CN106254072A - 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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- CN106254072A CN106254072A CN201610902950.2A CN201610902950A CN106254072A CN 106254072 A CN106254072 A CN 106254072A CN 201610902950 A CN201610902950 A CN 201610902950A CN 106254072 A CN106254072 A CN 106254072A
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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
Abstract
The invention provides a kind of quantum key distribution system and method.Method therein includes: dispensing device sends the three kinds of quantum states belonging to two groups of different measuring bases at random to reception device；Receiving device uses one group of measurement base in two groups of measurement bases to measure the quantum state received at random, obtains measurement result；Each quantum state preparation base information sent is sent to receive device by dispensing device；Receive device and the measurement base information being used the quantum state received is sent to dispensing device；Dispensing device and reception device carry out parameter estimation, obtain the bit error rate；If the bit error rate is more than predetermined threshold value, terminate whole flow process；Otherwise, dispensing device and reception device carry out error correction, privacy is amplified, and obtains key.The application present invention only can need to use three kinds of quantum states can carry out safe quantum key distribution, reduces equipment cost, improves key rate.
Description
Technical field
The present invention relates to quantum information technology field, particularly relate to a kind of quantum key distribution system and method.
Background technology
Flourish along with Internet technology, the importance of communication security grows with each passing day.Under numerous occasions, communication is double
Fang Xiwang carries out secure communication in the case of utilizing common signal channel.Such as, account and password are submitted as user to Web bank
When, user wishes that these information are secrecy in transmittance process, and the most any third party cannot eavesdrop.Currently extensively make
Encryption method be public key encryption algorithm.This type of algorithm algorithm complex based on some mathematical problem, along with sending out of science and technology
Exhibition, their safety is on the hazard.Therefore, we need the encryption method that exploitation is more safe and reliable badly.
Quantum key distribution technology is brand-new cipher key distribution scheme based on quantum mechanics characteristic, is quantum information technology
In one of technology having application prospect most.This technology use common signal channel make between communication two party share safety with secret
Key.In conjunction with the encryption method of one-time pad, shared random key can be used to be encrypted the information in communication, thus protects
Card communication security.The safety of quantum key distribution, based on basic physics theory, is therefore Information theoretical secure.
At present, prior art has been provided for the quantum key distribution system of some commercializations, these system major part bases
In BB84 agreement.System is divided into dispensing device and receives device.In BB84 agreement, the quantum signal source being used for transmitting key is
Single photon, the key information of its required transmission is that coding is in the polarization state (or polarised direction) of single photon.Dispensing device will
Information encodes at four kinds of different quantum states | and 0 >, | 1 >, |+>, | on->.On hardware view, above-mentioned four kinds of quantum states can be by
The different degree of freedom of photon encode realization.Such as, use polarization encoder time, can select in the horizontal direction, vertical direction,
The single photon of the linear polarization in 45 ° and 135 ° directions, as the carrier of quantum information, is in the polarization shape in above-mentioned four kinds of directions
The single photon of state can be used respectively | and 0 >, | 1 >, |+>, |-> wait four quantum states to represent；In like manner, when using phase code,
Four kinds of quantum states can be represented with four phase values between two coherent wave bags of photon | 0 >, | 1 >, |+>, |->.
Wherein, in four kinds of above-mentioned quantum states, | 0 > and | 1 > mutually orthogonal, therefore can form one group and measure base, be referred to as
For directly measuring base (be called for short Z base, lower with), | 0 > state and | 1 > state is two eigenstates of Z base；|+> and |-> the most mutually orthogonal, because of
This can form another group and measure base, referred to as tiltedly measures base (be called for short X base, lower with), |+> state and |-> state is two intrinsics of X base
State.
The above-mentioned relation between four kinds of quantum states is as follows:
In order to transmit classical information, a photon is prepared on four above-mentioned quantum states by BB84 agreement, and arranges every
Coding information representated by individual quantum state.Such as, in BB84 agreement, by the polarization of light, thus photon is encoded, with
Equiprobability random coded is on Z base and X base.Sender randomly generates a string number string being made up of 0,1 bit, when selecting at Z base
Under when encoding, sender is encoded into 0 | 0 >, be encoded into 1 | 1 >；And when selecting to encode under X base, sender
It is encoded into 0 |+>, it is encoded into 1 |->.Then, above-mentioned quantum state is sent to recipient by sender's throughput subchannel,
Recipient uses X base or Z base to measure the quantum state sent from sender with equiprobability；Then, sender and recipient are being reflected
Fixed classical channel is announced the measurement base of selected use when each leisure encodes or measures, thus filters out both sides and select
Identical measures coded data when base encodes or measures, as the key information transmitted.
Therefore, when performing above-mentioned BB84 agreement, dispensing device needs to launch above-mentioned four kinds of quantum states at random.For
This, hardware realizes typically having two kinds of methods: one is to use a laser instrument, and its light emitted is carried out (polarization,
The degree of freedom such as phase place) fast modulation；Another kind is to use four laser instrument (as shown in Figure 1), and transmission one fixed by every laser instrument
Plant quantum state, coordinate a photoswitch to be multiplexed on a channel by four road light.
One important performance characteristic of practical key distribution system is the emission rate of dispensing device.In general, launch
Speed is the highest, and system final key rate is the highest.But, quantum key distribution system of the prior art needs random transmission four kinds
Quantum state.As previously shown, if dispensing device uses the scheme of a laser instrument, the then system modulation rate requirement to modulating part
Higher；If using the scheme of multi-station laser, then system is higher to the rate requirement of number of lasers and photoswitch.Therefore may be used
Knowing, in above two method of the prior art, owing to employing four kinds of quantum states, therefore transmitting terminal is relatively costly, system
Final key rate is relatively low.
Summary of the invention
In view of this, the invention provides a kind of quantum key distribution system and method, thus only need to use three kinds of quantum
State can carry out safe quantum key distribution, reduces equipment cost, improves key rate.
Technical scheme is specifically achieved in that
A kind of quantum key delivering method, the method comprises the steps:
A, it is subordinated in four kinds of quantum states of two groups of different measuring bases arbitrarily select three kinds of quantum states, and in advance to selected
Three kinds of quantum states encode, and in three kinds of selected quantum states, same group of two quantum states measuring base will be belonged to
Corresponding coding is as primary key information, using the coding corresponding to another quantum state as parameter estimation information；
B, dispensing device send described three kinds of quantum states at random to receiving device；
C, reception device use two groups of one group of measurement bases measured in bases to measure the quantum state received at random,
To measurement result；
Each quantum state preparation base information sent is sent to receive device by D, dispensing device；Receive device by right
The measurement base information that the quantum state received is used is sent to dispensing device；
E, dispensing device and reception device carry out parameter estimation, obtain the bit error rate；If the bit error rate is more than predetermined threshold value,
Terminate whole flow process；Otherwise, step F is performed；
F, dispensing device and reception device carry out error correction；
G, dispensing device and reception device carry out privacy amplification, obtain key.
It is also preferred that the left described two groups of different measuring bases are measured base for straight and tiltedly measure base.
It is also preferred that the left selected three kinds of quantum states are:
|0>、|1>、|+>；
Or | 0 >, | 1 >, |->；
Or |+>, |->, | 0 >；
Or |+>, |->, | 1 >.
It is also preferred that the left when three kinds of selected quantum states are: | 0 >, | 1 >, |+> time:
It is encoded into 0 | 0 >, it is encoded into 1 | 1 >；
Using quantum state | 0 >, | 1 > corresponding to coding as primary key information, by quantum state |+> corresponding to coding make
For parameter estimation information.
Additionally providing a kind of quantum key distribution system in the present invention, this system includes: dispensing device and reception device；
Described dispensing device and reception device are connected by transmission channel；
Described dispensing device, for sending, to reception device, the three kinds of quantum states made an appointment at random；It is additionally operable to be sent out
Each quantum state preparation base information sent is sent to receive device；It is additionally operable to according to each quantum state sent and receives
Measurement base information carry out parameter estimation, obtain the bit error rate；When the bit error rate is not more than predetermined threshold value, carries out error correction and carry out hidden
Private amplification, obtains key；
Wherein, the three kinds of quantum states made an appointment described in are to be subordinated in four kinds of quantum states of two groups of different measuring bases arbitrarily
The three kinds of quantum states selected, and in advance three kinds of selected quantum states are encoded, and in three kinds of selected quantum states,
The coding corresponding to two quantum states that will belong to same group of measurement base is as primary key information, by right for another quantum state institute
The coding answered is as parameter estimation information；
Described reception device, is carried out for random one group that uses two groups to measure in the base measurement base quantum state to being received
Measure, obtain measurement result；It is additionally operable to be sent to the measurement base information that the quantum state received is used receive device, and
Carry out parameter estimation according to measurement result and the measurement base information received, obtain the bit error rate；Threshold is preset when the bit error rate is not more than
During value, carry out error correction and carry out privacy amplification, obtaining key.
It is also preferred that the left described dispensing device includes: the first controller, laser instrument and manipulator；
Described reception device includes: single photon detection unit and second controller；
The signal output part of described first controller is connected with laser instrument；The outfan of described laser instrument is with manipulator even
Connect；The outfan of described manipulator is connected with single photon detection unit by transmission channel；Described single photon detection unit defeated
Go out end to be connected with second controller；The synchronizing signal end of described first controller is connected with the synchronizing signal end of second controller；
Described first controller controls laser instrument output single photon by sending control signal；It is additionally operable to be sent out manipulator
Each quantum state preparation base information sent is sent to second controller；It is additionally operable to each quantum state sent according to manipulator
Carry out parameter estimation with the measurement base information received, obtain the bit error rate；When the bit error rate is not more than predetermined threshold value, carry out error correction
And carry out privacy amplification, obtain key；
Described laser instrument is for exporting single photon according to control signal to described manipulator；
Described manipulator for becoming the three kinds of quantum states made an appointment by the single photon Stochastic Modulation received, and will modulate
After quantum state by transmission channel to single photon detection unit, and the quantum state sent is sent to the first control simultaneously
Device processed；
Described single photon detection unit uses two groups of one group of measurement bases measured in base to enter the quantum state received at random
Row is measured, and obtains measurement result, and measurement result and the measurement base information that used the quantum state received are sent to the
Two controllers；
Described second controller, for being sent to the first control by the measurement base information being used the quantum state received
Device, is additionally operable to carry out parameter estimation according to measurement result and the measurement base information received, obtains the bit error rate；When the bit error rate is little
When predetermined threshold value, carry out error correction and carry out privacy amplification, obtaining key.
It is also preferred that the left described dispensing device includes: the first controller, the first laser instrument, second laser, the 3rd laser instrument and
Manipulator；
Described reception device includes: single photon detection unit and second controller；
The signal output part of described first controller is respectively with the first laser instrument, second laser and the 3rd laser instrument even
Connect；The outfan of described first laser instrument, second laser and the 3rd laser instrument is all connected with manipulator；Described manipulator defeated
Go out end to be connected with single photon detection unit by transmission channel；The outfan of described single photon detection unit is with second controller even
Connect；The synchronizing signal end of described first controller is connected with the synchronizing signal end of second controller；
It is defeated that described first controller controls the first laser instrument, second laser or the 3rd laser instrument by transmission control signal
Go out and there is the single photon determining quantum state；Each quantum state preparation base information being additionally operable to be sent by manipulator is sent to
Two controllers；It is additionally operable to each quantum state sent according to manipulator and the measurement base information received and carries out parameter estimation,
Obtain the bit error rate；When the bit error rate is not more than predetermined threshold value, carries out error correction and carry out privacy amplification, obtaining key；
Described first laser instrument, second laser and the 3rd laser instrument export to described manipulator according to control signal respectively
There is the first quantum state, the second quantum state and the single photon of the 3rd quantum state determined；Wherein, described first quantum state, second
Quantum state and the 3rd quantum state are the three kinds of quantum states made an appointment；
Described manipulator is used for randomly choosing a kind of quantum state from three kinds of received quantum states, and by selected
The quantum state sent to single photon detection unit, and is sent to the first control by transmission channel by quantum state simultaneously
Device；
Described single photon detection unit uses two groups of one group of measurement bases measured in base to enter the quantum state received at random
Row is measured, and obtains measurement result, and measurement result and the measurement base information that used the quantum state received are sent to the
Two controllers；
Described second controller, for being sent to the first control by the measurement base information being used the quantum state received
Device, is additionally operable to carry out parameter estimation according to measurement result and the measurement base information received, obtains the bit error rate；When the bit error rate is little
When predetermined threshold value, carry out error correction and carry out privacy amplification, obtaining key.
It is also preferred that the left described manipulator is photoswitch.
It is also preferred that the left described manipulator is electrooptic modulator EOM.
It is also preferred that the left described transmission channel is optical fiber or free space.
As seen from the above technical solution, in the quantum key distribution system and method for the present invention, due to dispensing device only
Three kinds of quantum states need to be used can to transmit key to receiving device without four kinds of quantum states of use, dividing of performance sub-key
Sending out, therefore, compared with prior art, technical scheme only need to use less quantum state can ensure safety
Carry out safe quantum key distribution under premise, such that it is able to be effectively reduced equipment cost, improve key rate.
Accompanying drawing explanation
Fig. 1 is the structural representation of quantum key distribution system of the prior art.
Fig. 2 is the schematic flow sheet of the quantum key delivering method in the embodiment of the present invention.
Fig. 3 is the overall structure schematic diagram of the quantum key distribution system in the embodiment of the present invention.
Fig. 4 is the structural representation of the quantum key distribution system in the specific embodiment one of the present invention.
Fig. 5 is the structural representation of the quantum key distribution system in the specific embodiment two of the present invention.
Detailed description of the invention
For making technical scheme and advantage clearer, below in conjunction with drawings and the specific embodiments, to this
Invention is described in further detail.
Fig. 2 is the schematic flow sheet of the quantum key delivering method in the embodiment of the present invention.As in figure 2 it is shown, the present invention is real
The quantum key delivering method executed in example includes:
Step 21, is subordinated in four kinds of quantum states of two groups of different measuring bases arbitrarily select three kinds of quantum states, and the most right
Three kinds of selected quantum states encode, and in three kinds of selected quantum states, will belong to two of same group of measurement base
Coding corresponding to another quantum state, as primary key information, is believed by the coding corresponding to quantum state as parameter estimation
Breath.
Such as, it is also preferred that the left in a particular embodiment of the present invention, two groups of different measuring bases can first be selected.Described two groups
Different measuring base can be above-mentioned directly measuring base (Z yl) and tiltedly measure base (X yl).Then, can be from above-mentioned Z base and the four of X base
Plant quantum state | 0 >, | 1 >, |+>, | in->, arbitrarily select three kinds of quantum states.
Such as, it is also preferred that the left in a particular embodiment of the present invention, three kinds of selected quantum states can be | 0 >, | 1 >, |+
>, it is also possible to it is: | 0 >, | 1 >, |->, it is also possible to it is: |+>, |->, | 0 >；It may also is that |+>, |->, | 1 >.
For the ease of describing, below will with a kind of selection mode therein (three kinds of i.e. selected quantum states are: | 0 >, | 1
>, |+>) as a example by, technical scheme is carried out clear and detailed introduction.
After have selected three kinds of quantum states, three kinds of selected quantum states can be encoded.
Such as, it is also preferred that the left in a particular embodiment of the present invention, when three kinds of selected quantum states are: | 0 >, | 1 >, |+>
Time, can be encoded into 0 | 0 >, it is encoded into 1 | 1 >.
It addition, in the inventive solutions, same group of two the quantum state institutes measuring base are also belonged to by making an appointment
Corresponding coding is as primary key information, and using the coding corresponding to another quantum state as parameter estimation information.
Such as, it is also preferred that the left in a particular embodiment of the present invention, when three kinds of selected quantum states are: | 0 >, | 1 >, |+>
Time, can be using quantum state | 0 >, | 1 > corresponding to coding as primary key information, and by quantum state |+> corresponding to coding
As parameter estimation information.
Below be all to be by three kinds of selected quantum states: | 0 >, | 1 >, |+> as a example by the description that carries out.When selected
When three kinds of quantum states are other selection mode, can therefore repeat no more by that analogy.
Step 22, dispensing device sends described three kinds of quantum states at random to receiving device.
In the inventive solutions, after have selected above-mentioned three kinds of quantum states, transmitting terminal can use above-mentioned institute
The three kinds of quantum states selected send described three kinds of amounts to receiving device transmission random information, i.e. dispensing device at random to receiving device
Sub-state.
Step 23, receives device and uses one group of measurement base in two groups of measurement bases to survey the quantum state received at random
Amount, obtains measurement result；
Such as, when the two groups of measurement bases used are respectively straight measurement base and tiltedly measure base, receiving device can be random
Use straight measurement base or oblique base of measuring that the quantum state received is measured, obtain corresponding measurement result.
Step 24, each quantum state preparation base information (i.e. basic vector information) sent is sent to receive by dispensing device
Device；Receive device and the measurement base information being used the quantum state received is sent to dispensing device.
Such as, it is also preferred that the left in a particular embodiment of the present invention, when three kinds of selected quantum states are: | 0 >, | 1 >, |+
>, and dispensing device to receive device send quantum state be respectively as follows: | 0 >, |+>, | 1 >, | 0 >, |+>, | 1 >, then in this step
In, dispensing device is sent to receive the measurement base information of device will be respectively as follows: Z base, X base, Z base, Z base, X base, Z base.
Owing to by appointment belongs to the coding corresponding to same group of two quantum states measuring base as primary key
Information, and using the coding corresponding to another quantum state as parameter estimation information, therefore, when three kinds of selected quantum states
For: | 0 >, | 1 >, |+> time, dispensing device and receive device all can be using quantum state | 0 >, | 1 > corresponding to coding as original close
Key information, and using quantum state |+> corresponding to coding as parameter estimation information, be used for carrying out parameter estimation.
Step 25, dispensing device and reception device carry out parameter estimation, obtain the bit error rate；If the bit error rate is more than presetting threshold
Value then terminates whole flow process；Otherwise, step 26 is performed.
In the inventive solutions, due to dispensing device with receive that device is the most known should use which quantum state institute
Corresponding coding is as parameter estimation information, and therefore, dispensing device and reception device all can be carried out according to this parameter estimation information
Parameter estimation, thus obtain the corresponding bit error rate.In the present invention, it is possible to use conventional method for parameter estimation obtains above-mentioned
The bit error rate, does not repeats them here.
After obtaining the above-mentioned bit error rate, i.e. can determine whether that whether this bit error rate is more than predetermined threshold value.If this bit error rate is big
In predetermined threshold value, then explanation error code is too many, it is necessary to abandons obtained key information, therefore will terminate whole flow process.If should
The bit error rate is more than predetermined threshold value, then the explanation bit error rate is within the acceptable range, such that it is able to carry out performing following step 26,
To obtain final key.
Step 26, dispensing device and reception device carry out error correction.
In the inventive solutions, it is possible to use received primary key information is entered by conventional error correction method
Row error correction, thus obtain the key information after error correction, therefore, concrete error correction method does not repeats them here.
Step 27, dispensing device and reception device carry out privacy amplification, obtain key.
In the inventive solutions, it is possible to use the key information after error correction is carried out by conventional privacy amplification method
Privacy is amplified, thus obtains final key, and therefore, concrete privacy amplification method does not repeats them here.
By above-mentioned step 21～27, between dispensing device and reception device, key can be transmitted.
In the inventive solutions, three kinds of quantum states only need to be used without using four kinds of quantum due to dispensing device
State can be to receiving device transmission key, the distribution of performance sub-key, and therefore the present invention only need to use less quantum state i.e.
Safe quantum key distribution can be carried out on the premise of ensureing safety, such that it is able to be effectively reduced equipment cost, improve
Key rate.
It addition, the above-mentioned quantum key delivering method provided according to the present invention, present invention also offers corresponding quantum close
Key dissemination system, specifically refers to Fig. 2.
Fig. 3 is the structural representation of the quantum key distribution system in the embodiment of the present invention.As it is shown on figure 3, the present invention is real
The quantum key distribution system executed in example includes: dispensing device 31 and reception device 32；
Described dispensing device 31 and reception device 32 are connected by transmission channel 33；
Described dispensing device 31, for sending three kinds of quantum states at random to reception device 32；It is additionally operable to each by sent
Individual quantum state preparation base information is sent to receive device 32；It is additionally operable to according to each quantum state sent and the survey received
Amount base information carries out parameter estimation, obtains the bit error rate；When the bit error rate is not more than predetermined threshold value, carries out error correction and carry out privacy and put
Greatly, key is obtained；
Wherein, described three kinds of quantum states are to be subordinated in four kinds of quantum states of two groups of different measuring bases optional three kinds
Quantum state, and in advance three kinds of selected quantum states are encoded, and in three kinds of selected quantum states, will belong to same
Coding corresponding to another quantum state, as primary key information, is made by the coding corresponding to two quantum states of group measurement base
For parameter estimation information；
Described reception device 32, enters the quantum state received for random one group that uses two groups to measure in base measurement base
Row is measured, and obtains measurement result；It is additionally operable to be sent to the measurement base information that the quantum state received is used receive device
31, and carry out parameter estimation according to measurement result and the measurement base information received, obtain the bit error rate；When the bit error rate is not more than pre-
If during threshold value, carry out error correction and carry out privacy amplification, obtaining key.
By above-mentioned quantum key distribution system, dispensing device 31 can use three kinds of quantum states to pass to receiving device 32
Defeated key, the distribution of performance sub-key.
It is also preferred that the left in a particular embodiment of the present invention, described transmission channel 33 is optical fiber or free space.
It addition, in the inventive solutions, can there are ways to realize above-mentioned dispensing device.Below will be with
As a example by two kinds of specific implementations therein, technical scheme is introduced.
Specific embodiment one, dispensing device are only provided with a laser instrument.
Such as, it is also preferred that the left in a particular embodiment of the present invention, Fig. 4 is the quantum in the specific embodiment one of the present invention
The structural representation of key distribution system, as shown in Figure 4, described dispensing device 31 includes: the first controller 311, laser instrument 312
With manipulator 313；Described reception device 32 includes: single photon detection unit 321 and second controller 322；
The signal output part of described first controller 311 is connected with laser instrument 312；The outfan of described laser instrument 312 with
Manipulator 313 connects；The outfan of described manipulator 313 is connected with single photon detection unit 321 by transmission channel 33；Described
The outfan of single photon detection unit 321 is connected with second controller 322；The synchronizing signal end of described first controller 311 with
The synchronizing signal end of second controller 322 connects；
Described first controller 311 exports single photon by sending control signal control laser instrument 312；It is additionally operable to modulate
Each quantum state preparation base information that device 313 is sent is sent to second controller 322；It is additionally operable to according to manipulator 313 institute
Each quantum state and the measurement base information received that send carry out parameter estimation, obtain the bit error rate；When the bit error rate is not more than pre-
If during threshold value, carry out error correction and carry out privacy amplification, obtaining key；
Described laser instrument 312 is for exporting single photon according to control signal to described manipulator 313；
Described manipulator 313 is used for becoming the single photon Stochastic Modulation received the three kinds of quantum states made an appointment, and will
Quantum state after modulation is transferred to single photon detection unit 321 by transmission channel 33, and is sent out by the quantum state sent simultaneously
Give the first controller 311, so that the first controller 311 can know each quantum state and each quantum state sent
The measurement base used；
Wherein, the three kinds of quantum states made an appointment described in are to be subordinated in four kinds of quantum states of two groups of different measuring bases arbitrarily
The three kinds of quantum states selected, and in advance three kinds of selected quantum states are encoded, and in three kinds of selected quantum states,
The coding corresponding to two quantum states that will belong to same group of measurement base is as primary key information, by right for another quantum state institute
The coding answered is as parameter estimation information；
Described single photon detection unit 321 uses two groups of one group of measurement base quantum states to being received measured in base at random
Measure, obtain measurement result, and measurement result and the measurement base information being used the quantum state received are sent to
Second controller 322；
Described second controller 322, for being sent to first by the measurement base information being used the quantum state received
Controller 311, is additionally operable to carry out parameter estimation according to measurement result and the measurement base information received, obtains the bit error rate；When by mistake
When code check is not more than predetermined threshold value, carries out error correction and carry out privacy amplification, obtaining key.
By above-mentioned quantum key distribution system, dispensing device can use three kinds of quantum states close to receiving device transmission
Key, the distribution of performance sub-key.
Specific embodiment two, dispensing device are provided with three laser instrument.
Such as, it is also preferred that the left in a particular embodiment of the present invention, Fig. 5 is the quantum in the specific embodiment two of the present invention
The structural representation of key distribution system, as it is shown in figure 5, described dispensing device 31 includes: first controller the 41, first laser instrument
42, second laser the 43, the 3rd laser instrument 44 and manipulator 45；Described reception device 31 includes: single photon detection unit 321 He
Second controller 322；
The signal output part of described first controller 41 respectively with the first laser instrument 42, second laser 43 and the 3rd laser
Device 44 connects；The outfan of described first laser instrument 42, second laser 43 and the 3rd laser instrument 44 is all connected with manipulator 45；
The outfan of described manipulator 45 is connected with single photon detection unit 321 by transmission channel 33；Described single photon detection unit
The outfan of 321 is connected with second controller 322；The synchronizing signal end of described first controller 41 and second controller 322
Synchronizing signal end connects；
Described first controller 41 controls the first laser instrument 42 by transmission control signal, second laser 43 or the 3rd swashs
Light device 44 output has the single photon determining quantum state；It is additionally operable to each quantum state preparation base letter sent by manipulator 45
Breath is sent to second controller 322；It is additionally operable to each quantum state sent according to manipulator 45 and the measurement base letter received
Breath carries out parameter estimation, obtains the bit error rate；When the bit error rate is not more than predetermined threshold value, carries out error correction and carry out privacy amplification,
To key；
Described first laser instrument 42, second laser 43 and the 3rd laser instrument 44 respectively according to control signal to described modulation
Device 45 output has the first quantum state, the second quantum state and the single photon of the 3rd quantum state determined；Wherein, described first quantum
State, the second quantum state and the 3rd quantum state are the three kinds of quantum states made an appointment；
The described three kinds of quantum states made an appointment are to be subordinated in four kinds of quantum states of two groups of different measuring bases arbitrarily select
Three kinds of quantum states, and in advance three kinds of selected quantum states are encoded, and in three kinds of selected quantum states, will belong to
In the coding corresponding to two quantum states of same group of measurement base as primary key information, corresponding to another quantum state
Coding is as parameter estimation information；
Described manipulator 45 is used for randomly choosing a kind of quantum state from three kinds of received quantum states, and by selected
Quantum state be transferred to single photon detection unit 321 by transmission channel 33, and the quantum state sent is sent to the simultaneously
One controller 41, so that the first controller 41 can know what each quantum state sent and each quantum state were used
Measure base；
Described single photon detection unit 321 uses two groups of one group of measurement base quantum states to being received measured in base at random
Measure, obtain measurement result, and measurement result and the measurement base information being used the quantum state received are sent to
Second controller 322；
Described second controller 322, for being sent to first by the measurement base information being used the quantum state received
Controller 41, is additionally operable to carry out parameter estimation according to measurement result and the measurement base information received, obtains the bit error rate；Work as error code
When rate is not more than predetermined threshold value, carries out error correction and carry out privacy amplification, obtaining key.
It addition, it is also preferred that the left in a particular embodiment of the present invention, described manipulator 45 can be photoswitch.Such as, at this
In one concrete preferred embodiment of invention, when using multi-station laser, then photoswitch can be used as manipulator 45.
Such as, it is also preferred that the left in a particular embodiment of the present invention, described manipulator 45 can be electrooptic modulator (EOM).
Such as, in a concrete preferred embodiment of the present invention, when only using a laser instrument, then EOM can be used as tune
Device 45 processed.
It addition, it is also preferred that the left in a particular embodiment of the present invention, described single photon detection unit 321 also can wrap further
Include: measure base selector and single-photon detector；
Before described measurement base selector is arranged on described single-photon detector；
Described measurement base selector, randomly selects one group of measurement base for measuring from two groups base；
Described single-photon detector, for measuring, according to selected base of measuring, the quantum state received, obtains
Measurement result, and measurement result and the measurement base information being used the quantum state received are sent to second controller 322.
It addition, it is also preferred that the left in a particular embodiment of the present invention, described measurement base selector can be manipulator, such as,
Photoswitch or electrooptic modulator (EOM).This manipulator can come from two groups of measurements by the way of dynamic modulation photon (polarization)
Base randomly selects one group and measures base.
It is also preferred that the left in a particular embodiment of the present invention, described measurement base selector can also be beam splitter (BS).This point
Two outlets of bundle device connect a single-photon detector after can connecing an optical module (such as polaroid) respectively again.Therefore, should
Beam splitter can be measured from two groups in the way of use is passive and randomly select one group of measurement base base.
By above-mentioned quantum key distribution system, dispensing device can use three kinds of quantum states close to receiving device transmission
Key, the distribution of performance sub-key.
In sum, in the inventive solutions, three kinds of quantum states only need to be used without making due to dispensing device
Can be to receiving device transmission key with four kinds of quantum states, the distribution of performance sub-key, therefore, compared with prior art, this
The technical scheme of invention only need to use less quantum state can carry out safe quantum key on the premise of ensureing safety
Distribution, such that it is able to be effectively reduced equipment cost, improves key rate.
It addition, in the inventive solutions, dispensing device can use a laser instrument, it is possible to use three are swashed
Light device, can according to actual application scenarios need select voluntarily.It addition, technical scheme can use polarization to compile
The multiple Physical realization of the quantum states such as code, phase code realizes, and specifically repeats no more.
Additionally, technical scheme is used directly for key distribution system based on single-photon source, it is also possible to knot
Close and inveigle state technology to use for system based on weak coherent light source.
The foregoing is only presently preferred embodiments of the present invention, not in order to limit the present invention, all essences in the present invention
Within god and principle, any modification, equivalent substitution and improvement etc. done, within should be included in the scope of protection of the invention.
Claims (10)
1. a quantum key delivering method, it is characterised in that the method comprises the steps:
A, it is subordinated in four kinds of quantum states of two groups of different measuring bases arbitrarily select three kinds of quantum states, and in advance to selected three
Plant quantum state to encode, and in three kinds of selected quantum states, same group of two the quantum states institutes measuring base are right by belonging to
The coding answered is as primary key information, using the coding corresponding to another quantum state as parameter estimation information；
B, dispensing device send described three kinds of quantum states at random to receiving device；
C, reception device use two groups of one group of measurement bases measured in bases to measure the quantum state received at random, are surveyed
Amount result；
Each quantum state preparation base information sent is sent to receive device by D, dispensing device；Receiving device will be to being connect
The measurement base information that the quantum state received is used is sent to dispensing device；
E, dispensing device and reception device carry out parameter estimation, obtain the bit error rate；If the bit error rate is more than predetermined threshold value, terminate
Whole flow process；Otherwise, step F is performed；
F, dispensing device and reception device carry out error correction；
G, dispensing device and reception device carry out privacy amplification, obtain key.
Method the most according to claim 1, it is characterised in that:
Described two groups of different measuring bases are measured base for straight and tiltedly measure base.
Method the most according to claim 2, it is characterised in that three kinds of selected quantum states are:
|0>、|1>、|+>；
Or | 0 >, | 1 >, |->；
Or |+>, |->, | 0 >；
Or |+>, |->, | 1 >.
Method the most according to claim 3, it is characterised in that when three kinds of selected quantum states are: | 0 >, | 1 >, |+>
Time:
It is encoded into 0 | 0 >, it is encoded into 1 | 1 >；
Using quantum state | 0 >, | 1 > corresponding to coding as primary key information, using quantum state |+> corresponding to coding as ginseng
Number estimated information.
5. a quantum key distribution system, it is characterised in that this system includes: dispensing device and reception device；
Described dispensing device and reception device are connected by transmission channel；
Described dispensing device, for sending, to reception device, the three kinds of quantum states made an appointment at random；It is additionally operable to be sent
Each quantum state preparation base information is sent to receive device；It is additionally operable to according to each quantum state sent and the survey received
Amount base information carries out parameter estimation, obtains the bit error rate；When the bit error rate is not more than predetermined threshold value, carries out error correction and carry out privacy and put
Greatly, key is obtained；
Wherein, the three kinds of quantum states made an appointment described in are to be subordinated in four kinds of quantum states of two groups of different measuring bases arbitrarily select
Three kinds of quantum states, and in advance three kinds of selected quantum states are encoded, and in three kinds of selected quantum states, will belong to
In the coding corresponding to two quantum states of same group of measurement base as primary key information, corresponding to another quantum state
Coding is as parameter estimation information；
Described reception device, surveys the quantum state received for random one group that uses two groups to measure in base measurement base
Amount, obtains measurement result；It is additionally operable to be sent to the measurement base information that the quantum state received is used receive device, and root
Carry out parameter estimation according to measurement result and the measurement base information received, obtain the bit error rate；When the bit error rate is not more than predetermined threshold value
Time, carry out error correction and carry out privacy amplification, obtaining key.
System the most according to claim 5, it is characterised in that
Described dispensing device includes: the first controller, laser instrument and manipulator；
Described reception device includes: single photon detection unit and second controller；
The signal output part of described first controller is connected with laser instrument；The outfan of described laser instrument is connected with manipulator；Institute
The outfan stating manipulator is connected with single photon detection unit by transmission channel；The outfan of described single photon detection unit with
Second controller connects；The synchronizing signal end of described first controller is connected with the synchronizing signal end of second controller；
Described first controller controls laser instrument output single photon by sending control signal；It is additionally operable to be sent manipulator
Each quantum state preparation base information is sent to second controller；It is additionally operable to each quantum state of being sent according to manipulator and connects
The measurement base information received carries out parameter estimation, obtains the bit error rate；When the bit error rate is not more than predetermined threshold value, carries out error correction and go forward side by side
Row privacy is amplified, and obtains key；
Described laser instrument is for exporting single photon according to control signal to described manipulator；
Described manipulator, and will be after modulation for the single photon Stochastic Modulation received becomes three kinds of quantum states making an appointment
The quantum state sent to single photon detection unit, and is sent to the first control by transmission channel by quantum state simultaneously
Device；
Described single photon detection unit uses two groups of one group of measurement bases measured in base to survey the quantum state received at random
Amount, obtains measurement result, and measurement result and the measurement base information being used the quantum state received is sent to the second control
Device processed；
Described second controller, for the measurement base information being used the quantum state received is sent to the first controller,
It is additionally operable to carry out parameter estimation according to measurement result and the measurement base information received, obtains the bit error rate；When the bit error rate is not more than
During predetermined threshold value, carry out error correction and carry out privacy amplification, obtaining key.
System the most according to claim 5, it is characterised in that
Described dispensing device includes: the first controller, the first laser instrument, second laser, the 3rd laser instrument and manipulator；
Described reception device includes: single photon detection unit and second controller；
The signal output part of described first controller is connected with the first laser instrument, second laser and the 3rd laser instrument respectively；Institute
The outfan stating the first laser instrument, second laser and the 3rd laser instrument is all connected with manipulator；The outfan of described manipulator
It is connected with single photon detection unit by transmission channel；The outfan of described single photon detection unit is connected with second controller；
The synchronizing signal end of described first controller is connected with the synchronizing signal end of second controller；
Described first controller controls the first laser instrument, second laser or the 3rd laser instrument output tool by sending control signal
There is the single photon determining quantum state；Each quantum state preparation base information being additionally operable to be sent manipulator is sent to the second control
Device processed；It is additionally operable to each quantum state sent according to manipulator and the measurement base information received and carries out parameter estimation, obtain
The bit error rate；When the bit error rate is not more than predetermined threshold value, carries out error correction and carry out privacy amplification, obtaining key；
Described first laser instrument, second laser and the 3rd laser instrument have to the output of described manipulator according to control signal respectively
The first quantum state, the second quantum state and the single photon of the 3rd quantum state determined；Wherein, described first quantum state, the second quantum
State and the 3rd quantum state are the three kinds of quantum states made an appointment；
Described manipulator is used for randomly choosing a kind of quantum state from three kinds of received quantum states, and by selected quantum
The quantum state sent to single photon detection unit, and is sent to the first controller by transmission channel by state simultaneously；
Described single photon detection unit uses two groups of one group of measurement bases measured in base to survey the quantum state received at random
Amount, obtains measurement result, and measurement result and the measurement base information being used the quantum state received is sent to the second control
Device processed；
Described second controller, for the measurement base information being used the quantum state received is sent to the first controller,
It is additionally operable to carry out parameter estimation according to measurement result and the measurement base information received, obtains the bit error rate；When the bit error rate is not more than
During predetermined threshold value, carry out error correction and carry out privacy amplification, obtaining key.
System the most according to claim 7, it is characterised in that:
Described manipulator is photoswitch.
System the most according to claim 6, it is characterised in that:
Described manipulator is electrooptic modulator EOM.
System the most according to claim 5, it is characterised in that:
Described transmission channel is optical fiber or free space.
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