A measurement device-independent multi-party quantum secure direct communication method based on hyperentanglement

Abstract

This invention belongs to the field of quantum communication technology and discloses a measurement-device-independent multi-party quantum secure direct communication method based on hyperentanglement. This method uses polarization-space hyperentanglement to construct a hyperentangled channel through hyperentanglement exchange, enabling users 1, 2, 3, and 4 to simultaneously transmit secret information to user 5. All measurements in this method are performed by an untrusted measurement terminal. User 5 can derive the coded information of other users based on the three rounds of hyperentangled Bell state measurements made by the measurement terminal, thus achieving multi-party quantum secure direct communication. Compared with existing two- and three-party quantum secure direct communication schemes, this method increases the number of communicating parties and improves the communication efficiency of quantum secure direct communication. Furthermore, this method can resist all attacks from the measurement terminal, enhancing the security of multi-party quantum secure direct communication under practical experimental conditions.

Description

Technical Field

[0001] The present invention belongs to the field of quantum communication technology, and in particular relates to a measurement device-independent multi-party quantum secure direct communication method based on hyper-entanglement. Background Art

[0002] Quantum communication, based on the fundamental principles of quantum mechanics, enables information transmission. Compared to traditional classical communication, its greatest advantage lies in its absolute security. Quantum secure communication encompasses several key sub-sectors, including quantum secure direct communication (QSDC), quantum key distribution (QKD), and quantum secret sharing (QSS). Professor Long Guilu first proposed QSDC in 2000. In 2003 and 2004, Deng Fuguo et al. proposed two-step QSDC protocols based on entanglement and single photons, respectively. These protocols defined, constructed, and implemented security criteria for QSDC, laying the foundation for further development. These protocols were demonstrated on experimental platforms in 2016 and 2017, respectively.

[0003] Subsequently, theoretical research on QSDC has continued to develop, and many new QSDC schemes have emerged. These not only provide proof of QSDC's security but also propose device-independent quantum secure direct communication (DI-QSDC) and measurement device-independent quantum secure direct communication (MDI-QSDC), which have greatly improved the security of QSDC in actual experiments. In 2022, Sheng Yubo et al. proposed one-step QSDC, reducing the photon transmission cycle from two to one, effectively simplifying the QSDC protocol and reducing information loss. They then proposed the DI and MDI one-step QSDC protocols, further improving the security of the protocol under practical conditions. The MDI-QSDC protocol can effectively resist all attacks from the detector end. Currently, all MDI schemes are implemented in single or two degrees of freedom. The number of communicating parties in the MDI-QSDC protocol is limited to two or three parties (as shown in patent application CN 114221713A), and the communication rate and information capacity are relatively low. Summary of the Invention

[0004] To solve the above problems, the present invention provides a measurement device-independent multi-party quantum secure direct communication method based on hyperentanglement exchange, which can realize quantum secure direct communication between five communicating parties, effectively improving communication efficiency, while also being able to resist all attacks from the detector end, ensuring the security of the transmission process.

[0005] The measurement device-independent multi-party quantum secure direct communication method based on hyperentanglement exchange described in the present invention comprises the following steps:

[0006] Step 1: User 1, User 2, User 3, User 4, and User 5 all prepare a large number of identical polarization-space super-entangled states. Where p and s represent the polarization degree of freedom and the spatial degree of freedom, respectively. User 1's super-entangled photon pairs are divided into the sequence (S1, S2), user 2's photon sequence is (S3, S4), user 3's photon sequence is (S5, S6), user 4's photon sequence is (S7, S8), and user 5's photon sequence is (S9, S10). All of the above users randomly insert a large number of single photons randomly prepared in the X basis or Z basis in both degrees of freedom into their respective two photon sequences as security detection photons.

[0007] Step 2: User 1 and User 2 send all photons of sequences S2 and S3 to the measurement end in sequence. At the same time, User 3 and User 4 send all photons of sequences S6 and S7 to the measurement end in sequence. The above users store the photons of sequences S1, S4, S5, and S8 in the quantum memory, and User 5 also stores the photons of sequences S9 and S10 in the quantum memory.

[0008] Step 3: The measuring end performs the first round of super-entangled Bell state measurement, or HBSM, on the photons of the S2 and S3 sequences, as well as the S6 and S7 sequences, and announces the measurement results. If one of the two photons undergoing HBSM comes from a super-entangled photon pair and the other is a single photon, the HBSM result and the remaining photons in the super-entangled photon pair are discarded. If both photons undergoing HBSM come from entangled photon pairs, the corresponding photons of the S1 and S4 sequences belonging to user 1 and user 2, or the photons of the S5 and S8 sequences belonging to user 3 and user 4, will be used to construct a super-entangled channel based on the HBSM results. If both photons undergoing HBSM are safety photons, the HBSM measurement results are used for safety testing. If the safety test fails, it means that the photon transmission process is unsafe and the communication is canceled. If the safety test passes, it means that the photon transmission process is safe and the next step is continued.

[0009] Step 4: Based on the information to be transmitted, User 1 and User 2 encode the super-entangled photon pairs in the S1 and S4 sequences in the polarization degree of freedom, respectively; User 3 and User 4 encode the super-entangled photon pairs in the S5 and S8 sequences in the spatial degree of freedom, respectively; User 5 randomly encodes all super-entangled photon pairs in the S9 and S10 sequences in two degrees of freedom; at the same time, the above five users do not perform any operations on the security detection photons in all photon sequences;

[0010] Step 5: After the encoding is completed, user 2 sends all photons of the S4 sequence, user 3 sends all photons of the S5 sequence, and user 5 sends all photons of the S9 and S10 sequences to the measurement end at the same time; the measurement end performs a second round of HBSM on the corresponding photons of the S4 and S9 sequences, as well as the corresponding photons of the S5 and S10 sequences, and announces the measurement results; if one of the two photons of the HBSM comes from a super-entangled photon pair and the other is a single photon, the HBSM result and the remaining photons in the super-entangled photon pair are discarded; if the photons of both HBSMs come from entangled photon pairs, the photons corresponding to the S1 and S8 sequences construct a super-entangled channel; if both photons of the HBSM are security photons, the HBSM measurement results are used for security detection. If the security detection fails, the communication is terminated. If the security detection passes, the next step is carried out;

[0011] Step 6: User 1 and User 4 send all the photons of the S1 and S8 sequences respectively to the measurement end for the third round of HBSM and announce the measurement results; similarly, if one of the two photons of HBSM comes from a super-entangled photon pair and the other is a single photon, the HBSM result and the remaining photons in the super-entangled photon pair are discarded; if both photons of HBSM are security photons, the HBSM measurement result is used for security detection. If the security detection fails, the communication is terminated; if the security detection passes, the next step is carried out; if the photons of HBSM all come from entangled photon pairs, User 5 infers the information transmitted by User 1, User 2, User 3, and User 4 based on the results of the previous three rounds of HBSM, and completes multi-party quantum secure direct communication.

[0012] Furthermore, step 1 is specifically as follows: the entangled states initially prepared by user 1, user 2, user 3, user 4 and user 5 are in, and There are four Bell states belonging to the following polarization degrees of freedom and spatial freedom:

[0013]

[0014]

[0015]

[0016]

[0017] Where H and V represent the horizontal polarization and vertical polarization of the photon, respectively, and a1, a2, a1′, a2′ represent the spatial mode. The randomly prepared single-photon polarization-spatial mode super-encoded quantum state is Among them, δ and κ belong to the polarization degree of freedom and spatial freedom, respectively.

[0018] One of the four quantum states of the degree:

[0019]

[0020]

[0021] Furthermore, the safety check process of steps 3, 5, and 6 is as follows: if the two photons undergoing HBSM have different preparation bases for a certain degree of freedom, the BSM result for that degree of freedom is discarded; if the two photons undergoing HBSM have the same preparation base for a certain degree of freedom, the BSM result for that degree of freedom is used for safety check. The specific process is as follows:

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030] If the HBSM obtains a measurement result different from the corresponding term in the above equation in any degree of freedom, it means that an error has occurred in that degree of freedom; user 1, user 2, user 3, and user 4 estimate the bit error rate of the two degrees of freedom based on the results of the HBSM. If the bit error rate of any degree of freedom is higher than the set threshold, it means that the photon transmission is unsafe and the communication is canceled; if the bit error rates of both degrees of freedom are lower than the set threshold, it means that the photon transmission process is safe and communication continues.

[0031] Furthermore, the construction process of the super-entangled channel in step 3 is specifically as follows:

[0032] After user 1 and user 2 send the photons of sequence S2 and S3 to the fourth-party measurement terminal for measurement, the quantum state of the system is:

[0033]

[0034] Where p represents the polarization degree of freedom, s represents the polarization degree of freedom, and the subscripts 1, 2, 3, and 4 represent the photon sequence numbers. After user 3 and user 4 send photons of sequences S5, S6, S7, and S8 to the fourth-party measurement end for HBSM, the quantum state of the system is:

[0035]

[0036] Among them, the subscripts 5, 6, 7, and 8 represent the photon sequence numbers respectively; users 1 and 2, and users 3 and 4 establish super-entangled channels according to the HBSM results respectively.

[0037] Furthermore, the specific encoding rules in step 4 are:

[0038] User 1 has an invariant operation (I) and a bit flipping operation (σ) on the photons of the S1 sequence under the polarization degree of freedom. xp ), representing classical information 0 and 1 respectively; User 2 has an invariant operation (I) and a phase flip operation (σ) on the photons of the S4 sequence under the polarization degree of freedom. zp ), representing classical information 0 and 1 respectively; at the same time, user 3 has an invariant operation (I) and a bit flip operation (σ) on the photons of the S5 sequence in the spatial degree of freedom. xs ), representing classical information 0 and 1 respectively; User 4 has an invariant operation (I) and a phase flip operation (σ) on the photons of the S8 sequence under the spatial degree of freedom. zs ), representing classical information 0 and 1 respectively; User 5 performs random operations on all photons of the S9 and S10 sequences in two degrees of freedom; where,

[0039] I p =HH+VV,I s =a1a1+a2a2

[0040] σ zp =HH-VV,σ zs =a1a1-a2a2

[0041] σ xp =VH+HV,σ xs =a1a2+a2a1

[0042] Furthermore, user 5 derives the encoding results of user 1, user 2, user 3, and user 4 based on the three rounds of HBSM measurement results and its own random operation to obtain the secret information transmitted by user 1, user 2, user 3, and user 4; specifically:

[0043] After the first round of photon transmission, the quantum states of user 1 and user 2, and the quantum states of user 3 and user 4 are:

[0044]

[0045]

[0046] Assume that the measurement result of HBSM is Then we can know that the super-entangled state shared by user 1 and user 2 is The super-entangled state shared by users 3 and 4 is If user 1 and user 2 respectively Conduct σ xp and σ zp Operation, the quantum state shared by user 1 and user 2 becomes User 3 and User 4 respectively Conduct σ xs and σ zs Operation, the quantum state shared by user 3 and user 4 becomes User 5 performs an unchanged operation on the two degrees of freedom of the super-entanglement in his hand. After the encoding is completed, the corresponding photons of the sequence S4, S9, S5, S10, S1, and S8 are sent to the measurement end for HBSM. The quantum state of the photons corresponding to the sequence S1, S4, S9, and S10 is:

[0047]

[0048] When the HBSM measurement results are published, it is assumed that the measurement results are Then the quantum state of the photon corresponding to the S1 and S10 sequences is Then the quantum states of the photons corresponding to the S4 and S9 sequences are The quantum state obtained by HBSM is:

[0049]

[0050] Assume that the measurement result is Then the entangled state between user 1 and user 5 is determined to be Then perform HBSM on the corresponding photons of S1 and S8. If the measurement result is User 5 determines that the quantum states of user 1, user 2, user 3, and user 4 after encoding are Therefore, user 5 compares the quantum states of the polarization and spatial degrees of freedom with those before encoding, and knows that user 1 performed a bit flip operation on the polarization degree of freedom, and user 2 performed a phase flip operation on the spatial degree of freedom. From this, user 5 can know that the information transmitted by user 1 and user 2 is 1, 1 respectively; similarly, the information transmitted by user 3 and user 4 is 1, 1 respectively.

[0051] Furthermore, the results of the three rounds of HBSM are public. However, since user 5's random operation on the S9 sequence photons is not disclosed, the measurement end and eavesdroppers cannot infer the encoded information of users 1-4 based on the results of the three rounds of HBSM, ensuring information security.

[0052] The beneficial effects of this invention are as follows: all measurement tasks in this method are performed by an untrusted measurement terminal. User 5 can deduce the coded information of other users based on the three rounds of super-entangled Bell state measurements made by the measurement terminal, thus achieving multi-party quantum secure direct communication. Compared with existing two-party and three-party quantum secure direct communication schemes, this method proposes the first MDI-QSDC protocol involving five communicating parties. This protocol has more communicating parties than the existing multi-party MDI-QSDC protocol and improves the communication efficiency of quantum secure direct communication. Furthermore, this method fully resists all attacks against imperfect measurement terminals, ensuring the security of multi-party quantum secure direct communication under practical experimental conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Schematic diagram of the communication process of the measurement device-independent multi-party quantum secure direct communication method based on hyperentanglement swapping of the present invention;

[0054] FIG2( a ) is a schematic diagram of the structure of entanglement prepared by user 1, user 2, user 3, user 4 and user 5 in the present invention;

[0055] FIG2( b ) is a schematic diagram of a structure in which photons of the sequences S2 , S3 , S6 , and S7 are sent to a fourth-party measurement terminal in the present invention;

[0056] FIG2( c ) shows the encoding operation performed by user 1 and user 2, and user 3 and user 4 in the present invention.

[0057] FIG2( d ) is a schematic diagram of the structure in which user 1 and user 4 form entanglement in the present invention;

[0058] FIG2(e) is a schematic diagram showing a structure in which user 5 determines the codes of user 1 and user 4 based on the measurement results in the present invention. DETAILED DESCRIPTION

[0059] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] like Figure 1 As shown, the present invention provides a measurement device-independent three-party quantum secure direct communication method based on hyperentanglement exchange, which mainly includes the following steps:

[0061] Step 1: User 1, User 2, User 3, User 4, and User 5 all prepare a large number of identical polarization-space super-entangled states. As shown in Figure 2(a), where p and s represent polarization and spatial degrees of freedom, respectively, the super-entangled photon pairs of user 1 can be divided into the sequence (S1, S2), the photon sequence of user 2 is (S3, S4), the photon sequence of user 3 is (S5, S6), and the photon sequence of user 4 is (S7, S8). The photon sequence of user 5 is (S9, S10). All of the above users randomly insert several single photons prepared in the X basis or Z basis in both degrees of freedom into their respective two photon sequences as security detection photons;

[0062] Step 2: User 1 and User 2 send all photons of sequences S2 and S3 to the measurement end in sequence. At the same time, User 3 and User 4 send all photons of sequences S6 and S7 to the measurement end in sequence. The above users store the photons of sequences S1, S4, S5, and S8 in the quantum memory, and User 5 also stores the photons of sequences S9 and S10 in the quantum memory.

[0063] Step 3: The measuring end performs the first round of super-entangled Bell state measurement (HBSM) on the photons of the S2 and S3 sequences, as well as the S6 and S7 sequences, as shown in Figure 2(b), and announces the measurement results. If one of the two photons undergoing HBSM comes from a super-entangled photon pair and the other is a single photon, the HBSM result and the remaining photons in the super-entangled photon pair are discarded. If both photons of the HBSM are safety photons, the HBSM measurement results are used for security detection. If the security detection fails, it means that the photon transmission process is not safe, and the communication is canceled; if the security detection passes, it means that the photon transmission process is safe;

[0064] Step 4: If both photons of HBSM come from entangled photon pairs, then the corresponding photons of S1 and S4 sequences at user 1 and user 2, and the corresponding photons of S5 and S8 sequences at user 3 and user 4 will construct a super-entangled channel based on the results of HBSM;

[0065] Step 5: Based on the information to be transmitted, User 1 and User 2 encode the super-entangled photon pairs in the S1 and S4 sequences in the polarization degree of freedom, as shown in Figure 2(c). User 3 and User 4 encode the super-entangled photon pairs in the S5 and S8 sequences in the spatial degree of freedom, respectively. User 5 randomly encodes all super-entangled photon pairs in the S9 sequence in two degrees of freedom. At the same time, the above five users do not perform any operations on the security detection photons in all photon sequences;

[0066] Step 6: After the encoding is completed, user 2 sends all photons of the S4 sequence, user 3 sends all photons of the S5 sequence, and user 5 sends all photons of the S9 and S10 sequences to the measurement end at the same time. The measurement end performs a second round of HBSM on the corresponding photons of the S4 and S9 sequences, as well as the corresponding photons of the S5 and S10 sequences, as shown in Figure 2(d), and announces the measurement results. If one of the two photons of HBSM comes from a super-entangled photon pair and the other is a single photon, the result of HBSM and the remaining photons in the super-entangled photon pair are discarded. If both photons of HBSM are security photons, the measurement result of HBSM is used for security detection. If the security detection fails, the communication is terminated. If the security detection passes, the next step is carried out.

[0067] Step 7: If the photons of both HBSMs come from entangled photon pairs, a super-entangled channel is established between the photons corresponding to sequences S1 and S8; User 1 and User 4 send all the photons of sequences S1 and S8 to the measurement end for a third round of HBSM, as shown in Figure 2(e), and publish the measurement results; Similarly, if one of the two photons of HBSM comes from a super-entangled photon pair and the other is a single photon, the HBSM result and the remaining photons in the super-entangled photon pair are discarded; If both photons of HBSM are safety photons, the HBSM measurement result is used for safety detection. If the safety detection fails, the communication is terminated. If the safety detection passes, the next step is carried out;

[0068] Step 8: If the photons of HBSM all come from entangled photon pairs, user 5 can infer the information transmitted by user 1, user 2, user 3, and user 4 based on the results of three rounds of HBSM, and complete multi-party quantum secure direct communication.

[0069] The process of the present invention is analyzed below in conjunction with specific examples:

[0070] The entangled state initially prepared by user 1, user 2, user 3, user 4 and user 5 is in, and Four Bell states belonging to the following polarization and spatial degrees of freedom:

[0071]

[0072]

[0073]

[0074]

[0075] Where H and V represent the horizontal polarization and vertical polarization of the photon, respectively, and a1, a2, a1′, a2′ represent the spatial mode. The randomly prepared single-photon polarization-spatial mode super-encoded quantum state is Among them, δ p and κ s One of four quantum states belonging to polarization and spatial degrees of freedom respectively:

[0076]

[0077]

[0078] If the two safety detection photons have different preparation bases in any degree of freedom, the BSM result of that degree of freedom is discarded. If the two safety detection photons for HBSM have the same preparation base in any degree of freedom, the BSM result of that degree of freedom is used for safety detection. The specific process is as follows:

[0079]

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087] After the first round of HBSM, the measuring party publicly discloses the measurement results. Users 1, 2, 3, and 4 all publicly disclose the basis and position of the inserted single photons. If the HBSM measurement result for any degree of freedom differs from the corresponding photon in the above equation, an error has occurred in that degree of freedom. Users 1, 2, 3, and 4 calculate the bit error rate based on the HBSM results. If the bit error rate is higher than a set threshold, the photon transmission is unsafe and communication is canceled. If the bit error rate for both degrees of freedom is lower than the set threshold, the photon transmission process is safe and communication continues.

[0088] After user 1 and user 2 send the photons of sequence S2 and S3 to the fourth-party measurement terminal for measurement, the quantum state of the system is:

[0089]

[0090]

[0091] Where p represents the polarization degree of freedom, s represents the polarization degree of freedom, and the subscripts 1, 2, 3, and 4 represent the photon sequence numbers. After user 3 and user 4 send the photons of sequence S5, S6, S7, and S8 to the fourth-party measurement end for HBSM, the quantum state of the system is:

[0092]

[0093] Wherein, the subscripts 5, 6, 7, and 8 represent the photon sequence numbers, respectively. According to the HBSM results, user 1 and user 2 establish an entangled channel, and user 3 and user 4 establish an entangled channel.

[0094] User 1 has an invariant operation (I) and a bit flipping operation (σ) on the photons of the S1 sequence under the polarization degree of freedom. xp ), representing classical information 0 and 1 respectively; User 2 has an invariant operation (I) and a phase flip operation (σ) on the photons of the S4 sequence under the polarization degree of freedom. zp ), representing classical information 0 and 1 respectively. At the same time, user 3 has an invariant operation (I) and a bit flip operation (σ) on the photons of the S5 sequence in the spatial degree of freedom. xs ), representing classical information 0 and 1 respectively; User 4 has an invariant operation (I) and a phase flip operation (σ) on the photons of the S8 sequence under the spatial degree of freedom. zs ), representing classical information 0 and 1 respectively. User 5 performs random operations on all photons of the S9 and S10 sequences in two degrees of freedom.

[0095] I p =HH+VV,I s =a1a1+a2a2

[0096] σ zp =HH-VV,σ zs =a1a1-a2a2

[0097] σ xp =VH+HV,σ xs =a1a2+a2a1

[0098] User 5 derives the encoding results of user 1, user 2, user 3, and user 4 based on the three rounds of HBSM measurement results and its own random operation to obtain the secret information transmitted by user 1, user 2, user 3, and user 4.

[0099] The results of the three rounds of HBSM are all public. However, since user 5's random operation on the S9 sequence photons is not disclosed, the measurement end and eavesdroppers cannot infer the coded information of users 1-4 based on the HBSM results, ensuring information security.

[0100] Specific implementation process: User 1 (S1, S2), User 2 (S3, S4), User 3 (S5, S6), User 4 (S7, S8), User 5 (S9, S10) prepare super-entangled states After the first round of photon transmission, the quantum states of user 1 and user 2, and the quantum states of user 3 and user 4 are:

[0101]

[0102]

[0103] Assume that the measurement result of HBSM is Then we can know that the super-entangled state shared by user 1 and user 2 is The super-entangled state shared by users 3 and 4 is If user 1 and user 2 respectively Conduct σ xp and σ zp Operation, the quantum state shared by user 1 and user 2 becomes User 3 and User 4 respectively Conduct σ xs and σ zs Operation, the quantum state shared by user 3 and user 4 becomes User 5 performs an unchanged operation on the two degrees of freedom of the super-entanglement in his hand. After the encoding is completed, the corresponding photons of the sequence S4, S9, S5, S10, S1, and S8 are sent to the measurement end for HBSM; the quantum state of the photons corresponding to the sequence S1, S4, S9, and S10 is:

[0104]

[0105] When the HBSM measurement results are published, it is assumed that the measurement results are Then the quantum state of the photon corresponding to the S1 and S10 sequences is Then the quantum states of the photons corresponding to the S4 and S9 sequences are The quantum state obtained by HBSM is:

[0106]

[0107] Assume that the measurement result is Then the entangled state between user 1 and user 5 can be determined as Then perform HBSM on the corresponding photons of S1 and S8. If the measurement result is User 5 can determine that the quantum states of user 1, user 2, user 3, and user 4 after encoding are User 5 then compares the quantum states of the polarization and spatial degrees of freedom with those before encoding and learns that User 1 performed a bit flip on the polarization degree of freedom, while User 2 performed a phase flip on the spatial degree of freedom. Therefore, User 5 can determine that the information transmitted by User 1 and User 2 is 1, 1, respectively. Similarly, the information transmitted by User 3 and User 4 is 1, 1, respectively.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to further limit the present invention. All equivalent changes made using the contents of the present invention description and drawings are within the scope of protection of the present invention.

Claims

1. A measurement device-independent multi-party quantum secure direct communication method based on hyperentanglement, characterized in that: The following steps are involved: Step 1: User 1, User 2, User 3, User 4, and User 5 all prepare a large number of identical polarization-space super-entangled states. Where p and s represent the polarization degree of freedom and the spatial degree of freedom, respectively. User 1's super-entangled photon pairs are divided into the sequence (S1, S2), user 2's photon sequence is (S3, S4), user 3's photon sequence is (S5, S6), user 4's photon sequence is (S7, S8), and user 5's photon sequence is (S9, S10). All of the above users randomly insert a large number of single photons randomly prepared in the X basis or Z basis in both degrees of freedom into their respective two photon sequences as security detection photons. Step 2: User 1 and User 2 send all photons of sequences S2 and S3 to the measurement end in sequence. At the same time, User 3 and User 4 send all photons of sequences S6 and S7 to the measurement end in sequence. The above users store the photons of sequences S1, S4, S5, and S8 in the quantum memory, and User 5 also stores the photons of sequences S9 and S10 in the quantum memory. Step 3: The measuring end performs the first round of super-entangled Bell state measurement (HBSM) on the photons of the S2 and S3 sequences, as well as the S6 and S7 sequences, and announces the measurement results. If one of the two photons undergoing HBSM comes from a super-entangled photon pair and the other is a single photon, the HBSM result and the remaining photons in the super-entangled photon pair are discarded. If both photons undergoing HBSM come from entangled photon pairs, the corresponding photons of the S1 and S4 sequences belonging to user 1 and user 2, or the photons of the S5 and S8 sequences belonging to user 3 and user 4, will be used to construct a super-entangled channel based on the HBSM results. If both photons undergoing HBSM are safety photons, the HBSM measurement results are used for security testing. If the security test fails, it means that the photon transmission process is unsafe and the communication is canceled. If the safety test passes, it means that the photon transmission process is safe and proceed to the next step; Step 4: Based on the information to be transmitted, User 1 and User 2 encode the super-entangled photon pairs in the S1 and S4 sequences in the polarization degree of freedom, respectively; User 3 and User 4 encode the super-entangled photon pairs in the S5 and S8 sequences in the spatial degree of freedom, respectively; User 5 randomly encodes all super-entangled photon pairs in the S9 and S10 sequences in two degrees of freedom; at the same time, the above five users do not perform any operations on the security detection photons in all photon sequences; Step 5: After the encoding is completed, user 2 sends all photons of the S4 sequence, user 3 sends all photons of the S5 sequence, and user 5 sends all photons of the S9 and S10 sequences to the measurement end at the same time; the measurement end performs a second round of HBSM on the corresponding photons of the S4 and S9 sequences, as well as the corresponding photons of the S5 and S10 sequences, and announces the measurement results; if one of the two photons of the HBSM comes from a super-entangled photon pair and the other is a single photon, the HBSM result and the remaining photons in the super-entangled photon pair are discarded; if the photons of both HBSMs come from entangled photon pairs, the photons corresponding to the S1 and S8 sequences construct a super-entangled channel; if both photons of the HBSM are security photons, the HBSM measurement results are used for security detection. If the security detection fails, the communication is terminated. If the security detection passes, the next step is carried out; Step 6: User 1 and User 4 send all photons of the S1 and S8 sequences respectively to the measurement end for the third round of HBSM and announce the measurement results. Similarly, if one of the two photons of the HBSM comes from a super-entangled photon pair and the other is a single photon, the HBSM result and the remaining photons in the super-entangled photon pair are discarded. If both photons of the HBSM are safety photons, the HBSM measurement result is used for safety testing. If the safety test fails, the communication is terminated. If the safety test passes, the next step is carried out. If the photons of HBSM all come from entangled photon pairs, user 5 can infer the information transmitted by user 1, user 2, user 3, and user 4 based on the results of the previous three rounds of HBSM, and complete multi-party quantum secure direct communication.

2. The method for measurement-device-independent multi-party quantum secure direct communication based on hyperentanglement according to claim 1, characterized in that: Step 1 is specifically as follows: the entangled states initially prepared by user 1, user 2, user 3, user 4 and user 5 are in, and There are four Bell states belonging to the following polarization degrees of freedom and spatial freedom: Where p represents the polarization degree of freedom, s represents the spatial degree of freedom, |H> and |V> represent the horizontal polarization and vertical polarization of the photon, respectively, and |a1>, |a2>, |a1′>, |a2′> represent the spatial mode. The randomly prepared single-photon polarization-spatial mode super-encoded quantum state is Among them, |δ> p and |κ> s One of four quantum states belonging to polarization and spatial degrees of freedom respectively:

3. The method for measurement-device-independent multi-party quantum secure direct communication based on hyperentanglement according to claim 2, characterized in that: The safety check process of steps 3, 5, and 6 is as follows: if the two photons undergoing HBSM have different preparation bases for a certain degree of freedom, the BSM result for that degree of freedom is discarded; if the two photons undergoing HBSM have the same preparation base for a certain degree of freedom, the BSM result for that degree of freedom is used for safety check. The specific process is as follows: If the HBSM obtains a measurement result different from the corresponding term in the above equation in any degree of freedom, it means that an error has occurred in that degree of freedom; user 1, user 2, user 3, and user 4 estimate the bit error rate of the two degrees of freedom based on the results of the HBSM. If the bit error rate of any degree of freedom is higher than the set threshold, it means that the photon transmission is unsafe and the communication is canceled; if the bit error rates of both degrees of freedom are lower than the set threshold, it means that the photon transmission process is safe and communication continues.

4. The method for measurement-device-independent multi-party quantum secure direct communication based on hyperentanglement according to claim 2, characterized in that: The construction process of the super-entangled channel in step 3 is as follows: After user 1 and user 2 send the photons of sequence S2 and S3 to the fourth-party measurement terminal for measurement, the quantum state of the system is: Wherein, the subscripts 1, 2, 3, and 4 represent the photon sequence numbers respectively. After user 3 and user 4 send the photons of sequence S5, S6, S7, and S8 to the fourth-party measurement end for HBSM, the quantum state of the system is: Among them, the subscripts 5, 6, 7, and 8 represent the photon sequence numbers respectively; users 1 and 2, and users 3 and 4 establish super-entangled channels according to the HBSM results respectively.

5. The method for measurement-device-independent multi-party quantum secure direct communication based on hyperentanglement according to claim 2, characterized in that: The specific encoding rules in step 4 are: User 1 has an invariant operation (I) and a bit flipping operation (σ) on the photons of the S1 sequence under the polarization degree of freedom. xp ), representing classical information 0 and 1 respectively; User 2 has an invariant operation (I) and a phase flip operation (σ) on the photons of the S4 sequence under the polarization degree of freedom. zp ), representing classical information 0 and 1 respectively; at the same time, user 3 has an invariant operation (I) and a bit flip operation (σ) on the photons of the S5 sequence in the spatial degree of freedom. xs ), representing classical information 0 and 1 respectively; User 4 has an invariant operation (I) and a phase flip operation (σ) on the photons of the S8 sequence under the spatial degree of freedom. zs ), representing classical information 0 and 1 respectively; User 5 performs random operations on all photons of the S9 and S10 sequences in two degrees of freedom; where, I p =|H> <H|+|V><V|,I s =|a1> <a1|+|a2><a2| σ zp =|H> <H|-|V><V|,σ zs =|a1> <a1|-|a2><a2| σ xp =|V> <H|+|H><V|,σ xs =|a1> <a2|+|a2><a1|。 6. The method for measurement-device-independent multi-party quantum secure direct communication based on hyperentanglement according to claim 2, characterized in that: User 5 derives the encoding results of User 1, User 2, User 3, and User 4 based on the three rounds of HBSM measurement results and its own random operation to obtain the secret information transmitted by User 1, User 2, User 3, and User 4; specifically: After the first round of photon transmission, the quantum states of user 1 and user 2, and the quantum states of user 3 and user 4 are: Assume that the measurement result of HBSM is Then we can know that the super-entangled state shared by user 1 and user 2 is The super-entangled state shared by users 3 and 4 is If user 1 and user 2 respectively Conduct σ xp and σ zp Operation, the quantum state shared by user 1 and user 2 becomes User 3 and User 4 respectively Conduct σ xs and σ zs Operation, the quantum state shared by user 3 and user 4 becomes User 5 performs an unchanged operation on the two degrees of freedom of the super-entanglement in his hand. After the encoding is completed, the corresponding photons of the sequence S4, S9, S5, S10, S1, and S8 are sent to the measurement end for HBSM. The quantum state of the photons corresponding to the sequence S1, S4, S9, and S10 is: When the HBSM measurement results are published, it is assumed that the measurement results are Then the quantum state of the photon corresponding to the S1 and S10 sequences is Then the quantum states of the photons corresponding to the S4 and S9 sequences are The quantum state obtained by HBSM is: Assume that the measurement result is Then the entangled state between user 1 and user 5 is determined to be Then perform HBSM on the corresponding photons of S1 and S8. If the measurement result is User 5 determines that the quantum states of user 1, user 2, user 3, and user 4 after encoding are Therefore, user 5 compares the quantum states of the polarization and spatial degrees of freedom with those before encoding, and knows that user 1 performed a bit flip operation on the polarization degree of freedom, and user 2 performed a phase flip operation on the spatial degree of freedom. From this, user 5 can know that the information transmitted by user 1 and user 2 is 1, 1 respectively; similarly, the information transmitted by user 3 and user 4 is 1, 1 respectively.

7. The method for measurement-device-independent multi-party quantum secure direct communication based on hyperentanglement according to claim 1, characterized in that: The results of the three rounds of HBSM are all public. However, since user 5's random operation on the S9 sequence photons is not disclosed, the measurement end and eavesdroppers cannot infer the encoded information of users 1-4 based on the results of the three rounds of HBSM, ensuring information security.

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