Quantum direct communication method and apparatus

Abstract

The present invention provides a quantum direct communication method and apparatus. Among them, the method applied to the sending end includes: obtaining the credibility parameter of the target light source, where the credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source, and the target light source belongs to the light source of the sending end or the light source of the receiving end; correcting the communication parameter based on the credibility parameter; determining the security capacity based on the corrected communication parameter and the security capacity formula; and determining whether to communicate with the receiving end based on the security capacity. The present invention reduces the requirements for state preparation equipment in quantum direct communication, defines the realistic security of quantum direct communication, and reduces the communication cost.

Description

Technical Field

[0001] The present invention relates to the field of quantum communication technology, and in particular, to a quantum direct communication method and apparatus. Background Art

[0002] Quantum communication is a new communication method for information transmission based on the basic principles of quantum mechanics. Quantum communication technology mainly includes quantum key distribution, quantum secure direct communication (QSDC), and quantum secret sharing, etc.

[0003] In the general QSDC protocol, it is generally assumed that the light source and detector are trustworthy. However, in actual situations, vulnerabilities in the light source and detection equipment may lead to various channel attack methods. In order to avoid information loss and eavesdropping caused by detector vulnerabilities, a measurement-device-independent quantum direct communication protocol has been proposed in related technologies.

[0004] However, the current measurement-device-independent quantum direct communication protocol assumes that the state preparation device is perfect, which is difficult to meet in actual applications, and the untrustworthiness of the light source will affect the secure communication capacity. Summary of the Invention

[0005] The present invention provides a quantum direct communication method and apparatus, which are used to solve the problem that it is difficult to meet the requirements of a perfect state preparation device in the prior art, and reduce the requirements of quantum direct communication for the state preparation device.

[0006] In a first aspect, the present invention provides a quantum direct communication method, which is applied to a sending end and includes:

[0007] Obtain the credibility parameter of the target light source, where the credibility parameter is determined based on the quantum state preparation correct rate of the target light source, and the target light source belongs to the sending-end light source or the receiving-end light source;

[0008] Modify the communication parameter based on the credibility parameter;

[0009] Determine the security capacity based on the modified communication parameter and the security capacity formula;

[0010] Determine whether to communicate with the receiving end based on the security capacity.

[0011] Optionally, the modifying the communication parameter based on the credibility parameter includes:

[0012] When the target light source is used to transmit information, modify the quantum bit error rate based on the credibility parameter; and / or

[0013] When the target light source is used for security detection, the detection bit error rate is corrected based on the credibility parameter.

[0014] Optionally, when the security capacity is greater than zero, the method further includes:

[0015] Using the transmitting light source to prepare a first photon sequence and a second photon sequence, the transmitting light source including a signal state light source and a decoy state light source;

[0016] Sending the first photon sequence to a third party;

[0017] Receiving a first measurement result announced by the third party, the first measurement result being obtained by the third party measuring the first photon sequence and a third photon sequence sent by the receiving end to the third party, the third photon sequence being composed of single photons;

[0018] Sending sequence information corresponding to the first photon sequence to the receiving party and receiving sequence information corresponding to the third photon sequence sent by the receiving party;

[0019] Performing security detection based on the sequence information corresponding to the first photon sequence, the sequence information corresponding to the third photon sequence, and the first measurement result;

[0020] When it is determined that the security detection passes, message encoding is performed on the second photon sequence;

[0021] Sending the encoded second photon sequence to the third party, the second photon sequence being used for the third party to measure and announce a second measurement result, and the second measurement result being used for the receiving party to determine the encoding information corresponding to the second photon sequence.

[0022] Optionally, the using the transmitting light source to prepare a first photon sequence and a second photon sequence includes:

[0023] Using an entanglement source to prepare a photon entanglement sequence and using a single photon source to prepare a plurality of single photons, the entanglement source including a signal state light source and a decoy state light source, the single photon source including a decoy state light source;

[0024] Dividing the photon entanglement sequence into a to-be-processed photon sequence and the second photon sequence;

[0025] Randomly inserting the single photons into the to-be-processed photon sequence to obtain the first photon sequence.

[0026] Optionally, the decoy state light source in the entanglement source used by the transmitting end is a double decoy state light source.

[0027] Optionally, the transmitting light source is a phase-randomized weak coherent light source and a parametric down-conversion entanglement source.

[0028] Optionally, the sequence information corresponding to the first photon sequence includes:

[0029] The positions of single photons in the first photon sequence;

[0030] The preparation basis information of the first photon sequence; and

[0031] The correspondence between the photon positions and light intensities in the first photon sequence.

[0032] Optionally, the message encoding of the second photon sequence includes:

[0033] Encrypting the information of the second photon sequence using a local random bit string and inserting random numbers into the information of the second photon sequence;

[0034] The method further includes: publishing random number information.

[0035] In a second aspect, the present invention further provides a quantum direct communication method, which is applied to a receiving end and includes:

[0036] When the receiving end light source includes an uncharacterized light source, sending the credibility parameter corresponding to the uncharacterized light source to the sending end, where the credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source, and the credibility parameter is used to correct communication parameters and security capacity.

[0037] Optionally, the method further includes:

[0038] Preparing a third photon sequence using the receiving end light source, where the third photon sequence is composed of single photons, and the receiving end light source includes a signal state light source and a decoy state light source;

[0039] Sending the third photon sequence to a third party;

[0040] Receiving the first measurement result announced by the third party, where the first measurement result is obtained by the third party measuring the third photon sequence and the first photon sequence sent by the sending end to the third party;

[0041] Announcing the sequence information corresponding to the third photon sequence and receiving the sequence information corresponding to the first photon sequence sent by the receiving party;

[0042] Performing security detection based on the sequence information corresponding to the first photon sequence, the sequence information corresponding to the third photon sequence, and the first measurement result;

[0043] When it is determined that the security detection is passed, receive the second measurement result sent by the third party, where the second measurement result is obtained by the third party measuring the second photon sequence sent by the sending end;

[0044] Based on the second measurement result and the sequence information corresponding to the third photon sequence, determine the coding information corresponding to the second photon sequence.

[0045] Optionally, the receiving end light source is a weak coherent light source with random phase.

[0046] Optionally, the sequence information corresponding to the third photon sequence includes:

[0047] The preparation basis information of the third photon sequence; and

[0048] The correspondence between the photon positions and light intensities in the third photon sequence.

[0049] Optionally, the coding information includes random numbers;

[0050] The method further includes:

[0051] Receive the random number information sent by the sending end;

[0052] Based on the random number information, the second measurement result and the sequence information corresponding to the third photon sequence, determine the transmission quantum bit error rate and information integrity.

[0053] In a third aspect, the present invention further provides a quantum direct communication device, applied to a sending end, including:

[0054] A first acquisition unit, configured to acquire the credibility parameter of a target light source, where the credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source, and the target light source belongs to the sending end light source or the receiving end light source;

[0055] A first correction unit, configured to correct the communication parameter based on the credibility parameter;

[0056] A first determination unit, configured to determine the security capacity based on the corrected communication parameter and the security capacity formula;

[0057] The first determination unit is further configured to determine whether to communicate with the receiving end based on the security capacity.

[0058] In a fourth aspect, the present invention further provides a quantum direct communication device, applied to a receiving end, including:

[0059] A second sending unit, configured to send the credibility parameter corresponding to the uncharacterized light source to the sending end when the receiving end light source includes an uncharacterized light source, where the credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source, and the credibility parameter is used to correct the communication parameter and the security capacity.

[0060] In a fifth aspect, the present invention further provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the quantum direct communication method described in the first aspect or the quantum direct communication method described in the second aspect is implemented.

[0061] In a sixth aspect, the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the quantum direct communication method described in the first aspect or the quantum direct communication method described in the second aspect is implemented.

[0062] The quantum direct communication method and device provided by the present invention allow some devices to be uncharacterized, solve the problem of the need for perfect state preparation devices and ideal single-photon sources that are difficult to achieve in actual situations in existing measurement-device-independent quantum direct communication, reduce the requirements for the devices used, save device costs, define the realistic security of quantum direct communication, and reduce communication costs. Description of the Drawings

[0063] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0064] Figure 1 is one of the schematic flowcharts of the quantum direct communication method provided by the embodiment of the present invention;

[0065] Figure 2 is another schematic flowchart of the quantum direct communication method provided by the embodiment of the present invention;

[0066] Figure 3 is yet another schematic flowchart of the quantum direct communication method provided by the embodiment of the present invention;

[0067] Figure 4 is one of the relationship diagrams between the security capacity and the communication distance provided by the embodiment of the present invention;

[0068] Figure 5 is another relationship diagram between the security capacity and the communication distance provided by the embodiment of the present invention;

[0069] Figure 6 One of the schematic structural diagrams of the quantum direct communication device provided by an embodiment of the present invention;

[0070] Figure 7 Another schematic structural diagram of the quantum direct communication device provided by an embodiment of the present invention;

[0071] Figure 8 Schematic structural diagram of the electronic device provided by an embodiment of the present invention. Detailed implementation manners

[0072] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0073] The following combines Figures 1 - 5 to describe the quantum direct communication method provided by an embodiment of the present invention.

[0074] Figure 1 One of the schematic flowcharts of the quantum direct communication method provided by an embodiment of the present invention. As Figure 1 shown, the quantum direct communication method provided by an embodiment of the present invention can be applied to a sending end, including:

[0075] Step 110: Obtain the credibility parameter of the target light source. The credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source. The target light source belongs to the light source at the sending end or the light source at the receiving end;

[0076] Specifically, the light source is used to prepare the quantum state. The sending end can use multiple light sources to prepare the quantum state, such as an entanglement source, a single-photon source, etc. The receiving end can also use multiple light sources to prepare the quantum state, which will not be elaborated here. The target light source can be the uncharacterized light source among the light sources at the receiving end or the sending end. Uncharacterized means that for a photon prepared by the light source, it can be regarded as a gray box that can output the quantum state in a two-dimensional Hilbert space.

[0077] In the embodiments of the present invention, at least one of the light sources at the receiving end and the light source at the sending end is a characterized light source (credible light source). Exemplarily, when the light source at the sending end is an uncharacterized light source, the receiving end uses a credible (i.e., characterized) light source to prepare the photon sequence.

[0078] The credibility parameter is caused by the imperfect preparation of the state by the light source. For example, during the encoding process, the state can be encoded into four cases: 0, 1, +, and -. The state output by the light source may be incorrect (not meeting the expectation). The credibility parameter defines the probability that the encoding system (such as the light source) can correctly output the desired quantum state, and the credibility parameter describes the reliability of the light source.

[0079] The correct rate of quantum state preparation refers to the ratio of the number of correctly output quantum states by the light source to the total number of output quantum states. The credibility parameter can be determined based on the correct rate of quantum state preparation. Exemplarily, a mapping relationship between the credibility parameter and the correct rate of quantum state preparation is preset, such as the correct rate of quantum state preparation being equal to the credibility parameter. The correct rate of quantum state preparation can be obtained by detecting the light source.

[0080] For the case where the target light source belongs to the light source at the receiving end, the sending end can obtain the credibility parameter of the target light source by receiving the credibility parameter sent by the receiving end, and both parties can publicly disclose the credibility parameter through a classical channel.

[0081] Step 120, correcting the communication parameter based on the credibility parameter;

[0082] Specifically, the uncharacterized target light source may affect communication parameters such as the quantum bit error rate and the detection bit error rate. Therefore, the communication parameter can be corrected through the credibility parameter to obtain the correct communication parameter.

[0083] Step 130, determining the security capacity based on the corrected communication parameter and the security capacity formula;

[0084] Specifically, substitute the corrected communication parameter into the security capacity formula to obtain the corrected security capacity (which can also be called the protocol security capacity). The security capacity formula can refer to related technologies and will not be elaborated here.

[0085] Step 140, determining whether to communicate with the receiving end based on the security capacity.

[0086] Specifically, when it is determined that the security capacity is greater than 0, communication can continue. It should be understood that the larger the security capacity, the better.

[0087] The quantum direct communication method provided by the embodiments of the present invention describes the credibility of a light source through a credibility parameter, and the credibility parameter represents the probability that the encoding system correctly outputs the required state. By correcting communication parameters through the credibility parameter, the protocol security capacity is further determined, and the reliability of the light source is introduced, so as to more accurately determine the security capacity when using an uncharacterized light source (state preparation device), and communication can be realized when using an uncharacterized light source. The embodiments of the present invention allow some devices to be uncharacterized, solve the problem that the existing measurement device-independent quantum direct communication requires perfect state preparation devices and ideal single-photon sources, which are difficult to achieve in actual situations, reduce the requirements for the used devices, save device costs, define the realistic security of quantum direct communication, and reduce communication costs.

[0088] Next, a further description will be made on possible implementation manners of the above steps in specific embodiments.

[0089] Optionally, in step 120, the correcting the communication parameter based on the credibility parameter includes:

[0090] In step 121, when the target light source is used to transmit information, correcting the quantum bit error rate based on the credibility parameter; and / or

[0091] In step 122, when the target light source is used for security detection, correcting the detection bit error rate based on the credibility parameter.

[0092] Specifically, if the quantum state prepared by the target light source is used to transmit information, the uncharacterized target light source will not affect the security detection process, but will affect the estimation of the quantum bit error rate, and the quantum bit error rate (E μ ) can be corrected based on the first correction formula.

[0093] The first correction formula is:

[0094] E μ ′ = E μ ·η s + 0.5(1 - η s ).

[0095] Where, E μ ′ represents the corrected quantum bit error rate, E μ represents the quantum bit error rate, and η s represents the credibility parameter.

[0096] If the quantum state prepared by the target light source is used for security detection, the uncharacterized target light source will affect the estimation of the detection bit error rate, and the detection bit error rate (∈ u ) can be corrected based on the second correction formula.

[0097] The second correction formula is as follows:

[0098] ∈ u ′ = ∈ u ·η s +0.5(1 - η s ).

[0099] Wherein, ∈ u ′ represents the corrected detection bit error rate, ∈ u represents the detection bit error rate, and η s represents the credibility parameter.

[0100] Optionally, when the security capacity is greater than zero, the method further includes:

[0101] Step 210: Use the light source at the sending end to prepare a first photon sequence and a second photon sequence. The light source at the sending end includes a signal state light source and a decoy state light source;

[0102] Specifically, the laser pulse for transmitting information (which can be simply referred to as the information - transmitting pulse) is the signal state light source, and the light source with an average photon number different from that of the information - transmitting pulse is the decoy state light source. The signal state light source is used to transmit information, and the decoy state light source is used for security detection.

[0103] The sending end can be referred to as Alice. The sending - end Alice uses the signal state light source and the decoy state light source to prepare a first photon sequence. The first photon sequence can include photons prepared by signal - state pulses and photons prepared by decoy - state pulses; The sending - end Alice uses the signal state light source and the decoy state light source to prepare a second photon sequence, that is, the second photon sequence can include photons prepared by signal - state pulses and photons prepared by decoy - state pulses.

[0104] Step 220: Send the first photon sequence to a third party;

[0105] Specifically, the third party can be a measurement device, which can be simply referred to as Charlie. The third - party Charlie can be an untrusted third party. The sending - end Alice sends the first photon sequence to the third - party Charlie.

[0106] Step 230: Receive the first measurement result announced by the third party. The first measurement result is obtained by the third party's measurement of the first photon sequence and a third photon sequence sent by the receiving end to the third party. The third photon sequence is composed of single photons;

[0107] Specifically, the third party can perform a Bell - basis measurement on the first photon sequence and the third photon sequence, and obtain and announce the first measurement result.

[0108] Step 240: Send the sequence information corresponding to the first photon sequence to the recipient and receive the sequence information corresponding to the third photon sequence sent by the recipient;

[0109] Specifically, the sequence information refers to information related to the corresponding photon sequence, such as the position of photons, the preparation basis information of photons, the correspondence between photon position and light intensity, etc.

[0110] Step 250: Perform security detection based on the sequence information corresponding to the first photon sequence, the sequence information corresponding to the third photon sequence, and the first measurement result;

[0111] Specifically, the bit error rate and response rate can be determined based on the sequence information corresponding to the first photon sequence, the sequence information corresponding to the third photon sequence, and the first measurement result, and whether the channel is secure can be determined through the bit error rate and response rate.

[0112] Step 260: Perform message encoding on the second photon sequence when it is determined that the security detection passes;

[0113] Step 270: Send the encoded second photon sequence to the third party. The second photon sequence is used for the third party to perform measurements to obtain and announce a second measurement result, and the second measurement result is used for the recipient to determine the encoded information corresponding to the second photon sequence.

[0114] The quantum direct communication method provided by the embodiments of the present invention prepares a quantum state sequence through a decoy state light source, uses the decoy state light source to resist photon number splitting attacks, ensures the security of the protocol, and prevents eavesdropping.

[0115] Optionally, in step 210, the using the light source at the sending end to prepare the first photon sequence and the second photon sequence includes:

[0116] Step 211: Use an entanglement source to prepare a photon entanglement sequence and use a single photon source to prepare multiple single photons. The entanglement source includes a signal state light source and a decoy state light source, and the single photon source includes a decoy state light source;

[0117] Specifically, the entanglement source used by the sender Alice alternately sends laser pulses with different average photon numbers with a first probability; the single photon source used by the sender Alice alternately sends laser pulses with different average photon numbers with a second probability. The entanglement source is used to prepare a photon entanglement sequence; the single photon source is used to prepare single photons.

[0118] The first probability and the second probability can be preset, and the first probability and the second probability can be the same or different.

[0119] The entanglement source includes a signal state light source and a decoy state light source, that is, the entanglement source sends both information-carrying pulses and laser pulses different from the information-carrying pulses; the single-photon source includes a decoy state light source, that is, the single-photon source sends security verification pulses for security detection.

[0120] Exemplarily, the first light source sends a first laser pulse with an average photon number of a with a probability of 0.1, the second light source sends a second laser pulse with an average photon number of b with a probability of 0.1, and the third light source sends a third laser pulse with an average photon number of c with a probability of 0.8; wherein, the third laser pulse is an information-carrying pulse for transmitting information, the third light source is a signal state light source, the first laser pulse and the second laser pulse are different from the third laser pulse, and the first light source and the second light source are decoy state light sources.

[0121] The sender Alice prepares a photon entanglement sequence of length n, which contains at least one entangled state (Einstein-Podolsky-Rosen, EPR) photon pair (which can also be simply referred to as an entangled pair), and the entangled pair is in the Bell state |Ψ - >.

[0122] Optionally, a single photon prepared by the sender can be a single photon in any one of four states in a non-orthogonal basis.

[0123] Exemplarily, taking polarization coding as an example, the four states are a horizontal polarization state (|0>), a -45° polarization state (|->), a vertical polarization state (|1>), and a +45° polarization state (|+>); phase coding can also be used, and the four corresponding states when using phase coding can refer to related technologies. It should be understood that the embodiments of the present invention are for the convenience of understanding the present invention and are examples, and the present invention does not limit the coding method and the four states corresponding to the coding method.

[0124] Optionally, the decoy state light source in the entanglement source used by the sender is a double decoy state light source.

[0125] Specifically, the entanglement source of the sender Alice uses one signal state light source and two decoy state light sources.

[0126] Optionally, the double decoy state light source includes a weak decoy state light source and a vacuum decoy state light source.

[0127] Specifically, the entanglement source of the sender Alice uses a double decoy state (weak+vacuum) light source, that is, Alice's entanglement source uses one signal state light source with an average photon number of μ, one weak decoy state light source with an average photon number of μ ′ ' and one vacuum decoy state light source with an average photon number of 0, where μ' is much smaller than μ (μ' << μ).

[0128] Optionally, the single - photon source of the transmitting end Alice may include at least one decoy - state light source.

[0129] Specifically, the number of decoy - state light sources in the single - photon source of the transmitting end Alice and the average number of photons of the decoy - state light sources in each single - photon source are not limited.

[0130] Preferably, the number of decoy states in the single - photon source of the transmitting end Alice is infinite.

[0131] Optionally, the light source at the transmitting end is a phase - random weak coherent light source and a parametric down - conversion entanglement source.

[0132] The direct quantum communication method provided by the embodiments of the present invention, by adopting a phase - random weak coherent light source and a parametric down - conversion entanglement source, solves the problem that the existing measurement - device - independent quantum direct communication is threatened by photon - number - splitting attacks due to the light source not being an ideal single - photon source. By using the method of parametric down - conversion entanglement source and weak coherent light source with the decoy - state technology, it can resist photon - number - splitting attacks under more practical light - source conditions and ensure the security of communication.

[0133] Step 212: Divide the photon entanglement sequence into a to - be - processed photon sequence and the second photon sequence;

[0134] Specifically, each entanglement pair in the photon entanglement sequence is divided into two parts, respectively forming two sequences: the second photon sequence A1 and the to - be - processed photon sequence A2.

[0135] Step 213: Randomly insert the single photons into the to - be - processed photon sequence to obtain the first photon sequence.

[0136] Specifically, m single photons in four states under non - orthogonal bases are randomly inserted into the to - be - processed photon sequence A2 to form the first photon sequence A0.

[0137] Optionally, the second photon sequence A1 is used for message transmission, and the first photon sequence A0 is used for security detection.

[0138] Step 220: The transmitting end Alice sends the first photon sequence A0 to the third party Charlie.

[0139] Step 230: Receive the first measurement result announced by the third party. The first measurement result is obtained by the third party measuring the first photon sequence and the third photon sequence sent by the receiving end to the third party. The third photon sequence is composed of single photons;

[0140] Specifically, a third party performs Bell basis measurement on the first photon sequence and the second photon sequence to obtain a first measurement result, which can also be referred to as the Bell basis measurement result.

[0141] During the Bell basis measurement, quantum teleportation will occur, causing the second photon sequence A1 (i.e., the unsent one) in the hands of the sender Alice to randomly collapse to one of the states |0>, |1>, |+>, |->.

[0142] Table 1 is a table showing the relationship of measurement results provided by an embodiment of the present invention, which shows the relationship between the first measurement result announced by the third party, the state held by the sender Alice, and the initial quantum state of the receiver Bob. The state held by the sender Alice refers to the quantum state of the photons in the second photon sequence A1 held by the sender Alice; the initial quantum state of the receiver Bob refers to the quantum state of the photons in the third photon sequence before the receiver Bob sends the third photon sequence to the third party Charlie. In Table 1, and are the measurement results. The first column is the initial quantum state of Bob, and the rest of the table represents the state held by Alice corresponding to the measurement result and the initial quantum state of Bob. Exemplarily, when the measurement result is and the initial quantum state of Bob is |+>, the state held by Alice is -|+>.

[0143] Table 1. Table of Measurement Result Relationships

[0144]

[0145]

[0146] Step 240: Send the sequence information corresponding to the first photon sequence to the receiver and receive the sequence information corresponding to the third photon sequence sent by the receiver.

[0147] Optionally, the sequence information corresponding to the first photon sequence A0 includes:

[0148] The positions of single photons in the first photon sequence A0;

[0149] The preparation basis information of the first photon sequence A0; and

[0150] The correspondence between the photon positions and the light intensities in the first photon sequence A0.

[0151] Optionally, the sequence information corresponding to the third photon sequence includes the preparation basis information corresponding to the third photon sequence

[0152] Step 250: Perform security detection based on the sequence information corresponding to the first photon sequence, the sequence information of the third photon sequence, and the first measurement result;

[0153] Specifically, single photons in the first photon sequence, and single photons in the third photon sequence corresponding to the photon positions of the single photons in the first photon sequence can form single - photon pairs, and the single - photon pairs are used for security detection.

[0154] Exemplarily, the position of the single photon in the first photon sequence A0 can be that Alice announces that the nth photon in the first photon sequence is a single photon; then the nth photon in the third photon sequence is the corresponding photon, and the nth photon in the first photon sequence and the nth photon in the third photon sequence form a single - photon pair.

[0155] Alice can use the Bell - basis measurement results of the single - photon pairs to estimate the detection bit - error rate and response rate. Under the condition of no Eve attack, the ratio of the response rates of light sources with different average photon numbers is equal to the ratio of the numbers of photons generated by light sources with different average photon numbers, and this ratio is broken under the condition of Eve's photon - number - splitting attack. At the same time, Alice can evaluate the security of the quantum channel and determine whether to continue communication.

[0156] Step 260: When it is determined that the security detection passes, perform message encoding on the second photon sequence;

[0157] Optionally, the sender Alice encrypts the information of the second photon sequence using a local random bit string and inserts random numbers into the information of the second photon sequence;

[0158] Specifically, after Alice confirms the security of the quantum channel, Alice uses the second photon sequence A1 for message encoding, and Bob announces the corresponding preparation - basis information of the third photon sequence. Alice applies a unitary operation U A = U M U t to the photons in the second photon sequence A1, where is to complete the process of quantum teleportation, and the specific operation depends on Charlie's Bell - basis measurement result (the first measurement result) and the preparation - basis information announced by Bob. U M is used to encode information, representing classical bits 0 and 1 respectively. Among them, Alice encrypts the information therein using a local random bit string and also randomly inserts a sequence of random numbers during message encoding for message integrity detection.

[0159] Step 270: Send the encoded second photon sequence to the third party. The second photon sequence is used by the third party for measurement to obtain and announce a second measurement result, and the second measurement result is used by the receiving party to determine the encoding information corresponding to the second photon sequence.

[0160] Specifically, after Alice encodes, she sends the encoded second photon sequence A1 to Charlie for single-photon measurement. Charlie performs single-photon measurement on the second photon sequence A1 according to the preparation basis information announced by Bob and announces the second measurement result.

[0161] For the relationship between the quantum state of the second photon sequence, the initial quantum state of the receiving end Bob, and the second measurement result, refer to Table 1. In Table 1, and are the measurement results. The first column is the initial quantum state of Bob, and the rest of the table represents the quantum state of the second photon sequence corresponding to the measurement result and the initial quantum state of Bob.

[0162] Optionally, the method further includes:

[0163] Announcing random number information;

[0164] Specifically, Alice announces the random number information after the preparation basis information announced by Bob and the second measurement result announced by Charlie. The random number information refers to the photon positions of the photons encoded as random numbers and the random numbers corresponding to the photon positions.

[0165] Optionally, the method further includes: ending the communication in case it is determined that the security detection fails.

[0166] Figure 2 is the second schematic flow chart of the quantum direct communication method provided by the embodiments of the present invention. As Figure 2 shown, the quantum direct communication method provided by the embodiments of the present invention can be applied to the receiving end and includes:

[0167] Step 310: When the receiving end light source includes an uncharacterized light source, send the credibility parameter corresponding to the uncharacterized light source to the sending end. The credibility parameter is determined based on the correct preparation rate of the quantum state of the target light source, and the credibility parameter is used to correct the communication parameter and the security capacity.

[0168] Specifically, when the receiving end light source includes an uncharacterized light source, the uncharacterized light source is the target light source. For the introduction of the credibility parameter, the correct preparation rate of the quantum state, and the correction of the communication parameter and the security capacity, refer to the above introduction and will not be elaborated here.

[0169] In a possible implementation, the receiving end may send the credibility parameter corresponding to the target light source to the sending end during the past communication process, or both parties may publicly disclose the credibility parameter through a classical channel.

[0170] The quantum direct communication method provided by the embodiments of the present invention introduces the reliability of the light source through the credibility parameter, so as to more accurately determine the security capacity when using an uncharacterized light source (state preparation device), and can realize communication when using an uncharacterized light source. The embodiments of the present invention allow some devices to be uncharacterized, solve the problem of the requirements of the existing measurement device-independent quantum direct communication for perfect state preparation devices and ideal single-photon sources that are difficult to achieve in actual situations, reduce the requirements for the used devices, and save device costs.

[0171] Next, a further description will be made on the possible implementation manners of the above steps in specific embodiments.

[0172] Optionally, the method further includes:

[0173] Step 410, using the receiving-end light source to prepare a third photon sequence, where the third photon sequence is composed of single photons, and the receiving-end light source includes a signal-state light source and a decoy-state light source;

[0174] Specifically, the receiving end may be referred to as Bob. The receiving end Bob uses the receiving-end light source to prepare a third photon sequence B0 with a length of n + m, and the third photon sequence B0 is a single-photon sequence. The single photons in the third photon sequence B0 randomly fall into one of the four single-photon states in the above first photon sequence.

[0175] Among them, at least one of the encoding systems between the receiving end and the sending end is characterized, that is, the encoding system at the Alice or Bob end may be uncharacterized.

[0176] The receiving-end light source (the source used by Bob to prepare the third photon sequence) alternately sends laser pulses with different average photon numbers at a third probability, and the light source different from the information transmission pulse is a decoy-state light source. Optionally, the number of decoy states in the receiving-end light source is infinite.

[0177] Optionally, the receiving-end light source is a phase-randomized weak coherent light source.

[0178] Step 420, sending the third photon sequence to a third party;

[0179] Step 430, receiving the first measurement result announced by the third party, where the first measurement result is obtained by the third party measuring the third photon sequence and the first photon sequence sent by the sending end to the third party;

[0180] For the introduction of the first measurement result, refer to the above introduction, and details will not be repeated here.

[0181] Step 440: Publish the sequence information corresponding to the third photon sequence and receive the sequence information corresponding to the first photon sequence sent by the receiving party;

[0182] Optionally, the sequence information corresponding to the third photon sequence includes:

[0183] The preparation basis information of the third photon sequence; and

[0184] The correspondence between the photon positions and light intensities in the third photon sequence.

[0185] Step 450: Perform security detection based on the sequence information corresponding to the first photon sequence, the sequence information corresponding to the third photon sequence, and the first measurement result;

[0186] The security detection reference at the receiving end refers to the introduction of the security detection at the sending end, which will not be elaborated here.

[0187] Step 460: When it is determined that the security detection passes, receive the second measurement result sent by the third party, where the second measurement result is obtained by the third party measuring the second photon sequence sent by the sending end;

[0188] Step 470: Determine the coding information corresponding to the second photon sequence through the second measurement result.

[0189] Bob decodes the second photon sequence through Charlie's second measurement result to determine the coding information corresponding to the second photon sequence.

[0190] The quantum direct communication method provided by the embodiments of the present invention prepares a quantum state sequence through a decoy state light source, uses the decoy state light source to resist photon number splitting attacks, ensures the security of the protocol, and prevents eavesdropping. Optionally, the coding information includes random numbers;

[0191] The method further includes:

[0192] Step 465: Receive the random number information sent by the sending end;

[0193] Step 470: Determining the coding information corresponding to the second photon sequence through the second measurement result includes:

[0194] Decoding the second photon sequence based on the random number information, the second measurement result, and the sequence information corresponding to the third photon sequence to determine the coding information corresponding to the second photon sequence.

[0195] Bob can use the random number information published by Alice and the second measurement result of Charlie to decode the second photon sequence and determine the encoded information corresponding to the second photon sequence.

[0196] Step 480: Determine the transmission quantum bit error rate and information integrity based on the random number information, the second measurement result, and the sequence information corresponding to the third photon sequence.

[0197] Specifically, the sender can determine the random number information based on the random number information, the second measurement result, and the sequence information corresponding to the third photon sequence. The sender compares the decoded random number information with the random number information published by Alice to determine the transmission quantum bit error rate and information integrity. Optionally, the information integrity can be determined by whether a qubit is lost during routing.

[0198] The quantum direct communication method provided by the embodiments of the present invention can determine whether there is an error in quantum transmission by calculating the transmission quantum bit error rate, so as to determine whether the information is eavesdropped; by comparing the message integrity, determine whether there is a loss in quantum transmission, and determine whether the quantum is intercepted by Eve.

[0199] Optionally, the method further includes: ending the communication when it is determined that the security detection fails.

[0200] The quantum direct communication method provided by the embodiments of the present invention ends the communication when the security detection fails, ensuring the security of the communication.

[0201] Figure 3 is the third flow diagram of the quantum direct communication method provided by the embodiments of the present invention, as Figure 3 shown, the quantum direct communication method provided by the embodiments of the present invention includes:

[0202] Step 0: In order to perform parameter estimation before practical communication, it is necessary to correct the communication parameters of the quantum direct communication scheme when the light source is a non-ideal source.

[0203] The protocol security capacity in the embodiments of the present invention is:

[0204] C S =Q μv [1 - g - H(E μ )] + gQ 11 [1 - h(∈ u )];

[0205] where μ and v are the average photon numbers of the signal states at the Alice and Bob ends respectively, E μ is the message reception quantum bit error rate, ∈ u is the detection bit error rate, Qμv The total transmission gain Q when the average photon numbers at the Alice and Bob ends are μ and v respectively 11 is the gain during the total single-photon transmission, which also includes the contributions of both step 2 and step 5. The ratio of the channel response rates between AE and AB is g. In the case of using the increase capacity using masking (INCUM) technique, g = 1. The specific estimation method for the corresponding parameters can be obtained from the results of quantum communication using the decoy state technique in related technologies.

[0206] In the embodiment of the present invention, a credibility parameter η is added s , which is used to describe the credibility of the light source. This parameter is caused by the imperfect preparation of the state by the light source and represents the probability of correctly outputting the required state by the coding system. If the entangled light source used at the Alice end or the source used at the Bob end for preparing single photons is not characterized, it will not affect the eavesdropping detection process, but will affect the estimation of the qubit error rate. Therefore, the qubit error rate (E μ ) is corrected as follows: E μ ′ = E μ ·η s + 0.5(1 - η s ).

[0207] If the light source used by Alice or Bob for preparing the single photons for eavesdropping detection is not characterized, it will affect the estimation of the detection bit error rate. Therefore, the detection bit error rate (∈ u ) is corrected as follows: ∈ u ′ = ∈ u ·η s + 0.5(1 - η s ).

[0208] Based on the corrected qubit error rate and the corrected detection bit error rate, the secure capacity of the protocol is determined.

[0209] Step 1: Alice or Bob uses an uncharacterized phase-randomized weak coherent light source and a parametric down-conversion entangled light source and combines the decoy state technique to prepare a sequence of quantum states. For example Figure 3 , Alice prepares a first photon sequence and a second photon sequence. The first photon sequence and the second photon sequence are entangled sequences inserted with single photons. Bob prepares a third photon sequence, and the third photon sequence is a single-photon sequence.

[0210] Among them, Alice prepares a photon entanglement sequence of length n, and the entangled pairs are in the Bell state |Ψ ->. Each EPR pair in the entangled sequence is divided into two parts, respectively forming the second photon sequence A1 and the photon sequence A2 to be processed. m single photons in four states under non-orthogonal bases are randomly inserted into the photon sequence A2 to be processed to form the first photon sequence A0.

[0211] Bob uses the third photon sequence B0 with a preparation length of n + m, and the single photon randomly is in one of the above four single-photon states.

[0212] The encoding system at the Alice or Bob side is uncharacterized. That is to say, for a single-photon source and one photon in the entanglement, it can be regarded as a gray box that can output quantum states in a two-dimensional Hilbert space. Here, it is required that the dimension output by the uncharacterized light source encoding system is fixed, otherwise Eve can steal all the information without introducing errors.

[0213] Meanwhile, the light sources used in the protocol (including the entanglement source used by Alice, the source for preparing the single-photon sequence, and the source for preparing the single-photon sequence used by Bob) alternately send laser pulses with different average photon numbers at a fixed probability (including the first probability, the second probability, and the third probability). The light source different from the information transmission pulse is the decoy state light source.

[0214] Optionally, in the case where the number of decoy states of the single-photon source is infinite and the entanglement source uses a double decoy state (weak + vacuum), that is, the entanglement source of Alice uses a signal state light source with an average photon number of μ and decoy state light sources with average photon numbers of μ′ (μ′ << μ) and 0 respectively.

[0215] Step 2: Alice and Bob perform the first information transmission with Charlie. Alice sends the first photon sequence to Charlie, and Bob sends the third photon sequence to Charlie. Charlie performs Bell basis measurement.

[0216] Specifically, when performing Bell basis measurement, the other photon sequence (the second photon sequence A1) held by Alice randomly collapses to one of the states |0>, |1>, |+>, |->. Bob can determine the information of the other photon sequence (the second photon sequence) held by Alice according to the sequence information (such as the preparation basis information) of the third photon sequence he holds, the first measurement result, and the first measurement result relationship shown in Table 1.

[0217] Step 3: Alice and Bob perform the first security detection according to the first measurement result announced by Charlie and estimate the detection bit error rate and response rate.

[0218] After Charlie announces the measurement results, Alice announces the single - photon positions of the first photon sequence, the information about the preparation bases of the first photon sequence, and the correspondence between the photon positions and light intensities in the first photon sequence.

[0219] Bob announces the information about the preparation bases corresponding to the third photon sequence.

[0220] The situation where single photons from the first photon sequence of Alice and single photons from the third photon sequence of Bob form photon pairs will be used for security detection. Using the Bell - basis measurement results (the first measurement results) of the single - photon pairs, Alice and Bob can estimate the detection bit - error rate and response rate.

[0221] Under the condition of no Eve attack, the ratio of the response rates of different average - photon - number light sources is equal to the ratio of their average photon numbers, and this ratio is broken under the condition of Eve's photon - number - splitting attack. At the same time, they evaluate the security of the quantum channel and decide whether to continue the communication.

[0222] Step 4: Alice uses the second photon sequence for message encoding and encrypts the information therein using a local random bit string.

[0223] After Alice confirms the security of the quantum channel, Alice uses the second photon sequence A1 for message encoding, and Bob announces the information about the preparation bases corresponding to the third photon sequence. Alice applies the unitary operation U A =U M U t to the photons in the second photon sequence A1, where is to complete the quantum teleportation process, and the specific operation depends on Charlie's Bell - basis measurement results (the first measurement results) and the information about the preparation bases announced by Bob. U M is used to encode information, representing classical bits 0 and 1 respectively. Among them, Alice encrypts the information therein using a local random bit string and also randomly inserts a sequence of random numbers during message encoding for message integrity detection.

[0224] Step 5: Alice and Charlie conduct a second information transmission. Charlie makes a measurement, and Alice and Bob conduct a second security detection, compare data integrity, and estimate the quantum - bit error rate.

[0225] After encoding, Alice sends the second photon sequence A1 to Charlie for single - photon measurement. Charlie makes a single - photon measurement on the second photon sequence A1 according to the information about the preparation bases announced by Bob and announces the second measurement results.

[0226] After Alice announces the random number information after the preparation basis information announced by Bob and the second measurement result announced by Charlie.

[0227] Bob can use the random number information announced by Alice and the second measurement result announced by Charlie to decode the second photon sequence A1.

[0228] Bob calculates the transmission quantum bit error rate and compares the integrity of the message based on the random number sequence obtained by his own decoding and the random number sequence obtained by decoding the announcement of Alice.

[0229] The quantum direct communication method provided by the embodiments of the present invention achieves the following technical effects: First, it solves the problem of the requirements of the existing measurement device-independent quantum direct communication for perfect state preparation devices and ideal single-photon sources that are difficult to achieve in actual situations, allows some devices to be uncharacterized, reduces the requirements for the devices used, and saves device costs. Second, it solves the problem of the threat of photon number splitting attacks in the existing measurement device-independent quantum direct communication due to the fact that the light source is not an ideal single-photon source. By using the method of parametric down-conversion entangled source and weak coherent light source with decoy state technology, it can resist photon number splitting attacks in a more practical light source situation and ensure the security of communication. At the same time, it can more accurately estimate the channel parameters and improve the security communication performance. Third, using the increase capacity using masking (INCUM) technology to mask the lost encrypted key information not only significantly increases the maximum secure communication distance, but also greatly reduces the impact of uncharacterized light sources on the communication capacity.

[0230] Figure 4 is one of the relationship diagrams of the secure capacity and communication distance provided by the embodiments of the present invention, Figure 5 is another relationship diagram of the secure capacity and communication distance provided by the embodiments of the present invention, Figure 4 and Figure 5 is to adopt the quantum direct communication method provided by the embodiments of the present invention, that is Figure 4 and Figure 5 is the relationship diagram of the asymptotic lower bound of the secure capacity of the unilateral measurement device-independent quantum direct communication protocol with INCUM technology and double decoy state technology and the communication distance between Alice and Bob.

[0231] Figure 4 shows the relationship between the secure capacity and the transmission distance when the entanglement source used by the sending end or the light source used by the receiving end for preparing single photons for transmitting information is uncharacterized, and the credibility of the light source is 1, 0.95, and 0.9 respectively; Figure 5For the case where the light source used to prepare single photons for security (wiretapping) detection is not characterized, the relationship between the security capacity and the transmission distance when the credibility of the light source is 1, 0.95, and 0.9 respectively. As Figure 4 and Figure 5 shown, the quantum direct communication method provided by the embodiments of the present invention can securely transmit information within a range of nearly 350 kilometers, and the one-sided measurement device-independent quantum direct communication protocol after using the INCUM technology has fewer requirements for the uncharacterized case of the entanglement source used at the Alice end or the source used at the Bob end to prepare single photons when achieving the same transmission distance.

[0232] The quantum direct communication device provided by the present invention will be described below. The quantum direct communication device described below can be correspondingly referred to the quantum direct communication method described above.

[0233] Figure 6 is one of the schematic structural diagrams of the quantum direct communication device provided by the embodiments of the present invention. As Figure 6 shown, the quantum direct communication device provided by the embodiments of the present invention can be applied to the sending end and includes:

[0234] A first acquisition unit 610, configured to acquire the credibility parameter of the target light source, where the credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source, the target light source is uncharacterized, and the target light source belongs to the light source at the sending end or the light source at the receiving end;

[0235] A first correction unit 620, configured to correct the communication parameter based on the credibility parameter;

[0236] A first determination unit 630, configured to determine the security capacity based on the corrected communication parameter and the security capacity formula;

[0237] The first determination unit 630 is further configured to determine whether to communicate with the receiving end based on the security capacity.

[0238] Optionally, the first determination unit 630 is configured to correct the quantum bit error rate based on the credibility parameter when the target light source is used to transmit information; and / or

[0239] The first determination unit 630 is configured to correct the detection bit error rate based on the credibility parameter when the target light source is used for security detection.

[0240] The device further includes: a first preparation unit, a first sending unit, a first receiving unit, a first information unit, a first detection unit, and a first encoding unit;

[0241] When the security capacity is greater than zero, a first preparation unit is configured to prepare a first photon sequence and a second photon sequence using a transmitting light source, where the transmitting light source includes a signal state light source and a decoy state light source;

[0242] A first transmitting unit is configured to transmit the first photon sequence to a third party;

[0243] A first receiving unit is configured to

[0244] receive a first measurement result announced by the third party, where the first measurement result is obtained by the third party measuring the first photon sequence and a third photon sequence transmitted by a receiving end to the third party, and the third photon sequence is composed of single photons;

[0245] A first information unit is configured to send sequence information corresponding to the first photon sequence to the receiving party and receive sequence information corresponding to the third photon sequence sent by the receiving party;

[0246] A first detection unit is configured to

[0247] perform security detection based on the sequence information corresponding to the first photon sequence, the sequence information corresponding to the third photon sequence, and the first measurement result;

[0248] A first encoding unit is configured to

[0249] perform message encoding on the second photon sequence when it is determined that the security detection passes;

[0250] The first transmitting unit is further configured to transmit the encoded second photon sequence to the third party, where the second photon sequence is used for the third party to measure and announce a second measurement result, and the second measurement result is used for the receiving party to determine the encoding information corresponding to the second photon sequence.

[0251] Optionally, the first preparation unit is configured to prepare a photon entanglement sequence using an entanglement source and prepare a plurality of single photons using a single photon source, where the entanglement source includes a signal state light source and a decoy state light source, and the single photon source includes a decoy state light source;

[0252] The first preparation unit is configured to divide the photon entanglement sequence into a to-be-processed photon sequence and the second photon sequence;

[0253] The first preparation unit is configured to randomly insert the single photons into the to-be-processed photon sequence to obtain the first photon sequence.

[0254] Optionally, the decoy state light source in the entanglement source used by the transmitting end is a double decoy state light source.

[0255] Optionally, the light source at the sending end is a weak coherent light source with random phase and a parametric down-conversion entanglement source.

[0256] Optionally, the sequence information corresponding to the first photon sequence includes:

[0257] The positions of single photons in the first photon sequence;

[0258] The preparation basis information of the first photon sequence; and

[0259] The correspondence between the photon positions and the light intensities in the first photon sequence.

[0260] Optionally, the first encoding unit is used to encrypt the information of the second photon sequence using a local random bit string and insert random numbers into the information of the second photon sequence;

[0261] The device further includes: a first announcement unit, configured to announce random number information.

[0262] It should be noted here that the above device provided by the embodiments of the present invention can implement all the method steps implemented by the above method embodiments and can achieve the same technical effects. The same parts and beneficial effects as those in the method embodiments will not be specifically described in this embodiment.

[0263] Figure 7 This is the second structural schematic diagram of the quantum direct communication device provided by the embodiments of the present invention. As Figure 7 shown, the quantum direct communication device provided by the embodiments of the present invention can be applied to the receiving end and includes:

[0264] A second sending unit 710, configured to send the credibility parameter corresponding to the uncharacterized light source to the sending end when the receiving end light source includes an uncharacterized light source. The credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source, and the credibility parameter is used to correct the communication parameter and the security capacity.

[0265] Optionally, the device further includes a second preparation unit, a second sending unit, a second receiving unit, a second information unit, a second detection unit, and a second decoding unit;

[0266] The second preparation unit is configured to prepare a third photon sequence using the receiving end light source. The third photon sequence is composed of single photons, and the receiving end light source includes a signal state light source and a decoy state light source;

[0267] The second sending unit is configured to send the third photon sequence to a third party;

[0268] A second receiving unit, configured to receive the first measurement result announced by the third party, where the first measurement result is obtained by the third party measuring the third photon sequence and the first photon sequence sent by the sending end to the third party;

[0269] A second information unit, configured to announce the sequence information corresponding to the third photon sequence and receive the sequence information corresponding to the first photon sequence sent by the receiving party;

[0270] A second detection unit, configured to perform security detection based on the sequence information corresponding to the first photon sequence, the sequence information corresponding to the third photon sequence, and the first measurement result;

[0271] The second receiving unit is further configured to, when it is determined that the security detection passes, receive the second measurement result sent by the third party, where the second measurement result is obtained by the third party measuring the second photon sequence sent by the sending end;

[0272] A second decoding unit, configured to determine the encoded information corresponding to the second photon sequence based on the second measurement result and the sequence information corresponding to the third photon sequence.

[0273] It should be noted here that the above device provided in the embodiment of the present invention can implement all the method steps implemented in the above method embodiment and can achieve the same technical effect. The same parts and beneficial effects as those in the method embodiment in this embodiment will not be specifically described here.

[0274] Figure 8 An example of a schematic physical structure diagram of an electronic device is shown in Figure 8 As shown, the electronic device may include: a processor 810, a communication interface 820, a memory 830, and a communication bus 840. Among them, the processor 810, the communication interface 820, and the memory 830 communicate with each other through the communication bus 840. The processor 810 can call the logical instructions in the memory 830 to execute the quantum direct communication method applied to the sending end or the quantum direct communication method applied to the receiving end.

[0275] The quantum direct communication method applied to the sending end includes:

[0276] Obtain the credibility parameter of the target light source, where the credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source, the target light source is uncharacterized, and the target light source belongs to the sending end light source or the receiving end light source;

[0277] Modify the communication parameter based on the credibility parameter;

[0278] Determine the security capacity based on the corrected communication parameters and the security capacity formula;

[0279] Determine whether to communicate with the receiving end based on the security capacity.

[0280] A quantum direct communication method applied to the receiving end, comprising:

[0281] In the case where the receiving end light source includes an uncharacterized light source, send the credibility parameter corresponding to the uncharacterized light source to the sending end, where the credibility parameter is determined based on the quantum state preparation correct rate of the target light source, and the credibility parameter is used to correct the communication parameters and the security capacity.

[0282] In addition, when the logical instructions in the above-mentioned memory 830 are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0283] On the other hand, the present invention also provides a computer program product, where the computer program product includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the quantum direct communication method applied to the sending end or the quantum direct communication method applied to the receiving end provided by the above-mentioned various methods.

[0284] A quantum direct communication method applied to the sending end includes:

[0285] Obtain the credibility parameter of the target light source, where the credibility parameter is determined based on the quantum state preparation correct rate of the target light source, the target light source is uncharacterized, and the target light source belongs to the sending end light source or the receiving end light source;

[0286] Correct the communication parameters based on the credibility parameter;

[0287] Determine the security capacity based on the corrected communication parameters and the security capacity formula;

[0288] Determine whether to communicate with the receiving end based on the security capacity.

[0289] A quantum direct communication method applied to the receiving end includes:

[0290] When the receiving-end light source includes an uncharacterized light source, send the credibility parameter corresponding to the uncharacterized light source to the sending end. The credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source, and the credibility parameter is used to correct the communication parameter and the security capacity.

[0291] On the other hand, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it is used to execute the quantum direct communication method applied to the sending end or the quantum direct communication method applied to the receiving end provided by the above methods.

[0292] A quantum direct communication method applied to the sending end includes:

[0293] Obtain the credibility parameter of the target light source. The credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source. The target light source is uncharacterized and belongs to the sending-end light source or the receiving-end light source;

[0294] Correct the communication parameter based on the credibility parameter;

[0295] Determine the security capacity based on the corrected communication parameter and the security capacity formula;

[0296] Determine whether to communicate with the receiving end based on the security capacity.

[0297] A quantum direct communication method applied to the receiving end includes:

[0298] When the receiving-end light source includes an uncharacterized light source, send the credibility parameter corresponding to the uncharacterized light source to the sending end. The credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source, and the credibility parameter is used to correct the communication parameter and the security capacity. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0299] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0300] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A quantum direct communication method, characterized in that, Applied to the sending end, including: Obtain the credibility parameter of the target light source, where the credibility parameter is determined based on the preparation correctness rate of the quantum state of the target light source, and the target light source belongs to the sending-end light source or the receiving-end light source; Modify the communication parameter based on the credibility parameter; Determine the security capacity based on the modified communication parameter and the security capacity formula; Determine whether to communicate with the receiving end based on the security capacity; The modifying the communication parameter based on the credibility parameter includes: When the target light source is used to transmit information, modify the quantum bit error rate based on the credibility parameter; When the target light source is used for security detection, modify the detection bit error rate based on the credibility parameter.

2. The quantum direct communication method according to claim 1, wherein When the security capacity is greater than zero, the method further includes: Use the sending-end light source to prepare a first photon sequence and a second photon sequence, where the sending-end light source includes a signal-state light source and a decoy-state light source; Send the first photon sequence to a third party; Receive the first measurement result announced by the third party, where the first measurement result is obtained by the third party measuring the first photon sequence and a third photon sequence sent by the receiving end to the third party, and the third photon sequence is composed of single photons; Send the sequence information corresponding to the first photon sequence to the receiving party and receive the sequence information corresponding to the third photon sequence sent by the receiving party; Perform security detection based on the sequence information corresponding to the first photon sequence, the sequence information corresponding to the third photon sequence, and the first measurement result; When it is determined that the security detection passes, perform message encoding on the second photon sequence; Send the encoded second photon sequence to the third party, where the second photon sequence is used for the third party to measure and announce a second measurement result, and the second measurement result is used for the receiving party to determine the encoded information corresponding to the second photon sequence.

3. The quantum direct communication method according to claim 2, wherein The using the sending-end light source to prepare the first photon sequence and the second photon sequence includes: Use an entanglement source to prepare a photon entanglement sequence and use a single-photon source to prepare multiple single photons, where the entanglement source includes a signal-state light source and a decoy-state light source, and the single-photon source includes a decoy-state light source; Divide the photon entanglement sequence into a to-be-processed photon sequence and the second photon sequence; Randomly insert the single photons into the to-be-processed photon sequence to obtain the first photon sequence.

4. The quantum direct communication method according to claim 3, wherein The decoy-state light source in the entanglement source used by the sending end is a double decoy-state light source.

5. The quantum direct communication method according to claim 3, characterized in that, The sending-end light source is a phase-randomized weak coherent light source and a parametric down-conversion entanglement source.

6. The quantum direct communication method according to claim 2, wherein The sequence information corresponding to the first photon sequence includes: The positions of the single photons in the first photon sequence; The preparation basis information of the first photon sequence; and The correspondence between the photon positions and the light intensities in the first photon sequence.

7. The quantum direct communication method according to claim 2, wherein The performing message encoding on the second photon sequence includes: Encrypt the information of the second photon sequence using a local random bit string and insert random numbers into the information of the second photon sequence; The method further includes: announcing the random number information.

8. A quantum direct communication method, characterized in that, Applied to the receiving end, including: When an uncharacterized light source is included in the receiving - end light source, send the credibility parameter corresponding to the uncharacterized light source to the sending - end. The credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source, and the credibility parameter is used to correct communication parameters and security capacity; Correcting the communication parameters based on the credibility parameter includes: When the target light source is used to transmit information, correct the quantum bit error rate based on the credibility parameter; When the target light source is used for security detection, correct the detection bit error rate based on the credibility parameter.

9. The quantum direct communication method according to claim 8, wherein The method further includes: Using the receiving - end light source to prepare a third photon sequence, the third photon sequence is composed of single photons, and the receiving - end light source includes a signal - state light source and a decoy - state light source; Send the third photon sequence to a third party; Receive the first measurement result announced by the third party. The first measurement result is obtained by the third party measuring the third photon sequence and the first photon sequence sent by the sending - end to the third party; Announce the sequence information corresponding to the third photon sequence and receive the sequence information corresponding to the first photon sequence sent by the receiving - party; Perform security detection based on the sequence information corresponding to the first photon sequence, the sequence information corresponding to the third photon sequence, and the first measurement result; When it is determined that the security detection passes, receive the second measurement result sent by the third party. The second measurement result is obtained by the third party measuring the second photon sequence sent by the sending - end; Based on the second measurement result and the sequence information corresponding to the third photon sequence, determine the coding information corresponding to the second photon sequence.

10. The quantum direct communication method according to claim 9, wherein, The receiving - end light source is a phase - random weak coherent light source.

11. The quantum direct communication method according to claim 9, characterized in that, The sequence information corresponding to the third photon sequence includes: The preparation basis information of the third photon sequence; and The correspondence between the photon position and the optical intensity in the third photon sequence.

12. The quantum direct communication method according to any one of claims 9-11, characterized in that, The coding information includes random numbers; The method further includes: Receive the random - number information sent by the sending - end; Based on the random - number information, the second measurement result, and the sequence information corresponding to the third photon sequence, determine the transmission quantum bit error rate and information integrity.

13. A quantum direct communication device, characterized in that, Applied to the sending - end, it includes: A first acquisition unit, configured to acquire the credibility parameter of the target light source. The credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source, and the target light source belongs to the sending - end light source or the receiving - end light source; A first correction unit, configured to correct the communication parameters based on the credibility parameter; A first determination unit, configured to determine the security capacity based on the corrected communication parameters and the security - capacity formula; The first determination unit is further configured to determine whether to communicate with the receiving - end based on the security capacity; The correcting the communication parameters based on the credibility parameter includes: When the target light source is used to transmit information, correct the quantum bit error rate based on the credibility parameter; When the target light source is used for security detection, correct the detection bit error rate based on the credibility parameter.

14. A quantum direct communication device, characterized in that, Applied to the receiving - end, it includes: A second sending unit, configured to send the credibility parameter corresponding to the uncharacterized light source to the sending end when the receiving end light source includes an uncharacterized light source, where the credibility parameter is determined based on the preparation correct rate of the quantum state of the target light source, and the credibility parameter is used to correct communication parameters and security capacity; Correcting the communication parameters based on the credibility parameter includes: When the target light source is used to transmit information, correcting the quantum bit error rate based on the credibility parameter; When the target light source is used for security detection, correcting the detection bit error rate based on the credibility parameter.

15. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, the quantum direct communication method described in any one of claims 1 to 7 or the quantum direct communication method described in any one of claims 8 to 12 is implemented.

16. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, the quantum direct communication method described in any one of claims 1 to 7 or the quantum direct communication method described in any one of claims 8 to 12 is implemented.

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