, where n, m, and l do not represent the specific number of signal state photons, but only represent the number of photons in the following two rounds of security detection and encoding.

[0060] Among them, the compressed state The coherent state |α> is specifically expressed as:

[0061]

[0062] Where, is the compression operator, n in {|n>,n=0,1,2....} represents the photon number state, and r is the compression coefficient.

[0063] Among them, the compressed state The role of the coherent state |α〉 in the crossed Kerr medium can be specifically expressed as:

[0064]

[0065] In the formula, |ψ out > 12 represents the new quantum state generated by the interaction between the squeezed state and the coherent state. 2kτ represents the overall phase of the coherent state, where k is a positive integer.

[0066] The coherent state of the measured output is generated, and the photon odd superposition state and the photon even superposition state are generated according to the measurement results; the specific expression is: let 2kτ = π, then

[0067]

[0068] In the above formula,

[0069]

[0070] Where N ± (r) is an expression containing the compression coefficient r; |r; +> represents a superposition state with the number of photons {0, 2, 4...}, and |r; -> represents a superposition state with the number of photons {1, 3, 5...}.

[0071] Project the quantum state onto |α>1 and |-α>2. When the measurement result is |α>1, the compressed state collapses to |r;+>. When the measurement result is |-α>2, the compressed state collapses to |r;->. The probabilities when the compressed state collapses to |r;+> and |r;-> are N respectively. + (r) / 4 and N - (r) / 4. In fact, here |α>1 and |-α>2 are not perfectly orthogonal. Only when |α|>1.3, |<α|-α>| is satisfied. 2 ≤0.0012. In practice, as long as |α> is large enough, the two coherent states |α>1 and |-α>2 can be perfectly distinguished.

[0072] The specific process of inputting the photon odd superposition state into the beam splitter BS to generate a dual-mode output state is as follows:

[0073] First, the compression operator After BS, it is expressed as:

[0074]

[0075] Among them, a + and a represent the creation operator and annihilation operator respectively. and represents a single-mode compressed state, Indicates bimodality, Expressed as:

[0076]

[0077] If any of the photon odd superposition state or even superposition state |r;±> is input into one port of BS, and a single-mode quantum state |0> is input into the other port b , then the single-mode quantum state|0> b After the BS operation, a dual-mode quantum state will be generated. a |0> b :

[0078]

[0079] Among them, the subscript a represents the predicted path for detection; the subscript b represents the signal path, and the output will be randomly encoded and sent to the information sender.

[0080] In S1, the random encoding process includes any of the following four encoding operations:

[0081] U0=|H> <H|+|V><V|

[0082] U1=|V> <H|-|H><V|

[0083]

[0084] Where U0, U1, U2, and U3 represent four encoding operations respectively. The single-photon preparation basis generated by the U0 and U1 operations is recorded as the Z basis, and the single photon is described as: {|H>, |V>}; the single-photon preparation basis generated by the U2 and U3 operations is recorded as the X basis, and the single photon is described as: Among them, H and V represent the two polarization states of the photon, H represents the horizontal polarization of the photon, V represents the vertical polarization, |+> and |-> represent the diagonal polarization state and the anti-diagonal polarization state.

[0085] S2, the information sender stores the photon sequence S A , and from the photon sequence S A A portion of photons are selected as the first round of security detection photons; the information sender extracts the security detection photon sequence, randomly selects a measuring machine to measure a single photon, and publishes the measurement basis and measurement results;

[0086] The information sender receives the photon sequence SA After that, all photons are stored in turn, and then n photons are randomly extracted from the memory as the first round of security detection photons, and a measurement basis is randomly selected to perform single-photon measurement on them. Then, the photon position, measurement basis and measurement results of the first round of security detection are announced.

[0087] It should be noted that the first round of security detection photons are from the photon sequence S A Therefore, the number of photons in the first round of security detection can also take other values besides n. This embodiment takes n as an example.

[0088] The information sender can randomly select a measurement basis to perform single-photon measurement on it and publish the position, measurement basis, and measurement results of the first round of security detection photons. The measurement basis includes the X basis (diagonal basis) and the Z basis (rectangular basis), as follows:

[0089] Z=|H> <H|+|V><V|

[0090]

[0091] Performing an X operation on a photon indicates selecting an X basis, and performing a Z operation on a photon indicates selecting a Z basis.

[0092] S3, the information receiver performs the first round of security testing based on the single-photon measurement basis and measurement results published by the information sender;

[0093] The specific steps of the first round of safety testing include:

[0094] S31, the information receiver obtains the photon positions and measurement basis of the first round of security detection published by the information sender; extracts the corresponding photons of the first round of security detection for measurement, and publishes the measurement results;

[0095] S32, the information sender compares the measurement result with the prepared initial quantum state; if the measurement result is the same as the initial quantum state, it is correct; otherwise, it indicates that an error has occurred;

[0096] S33, the information sender calculates the error rate based on the comparison results of all the first round of security detection photons. If the error rate does not exceed the set threshold, the first round of security detection is passed; when the error rate exceeds the preset threshold, it means that the photon sequence S A The transmission process is not secure; at this point, both parties need to terminate the communication.

[0097] It is worth noting that since the above sequence itself does not carry any encoded information, even if there is an unsafe situation in the transmission link, it will not cause information leakage.

[0098] S4: If the first round of security detection passes, the information sender extracts the remaining photons, selects a part as the second round of security detection photons for random encoding, and the other part for information encoding to generate a photon sequence S B , sent to the information receiver through the quantum channel; if the first round of security detection fails, the communication is terminated;

[0099] In this embodiment, the information sender extracts the remaining m+1 photons, selects m photons for random encoding, and encodes the remaining 1 photon for information encoding; the photon sequence S is generated by encoding. B , m+l photons are sent to the information receiver through the quantum channel in sequence.

[0100] After the first round of security detection is passed, the information sender selects a portion of the remaining photons as the second round of security detection photons for random encoding, and the remaining photons are encoded according to the information to be transmitted as information photons; all photons generate a photon sequence S B , sent to the information recipient.

[0101] In S4, the information sender also needs to randomly encode the remaining m photons using the following two unitary operations. The two unitary encoding operations are expressed as:

[0102] U0=|H> <H|+|V><V|

[0103] U1=|V> <H|-|H><V|

[0104] Among them, U0 and U1 represent two encoding operations respectively, U0 represents classical information 0, and U1 represents classical information 1.

[0105] After the information sender performs the above encoding operation, it then announces the photon position and encoding information of the second round of security detection.

[0106] S5, the information receiver receives and stores the photon sequence S B ; The information sender publishes the photon sequence S B The position and random operation of the second round of security detection photons; the information receiver extracts the security detection photons for the second round of security detection;

[0107] In this embodiment, the number of photons in the second round of safety detection is m;

[0108] The specific process of the second round of safety testing is as follows:

[0109] S51 The information receiver obtains the photon position and coding information of the second round of security detection published by the information sender; extracts the corresponding photon of the second round of security detection for measurement, and publishes the measurement result;

[0110] For example, after the information sender performs the encoding operation U0, it sends a signal state |H> to the information receiver. The information receiver randomly selects the information state as the second round of detection photons and selects the measurement basis as the Z basis. If the measurement result is |H>, the transmission process is safe; if the measurement result is |+>, it means that the photon sequence S B Not secure during transmission.

[0111] S52, the information receiver determines the security of the second transmission by comparing the random coding analysis error rate with the information sender; calculates the comparison error rate of all second-round security detection photons. If the error rate does not exceed the set second threshold, the second round of security detection passes; otherwise, it fails and the communication is terminated.

[0112] S6, if the second round of security check passes, the information receiver will receive the photon sequence S B Extract the remaining information-encoded photons, use the prepared basis to measure the information-encoded photons, compare them with the initial state for decoding, and infer the information sent by the sender; if the second round of security detection fails, the communication is terminated;

[0113] In the process of using the prepared basis to measure the information-encoded photons and decoding them by comparing with the initial state:

[0114] If the prepared basis is the Z basis, the Z basis is selected to perform the decoding operation on the extracted second-round security detection photons:

[0115] Z=|H> <H|+|V><V|

[0116] If the prepared basis is an X basis, the X basis is selected to perform a decoding operation on the extracted second-round security detection photons;

[0117]

[0118] Based on a similar inventive concept, an embodiment of the present invention further provides a computer storage medium storing a readable program. When the program is executed by a processor, it can execute the above-mentioned predicted quantum secure direct communication method based on squeezed state superposition.

[0119] Based on similar inventive concepts, an embodiment of the present invention provides an electronic device, comprising: a processor, a memory, a communication interface, and a communication bus, wherein the processor, the memory, and the communication interface communicate with each other via the communication bus;

[0120] The memory is used to store at least one executable instruction, and the executable instruction enables the processor to perform operations corresponding to the above-mentioned predicted quantum secure direct communication method based on squeezed state superposition.

[0121] Based on similar inventive concepts, an embodiment of the present invention further provides a computer program product, including computer instructions, which instruct a computing device to perform operations corresponding to the above-mentioned method for predicting quantum secure direct communication based on squeezed state superposition.

[0122] Example 2

[0123] In order to make the technical solution of the present invention more clear and thorough and easy to understand, this embodiment is further described by using specific examples:

[0124] Assume that the initial random encoding operation performed by the information receiver, Bob, is U0. The state of the photon it sends is |H>. The photon is sent to the information sender, Alice. If the encoded message Alice wants to convey is 1, Alice performs the U1 operation on the received photon, changing it to |V>, and then sends it to the information receiver, Bob. Since the initial encoding operation performed by the information receiver, Bob, is U0, the prepared basis is the Z basis. The information receiver, Bob, needs to perform a Z-basis measurement, perform a Z-basis decoding operation on the photon, and then perform a single-photon measurement. Through the single-photon measurement and the basis selection operation, the information receiver, Bob, can determine that the received photon is |V>. Based on the measurement result and his own initial photon state, the information receiver, Bob, can determine that the information sender, Alice, performed the U0 operation and thus conclude that the information encoded by the information sender, Alice, is 1.

[0125] It can be seen that the quantum secure direct communication method of the present invention uses a squeezed state-based light source to replace the weak coherent light source in the prior art, which can effectively reduce the probability of the light source generating a vacuum state and multiple photons, significantly improve the emission probability of predicted single photons, increase information capacity, extend the communication distance, and effectively improve the security of quantum secure direct communication under actual experimental conditions.

[0126] Example 3

[0127] Based on the predicted quantum secure direct communication method based on squeezed state superposition proposed in Example 1, in this embodiment, a predicted quantum secure direct communication system based on squeezed state superposition is proposed, specifically including:

[0128] Photon sequence S A Generation module: Use the predicted single photon source of squeezed state superposition to generate a series of signal state photons, and generate the photon sequence S through random coding A ;

[0129] Measurement module: The information sender stores the photon sequence S A , and select a portion of photons as the first round of security detection photons, randomly select a measuring machine to measure the single photons, and publish the measurement basis and measurement results;

[0130] First round detection module: The information receiver performs the first round of security detection based on the single-photon measurement basis and measurement results published by the information sender;

[0131] Photon sequence S B Generation module: If the first round of security detection passes, the information sender extracts the remaining photons, selects a part as the second round of security detection photons for random encoding, and the other part for information encoding to generate the photon sequence S B ;

[0132] Second round of detection module: the information receiver receives and stores the photon sequence S B ; The information sender publishes the photon sequence S B The position and random operation of the second round of security detection photons; the information receiver extracts the security detection photons for the second round of security detection;

[0133] And, decoding inference module: If the second round of security detection is passed, the information receiver will receive the information from the photon sequence S B The remaining information-encoded photons are extracted, the information-encoded photons are measured using the prepared basis, and decoded by comparing with the initial state to infer the information sent by the sender.

[0134] The method of the present invention can be implemented in hardware, firmware, or as software or computer code that can be stored in a recording medium (such as a CDROM, RAM, floppy disk, hard disk or magneto-optical disk), or as computer code that is originally stored in a remote recording medium or a non-temporary machine-readable medium downloaded over a network and will be stored in a local recording medium, so that the method described herein can be stored in such software processing on a recording medium using a general-purpose computer, a special-purpose processor or programmable or special-purpose hardware (such as an ASIC or FPGA). It will be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component (e.g., RAM, ROM, flash memory, etc.) that can store or receive software or computer code, and when the software or computer code is accessed and executed by a computer, a processor or hardware, the method described herein is implemented. In addition, when a general-purpose computer accesses the code for implementing the method shown here, the execution of the code converts the general-purpose computer into a special-purpose computer for executing the method shown here.

[0135] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A method for predicting quantum secure direct communication based on squeezed state superposition, characterized in that: The following steps are involved: A series of signal state photons are generated using a predicted single photon source of squeezed state superposition, and a photon sequence S is generated by random coding. A ; The information sender stores the photon sequence S A , and select a portion of photons as the first round of security detection photons, randomly select a measurement basis to measure single photons, and publish the measurement basis and measurement results; The information receiver conducts the first round of security testing based on the single-photon measurement base and measurement results published by the information sender; If the first round of security check passes, the information sender extracts the remaining photons, selects a part as the second round of security check photons for random encoding, and the other part for information encoding to generate the photon sequence S B and sent to the information recipient; Information receiving and storing photon sequence S B ; The information sender publishes the photon sequence S B The position and random operation of the second round of security detection photons; the information receiver extracts the security detection photons for the second round of security detection; If the second round of security check passes, the information receiver will receive the photon sequence S B The remaining information-encoded photons are extracted, the information-encoded photons are measured using the prepared basis, and decoded by comparing with the initial state to infer the information sent by the sender.

2. The method for predictive quantum secure direct communication based on squeezed state superposition according to claim 1, characterized in that: Generate photon sequence S A The process is: The information receiver interacts a compressed state and a coherent state through a crossed Kerr medium, measures the output coherent state, and generates a photon odd superposition state and a photon even superposition state according to the measurement results; the photon odd superposition state is input into the beam splitter, and the photons at one output end of the beam splitter are detected, and the photons at the other output end are used as signal light pulses; when the detector detects the photon signal, the output at the other end is randomly encoded and sent to the information sender through the quantum channel; the information receiver repeats the above operation to generate a photon sequence S A ; The photon odd superposition state is input into the beam splitter to generate a dual-mode output state. The dual-mode output state is a pair of entangled photon pairs, and the two photons of the photon pair are distributed in the prediction path and the signal path.

3. The method for predictive quantum secure direct communication based on squeezed state superposition according to claim 1, characterized in that: In generating the photon sequence S A During the random encoding process, the random encoding operation includes any of the following four encoding operations: U0=|H> <H|+|V><V| U1=|V> <H|-|H><V| Where U0, U1, U2, and U3 represent four encoding operations respectively. The single-photon preparation basis generated by the U0 and U1 operations is recorded as the Z basis, and the single photon is described as: {|H>, |V>}; the single-photon preparation basis generated by the U2 and U3 operations is recorded as the X basis, and the single photon is described as: Among them, H and V represent the two polarization states of the photon, H represents the horizontal polarization of the photon, V represents the vertical polarization, |+> and |-> represent the diagonal polarization state and the anti-diagonal polarization state.

4. The method for predictive quantum secure direct communication based on squeezed state superposition according to claim 1, characterized in that: The specific steps of the first round of safety testing include: S31, the information receiver obtains the photon positions and measurement basis of the first round of security detection published by the information sender; extracts the corresponding photons of the first round of security detection for measurement, and publishes the measurement results; S32, the information sender compares the measurement result with the prepared initial quantum state; if the measurement result is the same as the initial quantum state, it is correct; otherwise, it indicates that an error has occurred; S33, the information sender calculates the error rate based on the comparison results of all the first round of security detection photons. If the error rate does not exceed the set threshold, the first round of security detection is passed; when the error rate exceeds the preset threshold, it means that the photon sequence S A The transmission process is not secure; at this point, both parties need to terminate the communication.

5. The method for predictive quantum secure direct communication based on squeezed state superposition according to claim 1, characterized in that: The specific process of the second round of safety testing is as follows: S51 The information receiver obtains the photon position and coding information of the second round of security detection published by the information sender; extracts the corresponding photon of the second round of security detection for measurement, and publishes the measurement result; S52, the information receiver determines the security of the second transmission by comparing the random coding analysis error rate with the information sender; calculates the comparison error rate of all second-round security detection photons. If the error rate does not exceed the set second threshold, the second round of security detection passes; otherwise, it fails and the communication is terminated.

6. The method for predictive quantum secure direct communication based on squeezed state superposition according to claim 3, characterized in that: In the process of using the prepared basis to measure the information-encoded photons and decoding them by comparing with the initial state: If the prepared basis is the Z basis, the Z basis is selected to perform the decoding operation on the extracted second-round security detection photons: Z=|H> <H|+|V><V| If the prepared basis is X basis, then select X basis to perform decoding operation on the extracted second round security detection photons:

7. A predicted quantum secure direct communication system based on squeezed state superposition, characterized in that: include: Photon sequence S A Generation module: Use the predicted single photon source of squeezed state superposition to generate a series of signal state photons, and generate the photon sequence S through random coding A ; Measurement module: The information sender stores the photon sequence S A , and select a portion of photons as the first round of security detection photons, randomly select a measuring machine to measure the single photons, and publish the measurement basis and measurement results; First round detection module: The information receiver performs the first round of security detection based on the single-photon measurement basis and measurement results published by the information sender; Photon sequence S B Generation module: If the first round of security detection passes, the information sender extracts the remaining photons, selects a part as the second round of security detection photons for random encoding, and the other part for information encoding to generate the photon sequence S B and sent to the information recipient; Second round of detection module: the information receiver stores the photon sequence S B ; The information sender publishes the photon sequence S B The position and random operation of the second round of security detection photons; the information receiver extracts the security detection photons for the second round of security detection; And, decoding inference module: If the second round of security detection is passed, the information receiver will receive the information from the photon sequence S B The remaining information-encoded photons are extracted, the information-encoded photons are measured using the prepared basis, and decoded by comparing with the initial state to infer the information sent by the sender.

8. A computer storage medium storing a readable program, characterized in that: When the program is executed by a processor, it can execute the predicted quantum secure direct communication method based on squeezed state superposition described in any one of claims 1 to 6.

9. An electronic device, characterized in that: include: A processor, a memory, a communication interface, and a communication bus, wherein the processor, the memory, and the communication interface communicate with each other via the communication bus; The memory is used to store at least one executable instruction, and the executable instruction enables the processor to perform an operation corresponding to the predicted quantum secure direct communication method based on squeezed state superposition according to any one of claims 1 to 6.

10. A computer program product comprising computer instructions, characterized in that The computer instructions instruct the computing device to perform operations corresponding to the method for predicting quantum secure direct communication based on squeezed state superposition as described in any one of claims 1 to 6.

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