CN114793158A - Method for realizing sharing of continuous variable quantum key by partially-depicted entanglement source - Google Patents
Method for realizing sharing of continuous variable quantum key by partially-depicted entanglement source Download PDFInfo
- Publication number
- CN114793158A CN114793158A CN202210353414.7A CN202210353414A CN114793158A CN 114793158 A CN114793158 A CN 114793158A CN 202210353414 A CN202210353414 A CN 202210353414A CN 114793158 A CN114793158 A CN 114793158A
- Authority
- CN
- China
- Prior art keywords
- light
- entanglement
- phase
- optical fiber
- measurement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000005259 measurement Methods 0.000 claims abstract description 64
- 238000009826 distribution Methods 0.000 claims abstract description 15
- 230000005540 biological transmission Effects 0.000 claims abstract description 11
- 238000001514 detection method Methods 0.000 claims abstract description 10
- 239000000835 fiber Substances 0.000 claims abstract description 10
- 239000013307 optical fiber Substances 0.000 claims description 48
- 229920000181 Ethylene propylene rubber Polymers 0.000 claims description 38
- ZPUCINDJVBIVPJ-LJISPDSOSA-N cocaine Chemical compound O([C@H]1C[C@@H]2CC[C@@H](N2C)[C@H]1C(=O)OC)C(=O)C1=CC=CC=C1 ZPUCINDJVBIVPJ-LJISPDSOSA-N 0.000 claims description 21
- 230000010287 polarization Effects 0.000 claims description 12
- 239000000919 ceramic Substances 0.000 claims description 11
- 230000003321 amplification Effects 0.000 claims description 3
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 3
- 238000012512 characterization method Methods 0.000 claims 1
- 238000004891 communication Methods 0.000 abstract description 19
- 238000000691 measurement method Methods 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 7
- 230000003287 optical effect Effects 0.000 description 4
- 238000010187 selection method Methods 0.000 description 4
- 238000012216 screening Methods 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000001427 coherent effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000005610 quantum mechanics Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Images
Classifications
-
- 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
-
- 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 belongs to the technical field of quantum secret communication, and particularly relates to a method for realizing sharing of a continuous variable quantum key by a partially-depicted entanglement source. According to the invention, a complex and expensive entanglement source is placed in the shared relay node, and a user side only needs to configure low-cost and simple detection equipment. The entanglement source is used as a real mixed EPR source, the output characteristics of the entanglement source only need to be described, and loss and electronic noise of a real detector are considered. By selecting the optimal entanglement degree and anti-entanglement degree parameters and adopting a measurement method of stably and randomly switching measurement bases and a bias base method, the quantum security key rate and the transmission distance are effectively improved, and finally, the method is utilized to realize the distribution of the continuous variable quantum key of two users between 60 kilometers of single-mode fibers, thereby providing possibility for deploying a high-speed and low-cost metropolitan quantum network.
Description
Technical Field
The invention belongs to the technical field of quantum secret communication, and particularly relates to a method for realizing sharing of a continuous variable quantum key by a partially-depicted entanglement source.
Background
Quantum key distribution is a relatively main research direction in the field of quantum communication, and based on the quantum mechanics principle, two communication parties can be guaranteed to share a group of unconditionally safe keys. Different from a discrete variable quantum key distribution scheme, the continuous variable quantum key distribution system encodes multi-photon quantum state key information, measures orthogonal component values of a light field by using an efficient homodyne or heterodyne detector, has higher key rate in a metropolitan area network, is compatible with classical optical fiber communication, and has wide application prospect.
The continuous variable quantum key distribution system is mainly divided into a preparation measurement scheme and an entanglement scheme, wherein the entanglement source quantum state based on the entanglement scheme is relatively difficult to prepare, but can tolerate higher channel extra noise, further longer transmission distance is transmitted and higher safe key rate is generated, and along with the development of quantum relay, a quantum communication network of a global scale is expected to be realized by utilizing an entanglement light field, so that the system has important significance for the establishment of a future quantum communication network.
The construction of a high-speed, low-cost and safe quantum communication network is an important task of quantum communication. At present, most of entanglement-based continuous variable quantum key distribution systems are realized through a one-way mechanism, namely, one of two communication parties (a transmitting end) prepares a quantum entanglement light source, and the other party (a receiving end) receives a quantum signal for detection. In this way, each two parties need to provide a complicated and expensive entanglement source, which greatly increases the communication cost. If the entanglement source is locked on the shared relay node, the entanglement source is placed between two users and is shared by the two users, wherein each user only needs to be provided with a simple homodyne detector with low cost, and an effective method can be provided for carrying out safe communication by efficiently utilizing quantum resources. The method for distributing the continuous variable quantum key based on entanglement source sharing can further construct a star-shaped entanglement network, wherein the relay station holds the high-cost entanglement source and is shared by a plurality of terminal users, each terminal only needs to establish a simple detection device, and any pair of terminal users can be connected by using light-on light controlled by a computer according to the requirements of the users. Once a connection is established between a pair of users, the entanglement sources are distributed to them through quantum channels (optical fibers or free space). In principle, any two users can share one group of security keys through the star quantum network, and an important step is provided for building a low-cost and extensible metropolitan area quantum communication network.
The original scheme of entanglement source shared Continuous variable quantum key distribution is proposed in the literature "Continuous-variable quantum key distribution with the same and the scheme allows both parties of communication to obtain a secure key with the entanglement source placed in the middle, thus being very suitable for constructing a Continuous variable quantum key distribution network with shared entanglement sources. However, in this scheme, the entanglement source is assumed to be completely pure, and the balanced homodyne detector is ideal (quantum efficiency is 100% and no dark noise), and obviously this assumption does not fit practical application. The production of any actual EPR entanglement source inevitably introduces losses and additional noise, and in real scenes it is not possible to produce a pure EPR entanglement source.
Disclosure of Invention
The invention aims to take an entanglement source as a real mixed EPR source and provides a method for realizing sharing of a continuous variable quantum key by partially depicting the entanglement source under the condition of considering quantum efficiency, loss and electronic noise of a real detector.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for realizing sharing of continuous variable quantum key by partially-depicted entanglement sources comprises the following steps:
step 2, at an Alice end, local light from a first dichroic mirror is subjected to phase modulation through a first optical fiber phase modulator, signal light from a second dichroic mirror is subjected to slow drift phase compensation through a reflector connected with a piezoelectric ceramic phase shifter, the local light and the signal light are interfered on a first 50:50 beam splitter and then are incident to a first balanced homodyne detector for measurement, and the first optical fiber phase modulator modulates the relative phase of the local light and the signal light to realize random switching of a balanced homodyne detection orthogonal component measurement basis;
and 4, performing parameter estimation, data coordination and privacy amplification on the orthogonal component data measured by the Alice terminal and the Bob terminal to extract a safe quantum key.
Further, the EPR entanglement source in the step 1 is a real mixed-state EPR source, the Charlie relay end only needs to depict the output characteristics of the EPR entanglement source, and the output is guaranteed to be in a Gaussian EPR entanglement state.
Further, the output mode of the EPR entanglement source in the step 1 meets the characteristics of Gaussian and independent equal distribution.
Further, the quantum efficiency and the electronic noise of the first balanced homodyne detector and the second balanced homodyne detector are considered in the parameter estimation in the step 4.
Further, the random switching of the orthogonal component measurement bases in the Alice terminal and the Bob terminal specifically includes:
3.1, compensating the relatively slow drifting phase of the local light and the signal light by adopting a piezoelectric ceramic phase shifter in an Alice end, modulating the relative phase at a high speed by adopting a first optical fiber phase modulator, compensating the relatively slow drifting phase of the local light and the signal light by adopting an optical fiber phase shifter in a Bob end, and modulating the relative phase at a high speed by adopting a second optical fiber phase modulator;
step 3.2, using a piezoelectric ceramic phase shifter and an optical fiber phase shifter to respectively lock the relative phases of the local light and the signal light at the Alice end and the Bob end to a pi/2 phase;
and 3.3, adding random independent measurement base electric signals at the radio frequency ends of the first optical fiber phase modulator of Alice and the second optical fiber phase modulator of Bob end respectively, so that random switching measurement can be performed on the orthogonal phase component and the orthogonal amplitude component.
Further, the period of the measurement base electric signal is T, if the orthogonal phase component is measured, zero voltage is loaded in the first half period T/2 of the measurement base pulse, and iV is loaded in the last T/2 π/2 (i ═ 1, -1) voltage; if the quadrature amplitude component is measured, the first half period T/2 is loaded with iV π/2 The voltage is converted to zero in the second half period to ensure the voltage loaded by the current measurement basic pulse
I in (1) and the previous pulse voltage
Conversely, and when n is 1, i is 1.
Further, the measurement time point of the signal light for measurement corresponds to the latter half of the first half period of the measurement base electric signal.
Further, the first balanced homodyne detector in the Alice end and the second balanced homodyne detector in the Bob end both adopt a bias selection method that the quadrature phase component measuring basis is far larger than the quadrature amplitude component measuring basis.
Further, the Charlie end is closer to one of the user ends, that is, the Alice end and the Bob end are asymmetric with respect to the Charlie relay end.
Further, the power of the pump light of the EPR entanglement source, which is lower than a threshold value, is changed, so that the entanglement degree and the anti-entanglement degree of the prepared entanglement source meet the maximum safe key rate under a given transmission distance.
Compared with the prior art, the invention has the following advantages:
(1) the invention provides a method for distributing the continuous variable quantum key shared by the entanglement sources on the basis of taking the entanglement sources as a real mixed entanglement source only by depicting that the output characteristic of the real mixed entanglement source is a Gaussian EPR source and considering the quantum efficiency, the loss and the electronic noise of a real detector.
(2) By selecting the optimal entanglement degree and anti-entanglement degree parameters, and adopting a measurement method of stably and randomly switching measurement bases and a bias base method of measuring that the ratio of orthogonal phase components to orthogonal amplitude components is far greater than 1, the quantum security key rate and the transmission distance are effectively improved, and finally the method is utilized to realize the high-efficiency continuous variable quantum key distribution process of two users between 60 kilometers of single-mode optical fibers, thereby providing possibility for deploying a high-speed and low-cost metropolitan quantum network.
(3) A plurality of end users share a complex and expensive high-quality entanglement source, and each user only needs to use cheap detection equipment, so that the quantum communication cost is greatly reduced.
Drawings
FIG. 1 is a schematic flow chart diagram for implementing a method for sharing a continuous variable quantum key by partially depicting an entanglement source according to the present invention;
FIG. 2 is a schematic diagram of a module structure for implementing a method for sharing a continuous variable quantum key by partially depicting an entanglement source according to the present invention;
FIG. 3 is a schematic diagram of an apparatus for implementing a method for sharing a continuous variable quantum key by partially depicting an entanglement source according to the present invention;
FIG. 4 is a timing diagram of a measurement signal and its corresponding measurement base electrical pulse;
FIG. 5 is a schematic diagram showing the variation of the security key rate with the communication distance between Charlie and Bob under the condition that Charlie is 0km away from Alice;
FIG. 6 is a schematic diagram showing the variation of the security key rate with the communication distance between Charlie and Bob under the condition that Charlie is 1km away from Alice;
the optical fiber phase shifter comprises a 1-four-mirror ring-shaped resonant cavity, a 2-first dichroic mirror, a 3-second dichroic mirror, a 4-amplitude modulator, a 5-first optical fiber phase modulator, a 6-piezoelectric ceramic phase shifter, a 7-optical fiber phase shifter, an 8-second optical fiber phase modulator, a 9-reflector, a 10-first 50:50 beam splitter, an 11-first balanced homodyne detector, a 12-long-distance single-mode optical fiber, a 13-second 50:50 beam splitter and a 14-second balanced homodyne detector.
Detailed Description
Example 1
As shown in fig. 1 and fig. 3, a method for realizing sharing of a continuous variable quantum key by partially depicting an entanglement source includes the following steps:
the EPR entanglement source is a real mixed state EPR source, and the Charlie end only needs to depict the output characteristics of the EPR entanglement source, so that the output is guaranteed to be in a Gaussian EPR entanglement state.
The output mode of the EPR entanglement source meets the characteristics of Gaussian and independent equal distribution.
And changing the power of the pump light of the EPR entanglement source, which is lower than the threshold value, so that the entanglement degree and the anti-entanglement degree of the prepared entanglement source meet the maximization of the security key rate under the given transmission distance.
Step 2, at the Alice end, local light from a first dichroic mirror 2 is subjected to phase modulation through a first optical fiber phase modulator 5 with inherent loss of 3dB, signal light from a second dichroic mirror 3 is subjected to phase compensation slow drift through a reflector connected with a piezoelectric ceramic phase shifter 6, the local light and the signal light are interfered on a first 50:50 beam splitter 10 and then are incident to a first balanced homodyne detector 11 for measurement, wherein the first optical fiber phase modulator 5 is used for modulating the relative phase of the local light and the signal light to realize random switching of a balanced homodyne detection orthogonal component measurement base, and a signal light path and a coherent measurement light path at the Alice end are both performed in a free space;
the random switching of the orthogonal component measurement bases in the Alice terminal and the Bob terminal comprises the following specific steps:
3.1, compensating the relatively slow drifting phase of the local light and the signal light by adopting a piezoelectric ceramic phase shifter 6 in an Alice end, modulating the relative phase at a high speed by adopting a first optical fiber phase modulator 5, compensating the relatively slow drifting phase of the local light and the signal light by adopting an optical fiber phase shifter 7 in a Bob end, and modulating the relative phase at a high speed by adopting a second optical fiber phase modulator 8;
step 3.2, using a piezoelectric ceramic phase shifter 6 and an optical fiber phase shifter 7 to respectively lock the relative phases of the local light and the signal light at the Alice end and the Bob end to pi/2 phase;
and 3.3, adding random independent measurement base electric signals to the radio frequency ends of the first optical fiber phase modulator 5 of Alice and the second optical fiber phase modulator 8 of Bob respectively, so that random switching measurement can be performed on the orthogonal phase component and the orthogonal amplitude component.
The period of the measurement base electric signal is T, if the orthogonal phase component is measured, zero voltage is loaded in the first half period T/2 of the measurement base pulse, and iV is loaded in the last T/2 π/2 (i ═ 1, -1) voltage; if the quadrature amplitude component is measured, the first half period T/2 is loaded with iV π/2 The voltage is converted to zero in the latter half period to ensure the voltage loaded by the current measurement basic pulse
I in (1) and the previous pulse voltage
Conversely, and when n is 1, i is 1.
The measurement time point of the signal light for measurement corresponds to the latter half of the first half period of the measurement base electric signal.
The first balanced homodyne detector 11 at the Alice end and the second balanced homodyne detector 14 at the Bob end adopt a bias selection method that the quadrature phase component measurement basis is far larger than the quadrature amplitude component measurement basis.
The Charlie end is closer to Alice at one of the user ends, namely the Alice end and the Bob end are asymmetric with respect to the Charlie end.
And 4, extracting a safe quantum key from the orthogonal component data measured by the Alice terminal and the Bob terminal through parameter estimation, data coordination and privacy amplification, wherein the parameter estimation considers the quantum efficiency and the electronic noise of the actual detectors (namely the first balanced homodyne detector 11 and the second balanced homodyne detector 14).
Fig. 2 shows a schematic block structure diagram of a method for realizing sharing of a continuous variable quantum key by partially depicting an entanglement source according to the present invention, where the method includes valid users Alice and Bob at both ends, and Charlie in an entangled state where gaussian EPR is prepared in the middle. Two bundles of light fields of the entanglement source are transmitted to legal user terminals Alice and Bob through two independent quantum channels respectively, and then the user carries out measurement through a balanced homodyne detector.
The entanglement degree and the anti-entanglement degree of the entangled optical field output by the four-mirror ring-shaped resonant cavity 1 are closely related to the rate of a safety key generated by quantum communication. The higher entanglement of the entangled optical field does not mean that a higher security key rate can be generated, and particularly in the case of long-distance transmission, the higher double-mode entanglement is generally accompanied by higher anti-entanglement, so that redundant noise which can be utilized by an eavesdropper is introduced. In our example, the entanglement and de-entanglement levels of the EPR source are made-5.3 dB and 9.1dB respectively by adjusting the power of the pump light below a threshold value for the entanglement source, in which case the secure key rate can be maximised over a transmission distance of 80 km.
When Alice and Bob randomly measure the orthogonal amplitude or the orthogonal phase component of the entangled light field with a probability of 1/2, the security key can be extracted only when both choose the same orthogonal measurement basis, so that half of the original data must be discarded in the process of screening the measurement basis, resulting in the waste of quantum state resources and low security key rate. Therefore, in order to improve the key rate, a bias selection method is adopted in a continuous variable quantum key distribution method based on entanglement source sharing, namely, different probabilities are selected to measure orthogonal amplitude and orthogonal phase components.
Suppose that Alice (Bob) measures the probability of the quadrature phase and quadrature amplitude components at random, respectively, P A (P B ) And 1-P A (1-P B ) Under asymptotic conditions, considering collective attack and reverse coordination, the rate of security keys available to both parties is given by:
wherein: (1-P) A )(1-P B )、P A P B Respectively representing the screening probabilities of the two measurement bases, beta is the coordination efficiency,
representing the shannon mutual information quantity of both communication parties in measuring orthogonal amplitude (phase) component,
representing the upper bound of information that an eavesdropper can obtain when measuring the quadrature amplitude (phase) component in the case of inverse coordination.
By optimizing the measurement probability of the quadrature amplitude and quadrature phase components, the security key rate can be increased. Current probability P A And P B When the value approaches to 1 or 0, the total screening probability of the measurement base is increased continuously, and the secret key rate is improved. But P is A And P B The value of 1 or 0 cannot be taken because the absence of another orthogonal component can cause the covariance matrix for evaluating the key rate to be not completely estimated, and at this time, the unknown parameters in the covariance matrix need to be limited by using physical principles, resulting in the reduction of the key rate. P is selected in the embodiment of the continuous variable quantum key distribution method based on partial description entanglement source sharing A ＝P B P0.9, which indicates that the quadrature phase component is selected for measurement most of the time. On the basis of the above, the generated key rate is higher than that of the conventional unbiased selection method.
In the embodiment, in order to realize random switching of the measurement basis, firstly, a piezoelectric ceramic phase shifter 6 adhered to a free space signal light path light guide mirror at an Alice end and an optical fiber phase shifter 7 connected with a local light path at a Bob end are used for respectively compensating slow drift phases of the local light and the signal light path at the Alice end and the Bob end, and the relative phase of the local light and the signal light is locked to a pi/2 phase; then, random independent measurement base electric signals are added to radio frequency ends of the first optical fiber phase modulator 5 and the second optical fiber phase modulator 8 on local optical paths of the Alice end and the Bob end, so that random switching measurement can be performed on orthogonal phase components and orthogonal amplitude components.
The random independent measurement base electric signal added to the radio frequency end of the optical fiber phase modulator is shown in fig. 4, wherein the solid line signal is the measured signal with the period of 20 mus, and the black square partThe broken line signal is a random independent measuring base electric signal with the period of 40 mus. When measuring orthogonal amplitude components (such as signals 1 and 2), the first 20 mus is loaded with iV pi/2 (i is 1, -1), and the last 20 mus is loaded with zero voltage; when measuring quadrature phase components (e.g. signals 3 and 4), the measurement base pulse is applied with zero voltage 20 μ s first and with iV pi/2 (i ═ 1, -1) voltage 20 μ s later. Ensuring the voltage loaded by the current measurement base pulse
I in (1) and the previous pulse voltage
Conversely, and when n is 1, i is 1. Wherein V π/2 The voltage value which is required to be added at the radio frequency end when the fiber phase modulator modulates the pi/2 phase is shown.
In fig. 4, the measured signal (black square part) corresponds to the second half part of the first half period of the measured base electric pulse, so as to reduce the influence of the instability of the rising edge on the measurement result.
Placing Charlie at Alice end, namely the distance (L) from Charlie to Alice A ) At 0km, FIG. 5 shows Charlie to Bob end (L) for the case of a measurement of quadrature phase and quadrature amplitude component ratio of 0.9:0.1 (squares) (0.5:0.5 (triangles)) B ) The measured security key rates for 10km, 20km, 40km and 60km of transmission long-haul fiber were 0.0961(0.0602), 0.0477(0.0402), 0.0126(0.0076) and 0.0038(0.0026) bits per pulse, respectively. Wherein the solid line and the dotted line are theoretical simulation curves obtained by using formula 1 under the condition that the ratio of the measurement basis is 0.9:0.1 and 0.5:0.5, respectively.
Alice signal optical path added with neutral attenuation sheet to simulate transmission distance (L) from Charlie to Alice A ) For 1km, fig. 6 shows Charlie to Bob end (L) in the case of a measurement of a quadrature phase to quadrature amplitude component ratio of 0.9:0.1 (square) (0.5:0.5 (triangle block)) B ) The measured security key rates for 10km, 20km and 40km of transmission long haul fiber were 0.0718(0.0363), 0.0283(0.0205) and 0.0053(0.0042) bits per pulse, respectively. Wherein the solid and dashed lines are, respectivelyA theoretical simulation curve was obtained using equation 1 for the measured basis ratios of 0.9:0.1 and 0.5: 0.5.
As can be seen from fig. 5 and 6, the resulting security key rate is significantly higher for the biased base (0.9:0.1) than for the unbiased base (0.5: 0.5).
Claims (10)
1. A method for realizing sharing of continuous variable quantum key by partially-depicted entanglement sources is characterized by comprising the following steps:
step 1, at a Charlie relay end, continuous laser is divided into two parts through a beam splitter, one part of the continuous laser directly enters a four-mirror ring-shaped resonant cavity as pump light of an EPR (ethylene-propylene-rubber) entanglement source higher than a threshold value, one part of the pump light of the EPR entanglement source lower than the threshold value reversely enters the four-mirror ring-shaped resonant cavity after passing through a plurality of reflectors, the local light of the EPR entanglement source output by the four-mirror ring-shaped resonant cavity is divided into two light fields through a first dichroic mirror, one light field enters an Alice end, the other light field enters an amplitude modulator after passing through the reflectors, the two light fields are modulated into pulse light with the duty ratio of below 50%, and then the pulse light enters a polarization beam combiner through a first time delay device; the signal light of the EPR entanglement source output by the four-mirror ring-shaped resonant cavity is divided into two mutually entangled signal light fields by a second dichroic mirror, one light field enters an Alice end, the other light field directly enters a polarization beam combiner after passing through a reflector, local light and the signal light in the polarization beam combiner are combined, and the local light and the signal light are transmitted by a long-distance single-mode fiber in a time division multiplexing and polarization multiplexing mode and then reach a Bob end;
step 2, at an Alice end, local light from a first dichroic mirror is subjected to phase modulation through a first optical fiber phase modulator, signal light from a second dichroic mirror is subjected to slow drift phase compensation through a reflector connected with a piezoelectric ceramic phase shifter, the local light and the signal light are subjected to interference on a first 50:50 beam splitter and then are incident to a first balanced homodyne detector for measurement, and the first optical fiber phase modulator is used for modulating the relative phase of the local light and the signal light to realize random switching of a balanced homodyne detection orthogonal component measurement base;
step 3, at the Bob end, beam combining light from the long-distance single-mode optical fiber is divided into local light and signal light through a second beam splitter, wherein the local light passes through an optical fiber phase shifter and a second optical fiber phase modulator, then is interfered with the signal light passing through a second delayer in a second 50:50 beam splitter and then is incident to a second balanced homodyne detector for measurement, the optical fiber phase shifter compensates a slow drift phase, and the second optical fiber phase modulator modulates the relative phase of the local light and the signal light to realize random switching of a balanced homodyne detection orthogonal component measurement basis;
and 4, performing parameter estimation, data coordination and privacy amplification on the orthogonal component data measured by the Alice end and the Bob end to extract a safe quantum key.
2. The method for realizing sharing of the continuous variable quantum key by the partially depicted entanglement source according to claim 1, wherein the EPR entanglement source in the step 1 is a real mixed-state EPR source, and the Charlie relay end only needs to depict the output characteristics of the EPR entanglement source to ensure that the output is in a Gaussian EPR entangled state.
3. The method for realizing the sharing of the continuous variable quantum key by the partially characterization entanglement source according to claim 1, wherein the output mode of the EPR entanglement source in the step 1 meets the characteristics of Gaussian and independent equal distribution.
4. The method for realizing the sharing of the continuous variable quantum key by the partially depicted entanglement sources according to claim 1, wherein the parameter estimation in the step 4 considers the quantum efficiency and the electronic noise of the first balanced homodyne detector and the second balanced homodyne detector.
5. The method for realizing the sharing of the continuous variable quantum key by the partially depicted entanglement sources according to claim 1, wherein the random switching of orthogonal component measurement bases in the Alice terminal and the Bob terminal comprises the following specific steps:
3.1, compensating the relatively slow drifting phase of the local light and the signal light by adopting a piezoelectric ceramic phase shifter in an Alice end, modulating the relative phase at a high speed by adopting a first optical fiber phase modulator, compensating the relatively slow drifting phase of the local light and the signal light by adopting an optical fiber phase shifter in a Bob end, and modulating the relative phase at a high speed by adopting a second optical fiber phase modulator;
step 3.2, using a piezoelectric ceramic phase shifter and an optical fiber phase shifter to respectively lock the relative phases of the local light and the signal light at the Alice end and the Bob end to a pi/2 phase;
and 3.3, adding random independent measurement base electric signals to the radio frequency ends of the first optical fiber phase modulator of Alice and the second optical fiber phase modulator of Bob respectively, so that random switching measurement can be performed on the orthogonal phase component and the orthogonal amplitude component.
6. The method as claimed in claim 5, wherein the period of the measurement base electrical signal is T, and if the quadrature phase component is measured, zero voltage is applied to the first half period of T/2 of the measurement base pulse, and iV is applied to the last T/2 π/2 (i ═ 1, -1) voltage; if the quadrature amplitude component is measured, the first half period T/2 is loaded with iV π/2 The voltage is converted to zero in the second half period to ensure the voltage loaded by the current measurement basic pulse
I in (1) and the previous pulse voltage
Conversely, and when n is 1, i is 1.
7. The method for realizing the sharing of the continuous variable quantum key by the partially depicted entanglement sources as claimed in claim 5, wherein the measuring time point of the signal light for measurement corresponds to the second half of the first half period of the measured base electrical signal.
8. The method for realizing the sharing of the continuous variable quantum key by the partially-characterized entanglement source according to claim 1, wherein the first balanced homodyne detector at Alice end and the second balanced homodyne detector at Bob end both use a bias basis method in which a quadrature phase component measurement basis is much larger than a quadrature amplitude component measurement basis.
9. The method for realizing the sharing of the continuous variable quantum key by the partially depicted entanglement source according to claim 1, wherein the Charlie end is closer to one of the user ends, that is, the Alice end and the Bob end are asymmetric with respect to the Charlie relay end.
10. The method for realizing the sharing of the continuous variable quantum key by the partially-characterized entanglement source according to claim 1, wherein the power of the pump light of the EPR entanglement source below a threshold value is changed, so that the entanglement degree and the anti-entanglement degree of the prepared entanglement source meet the maximization of the safe key rate under a given transmission distance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210353414.7A CN114793158B (en) | 2022-04-06 | 2022-04-06 | Method for realizing partial characterization entanglement source sharing continuous variable quantum key distribution |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210353414.7A CN114793158B (en) | 2022-04-06 | 2022-04-06 | Method for realizing partial characterization entanglement source sharing continuous variable quantum key distribution |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114793158A true CN114793158A (en) | 2022-07-26 |
| CN114793158B CN114793158B (en) | 2024-04-12 |
Family
ID=82461700
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210353414.7A Active CN114793158B (en) | 2022-04-06 | 2022-04-06 | Method for realizing partial characterization entanglement source sharing continuous variable quantum key distribution |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114793158B (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20140099104A1 (en) * | 2012-10-04 | 2014-04-10 | Applied Communication Sciences | Method to mitigate propagation loss in waveguide transmission of quantum states |
| CN111130779A (en) * | 2019-12-31 | 2020-05-08 | 华南师范大学 | OAM entanglement modulation key distribution network system and method for real-time tracking compensation |
| CN112130396A (en) * | 2020-09-07 | 2020-12-25 | 济南量子技术研究院 | Multi-mode receiving miniaturized entanglement source system based on PPKTP crystal |
-
2022
- 2022-04-06 CN CN202210353414.7A patent/CN114793158B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20140099104A1 (en) * | 2012-10-04 | 2014-04-10 | Applied Communication Sciences | Method to mitigate propagation loss in waveguide transmission of quantum states |
| CN111130779A (en) * | 2019-12-31 | 2020-05-08 | 华南师范大学 | OAM entanglement modulation key distribution network system and method for real-time tracking compensation |
| CN112130396A (en) * | 2020-09-07 | 2020-12-25 | 济南量子技术研究院 | Multi-mode receiving miniaturized entanglement source system based on PPKTP crystal |
Non-Patent Citations (3)
| Title |
|---|
| SHANNA DU ET AL.: "Experimental demonstration of continuous-variable measurement-device-independent quantum key distribution over optical fiber", OPTICA, 31 March 2022 (2022-03-31) * |
| 任继刚;张涵;蔡昕东;印娟;周飞;彭承志;: "基于周期极化KTiOPO_4晶体的高亮度纠缠源研制", 物理学报, no. 08, 15 August 2009 (2009-08-15) * |
| 袁素真;孙志富;田俊龙;: "基于N个有序纠缠光子对的量子机密共享方案", 光子学报, no. 08, 15 August 2011 (2011-08-15) * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114793158B (en) | 2024-04-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Mao et al. | Integrating quantum key distribution with classical communications in backbone fiber network | |
| Bacco et al. | Boosting the secret key rate in a shared quantum and classical fibre communication system | |
| Gleim et al. | Secure polarization-independent subcarrier quantum key distribution in optical fiber channel using BB84 protocol with a strong reference | |
| Bacco et al. | Field trial of a three-state quantum key distribution scheme in the Florence metropolitan area | |
| Wu et al. | Simulation of bidirectional long-distance chaos communication performance in a novel fiber-optic chaos synchronization system | |
| Zhang et al. | Tbit/s multi-dimensional multiplexing THz-over-fiber for 6G wireless communication | |
| Wang et al. | Long-distance transmission of quantum key distribution coexisting with classical optical communication over a weakly-coupled few-mode fiber | |
| Jiang et al. | Physically enhanced secure wavelength division multiplexing chaos communication using multimode semiconductor lasers | |
| CN107508665A (en) | A kind of high-dimensional chaotic laser light secret signalling | |
| Mlejnek et al. | Reducing spontaneous Raman scattering noise in high quantum bit rate QKD systems over optical fiber | |
| Luo et al. | Real-time coherent UDWDM-PON with dual-polarization transceivers in a field trial | |
| Wang et al. | Practical quantum access network over a 10 Gbit/s Ethernet passive optical network | |
| Koch et al. | Transmission of higher order solitons created by optical multiplexing | |
| Gill et al. | Comparative investigation of CSRZ‐DQPSK, DRZ‐DQPSK, and MDRZ‐DQPSK modulation techniques in MDM IS‐OWC system | |
| Shao et al. | 100 km coherent Nyquist ultradense wavelength division multiplexed passive optical network using a tunable gain-switched comb source | |
| Zhang et al. | Clone-comb-enabled high-capacity digital-analogue fronthaul with high-order modulation formats | |
| Bacco et al. | Field trial of a finite-key quantum key distribution system in the florence metropolitan area | |
| Boriboon et al. | Polarization insensitive self-homodyne detection receiver for 360 gb/s data center links | |
| Temprana et al. | Transmitter-side digital back propagation with optical injection-locked frequency referenced carriers | |
| Sugumaran et al. | Optimized FWM Parameters for FTTH Using DWDM Network | |
| CN114793158B (en) | Method for realizing partial characterization entanglement source sharing continuous variable quantum key distribution | |
| Pan et al. | Experimental demonstration of 4-user quantum access network based on passive optical network | |
| Tan et al. | A novel realization of PSK quantum-noise randomized cipher system based on series structure of multiple phase modulators | |
| Wen et al. | Simultaneous all-optical transparent phase multiplexing/de-multiplexing based on FWM in a HNLF | |
| Essiambre et al. | Capacity limits of information transmission in optically-routed fiber networks |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |