CN108123803A - A kind of quantum key distribution system and method - Google Patents
A kind of quantum key distribution system and method Download PDFInfo
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- CN108123803A CN108123803A CN201810151779.5A CN201810151779A CN108123803A CN 108123803 A CN108123803 A CN 108123803A CN 201810151779 A CN201810151779 A CN 201810151779A CN 108123803 A CN108123803 A CN 108123803A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0852—Quantum cryptography
- H04L9/0858—Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding
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- H—ELECTRICITY
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- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/70—Photonic quantum communication
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0852—Quantum cryptography
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- H—ELECTRICITY
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- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
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Abstract
The present invention provides a kind of quantum key distribution system and methods.System therein includes：Transmitting terminal and receiving terminal；Quantum channel and classical channel are provided between the transmitting terminal and receiving terminal；The transmitting terminal includes：Laser, the first quantum random number generators, signal state and trick state encoder, phase-modulator, the second quantum random number generators, register, first transceiver and the first quantum key maker；The receiving terminal includes：First beam splitter, the second beam splitter, translation device, the 3rd quantum random number generators, the first detector, the second detector, second transceiver and the second quantum key maker.Using the present invention can reduce demand of the whole system for number of signals, improve system into code check, improve the transmission range of quantum key and key generating rate.
Description
Technical field
This application involves quantum communication technical field more particularly to it is a kind of based on inveigle state quantum key distribution system and
Method.
Background technology
The application prospect that quantum key distribution (Quantum Key Distribution, QKD) agreement has this very extensive.
It has been widely used at present is needing high-level safe field, such as National Day military parade, the National People's Congress with
And some banks and government organs.Different from classical communication, the security of quantum key distribution agreement is by quantum-mechanical base
What this law ensured.Wherein, most widely used is exactly BB84 agreements.
The security of quantum key distribution agreement of the prior art is to be based on Heisenberg's uncertainty relationship, specifically,
Exactly will interference inevitably be generated to the signal being transmitted in channel for the eavesdropping operation of channel.If that is,
The information transmitted is ravesdropping, then wrong will be generated in the obtained primary key of communicating pair.Therefore, in an amount
In quantum key distribution system, can according to the middle mistake of key number estimate the information that may be ravesdropping；Then, using
Post processing, i.e. error correction procedure ensure that the key of transmitting terminal and receiving terminal is identical；It then, will using privacy amplifieroperation
The part that may be ravesdropping in primary key is taken out and is discarded, so as to obtain safe key.
But in the system of a practical application, primary key between receiving terminal and transmitting terminal differs, often
It is not due to what eavesdropping generated, but is generated due to the noise in the imperfect of equipment and communication.Therefore, existing skill
In art in common quantum key distribution agreement, it will usually the part being ravesdropping excessively is over-evaluated, so as to cause implementing
Occur, when the bit error rate between transmitting terminal and receiving terminal is more than 11%, can not just generating safe key in the process.It is well known that
The power of the signal transmitted in a fiber will exponentially decay with the increase of distance D；Simultaneously as the presence of ambient noise,
When carrying out the remote transmission of signal, always there are one the moment, the intensity of ambient noise by the intensity with signal be it is similar,
The bit error rate of signal transmission at this time will be very high.Therefore, because there are the limitation of the above-mentioned bit error rate, quantum of the prior art
Key distribution is difficult to transfer signals to far distance.
To solve the above-mentioned problems, a kind of agreement of new quantum key distribution is proposed in the prior art.In the agreement
In, due to the use of new Safety Analysis Method so that the agreement is without the limitation for the bit error rate, even in error code
Rate is close to can also be into code when 50%.
But, it is necessary to which L pulse (the L pulse can be collectively referred to as a signal state) participates in just may be used jointly in the agreement
To generate a primary key.Due to technical reason, the quantity of pulse becomes the most disaster for the system performance for limiting the agreement
Point.Reason is：First, many pulses are relevant simultaneously has very high requirement for the preparation of systematic thinking way；Meanwhile if
The quantity of L is very big, then in terms of detection, can also have very high requirement for delayed transformation device.In addition, when the number of L
When measuring excessive, if the transmission rate of light source is certain, quantity L is in itself for can also there is a kind of linear reduction into code check.
The content of the invention
In view of this, the present invention provides a kind of quantum key distribution system and method, so as to reduce whole system
For the demand of number of signals, improve system into code check, improve the transmission range of quantum key and key generating rate.
What technical scheme was specifically realized in：
A kind of quantum key distribution system, the system include：Transmitting terminal and receiving terminal；
Quantum channel and classical channel are provided between the transmitting terminal and receiving terminal；
The transmitting terminal includes：Laser, the first quantum random number generators, signal state and trick state encoder, phase
Modulator, the second quantum random number generators, register, first transceiver and the first quantum key maker；
The receiving terminal includes：First beam splitter, the second beam splitter, translation device, the 3rd quantum random number generators, first
Detector, the second detector, second transceiver and the second quantum key maker；
The laser is connected with the first input end of signal state and trick state encoder；
First quantum random number generators are respectively with signal state and inveigling the second input terminal of state encoder, the first amount
Sub-key generator is connected with first transceiver；
The first input end of the output terminal and phase-modulator of the signal state and trick state encoder connects；
Second quantum random number generators are connected respectively with the second input terminal and register of phase-modulator；
The output terminal of the phase-modulator is connected by quantum channel with the input terminal of the first beam splitter；
First output terminal of first transceiver is connected by classical channel with second transceiver；The first transceiver
Second output terminal is connected with the register；
The output terminal of the register is connected with the first quantum key maker；
Received pulse is sent to second point by first beam splitter by the first light path and the second light path respectively
Beam device；
The translation device is provided at least one light path in first light path and the second light path；
3rd quantum random number generators are connected with the translation device；
First output terminal of second beam splitter is connected with the first detector；
The second output terminal of second beam splitter is connected with the second detector；
The output terminal of the output terminal of first detector and second detector respectively with second quantum key
Maker connects；
The second quantum key maker is connected with the second transceiver.
Preferably, the translation device is arranged in the first light path.
Preferably, the translation device is arranged in the second light path.
Preferably, the translation device is controllable delay line.
Preferably, the system still further comprises：4th quantum random number generators；
4th quantum random number generators are connected with the laser.
Preferably, the system still further comprises：Random switching device；
The random switching device is connected with the laser, for being turned on and off the laser at random.
The present invention also provides a kind of quantum key delivering methods, and this method comprises the following steps：
Transmitting terminal prepares N number of quantum state being made of L pulse at random, while prepares one first for each quantum state
Random binary number；Wherein, N and L is natural number；
Prepared quantum state is encoded to signal state or trick by transmitting terminal according to the first prepared random binary number
State；Wherein, the total light intensity of L pulse of the signal state is more than the total light intensity of L pulse of the trick state；
Transmitting terminal prepares N number of random binary sequence, include in each random binary sequence L second random two into
Number processed, and the second random binary number in the random binary sequence to each signal state or are inveigled every in state
The phase of one pulse is modulated so that same signal state inveigles L pulsion phase in state for the signal state or to lure
The phase offset for deceiving total phase of state is 0 or π；
Transmitting terminal is by modulated Information State and state is inveigled to issue receiving terminal；
Receiving terminal is each signal state received or state is inveigled to prepare a random number r；Wherein, r ∈ { 1-L, 2-
L ..., -1,1 ..., L-1 }；
Receiving terminal by each the signal state received or inveigles state to pass through the first light path and the using the first beam splitter
Two light paths are sent to the second beam splitter, and translation device is provided at least one light path in first light path and the second light path,
The translation device to the signal state in light path where it or inveigles the pulse in state to translate according to corresponding random number r；
Received pulse is sent respectively to the first detector and the second detector by the second beam splitter；
When the first detector or the second detector measurement are to a photon, record measurement result and measurement result institute is right
Position (i, j) of two pulses answered in pulse train, and the position (i, j) by two current pulses in pulse train
It is sent to transmitting terminal；
Transmitting terminal and receiving terminal generate original quantum key；
Transmitting terminal and receiving terminal carry out error correction and privacy amplifieroperation to primary key respectively, and it is close to obtain final quantum
Key.
Include preferably, the transmitting terminal prepares N number of quantum state being made of L pulse at random：
N number of 3rd random number is generated, and N number of 3rd random number generated is sent to laser.
The laser according to N number of 3rd random number to the total phase of N number of quantum state generated into line displacement, and
Obtain prepared N number of quantum state.
Preferably, the translation device is arranged in the first light path or the second light path.
Preferably, the translation device is controllable delay line.
As seen from the above technical solution, in the agreement of quantum key distribution in the prior art, due to state estimation simultaneously
Inaccurately, so the problem of the information that excessively high estimation may be stolen can be caused.And in the inventive solutions, due to making
It is encoded with trick state, therefore can accurately estimate the information that listener-in Eve may be stolen, without used high estimation
The information that may be stolen so as to substantially reduce demand of the whole system for number of signals L, while also improves entire
Quantum key distribution system into code check, improve the transmission range of quantum key and key generating rate.
Description of the drawings
Fig. 1 is the structure diagram of the quantum key distribution system in the embodiment of the present invention.
Fig. 2 is the flow chart of the quantum key delivering method in the embodiment of the present invention.
Specific embodiment
For technical scheme and advantage is more clearly understood, below in conjunction with drawings and the specific embodiments, to this
Invention is described in further detail.
Fig. 1 is the structure diagram of the quantum key distribution system in the embodiment of the present invention.As shown in Figure 1, the present invention is real
The quantum key distribution system applied in example includes：Transmitting terminal 10 and receiving terminal 20；
Quantum channel 30 and classical channel 40 are provided between the transmitting terminal 10 and receiving terminal 20；
The transmitting terminal 10 includes：Laser 11, the first quantum random number generators 12, signal state and trick state encoder
13rd, phase-modulator 14, the second quantum random number generators 15, register 16, the life of 17 and first quantum key of first transceiver
Grow up to be a useful person 18；
The receiving terminal 20 includes：First beam splitter 21, the second beam splitter 22, translation device 23, the life of the 3rd quantum random number
It grows up to be a useful person the 24, first detector D1, the second detector D2,27 and second quantum key maker 28 of second transceiver；
The laser 11 is connected with the first input end of signal state and trick state encoder 13；
First quantum random number generators 12 with signal state and inveigle the second input terminal of state encoder 13, the respectively
One quantum key maker 18 and first transceiver 17 connect；
The output terminal of the signal state and trick state encoder 13 is connected with the first input end of phase-modulator 14；
Second quantum random number generators 15 connect respectively with the second input terminal of phase-modulator 14 and register 16
It connects；
The output terminal of the phase-modulator 14 is connected by quantum channel 30 with the input terminal of the first beam splitter 21；
First output terminal of the first transceiver 17 is connected by classical channel 40 with second transceiver 27；Described first
The second output terminal of transceiver 17 is connected with the register 16；
The output terminal of the register 16 is connected with the first quantum key maker 18；
First beam splitter 21 sends received pulse by the first light path 211 and the second light path 212 respectively
To the second beam splitter 22；
Described 23 (Fig. 1 of translation device is provided at least one light path in first light path, 211 and second light path 212
Shown in translation device 23 be arranged in the first light path 211)；
3rd quantum random number generators 24 are connected with the translation device 23；
First output terminal of second beam splitter 22 is connected with the first detector D1；
The second output terminal of second beam splitter 22 is connected with the second detector D2；
The output terminal of the output terminal of the first detector D1 and the second detector D2 respectively with second quantum
Key generator 28 connects；
The second quantum key maker 28 is connected with the second transceiver 27.
According to the structure of above-mentioned quantum key distribution system, the laser of transmitting terminal can be given birth to time interval T
Into N number of pulse train, and the pulse train generated is sent to signal state and inveigles state encoder.Wherein, N is natural number,
One pulse train is made of L pulse, therefore can be using a pulse train as a quantum state.
In addition, in the inventive solutions, N and L are natural number.Can according to the needs of practical situations,
Pre-set the value of above-mentioned N and L.Details are not described herein for specific setting method.
In addition, the first quantum random number generators can generate N number of random binary number (for example, value is 0 or 1
Number), and the random binary number generated is sent to signal state and inveigles state encoder, the first quantum key maker and the
One transceiver.Thus, it can be known that the number for the random binary number that the first quantum random number generators are generated is generated with laser
Pulse train number N it is equal.
Signal state and the random binary number for inveigling state encoder that can be generated according to the first quantum random number generators are right
The pulse train (i.e. quantum state) that laser is generated is modulated (coding), so as to generate corresponding signal state or inveigle state.
Wherein, the total light intensity of L pulse of the signal state is more than the total light intensity of L pulse of the trick state.
For example, if n-th (n≤N) a random binary number of the first quantum random number generators generation is 0, will swash
N-th of the pulse train that light device is generated is modulated into trick state；If n-th of the first quantum random number generators generation is random
Binary number is 1, then n-th of the pulse train generated laser is modulated into signal state；Vice versa.It alternatively, can also
It is other modulation systems, this is no longer going to repeat them.
Signal state and trick state encoder by the signal state generated or inveigle state to be sent to phase-modulator.
In addition, the second quantum random number generators can generate N number of random binary sequence, and each random binary sequence
Include L random binary number in row；Then, the second quantum random number generators send out the random binary sequence generated
Give phase-modulator and register.Thus, it can be known that the random binary sequence that the second quantum random number generators are generated
Number is equal with signal state and the total N of trick state that signal state and trick state encoder are generated, each random binary sequence
The number of random binary number in row is equal with the number L of the pulse in a signal state or trick state.
The random binary sequence that phase-modulator can be generated according to the second quantum random number generators, to signal state and
The signal state or the phase of each pulse in state is inveigled to be modulated that state encoder is generated are inveigled, so as to each signal state
Or each pulse in state is inveigled to be encoded.
If for example, l (l in n-th (n≤N) a random binary sequence of the second quantum random number generators generation
≤ L) a random binary number is 0, then by signal state and inveigle n-th of quantum state that state encoder generated (i.e. signal state or
Inveigle state) in l-th of pulse phase be modulated to compared with total phase of the quantum state offset be 0 (i.e. l-th of arteries and veins
0) phase offset of punching is；If in n-th (n≤N) a random binary sequence of the second quantum random number generators generation
L (l≤L) a random binary number is 1, then by signal state and n-th of quantum state (i.e. signal that state encoder is inveigled to be generated
State or inveigle state) in l-th of pulse phase be modulated to compared with total phase of the quantum state offset be π (i.e. l
The phase offset of a pulse is π)；Vice versa.Or or other modulation system, this is no longer going to repeat them.
Pass through above-mentioned phase-modulation, you can complete to each signal state or inveigle the coding of each pulse in state.Example
Such as, in the inventive solutions, transmitting terminal and receiving terminal can arrange coding mode in advance.For example, can arrange in advance,
The pulse that phase offset is 0 is considered as and is encoded to 0, the pulse that phase offset is π is considered as and is encoded to 1；Vice versa.Alternatively,
Can also be other coding modes, this is no longer going to repeat them.
Signal state after coding or trick state are sent to the first beam splitter (Beam of receiving terminal by phase-modulator
Splitter)。
First beam splitter is by received signal state or state is inveigled to be sent to respectively by the first light path and the second light path
Second beam splitter；
In addition, the 3rd quantum random number generators can be each signal state that the first beam splitter receives or inveigle state
A random number r is prepared, and the random number r generated is sent to translation device；Wherein, r ∈ 1-L, 2-L ..., -1,1 ...,
L-1 }, i.e., the value of r is one in above-mentioned (2L-2) a value；Wherein, L is a pulse train (i.e. signal state or trick state)
In pulse number.Moreover, each random number r corresponds respectively to the pulse train that the first beam splitter receives.Also
It is to say, the number for the pulse train that the number of the random number that the 3rd quantum random number generators are generated is received with the first beam splitter
Mesh is equal.For example, when the first beam splitter receives N number of pulse train including L pulse, the 3rd quantum random number generators
N number of random number r will be generated.
The translation device can be arranged at least one light path in first light path and the second light path.For example, institute
(as shown in Figure 1) can be arranged in the first light path by stating translation device, can also be arranged on (not shown) in the second light path；
One translation device (not shown) can be all set in the first light path and the second light path.
The translation device to the signal state in light path where it or inveigles the pulse in state to translate according to random number r.
For example, if random number r is more than 0, by the signal state in light path where it or the pulse in state is inveigled to put down backward
Move rT durations (postponing rT durations)；If random number r is less than 0, by the signal state in light path where it or inveigle in state
Pulse translates forward rT durations, and (its effect also corresponds to the pulse in another light path translating rT durations backward, that is, postpones rT
Duration).Wherein, T is the time interval that laser sends pulse train, i.e. time slot between adjacent pulse sequence.
For example, preferably, in a specific embodiment of the present invention, the translation device can be controllable delay line, so as to come
Realize above-mentioned translation.
For example, when needing backward to translate the pulse in a light path, then the controllable delay line is linked into the pulse
In the light path at place.
Similarly, when need by pulse translates forward in a light path when, then the controllable delay line is linked into another light
On the road.
Received pulse is sent respectively to the first detector D1 and the second detector D2 by the second beam splitter.
For example, the pulse received from the first light path 211 is sent respectively to the first detector D1 and by the second beam splitter
The pulse received from the second light path 212 is also sent respectively to the first detector D1 and the second detector D2 by two detector D2.
When the first beam splitter receives pulse train (i.e. a quantum state), L pulse in the pulse train will divide
The second beam splitter is not sent to by the first light path and the second light path.
Due to being provided with translation device at least one light path in the first light path and the second light path, and pass through translation device pair
A light path in two light paths is postponed so that the same pulse of the second beam splitter is arrived separately at by two light paths
Two pulses (for example, i-th of pulse and j-th of pulse, wherein, 0≤j=i+r≤L-1) in sequence are at the second beam splitter
It interferes, then can be measured by the first detector D1 and the second detector D2.
It for example, in the inventive solutions, can be preset so that sent out when two at the second beam splitter
When phase difference between the pulse of raw interference is 0, the first detector D1 will detect photon, and when two at the second beam splitter
When phase difference between the pulse interfered is π, the second detector D2 will detect photon；Vice versa.
When the first detector D1 or the second detector D2 measure a photon, you can measurement result (is detected
One photon) and measurement result corresponding to be sent to the second quantum close for position (i, j) of two pulses in pulse train
Key maker.
For example, (it can be described as a successful probe when the first detector D1 or the second detector D2 detect a photon
Event), the position (i, j) of measurement result and two current pulses in pulse train is recorded, and measurement result (is examined
Measure a photon) and position (i, j) of the two current pulses in pulse train be sent to the second quantum key maker.
Then, position (i, j) of two pulses in pulse train can be sent to by the second quantum key maker
Two transceivers, second transceiver by the position (i, j) received by classical channel 40 (i.e. the communication channel of non-quantum channel,
For example, communication channel commonly used in the prior art etc.) first transceiver that end occurs is sent to, and first transceiver will then receive
The position (i, j) arrived is sent to register, and register again gives birth to the position (i, j) received and the second quantum random number generators
Into random binary sequence be sent to the first quantum key maker.
In addition, the random binary number that the first quantum random number generators generate can also be passed through classics by first transceiver
Channel 40 is sent to second transceiver, and the random binary number that second transceiver generates the first quantum random number generators is sent
To the second quantum key maker.
At this point, the first quantum key maker and the second quantum key maker would know that the first quantum random number generates
Position (i, j) of two pulses in pulse train corresponding to the random binary number and measurement result of device generation, and root
Original quantum key is obtained according to above- mentioned information.
For example, in the inventive solutions, transmitting terminal and receiving terminal can arrange original quantum key in advance
Coding mode.
For example, can arrange in advance, if the first detector D1 detects photon, the corresponding volume of successful probe event
Code is 0；If the second detector D1 detects photon, successful probe event is corresponding is encoded to 1 for this；Vice versa.Alternatively,
Can also be other coding modes, this is no longer going to repeat them.
Then, the first quantum key maker and the second quantum key maker to obtained original quantum key into
The operations such as row error correction and privacy amplifieroperation, obtain final quantum key.
In addition, in the inventive solutions, due to the first quantum random number generators, the second quantum in the application
Random number generator and the 3rd quantum random number generators are quantum random number generators, therefore the random number produced is
Quantum random number, i.e. true random number.
In addition, in the inventive solutions, the total phase for the quantum state (i.e. pulse train) that laser is produced can
To be random or constant.
For example, preferably, in one particular embodiment of the present invention, above-mentioned quantum key distribution system can also be into
One step includes：4th quantum random number generators (not shown)；
4th quantum random number generators are connected with the laser.
4th quantum random number generators can generate N number of random number, and the random number generated is sent to institute
Laser is stated, to carry out total phase randomization；Thus, it can be known that the number for the random number that the 4th quantum random number generators are generated
It is equal with the number N of the pulse train of laser generation.
The laser can be according to the random number that the 4th quantum random number generators generate to the quantum that is produced
The quantum state for deviating total phase is sent to signal state and inveigles state coding by total phase of state (i.e. pulse train) into line displacement
Device.
In this specific embodiment, the value range for the random number that the 4th quantum random number generators are generated does not limit
To be only 0 or 1, and it can be the random number of arbitrary value.At this point, the quantum state (i.e. pulse train) that laser is produced
Total phase is completely random.
For example, preferably, in one particular embodiment of the present invention, above-mentioned quantum key distribution system can also be into
One step includes：Random switching device (not shown)；
The random switching device is connected with the laser, and the random switching device is described sharp for being turned on and off at random
Light device.
Due in addition to stimulated radiation, also having spontaneous radiation in laser.Wherein, stimulated radiation is controllable, still
Spontaneous radiation is uncontrollable, random.So the laser is randomly turned on and off by above-mentioned random switching device,
The total phase that can cause quantum state (i.e. pulse train) caused by moment that the laser operated in open and close be also completely with
Machine.
In addition, according to above-mentioned quantum key distribution system, a kind of quantum key delivering method is also proposed in of the invention.
Fig. 2 is the flow chart of the quantum key delivering method in the embodiment of the present invention.As shown in Fig. 2, the embodiment of the present invention
In quantum key delivering method can include step as described below：
Step 301, transmitting terminal prepares N number of quantum state being made of L pulse at random, while is prepared for each quantum state
One the first random binary number.
In the inventive solutions, transmitting terminal can generate N number of pulse train, and each arteries and veins at random using laser
Sequence is rushed all to be made of L pulse, therefore can be using a pulse train as a quantum state.It in addition, can also be simultaneously
First random binary number is prepared for each quantum state.For example, N can be generated by the first quantum random number generators
A first random binary number (for example, value is 0 or 1 number).
In addition, in the inventive solutions, N and L are natural number.Can according to the needs of practical situations,
Pre-set the value of above-mentioned N and L.Details are not described herein for specific setting method.
In addition, preferably, in one particular embodiment of the present invention, the transmitting terminal prepares N number of by L pulse at random
The quantum state of composition can include the steps：
Step 41, N number of 3rd random number is generated, and the random number generated is sent to laser.
For example, in the preferred embodiment of the present invention, can be generated by the 4th above-mentioned quantum random number
Device generates N number of 3rd random number, and N number of 3rd random number generated is sent to laser.
Step 42, the laser is carried out according to total phase of N number of quantum state of N number of 3rd random number to being generated
Offset, and obtain prepared N number of quantum state.
Since N number of 3rd random number generated and N number of quantum state that laser is generated correspond, it is described
Laser can according to N number of 3rd random number to the total phase of N number of quantum state generated into line displacement, and obtain made
Standby N number of quantum state.
Through the above steps 41~42, you can generate the quantum state of total phase completely random.
Step 302, prepared quantum state is encoded to signal by transmitting terminal according to the first prepared random binary number
State inveigles state；Wherein, the total light intensity of L pulse of the signal state is more than the total light intensity of L pulse of the trick state.
Due in above-mentioned step 301, transmitting terminal has been prepared for quantum state and the first random binary number, therefore
In this step, by signal state and state encoder can be inveigled and according to the first prepared random binary number to prepared
Quantum state performs the encoding operation, and quantum state is encoded to signal state or inveigles state.
For example, if a first random binary numbers of n-th (n≤N) are 0, n-th of quantum state is encoded into trick state
(such as so that the total light intensity of L pulse in the quantum state is mu)；It, will if n-th of first random binary numbers are 1
N-th of quantum state be encoded into signal state (such as so that the total light intensity of L pulse in the quantum state be nu)；Vice versa.Or
Person or other modulation systems, this is no longer going to repeat them.
In addition, if set inveigle state in L pulse total light intensity as mu, the total light intensity of L pulse in signal state is
Mu, then mu ＞ nu.
Step 303, transmitting terminal prepares N number of random binary sequence, includes L second in each random binary sequence
Random binary number, and the second random binary number in the random binary sequence, to each signal state or trick
The phase of each pulse in state is modulated so that same signal state inveigles L pulsion phase in state for the letter
Number state or the phase offset of total phase for inveigling state are 0 or π.
For example, specifically, preferably, in one particular embodiment of the present invention, such a way pair can be passed through
Each pulse in L pulse in same signal state or trick state carries out phase-modulation：
It, will if a second random binary numbers of l (l≤L) in n-th (n≤N) a random binary sequence are 0
The phase of l-th of pulse in n-th of quantum state (i.e. signal state or trick state) that signal state and trick state encoder are generated
It is 0 (i.e. the phase offset of l-th of pulse is 0) to be modulated to compared with the offset of total phase of the quantum state；
It, will if a second random binary numbers of l (l≤L) in n-th (n≤N) a random binary sequence are 1
The phase of l-th of pulse in n-th of quantum state (i.e. signal state or trick state) that signal state and trick state encoder are generated
It is π to be modulated to compared with the offset of total phase of the quantum state (i.e. the phase offset of l-th of pulse is π)；Vice versa.Or
Person or other modulation systems, this is no longer going to repeat them.
Pass through above-mentioned phase-modulation, you can complete to each signal state or inveigle the coding of each pulse in state.Example
Such as, in the inventive solutions, transmitting terminal and receiving terminal can arrange coding mode in advance.For example, can arrange in advance,
The pulse that phase offset is 0 is considered as and is encoded to 0, the pulse that phase offset is π is considered as and is encoded to 1；Vice versa.Alternatively,
Can also be other coding modes, this is no longer going to repeat them.
Step 304, transmitting terminal by modulated Information State and inveigles state to issue receiving terminal.
In addition, in the inventive solutions, transmitting terminal can also pass through the first prepared random binary number
Classical channel is sent to receiving terminal.
For example, in one particular embodiment of the present invention, transmitting terminal can will be made by above-mentioned first transceiver
The first standby random binary number is sent to the second transceiver of receiving terminal by classical channel.
Step 305, receiving terminal is each signal state received or state is inveigled to prepare a random number r.
In this step, receiving terminal will receive modulated signal state and the trick state that transmitting terminal is sent, and to be received
To each signal state or inveigle state prepare a random number r.
For example, if receiving terminal receives N number of quantum state (i.e. signal state or trick state), each quantum state includes L
Pulse, then receiving terminal will be each signal state or state is inveigled to prepare a random number r, that is, prepare N number of random number r.Wherein,
R ∈ 1-L, 2-L ..., and -1,1 ..., L-1 }, i.e., the value of r is one in above-mentioned (2L-2) a value.
Step 306, receiving terminal by each the signal state received or inveigles state by first using the first beam splitter
Light path and the second light path are sent to the second beam splitter, are provided at least one light path in first light path and the second light path
Translation device, the translation device to the signal state in light path where it or inveigle the pulse in state to carry out according to corresponding random number r
Translation.
For example, in a preferred embodiment of the present invention, if with the signal state in light path where it or inveigling in state
The corresponding random number r of pulse be more than 0, then the pulse is translated into rT durations (postpone rT durations) backward；
If random number r corresponding with the signal state in light path where it or the pulse in trick state is less than 0, by the arteries and veins
Rushing ahead, (its effect also corresponds to the pulse in another light path translating rT durations backward translation rT durations, that is, when postponing rT
It is long).
Wherein, T is the time interval that laser sends pulse train, i.e. time slot between adjacent pulse sequence.
Step 307, receiving terminal using the second beam splitter by received pulse be sent respectively to the first detector D1 and
Second detector D2.
For example, the pulse received from the first light path 211 is sent respectively to the first detector D1 and by the second beam splitter
The pulse received from the second light path 212 is also sent respectively to the first detector D1 and the second detector D2 by two detector D2.
Step 308, when the first detector D1 or the second detector D2 measure a photon, record measurement result and
Position (i, j) of two pulses in pulse train corresponding to measurement result, and by two current pulses in pulse train
In position (i, j) be sent to transmitting terminal.
For example, (it can be described as a successful probe when the first detector D1 or the second detector D2 detect a photon
Event), record the position (i, j) of measurement result and two current pulses in pulse train, and by two current arteries and veins
The position (i, j) being punched in pulse train is sent to transmitting terminal by classical channel.
Step 309, transmitting terminal and receiving terminal generate original quantum key.
In the inventive solutions, since transmitting terminal and receiving terminal would know that the first random binary number and survey
Position (i, j) of two pulses corresponding to result in pulse train is measured, therefore transmitting terminal and receiving terminal can be according to above-mentioned
Information obtains original quantum key.
For example, in the inventive solutions, transmitting terminal and receiving terminal can arrange original quantum key in advance
Coding mode.
For example, can arrange in advance, if the first detector D1 detects photon, the corresponding volume of successful probe event
Code is 0；If the second detector D1 detects photon, successful probe event is corresponding is encoded to 1 for this；Vice versa.Alternatively,
Can also be other coding modes, this is no longer going to repeat them.
Step 310, transmitting terminal and receiving terminal carry out error correction and privacy amplifieroperation to primary key respectively, obtain final
Quantum key.
In this step, transmitting terminal and receiving terminal can be by methods commonly used in the prior art, respectively to primary key
Error correction and privacy amplifieroperation are carried out, obtains final quantum key.
Through the above steps 301~310, you can obtain the quantum key of final safety.
In conclusion in the agreement of quantum key distribution in the prior art, due to the estimation of state and inaccurate, so
The problem of information that can cause excessively high estimation that may be stolen.And in the inventive solutions, due to the use of trick state
It is encoded, therefore can accurately estimate the information that listener-in Eve may be stolen, may be stolen without used high estimation
Information, so as to substantially reduce demand of the whole system for number of signals L, while also improve entire quantum key point
Hair system into code check, improve the transmission range of quantum key and key generating rate.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all essences in the present invention
God and any modification, equivalent substitution, improvement and etc. within principle, done, should be included within the scope of protection of the invention.
Claims (10)
1. a kind of quantum key distribution system, which is characterized in that the system includes：Transmitting terminal and receiving terminal；
Quantum channel and classical channel are provided between the transmitting terminal and receiving terminal；
The transmitting terminal includes：Laser, the first quantum random number generators, signal state and trick state encoder, phase-modulation
Device, the second quantum random number generators, register, first transceiver and the first quantum key maker；
The receiving terminal includes：First beam splitter, the second beam splitter, translation device, the 3rd quantum random number generators, the first detection
Device, the second detector, second transceiver and the second quantum key maker；
The laser is connected with the first input end of signal state and trick state encoder；
First quantum random number generators are close with the second input terminal, the first quantum of signal state and trick state encoder respectively
Key maker is connected with first transceiver；
The first input end of the output terminal and phase-modulator of the signal state and trick state encoder connects；
Second quantum random number generators are connected respectively with the second input terminal and register of phase-modulator；
The output terminal of the phase-modulator is connected by quantum channel with the input terminal of the first beam splitter；
First output terminal of first transceiver is connected by classical channel with second transceiver；The second of the first transceiver
Output terminal is connected with the register；
The output terminal of the register is connected with the first quantum key maker；
Received pulse is sent to the second beam splitter by first beam splitter by the first light path and the second light path respectively；
The translation device is provided at least one light path in first light path and the second light path；
3rd quantum random number generators are connected with the translation device；
First output terminal of second beam splitter is connected with the first detector；
The second output terminal of second beam splitter is connected with the second detector；
The output terminal of the output terminal of first detector and second detector generates respectively with second quantum key
Device connects；
The second quantum key maker is connected with the second transceiver.
2. system according to claim 1, it is characterised in that：
The translation device is arranged in the first light path.
3. system according to claim 1, it is characterised in that：
The translation device is arranged in the second light path.
4. system according to claim 1, it is characterised in that：
The translation device is controllable delay line.
5. system according to claim 1, which is characterized in that the system still further comprises：4th quantum random number
Maker；
4th quantum random number generators are connected with the laser.
6. system according to claim 1, which is characterized in that the system still further comprises：Random switching device；
The random switching device is connected with the laser, for being turned on and off the laser at random.
7. a kind of quantum key delivering method, which is characterized in that this method comprises the following steps：
Transmitting terminal prepares N number of quantum state being made of L pulse at random, while prepares one first at random for each quantum state
Binary number；Wherein, N and L is natural number；
Prepared quantum state is encoded to signal state or inveigles state by transmitting terminal according to the first prepared random binary number；
Wherein, the total light intensity of L pulse of the signal state is more than the total light intensity of L pulse of the trick state；
Transmitting terminal prepares N number of random binary sequence, includes L the second random binaries in each random binary sequence
Number, and the second random binary number in the random binary sequence to each signal state or are inveigled each in state
The phase of a pulse is modulated so that same signal state inveigles L pulsion phase in state for the signal state or trick
The phase offset of total phase of state is 0 or π；
Transmitting terminal is by modulated Information State and state is inveigled to issue receiving terminal；
Receiving terminal is each signal state received or state is inveigled to prepare a random number r；Wherein, r ∈ 1-L, 2-L ... ,-
1,1 ..., L-1 }；
Receiving terminal by each the signal state received or inveigles state to pass through the first light path and the second light using the first beam splitter
Road is sent to the second beam splitter, and translation device is provided at least one light path in first light path and the second light path, described
Translation device to the signal state in light path where it or inveigles the pulse in state to translate according to corresponding random number r；
Received pulse is sent respectively to the first detector and the second detector by the second beam splitter；
When the first detector or the second detector measurement are to a photon, record corresponding to measurement result and measurement result
Position (i, j) of two pulses in pulse train, and position (i, j) of the two current pulses in pulse train is sent
To transmitting terminal；
Transmitting terminal and receiving terminal generate original quantum key；
Transmitting terminal and receiving terminal carry out error correction and privacy amplifieroperation to primary key respectively, obtain final quantum key.
8. the method according to the description of claim 7 is characterized in that the transmitting terminal prepares N number of be made of L pulse at random
Quantum state includes：
N number of 3rd random number is generated, and N number of 3rd random number generated is sent to laser.
The laser according to N number of 3rd random number to the total phase of N number of quantum state generated into line displacement, and obtain
Prepared N number of quantum state.
9. the method according to the description of claim 7 is characterized in that
The translation device is arranged in the first light path or the second light path.
10. according to the method described in claim 7, it is characterized in that：
The translation device is controllable delay line.
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