CN110855440A - High-speed quantum key encoding device and encoding method - Google Patents
High-speed quantum key encoding device and encoding method Download PDFInfo
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Abstract
The application provides a high-speed quantum key coding device and a coding method, which relate to the technical field of quantum communication, wherein the coding device comprises a first signal light source, a second signal light source, an unequal arm interferometer, a first phase modulator, an intensity modulator and a fourth beam splitter; the first signal light source is sequentially connected with the unequal arm interferometer in series, the second signal light source is sequentially connected with the intensity modulator in series, the fourth beam splitter comprises two input ends and one output end, the unequal arm interferometer is connected with one input end of the fourth beam splitter, and the intensity modulator is connected with the other input end of the fourth beam splitter; the unequal-arm interferometer comprises a long arm and a short arm, and the first phase modulator is arranged on the long arm or the short arm; the driving signal frequency of the first signal light source, the second signal light source, the first phase modulator and the intensity modulator are the same. The method and the device can realize high-speed quantum key coding exceeding gigahertz with high precision.
Description
Technical Field
The application relates to the technical field of quantum communication, in particular to a high-speed quantum key encoding device and an encoding method.
Background
Quantum key distribution is one of the research hotspots in the field of quantum communication, and with the advance of quantum communication industrialization, the realization of high-speed quantum key distribution has great significance for improving quantum communication performance, increasing user experience and the like.
The high-speed quantum key distribution needs a corresponding high-speed quantum key encoding device, the optical pulse frequency output by a system in the existing encoding device is basically in the order of hundred megahertz (MHz), the high-speed encoding device exceeding gigahertz (GHz) has fewer solutions with great difficulty in implementation, and the main limitation is the matching of some optical devices in the encoding device and the driving signal frequency thereof. The difficulty in implementing the high-frequency and high-amplitude pulse driving signal is high, and the quality of the generated driving signal is not high, for example: the signal consistency and flatness are poor, so that when some optical devices are driven to work by the signal consistency and flatness, the modulation result has large deviation, and finally, the resultant code rate is low.
Time-phase encoding is one of important quantum key distribution encoding schemes, the scheme combines time basis vectors and phase basis vectors, and compared with other encoding schemes, the scheme has many advantages, for example, the time basis vectors are not influenced by the environment, and the stability is good, so the resultant code rate is improved to a certain extent, and in addition, the phase basis vectors can appropriately get rid of the influence of the system on polarization to adapt to a complex external environment.
Fig. 1 shows a simplified prior art time-phase based encoding apparatus, which, if it is desired to achieve high-speed encoding at a system frequency of gigahertz (GHz), the driving signal frequencies of the light source, the phase modulator and the intensity modulator are required to reach the gigahertz (GHz) level, however, due to the limitation of technical conditions, the light source, the intensity modulator and the phase modulator used for quantum key distribution in the market at present have low working accuracy and large error when applying a driving signal with a frequency exceeding gigahertz (GHz), and cannot meet the requirements of decoy state preparation and high accuracy during phase encoding, and finally the system has a low code rate and cannot be implemented, so that the existing time-phase encoding scheme cannot realize high speed in a true sense.
Disclosure of Invention
The application provides a high-speed quantum key coding device and a coding method, which are used for solving the problem that the high-speed coding exceeding gigahertz (GHz) is difficult to realize in the existing time-phase coding scheme.
A high-speed quantum key encoding device, the encoding device comprising: the system comprises a first signal light source, a second signal light source, an unequal arm interferometer, a first phase modulator, an intensity modulator and a fourth beam splitter; the first signal light source is sequentially connected with the unequal arm interferometer in series, the second signal light source is sequentially connected with the intensity modulator in series, the fourth beam splitter comprises two input ends and one output end, the unequal arm interferometer is connected with one input end of the fourth beam splitter, and the intensity modulator is connected with the other input end of the fourth beam splitter; the unequal-arm interferometer comprises a long arm and a short arm, and the first phase modulator is arranged on the long arm or the short arm; the driving signal frequency of the first signal light source, the second signal light source, the first phase modulator and the intensity modulator are the same.
Preferably, the encoding device further includes a main light source, a first beam splitter, a first circulator and a second circulator, the first beam splitter includes an input end and two output ends, the output end of the main light source is connected with the input end of the first beam splitter, an output end of the first beam splitter is connected with the first port of the first circulator, another output end of the first beam splitter is connected with the first port of the second circulator, the output end of the first signal light source is connected with the second port of the first circulator, the third port of the first circulator is connected with the unequal arm interferometer, the output end of the second signal light source is connected with the second port of the second circulator, and the third port of the second circulator is connected with the intensity modulator.
Preferably, the encoding apparatus further includes a second phase modulator, the first phase modulator is disposed on the long arm, the second phase modulator is disposed on the short arm, or the first phase modulator is disposed on the short arm, and the second phase modulator is disposed on the long arm.
Preferably, the encoding apparatus further comprises a real-time stability maintaining system, and the intensity modulator is connected to the real-time stability maintaining system.
Preferably, the encoding apparatus further comprises a filter connected to an output of the fourth beam splitter.
Preferably, the encoding device further comprises a variable optical attenuator, and the variable optical attenuator is arranged at the tail end of the encoding device.
Preferably, the driving signal frequency of the first signal light source and the second signal light source is 10MHz to 1 GHz.
Preferably, the frequency of the driving signal of the second phase modulator is the same as the frequency of the driving signal of the first signal light source.
Preferably, the first signal light source and the second signal light source are light sources with an inner modulation function.
A high-speed quantum key coding method is applied to a high-speed quantum key coding device, wherein the coding device comprises a first signal light source, a second signal light source, an unequal arm interferometer, a first phase modulator, an intensity modulator and a fourth beam splitter; the first signal light source is sequentially connected with the unequal arm interferometer in series, the second signal light source is sequentially connected with the intensity modulator in series, the fourth beam splitter comprises two input ends and one output end, the unequal arm interferometer is connected with one input end of the fourth beam splitter, and the intensity modulator is connected with the other input end of the fourth beam splitter; the unequal-arm interferometer comprises a long arm and a short arm, and the first phase modulator is arranged on the long arm or the short arm; the method comprises the following steps: a first signal light source with a driving signal frequency f randomly generates a first light pulse for phase encoding; a second signal light source with the driving signal frequency f randomly generates a second light pulse with time coding or vacuum state coding; the method comprises the steps that an unequal arm interferometer and a first phase modulator with a driving signal frequency f carry out phase coding, the unequal arm interferometer changes one beam of light pulse generated by a first signal light source into two temporally separated beams of first sub-light pulses, the first phase modulator with the driving signal frequency f adjusts the phase difference of the two beams of first sub-light pulses, the phase difference of the two beams of first sub-light pulses after combination is made to be 0 or pi, and the light pulse with the frequency of 2f after combination is obtained; the intensity modulator with the driving signal frequency f is used for preparing a decoy state, and the intensity modulator with the driving signal frequency f attenuates the intensity of a second light pulse used for preparing the decoy state; and the fourth beam splitter combines two paths of light pulses generated by the first signal light source and the second signal light source into one path to obtain the light pulse with the output frequency of 2 f.
According to the technical scheme provided by the application, a brand-new high-speed quantum key encoding device and encoding method are provided, and the device can enable a system to output optical pulses with higher frequency by adopting a driving signal with lower frequency; the encoding device can adopt a driving signal with lower frequency in the processes of optical pulse preparation, phase encoding and decoy state modulation with higher requirement on the realization precision so as to improve the code rate of high-speed encoding.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a simplified prior art time-phase encoding apparatus;
FIG. 2 is a schematic diagram of a high-speed quantum key encoding apparatus according to the present application;
FIG. 3 is a schematic diagram of a high-speed quantum key encoding apparatus including injection locking according to the present application;
FIG. 4 is a schematic diagram of a high-speed quantum key encoding apparatus including two phase modulators according to the present application;
FIG. 5 is a schematic diagram of a high-speed quantum key encoding apparatus including a real-time stability maintenance system according to the present application;
FIG. 6 is a schematic diagram of a high-speed quantum key encoding apparatus including a filter according to the present application;
FIG. 7 is a schematic diagram of a high-speed quantum key encoding device incorporating a variable optical attenuator according to the present application;
fig. 8 is a schematic diagram of the real-time stability maintaining system according to the present application.
Detailed Description
The technical solutions of the present invention will be described in detail with reference to the accompanying drawings and specific embodiments, it should be understood that these embodiments are merely illustrative of the present invention and are not intended to limit the scope of the present invention, and various equivalent modifications of the present invention by those skilled in the art after reading the present invention fall within the scope of the appended claims.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The invention provides a high-speed quantum key coding device and a coding method, which can solve the problem that the high-speed coding exceeding gigahertz (GHz) is difficult to realize in the existing time-phase coding scheme.
Optical connection in this application means that two or more optical devices are connected by optical fiber or polarization maintaining optical fiber, and of course, connecting optical devices by other optical means is also called optical connection.
Referring to fig. 2, a high-speed quantum key encoding apparatus provided in an embodiment of the present application includes: a first signal light source, a second signal light source, an unequal arm interferometer, a first phase modulator PM1, an intensity modulator IM, a fourth beam splitter PMBS 4; the first signal light source is sequentially connected with the unequal arm interferometer in series, the second signal light source is sequentially connected with the intensity modulator IM in series, the fourth beam splitter PMBS4 comprises two input ends and one output end, the unequal arm interferometer is connected with one input end of the fourth beam splitter PMBS4, and the intensity modulator IM is connected with the other input end of the fourth beam splitter PMBS 4; the unequal arm interferometer comprises a long arm and a short arm, and the first phase modulator IM is arranged on the long arm or the short arm of the unequal arm interferometer; the driving signal frequencies of the first signal light source, the second signal light source, the first phase modulator PM1 and the intensity modulator IM are the same. Specifically, referring to fig. 2, the unequal arm interferometer comprises a second beam splitter PMBS2, a third beam splitter PMBS3, a long arm and a short arm, wherein an output end of a first signal light source is connected with an input end of the second beam splitter PMBS2, an output end of the third beam splitter PMBS3 is connected with one input end of the fourth beam splitter PMBS4, an output end of the second signal light source is connected with an input end of an intensity modulator IM, an output end of the intensity modulator IM is connected with the other input end of the fourth beam splitter PMBS4, and an output end of a fourth beam splitter PMBS4 is used for outputting encoded light pulses.
In a possible embodiment, the splitting ratio of the second splitter PMBS2 to the third splitter PMBS3 in the unequal arm interferometer is 50:50 (actually, fine tuning can be performed around 50: 50), the optical path length of the long arm in the unequal arm interferometer is greater than the optical path length of the short arm, the second splitter PMBS2 is configured to split one optical pulse emitted by the first signal light source into two first sub optical pulses and output the two first sub optical pulses through different optical paths, and the third splitter PMBS3 is configured to combine the two first sub optical pulses respectively passing through the long arm and the short arm and output the combined optical pulses.
Preferably, the second signal light source adopts a light source with an internal modulation function, such as an electro-absorption modulation laser, the intensity of the light pulse emitted by the internal modulation light source is already subjected to partial intensity modulation, and the second light pulse with time coding or vacuum coding can be directly modulated. The first signal light source may also be a light source with internal modulation function, such as an electro-absorption modulated laser, but one skilled in the art will recognize that any light source that can meet the coding requirements may be used.
In one coding period, only one of the first signal light source and the second signal light source outputs light pulses.
Referring to fig. 3, the high-speed quantum key encoding apparatus of the present application may further include a main light source, a first beam splitter PMBS1, a first circulator, and a second circulator, forming an injection locking module; the first beam splitter PMBS1 comprises an input and two outputs, the output of the main light source is connected to the input of the first beam splitter PMBS1, one output of the first beam splitter PMBS1 is connected to the first port 1 of the first circulator, the other output of the first beam splitter PMBS1 is connected to the first port 1 of the second circulator, the output of the first signal light source is connected to the second port 2 of the first circulator, the third port 3 of the first circulator is connected to the unequal arm interferometer, the output of the second signal light source is connected to the second port 2 of the second circulator, and the third port 3 of the second circulator is connected to the intensity modulator IM. And injecting and locking the first signal light source and the second signal light source by the light pulse emitted by the main light source to obtain the first light pulse and the second light pulse, so that the first light pulse and the second light pulse have better consistency, such as light intensity and line width.
In a possible embodiment, referring to fig. 4, the high-speed encoding apparatus may further include a second phase modulator PM2, where the first phase modulator PM1 is disposed on the long arm of the unequal-arm interferometer and the second phase modulator PM2 is disposed on the short arm of the unequal-arm interferometer, or the first phase modulator PM1 is disposed on the short arm of the unequal-arm interferometer and the second phase modulator PM2 is disposed on the long arm of the unequal-arm interferometer. The second phase modulator PM2 is also suitable for phase encoding and cooperates with the first phase modulator PM1 to modulate the phase of the two first sub-optical pulses separately.
Referring to fig. 5, the high-speed quantum key encoding apparatus of the present application may further include a real-time stability maintaining system connected to the intensity modulator IM. Referring to fig. 8, specifically, the real-time stability maintaining system includes a light intensity monitor, a wavelength division device, a reference light source and a fifth beam splitter PMBS5, where the reference light source emits a reference light, and the reference light is only used for stability maintenance, so that the real-time stability maintaining system of the present application can perform stability maintenance operation without affecting communication efficiency, as shown in fig. 8, a signal light pulse emitted by the signal light source and the reference light output a combined light through the fifth beam splitter PMBS5, the combined light is sent to an intensity modulator IM, the intensity modulator IM is configured to modulate the combined light and output a modulated light, the modulated light is sent to the wavelength division device, the wavelength division device is configured to split the modulated light, and a modulated signal light pulse, that is, the signal light pulse and the modulated reference light emitted by the signal light source are respectively obtained, the modulated signal light pulse is sent to the unequal arm interferometer, and the modulated reference light is sent to the wavelength division monitor, the light intensity monitor is used for feeding back and adjusting the working point voltage of the intensity modulator IM in real time according to the measured average light power value of the modulation reference light, so that the light intensity of the output modulation signal light pulse meets the system requirement. The wavelength division device may be a dense wavelength division multiplexer or other common wavelength division devices as long as it can split the modulated light.
The high-speed quantum key encoding apparatus may further comprise a filter, as shown in fig. 6, connected to an output of the fourth beam splitter PMBS4, for filtering the encoded optical pulses.
Referring to fig. 7, the high-speed quantum key encoding device may further include a variable optical attenuator ATT disposed at an end of the encoding device, which may be used to reduce the overall signal strength to an optimal number of photons per pulse to complete quantum state preparation.
On the basis of the embodiment shown in fig. 2, the high-speed quantum key encoding apparatus may have various implementations, and the encoding apparatus of the embodiment shown in fig. 2 may further include any combination of one or more of an injection locking module, a real-time multidimensional system, a filter, a second phase modulator PM2, and a variable optical attenuator ATT. For example, in a possible implementation manner, based on the embodiment shown in fig. 2, the high-speed quantum key encoding apparatus may further include an injection locking module, a real-time maintenance system, a filter, a second phase modulator PM2, and a variable optical attenuator ATT, wherein an output of the main light source is connected to an input of the first beam splitter PMBS1, one output of the first beam splitter PMBS1 is connected to the first port 1 of the first circulator, another output of the first beam splitter PMBS1 is connected to the first port 1 of the second circulator, an output of the first signal light source is connected to the second port 2 of the first circulator, the third port 3 of the first circulator is connected to an input of the unequal arm interferometer, an output of the second signal light source is connected to the second port 2 of the second circulator, and the third port 3 of the second circulator is connected to an input of the intensity modulator IM, the real-time stability maintaining system is connected with an intensity modulator IM, the output end of the unequal arm interferometer is connected with one input end of a fourth beam splitter PMBS4, the output end of the intensity modulator IM is connected with the other input end of a fourth beam splitter PMBS4, the output end of a fourth beam splitter PMBS4 is connected with the input end of a filter, the output end of the filter is connected with the input end of a variable optical attenuator ATT, and finally coded optical pulses are output by the variable optical attenuator ATT. The above is an embodiment containing more optical devices, and one or more of the injection locking module, the real-time stability maintaining system, the filter, the second phase modulator PM2 and the variable optical attenuator ATT can be subtracted to form other embodiments while the connection relationship is kept unchanged.
In the above embodiments, the driving signal frequencies of the first signal light source, the second signal light source, the first phase modulator and the intensity modulator are the same, and the driving signal frequency ranges of the first signal light source and the second signal light source are 10MHz to 1 GHz. In embodiments including the second phase modulator PM2, the drive signal frequency of the second phase modulator is the same magnitude as the drive signal frequency of the first signal light source. Specifically, one beam of optical pulse emitted by the first signal light source passes through the unequal-arm interferometer and then becomes two beams of first sub-optical pulses after being combined, and the frequency of the optical pulse becomes twice of the frequency of the optical pulse output by the first signal light source, so that the frequency of the optical pulse output by the encoding device is twice of the frequency of the optical pulse output by the first signal light source, and correspondingly, the frequency of the optical pulse output by the encoding device is twice of the frequency of the driving signals of the first signal light source, the second signal light source, the first phase modulator and the intensity modulator; in order to enable the optical pulse frequency finally output by the encoding device to exceed gigahertz so as to realize high-speed quantum key encoding, the driving signal frequency of the first signal light source, the second signal light source, the first phase modulator and the intensity modulator is preferably 625 MHz-1 GHz.
A high-speed quantum key coding method is applied to a high-speed quantum key coding device, and specifically the coding device comprises a first signal light source, a second signal light source, an unequal arm interferometer, a first phase modulator, an intensity modulator and a fourth beam splitter, wherein the first signal light source is sequentially connected with the unequal arm interferometer in series, the second signal light source is sequentially connected with the intensity modulator in series, the fourth beam splitter comprises two input ends and one output end, the unequal arm interferometer is connected with one input end of the fourth beam splitter, and the intensity modulator is connected with the other input end of the fourth beam splitter; the unequal-arm interferometer comprises a long arm and a short arm, and the first phase modulator is arranged on the long arm or the short arm; the high-speed quantum key encoding method comprises the following steps of:
in a first step, a first signal light source with a driving signal frequency f randomly generates a first light pulse for phase encoding.
In the second step, a second signal light source with the driving signal frequency f randomly generates a second light pulse with time coding or vacuum coding, the second signal light source is a light source with an internal modulation function, and the second light pulse emits a light pulse which is already time-coded or vacuum-coded once.
In the third step, the unequal-arm interferometer performs phase encoding with the first phase modulator with the driving signal frequency f, the unequal-arm interferometer changes one beam of optical pulse generated by the first signal light source into two temporally separated first sub optical pulses, the first phase modulator with the driving signal frequency f adjusts the phase difference of the two first sub optical pulses, so that the phase difference of the two combined first sub optical pulses is 0 or pi, and the optical pulse with the frequency of 2f after combination is obtained. For example, the first phase modulator PM1 may be adjusted such that the phase of a bundle of first sub optical pulses passing through the first phase modulator PM1 is changed by pi, or the first phase modulator PM1 may be adjusted such that the phase of a bundle of first sub optical pulses passing through the first phase modulator PM1 is changed by 0.
In the fourth step, the intensity modulator of the driving signal frequency f performs the decoy state preparation, and the intensity modulator of the driving signal frequency f attenuates the intensity of the second light pulse used for preparing the decoy state. Specifically, the intensity of the trick-state time-encoded light pulse is suppressed by the intensity modulator while the intensity of the signal-state time-encoded light pulse remains unchanged, preferably, the intensity of the light pulse for the trick-state time-encoding is attenuated to half of the original intensity.
In the fifth step, the fourth beam splitter combines two paths of light pulses generated by the first signal light source and the second signal light source into one path to obtain the light pulse with the output frequency of 2 f.
In the high-speed quantum key encoding method, only one of the first signal light source and the second signal light source outputs a light pulse in one encoding period.
In the high-speed quantum key encoding method, an injection locking step may be further included, in which a main light source with a driving signal frequency f is used to obtain a first optical pulse and a second optical pulse through injection locking of the first circulator and the second circulator.
In the high-speed quantum key encoding method, the two phase modulators may be used to modulate the phase difference between the two first sub-optical pulses, so that the phase difference between the two combined first sub-optical pulses is 0 or pi. For example, the first phase modulator PM1 may be adjusted to change the phase of one first sub-optical pulse passing through the first phase modulator PM1 by pi/2, and the second phase modulator PM2 may be adjusted to change the phase of another first sub-optical pulse passing through the second phase modulator PM2 by-pi/2, and those skilled in the art may adopt various phase modulation methods to make the phase difference between the two combined first sub-optical pulses be 0 or pi, which is only an example and is not a specific limitation herein.
In the high-speed quantum key encoding method, a quantum state preparation step may be further included, in which the variable optical attenuator ATT is used to reduce the overall optical pulse signal intensity to the optimal average photon number per optical pulse, so as to obtain a quantum state signal.
In the high-speed quantum key encoding method, the method may further include a filtering step of filtering the optical pulses after the final combination to remove clutter influence.
Those skilled in the art will recognize that the high-speed quantum key encoding apparatus provided herein is suitable for use in a variety of encoding protocols, including but not limited to encoding schemes based on the spoofed state BB84 protocol, RFIQKD protocol, tri-state protocol, simplified BB84 protocol, MDIQKD protocol, and the like.
It should be noted that, in the description of the present application, the terms "first", "second", and the like are used for descriptive purposes only and for distinguishing similar objects, and no precedence between the two is intended or should be construed to indicate or imply relative importance. In addition, in the description of the present application, "a plurality" means two or more unless otherwise specified.
The present application has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to limit the application. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the presently disclosed embodiments and implementations thereof without departing from the spirit and scope of the present disclosure, and these fall within the scope of the present disclosure. The protection scope of this application is subject to the appended claims.
Claims (10)
1. A high-speed quantum key encoding apparatus, the encoding apparatus comprising: the system comprises a first signal light source, a second signal light source, an unequal arm interferometer, a first phase modulator, an intensity modulator and a fourth beam splitter;
the first signal light source is sequentially connected with the unequal arm interferometer in series, the second signal light source is sequentially connected with the intensity modulator in series, the fourth beam splitter comprises two input ends and one output end, the unequal arm interferometer is connected with one input end of the fourth beam splitter, and the intensity modulator is connected with the other input end of the fourth beam splitter;
the unequal-arm interferometer comprises a long arm and a short arm, and the first phase modulator is arranged on the long arm or the short arm;
the driving signal frequency of the first signal light source, the second signal light source, the first phase modulator and the intensity modulator are the same.
2. The high-speed quantum key encoding device of claim 1, wherein the encoding device further comprises a primary light source, a first beam splitter, a first circulator, a second circulator, the first beam splitter comprises an input end and two output ends, the output end of the main light source is connected with the input end of the first beam splitter, one output end of the first beam splitter is connected with the first port of the first circulator, the other output end of the first beam splitter is connected with the first port of the second circulator, the output end of the first signal light source is connected with the second port of the first circulator, the third port of the first circulator is connected with the unequal arm interferometer, the output end of the second signal light source is connected with the second port of the second circulator, and the third port of the second circulator is connected with the intensity modulator.
3. The high-speed quantum key encoding apparatus of claim 1, wherein the encoding apparatus further comprises a second phase modulator, the first phase modulator is disposed on the long arm, the second phase modulator is disposed on the short arm, or the first phase modulator is disposed on the short arm, and the second phase modulator is disposed on the long arm.
4. The high-speed quantum key encoding apparatus of claim 1, wherein the encoding apparatus further comprises a real-time stability maintenance system, the intensity modulator being connected to the real-time stability maintenance system.
5. The high-speed quantum key encoding apparatus of claim 1, wherein the encoding apparatus further comprises a filter connected to an output of the fourth beam splitter.
6. The high-speed quantum key encoding device of claim 1, wherein the encoding device further comprises a variable optical attenuator disposed at an end of the encoding device.
7. The high-speed quantum key encoding device of claim 1, wherein the driving signal frequency of the first signal light source and the second signal light source is 10 MHz-1 GHz.
8. The high-speed quantum key encoding apparatus of claim 3, wherein the driving signal frequency of the second phase modulator is the same magnitude as the driving signal frequency of the first signal light source.
9. The high-speed quantum key encoding device of any one of claims 1 to 8, wherein the first signal light source and the second signal light source are light sources with inner modulation function.
10. The high-speed quantum key coding method is applied to a high-speed quantum key coding device, wherein the coding device comprises a first signal light source, a second signal light source, an unequal arm interferometer, a first phase modulator, an intensity modulator and a fourth beam splitter; the first signal light source is sequentially connected with the unequal arm interferometer in series, the second signal light source is sequentially connected with the intensity modulator in series, the fourth beam splitter comprises two input ends and one output end, the unequal arm interferometer is connected with one input end of the fourth beam splitter, and the intensity modulator is connected with the other input end of the fourth beam splitter; the unequal-arm interferometer comprises a long arm and a short arm, and the first phase modulator is arranged on the long arm or the short arm;
the method comprises the following steps:
a first signal light source with a driving signal frequency f randomly generates a first light pulse for phase encoding;
a second signal light source with the driving signal frequency f randomly generates a second light pulse with time coding or vacuum state coding;
the method comprises the steps that an unequal arm interferometer and a first phase modulator with a driving signal frequency f carry out phase coding, the unequal arm interferometer changes one beam of light pulse generated by a first signal light source into two temporally separated beams of first sub-light pulses, the first phase modulator with the driving signal frequency f adjusts the phase difference of the two beams of first sub-light pulses, the phase difference of the two beams of first sub-light pulses after combination is made to be 0 or pi, and the light pulse with the frequency of 2f after combination is obtained;
the intensity modulator with the driving signal frequency f is used for preparing a decoy state, and the intensity modulator with the driving signal frequency f attenuates the intensity of a second light pulse used for preparing the decoy state;
and the fourth beam splitter combines two paths of light pulses generated by the first signal light source and the second signal light source into one path to obtain the light pulse with the output frequency of 2 f.
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