CN108183793B - Multi-user measuring equipment independent quantum key distribution system and method - Google Patents
Multi-user measuring equipment independent quantum key distribution system and method Download PDFInfo
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- CN108183793B CN108183793B CN201711420061.3A CN201711420061A CN108183793B CN 108183793 B CN108183793 B CN 108183793B CN 201711420061 A CN201711420061 A CN 201711420061A CN 108183793 B CN108183793 B CN 108183793B
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Abstract
The invention discloses a system and a method for distributing quantum keys irrelevant to multi-user measuring equipment, which comprise a plurality of user sides and an intermediate measuring unit; pulse laser emitted by lasers at a plurality of user ends passes through a polarization modulator, is randomly loaded with horizontal, vertical, + 45-degree and-45-degree polarization light pulses, passes through an intensity modulator, is added with decoy state components, and is precisely attenuated into weak coherent laser pulses with the average photon number smaller than 1 by an adjustable attenuator. The middle measuring unit measures signals transmitted by a plurality of user terminals through a quantum channel, different results are output according to the combined polarization quantum states of all the users, the middle measuring unit announces the measuring results, and the plurality of user terminals locally generate keys according to the measuring results. The invention can generate the same key by multiple parties at the same time, is easy to expand, adopts simple structure, uses mature components, is simple to operate and has stable transmission.
Description
Technical Field
The invention relates to the technical field of quantum information and optical communication, in particular to a system and a method for distributing quantum keys irrelevant to multi-user measuring equipment.
Background
Quantum Key Distribution (QKD) is an emerging cipher generation mode developed in the 80 th 20 th century based on Quantum mechanics and information theory, and can enable legal participants at different positions to share keys in an absolutely safe manner, so that the point-to-point Quantum Key Distribution is mature day by day for the present time, the commonly used protocols include BB84 protocol, B92 protocol, EPR protocol and the like, the BB84 protocol proposed by Bennett in 1984 adopts two identical unequal arm M-Z interferometers as an encoder and a decoder, and the encoding mode enables the polarization state of photons to change due to the stretching and bending of optical fibers, so that the work is not stable enough, and the operation is complex. The B92 protocol, simplified on the basis of BB84 in 1992, has a low bit rate despite its simple operation, and only 25% of the resulting bit strings are valid. The EPR protocol needs a perfect entanglement source, and the conversion light path under the currently mainly adopted spontaneous parameter is complex and has high cost. In addition, the CHSH inequality is judged by very fine operation, the requirement on the precision of a device is high, the transmission of an entangled state in an optical fiber faces the problem of loss, and a single-photon detector has noise, dark count and the like, which all have great influence on the final measurement result. The DPS (Differential Phase Shift), the Differential quantum key distribution protocol, first proposed in 2002 transfers key information by using the Phase difference of two consecutive photons, so that the information has continuity, and the two pulses are almost uniformly affected by the outside during the optical fiber transmission, and has stronger anti-interference performance.
For the proposed QKD scheme, attackers also study different attack schemes to attack QKD, which typically include detection efficiency mismatch attack, time shift attack, photon number splitting attack (PNS), and the like, and the schemes cannot solve the attack on the single photon detector end. The protocol for distributing the independent quantum key of the measuring equipment is proposed by Luokuan and others in 2012, can eliminate loopholes caused by imperfection of a single-photon detector, and can utilize a classical device to complete key generation and long-distance safe communication by combining a decoy state protocol. At present, research aiming at a quantum key distribution protocol irrelevant to measuring equipment mainly focuses on the aspects of optimizing performance, improving stability and multiple users. Recent research contents on multiple users are also gradually developed, such as a scheme and a simulation of three-way communication using a GHZ (Greenberger-Horne-Zeilinger) state, and a measurement device independent scheme based on time path entanglement using a W state. The obvious difference between the scheme and the scheme based on the wavelength division multiplexing quantum key distribution is that the quantum key distribution based on the wavelength division multiplexing scheme is essentially point-to-point quantum key distribution, and the scheme of multi-user quantum key distribution can enable participants to simultaneously generate keys, so that each participant can share the same key.
The GHZ state is a typical multi-particle entangled state with the maximum entanglement, and has important potential application in multi-user communication. The GHZ state can be described by the following formula:
in the formula
And &>
Where i =1,2 and 3, respectively, represent state vectors, | H>And | V>Represents respectively a horizontal and a vertical polarization state of a photon>
The indices 0, 1, 2. Cndot. N represent the difference in polarization state of the fourth photon from the remaining photons, representing the normalization constant.
The GHZ state measuring unit proposed by Panama in 1998 can be applied to a measuring device-independent quantum key distribution protocol as a measuring unit to complete measurement and distribution of quantum keys. The scheme provided by the invention realizes multi-user quantum key distribution with higher efficiency and code rate by using a more simplified light path and fewer single photon detectors. By combining with the decoy state protocol, namely detecting whether the eavesdropper Eve exists or not by using pulse signals with different intensities, the scheme provided by the invention can resist attacks such as a detector end and photon number splitting. The quantum key distribution structure irrelevant to the multi-user measuring equipment is complex, the cost is high, the code rate is relatively low, and the stability and the reliability are low.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a quantum key distribution system independent of multi-user measuring equipment, which sends weak coherent laser pulses containing decoy states, wherein the number of photons generated by pulse lasers, intensity modulators, polarization modulators and adjustable attenuators by different users is less than 1, the weak coherent laser pulses are sent to a middle measuring unit, the middle measuring unit measures the polarization states sent by three parties, the middle measuring unit publishes the response condition of a single detector according to the measurement result, and N users immediately generate keys locally according to the response condition.
The invention further aims to provide an irrelevant quantum key distribution method of multi-user measuring equipment, which is an untrusted intermediate measuring unit and can effectively avoid the attack to a single photon detector end.
In order to achieve the above object, the present invention is realized by: a multi-User measuring equipment irrelevant quantum key distribution system comprises N User ends, namely a User-1, a User-2, a User-3 and a middle measuring unit,
the N user terminals are respectively connected with the intermediate measurement unit through quantum channels, wherein:
the N user sides respectively comprise a pulse laser, a polarization modulator, an intensity modulator and an adjustable attenuator, wherein the pulse laser selects the pulse laser in a communication waveband; the polarization modulator can randomly modulate the pulse light into a horizontal polarization state, a vertical polarization state and a + 45-degree or 45-degree polarization state; the intensity modulator is used for generating a decoy state photon, and can be triggered and controlled accurately; the adjustable attenuator can be accurately controlled and attenuates the average photon number of the pulse to a level less than 1;
the intermediate measurement unit comprises a first polarization beam splitter, a second polarization beam splitter, an N-1 polarization beam splitter and N single photon detectors, wherein the first polarization beam splitter, the second polarization beam splitter and the N-1 polarization beam splitter are sequentially connected; the first polarization beam splitter and the second polarization beam splitter are all four-port polarization beam splitters, and can transmit a horizontal polarization state and reflect a vertical polarization state.
The pulse lasers of the N user sides respectively emit pulse lasers, the pulse lasers enter the corresponding polarization modulators, the pulse lasers are respectively randomly modulated into horizontal, vertical, + 45-degree or-45-degree polarization pulse lasers according to randomly generated bits, the polarization pulse lasers are respectively modulated into decoy states through the intensity modulators, the decoy states are attenuated into the pulse lasers with the average photon number smaller than 1 through the adjustable attenuators, and then the pulse lasers are sent to the intermediate measurement unit for detection;
the pulse laser output by N user terminals and smaller than 1 enters a first polarization beam splitter, a second polarization beam splitter, an N-1 polarization beam splitter of the middle measurement unit, the first polarization beam splitter, the second polarization beam splitter, the N-1 polarization beam splitter transform the combined quantum state formed by the horizontal or vertical polarization state input by the multi-user terminal, and the N single photon detectors respond according to the input quantum state:
if the N single-photon detectors all have responses and the basis selected by the N user sides is a Z basis vector formed horizontally or vertically, judging that the polarization states of the pulse laser sent by the N user sides are the same, directly reserving bit positions at the N user sides at the moment, and directly generating a secret key according to the reserved bit positions;
if any N-1 responses exist in the N single-photon detectors, and the basis selected by the N clients is a Z basis vector formed horizontally or vertically, it is determined that m (m < N, m is a positive integer) of the N clients send polarization states different from those sent by the other N-m clients, that is, m of the N clients send horizontal (vertical) polarization states, and the other N-m clients send vertical (horizontal) polarization states. Then m or N-m bits are inverted once (i.e. changing "0" to "1" or changing "1" to "0") to ensure the key of multiple users to be completely consistent, and the obtained bits are the generated key; if the number of the single-photon detectors is less than N-1 or no single-photon detector responds, the communication is regarded as invalid.
Specifically, the coded photon polarization state includes a horizontal polarization state and a vertical polarization state, and the coded polarization state includes a horizontal polarization state, a vertical polarization state, +45 degrees or-45 degrees, and +45 degrees or-45 degrees can be used for detecting the bit error rate, wherein a process of sending out randomly generated bits by a user side is called a coding process, and a process of finally reserving the bits is called a coding process.
Specifically, the bits include "0" and "1", and the inversion of the bit indicates the mutual conversion between "0" and "1".
The N User sides are respectively a User-1 end, a User-2 end, a User-3 end \8230, a User 8230and a User-N end which have the same structure, wherein:
the adjustable attenuator at the User-1 end and the adjustable attenuator at the User-2 end are respectively connected with the first polarization beam splitter, the adjustable attenuator at the User-3 end is connected with the second polarization beam splitter, and so on, and the adjustable attenuator at the second User-N end and the N-1 polarization beam splitter.
The N single-photon detectors are respectively a first single-photon detector, a second single-photon detector, a third single-photon detector, a fourth single-photon detector, a fifth single-photon detector and a sixth single-photon detector, the first single-photon detector is connected with the first polarization beam splitter, the second single-photon detector is connected with the second polarization beam splitter, and so on, the N-2 single-photon detector is connected with the N-2 polarization beam splitter, and the N-1 single-photon detector and the N single-photon detector are both connected with the N-1 polarization beam splitter.
All the polarization beam splitters are four-port polarization beam splitters.
The quantum channel adopts optical fiber or air.
A key distribution and sharing method applying the above-mentioned multi-user measurement device independent quantum key distribution system comprises the following steps:
s1, system initialization: checking hardware facilities of a User-1 end, a User-2 end, a User-3 end and a middle measuring unit, checking whether equipment normally operates or not, and setting initial conditions;
s2, testing the noise level of the system: a series of laser pulses are transmitted at a User-1 end, a User-2 end and a User-3 end, wherein the signal to noise ratio of the test system is SNR =10lg (PS/PN), PS is signal power, and PN is noise power;
s3, optical fiber length testing and pulse delay setting: the method comprises the following steps that a User-1 end, a User-2 end and a User-3 end (User-n) send a group of strong pulses, an intermediate measurement unit determines the length of an optical fiber in a link by measuring the arrival time of the pulses, and the lengths of the optical fibers of the User-1 end, the User-2 end, the User-3 end (User-3) and the User-n are preset according to the length relationship among the User-1 end, the User-2 end, the User-3 end (User-n) and a David end;
s4, quantum information encoding: the laser at the User-1 end, the User-2 end and the User-3 end, which is used as the User-n end, emits pulse laser, the pulse laser is randomly loaded with horizontal, vertical, + 45-degree and-45-degree polarized light pulses through a polarization modulator, decoy state components are added after the pulse laser passes through an intensity modulator, and the pulse laser is modulated into weak coherent laser pulses with the average photon number less than 1 through an adjustable attenuator and is respectively sent to a middle measuring unit;
s5, key screening and code forming: if the N single-photon detectors all have responses, the polarization states of the pulse laser sent by the N user sides are judged to be the same, at the moment, the N user sides respectively directly reserve bit positions, and a secret key is directly generated according to the reserved bit positions;
if any N-1 responses exist in the N single-photon detectors, judging that m (m is less than N, and m is a positive integer) polarization states sent by the user terminals in the N user terminals are different from polarization states sent by other N-m user terminals, carrying out bit reversal on the m user terminals with different sending polarization states or carrying out bit reversal on the other N-m user terminals simultaneously, and obtaining bit positions as generated keys;
if the number of the single-photon detectors is less than N-1 or no single-photon detector responds, the communication is regarded as invalid;
s6, detecting the error rate: QBER = Nerr/Nsift, nsift is the number of the screened data, nerr is the number of code value errors, the numbers of Nsift and Nerr are the results of experimental detection, if QBER >11%, interception is possible, the communication is abandoned, and the communication is restarted.
S7, data coordination and confidentiality amplification: the data coordination is the whole process of correcting errors of the screened data by using a common classical channel, and after the data coordination, the data owned by the User-1, the User-2 and the User-3. The. User-n ends are highly consistent, and the error rate is very low; the confidentiality amplification is a technology for improving the data confidentiality through open communication, an eavesdropper Eve can steal partial data due to data coordination, and in order to improve the data confidentiality, the terminals of the User-1, the User-2 and the User-3 are subjected to confidentiality amplification at the cost of reducing valid information, so that the information obtained by Eve is invalid, and the safety of the valid information is improved.
Preferably, the security keys obtained in step S5 are stored in bits, and a storage prefix is added to each group of security keys, so as to facilitate processing and management of the keys.
Preferably, the storage prefix of the security key adopts the key sending time, so that the key processing and management are convenient.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention has simple structure, less detectors and optical elements, low loss, low cost and more stability.
2. The key distribution method of the invention has high key generation rate.
3. The components adopted by the invention have mature technical schemes, and the scheme is easy to realize.
4. The invention is easy to expand, can be expanded into more users more easily, and only one PBS and one single-photon detector need to be added if one user needs to be added.
Drawings
FIG. 1 is a block diagram of a User-1 end configuration of the present invention;
FIG. 2 is a block diagram of a User-2 end configuration of the present invention;
FIG. 3 is a block diagram of a User-3 end architecture of the present invention;
FIG. 4 is a block diagram of a User-n terminal structure according to the present invention
FIG. 5 is a block diagram of an intermediate measurement unit according to the present invention;
FIG. 6 is a block diagram of the overall operation of the present invention;
fig. 7 is a block diagram of the working principle of the three-user system of the present invention.
Fig. 8 is a flow chart of the operation of the present invention.
Names of the components in the figure correspond to: user-1 end-1'; a first pulse laser-101, a first polarization modulator-102, a first intensity modulator-103, a first adjustable attenuator-104; a User-2 terminal-2', a second pulse laser-201, a second polarization modulator-202, a second intensity modulator-203 and a second adjustable attenuator-204; a User-3 terminal-3', a third pulse laser-301, a third polarization modulator-302, a third intensity modulator-303 and a third adjustable attenuator-304; a User-N end-N', an Nth pulse laser-N01, an Nth polarization modulator-N02, an Nth intensity modulator-N03 and an Nth adjustable attenuator-N04; the intermediate measurement unit 4', a first polarization beam splitter-401, a second polarization beam splitter-402. The N-1 polarization beam splitter-40 (N-1), a first single-photon detector-411, a second single-photon detector-412. The N-single-photon detector-41N.
Detailed Description
The following further describes embodiments of the present invention with reference to the drawings.
Referring to the attached drawings 1-6, the system for distributing the irrelevant quantum key of the multi-User measuring equipment comprises a User-1 end-1 ', a User-2 end-2', a User-3 end-3 '\ 8230 \ 8230, a User-n and a middle measuring unit-4'; wherein:
wherein the structures of the User-1 terminal, the User-2 terminal and the User-3 terminal are completely the same and are all User terminals, namely User terminals, and are used for generating pulse laser to form a secret key.
In this embodiment, the User-1 terminal-1' comprises a first pulse laser-101, a first polarization modulator-102, a first intensity modulator-103 and a first adjustable attenuator-104;
the User-2 terminal-2' comprises a second pulse laser-201, a second polarization modulator-202, a second intensity modulator-203 and a second adjustable attenuator-204;
the User-3 end-3' comprises a third pulse laser-301, a third polarization modulator-302, a third intensity modulator-303 and a third adjustable attenuator-304;
by analogy, the User-N terminal-N' comprises an Nth pulse laser-N01, an Nth polarization modulator-N02, an Nth intensity modulator-N03 and an Nth adjustable attenuator-N04;
the intermediate measurement unit 4', a first polarization beam splitter-401, a second polarization beam splitter-402. Cnth-1 polarization beam splitter-40 (N-1), a first single-photon detector-411, a second single-photon detector-412. Cnth-third single-photon detector-41N.
During the operation of the present invention, the first, second, third, and N- th pulse lasers 101, 201, 301, and N01 at the User-1 and User-2 ends, user-3 ends, respectively, emit pulsed lasers, which are respectively modulated into trap states by the first, second, and third-N- polarization modulators 102, 202, 302-N02 at random levels, respectively, and vertical, + 45-degree or-45-degree polarized pulsed lasers, respectively, and then modulated into trap states by the first, second, and third-N- intensity modulators 103, 203, 303-N03, respectively, and then the trap states are measured by the first, second, and third-N- intensity modulators 104, 204, and N-th attenuators, respectively, and then the average attenuation of the pulses becomes smaller than the average attenuation of the pulses, which is measured by the first, second, and third-N-degree attenuators, 101, 201, and N-01;
the laser pulse with the average photon number less than 1 is transmitted to an intermediate measurement unit-4', and a linear optical device of the intermediate measurement unit, namely a first polarization beam splitter-401, a second polarization beam splitter-402, an N-1 polarization beam splitter-40 (N-1), transforms a combined quantum state formed by horizontal or vertical polarization states input by N users, and then N single photon detectors respond according to the input quantum state.
And announcing a measurement result after measurement by the intermediate measurement unit, and if the N single-photon detectors all respond, indicating that the quantum states emitted by the N users are in the states after being converted by the first polarization beam splitter and the second polarization beam splitter:
(|H>and | V>Represents respectively a horizontal and a vertical polarization state of a photon>
Representing a normalization constant, i.e. the N users transmitting exactly the same polarization state, are all | H>And | V>Polarization, N users generate keys directly.
If N-1 single-photon detectors respond to the N single-photon detectors, the quantum states emitted by the N users are in the states after being converted by the polarization beam splitter:
subscript 1, 2. Cndot. Represents the difference between the polarization state of the second photon and the polarization state of the rest photons), and then the m-square or N-m-square transmitting | H > or | V > performs a bit inversion, and the bit code obtained after the inversion is the generated key.
The following example describes the whole operation process of the present invention in the case where there are three users, as shown in fig. 7.
Three of the users are named as: an Alice end, a Bob end and a Charles end.
In the first case: the first, second and third pulse lasers 101, 201 and 301 respectively emit pulse laser, the pulse laser is respectively modulated into horizontal or vertical polarization pulse laser by the first, second and third polarization modulators 102, 202 and 302 according to randomly generated bits, the decoy state is respectively modulated by the first, second and third intensity modulators 103, 203 and 303, and the pulse laser is attenuated into the pulse laser with the average photon number less than 1 by the first, second and third adjustable attenuators 104, 204 and 304.
The linear optics of the intermediate measurement unit David, namely the first polarization beam splitter-401 and the second polarization beam splitter-402, transform the combined quantum state composed of the horizontal polarization state and the vertical polarization state input by the three parties, and due to the properties that the polarization beam splitters transmit the horizontal polarization and reflect the vertical polarization, when the polarization states sent by the three parties are all horizontal or vertical, the three single-photon detectors of the intermediate measurement unit David all respond, and the three parties directly reserve the bit "0" or "1" as a secret key.
In the second case: the first, second and third pulse lasers 101, 201 and 301 respectively emit pulse lasers, one of the first, second and third polarization modulators 102, 202 and 302 is used for modulating the pulse lasers into horizontal pulse lasers according to randomly generated bits, the other two pulse lasers are modulated into vertical polarization pulse lasers, the pulse lasers are respectively modulated into decoy states through the first, second and third intensity modulators 103, 203 and 303, and the decoy states are attenuated into pulse lasers with the average photon number smaller than 1 through the adjustable attenuator.
Due to the fact that the polarization beam splitter transmits horizontal polarization and reflects vertical polarization, when the polarization states transmitted by the three parties are all horizontal or vertical, only two single photon detectors of the intermediate measurement unit David can respond. Bit inversion is carried out horizontally or vertically in three parties, and then bits are reserved as keys.
As shown in fig. 8, the method is a method for distributing an independent quantum key of a three-user measurement device, where the three users include three user terminals, namely Alice, bob and Charles, and the method includes the following steps:
s1, system initialization: checking hardware facilities of Alice, bob, charles and the intermediate measurement unit David, checking whether the equipment runs normally or not, and setting initial conditions;
s2, testing the noise level of the system: a series of laser pulses are transmitted at Alice, bob and Charles ends, and the signal to noise ratio of a system is tested, wherein SNR =10lg (PS/PN), PS is signal power, and PN is noise power; the noise of the coder-decoder, the channel and the single-photon detector can affect the signal-to-noise ratio of the system during long-distance transmission, and the signal-to-noise ratio is not available even when communication is available due to the fact that the signal-to-noise ratio is required to a certain degree safely;
s3, optical fiber length testing and pulse delay setting: the method comprises the following steps that Alice, bob and Charles ends send a group of strong pulses, an intermediate measurement unit David determines the length of an optical fiber in a link by measuring the arrival time of the pulses, and the length of the optical fiber of each user is preset according to the length relation between each user and the David end; setting the time delay between the upper arm path and the lower arm path and feeding the time delay back to the system initialization;
s4, quantum information encoding: pulse lasers emitted by lasers at an Alice end, a Bob end and a Charles end pass through a polarization modulator, are randomly loaded with horizontal, vertical, + 45-degree and-45-degree polarization light pulses, pass through an intensity modulator, are added with decoy state components, are modulated into weak coherent laser pulses with the average photon number smaller than 1 through an adjustable attenuator, and are respectively sent to a middle measuring unit David;
s5, key screening and code forming: the intermediate measurement unit David declares the measurement result, and it is noted that we may choose to record only the case where the Alice terminal, the Bob terminal, and the Charles terminal send Z basis vectors and the three single-photon detectors respond simultaneously in a short period of time when the key is generated at the beginning, for example, the first 5 minutes when the key is generated at the beginning, and during this period of time, we can be sure that the local keys of Alice, bob, and Charles are substantially the same, and a small string of bits can be reserved after data coordination and confidentiality amplification; in the subsequent key generation, if Alice, bob and Charles send the polarization state of the Z-basis vector and there are three single-photon detector responses, alice, bob and Charles can directly generate the key, and if Alice, bob and Charles send the polarization state of the Z-basis vector and there are two single-photon detector responses, then bit inversion is performed according to the bit string generated at the beginning for a period of time, for example: when the bit is '0', one or two bits of the horizontal polarization state are sent to be inverted, and when the bit is '1', one or two bits of the vertical polarization state are sent to be inverted, so that the bit string can be recycled and can be updated at any time;
s6, detecting the error rate: QBER = Nerr/Nsift, nsift is the number of data after screening, nerr is the number of code value errors, if QBER >11%, the interception is possible, the communication is abandoned, and the communication is restarted;
s7, data coordination and confidentiality amplification: the data coordination is the whole process of correcting errors of the screened data by using a public classical channel, and after the data coordination, the data owned by Alice, bob and Charles are highly consistent, and the error rate is very low; the confidentiality amplification is a technology for improving data confidentiality through open communication, an eavesdropper Eve can steal partial data due to data coordination, and in order to improve the data confidentiality, alice, bob and Charles perform confidentiality amplification at the cost of reducing effective information, so that the information obtained by Eve is invalid, and the safety of the effective information is improved.
And storing the security keys obtained in the step S5 according to bits, and adding a storage prefix in front of each group of security keys. The storage prefix of the secure key can employ a key transmission time.
1. The invention has simple structure, less detectors and optical elements, low loss, low cost and more stability.
2. The key distribution method has high key generation rate, and Z basis vectors sent by Alice, bob and Charles can be used for coding.
3. The components adopted by the invention have mature technical schemes, and the schemes are easy to realize.
4. The invention is easy to expand and can be expanded into more users relatively easily.
Variations and modifications to the above-described embodiments may occur to those skilled in the art, which fall within the scope and spirit of the above description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and modifications and variations of the present invention are also intended to fall within the scope of the appended claims. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (7)
1. A multi-user measurement device independent quantum key distribution system comprises a plurality of user terminals and an intermediate measurement unit,
the plurality of user terminals are respectively connected through quantum channels and an intermediate measurement unit, wherein:
the plurality of user sides comprise pulse lasers, polarization modulators, intensity modulators and adjustable attenuators;
the middle measuring unit comprises a first polarization beam splitter, a second polarization beam splitter, an N-1 polarization beam splitter and N single-photon detectors;
the first polarization beam splitter, the second polarization beam splitter and the N-1 polarization beam splitter are sequentially connected;
the plurality of User sides are respectively a User-1 end, a User-2 end and a User-3 end which have the same structure, wherein:
the adjustable attenuator at the User-1 end and the adjustable attenuator at the User-2 end are respectively connected with a first polarization beam splitter, the adjustable attenuator at the User-3 end is connected with a second polarization beam splitter, and the like, and the adjustable attenuator at the User-N end is connected with the N-1 polarization beam splitter;
the N single-photon detectors are respectively a first single-photon detector, a second single-photon detector, a third single-photon detector and an Nth single-photon detector, the first single-photon detector is connected with the first polarization beam splitter, the second single-photon detector is connected with the second polarization beam splitter, and so on, the N-2 single-photon detector is connected with the N-2 polarization beam splitter, and the N-1 single-photon detector and the Nth single-photon detector are both connected with the N-1 polarization beam splitter;
the pulse lasers of the plurality of user sides respectively emit pulse lasers, the pulse lasers enter the corresponding polarization modulators, the pulse lasers are respectively randomly modulated into horizontal, vertical, + 45-degree or-45-degree polarization pulse lasers according to randomly generated bits, the polarization pulse lasers are respectively modulated into a decoy state and a signal state through the intensity modulator, the pulse lasers are attenuated into pulse lasers with the average photon number smaller than 1 through the adjustable attenuator, and then the pulse lasers are sent to the intermediate measurement unit for detection;
the pulse laser with the average photon number less than 1 output by the plurality of user sides respectively enters the polarization beam splitters corresponding to the middle measurement units, the first polarization beam splitter, the second polarization beam splitter and the N-1 polarization beam splitter transform the combined quantum state formed by the horizontal or vertical polarization states input by the plurality of user sides, and the N single photon detectors respond according to the input quantum states:
when all users select Z basis vectors composed of horizontal and vertical polarization states, if the N single-photon detectors all respond, the polarization states of pulse laser sent by all the users are judged to be the same, at the moment, the N users respectively and directly reserve bit positions, and a secret key is directly generated according to the reserved bit positions;
when all users select a Z basis vector consisting of horizontal and vertical polarization states, if only any N-1 responses exist in the N single-photon detectors, the polarization states sent by m (m is less than N, and m is a positive integer) user terminals in the N user terminals are judged to be different from the polarization states sent by other N-m user terminals, bit reversal is carried out on the m user terminals with different sending polarization states or bit reversal is carried out on the other N-m user terminals, and the obtained bit is a generated secret key;
if the number of the single-photon detectors is less than N-1 or no single-photon detector responds, the communication is regarded as invalid.
2. The multi-user measurement device-independent quantum key distribution system of claim 1, wherein the bits comprise "0" and "1", and wherein an inversion of a bit indicates a reciprocal transformation between a "0" and a "1".
3. The system for distributing the quantum key independent of multi-user measurement equipment according to claim 1, wherein the N-1 polarization beam splitters all use four-port polarization beam splitters.
4. The multi-user measurement device-independent quantum key distribution system of claim 1, wherein the quantum channel employs optical fiber or air.
5. A key distribution and sharing method for applying the multi-user measurement equipment independent quantum key distribution system of claim 3 or 4, characterized by comprising the following steps:
s1, system initialization: checking hardware facilities of a User-1 end, a User-2 end, a User-3 end and a middle measuring unit, checking whether equipment normally operates or not, and setting initial conditions;
s2, testing the noise level of the system: a series of laser pulses are transmitted at a User-1 end, a User-2 end and a User-3 end, and the signal to noise ratio of the test system is SNR =10lg (PS/PN), wherein PS is signal power and PN is noise power;
s3, optical fiber length testing and pulse delay setting: the method comprises the following steps that a User-1 end, a User-2 end and a User-3 end (User-n) send a group of strong pulses, an intermediate measurement unit determines the length of an optical fiber in a link by measuring the arrival time of the pulses, and the lengths of the optical fibers of the User-1 end, the User-2 end, the User-3 end (User-3) and the intermediate measurement unit are preset according to the length relationship among the User-1 end, the User-2 end, the User-3 end (User-n) and the intermediate measurement unit;
s4, quantum information encoding: the method comprises the following steps that pulse lasers emitted by a laser at a User-1 end, a User-2 end and a User-3 end are subjected to polarization pulses of horizontal, vertical, + 45-degree and-45-degree polarization pulses randomly loaded by a polarization modulator, are added with decoy state components after passing through an intensity modulator, are modulated into weak coherent laser pulses with the average photon number smaller than 1 by an adjustable attenuator, and are respectively sent to a middle measuring unit;
s5, key screening and code forming: if the N single-photon detectors all have responses, the polarization states of the pulse laser sent by the N user sides are judged to be the same, at the moment, the N user sides respectively directly reserve bit positions, and a secret key is directly generated according to the reserved bit positions;
if only any N-1 responses exist in the N single-photon detectors, judging that m (m < N, m is a positive integer) polarization states sent by the user terminals in the N user terminals are different from polarization states sent by other N-m user terminals, carrying out bit reversal on the m user terminals with different sending polarization states or carrying out bit reversal on the other N-m user terminals simultaneously, and obtaining bit positions as generated keys;
if the number of the single-photon detectors is smaller than N-1 or no single-photon detector responds, the communication is regarded as invalid;
s6, detecting the error rate: QBER = Nerr/Nsift, nsift is the number of data after screening, nerr is the number of code value errors, and the numbers of Nsift and Nerr are the results of experimental detection; if QBER >11%, it is indicated that the communication may be intercepted, and the communication is abandoned and restarted.
6. The key distribution and sharing method of claim 5, wherein the security keys obtained in step S5 are stored in bits, and each set of security keys is preceded by a storage prefix.
7. The key distribution and sharing method of claim 6, wherein the storage prefix is a key transmission time.
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| CN111555867A (en) * | 2020-04-10 | 2020-08-18 | 中国人民解放军国防科技大学 | Measuring equipment independent quantum key distribution method based on threshold selection technology |
| CN114337845B (en) * | 2021-12-24 | 2023-11-03 | 南京邮电大学 | Measurement equipment independent quantum secret sharing method based on single photon super coding |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104579643A (en) * | 2015-01-04 | 2015-04-29 | 华南师范大学 | Two-node measuring equipment unrelated quantum key distribution system |
| CN105515767A (en) * | 2015-12-31 | 2016-04-20 | 华南师范大学 | DPS-based multi-user QKD network system and key distribution method thereof |
| CN106656494A (en) * | 2017-03-08 | 2017-05-10 | 浙江九州量子信息技术股份有限公司 | Quantum key allocation system and method based on continuous light chopping |
-
2017
- 2017-12-25 CN CN201711420061.3A patent/CN108183793B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104579643A (en) * | 2015-01-04 | 2015-04-29 | 华南师范大学 | Two-node measuring equipment unrelated quantum key distribution system |
| CN105515767A (en) * | 2015-12-31 | 2016-04-20 | 华南师范大学 | DPS-based multi-user QKD network system and key distribution method thereof |
| CN106656494A (en) * | 2017-03-08 | 2017-05-10 | 浙江九州量子信息技术股份有限公司 | Quantum key allocation system and method based on continuous light chopping |
Non-Patent Citations (1)
| Title |
|---|
| 基于指示单光子源的非对称信道量子密钥分配;何业锋等;《光学学报》;20171123(第03期);全文 * |
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