CN116609983A - Time entangled two-photon generation system and generation method - Google Patents
Time entangled two-photon generation system and generation method Download PDFInfo
- Publication number
- CN116609983A CN116609983A CN202310658685.8A CN202310658685A CN116609983A CN 116609983 A CN116609983 A CN 116609983A CN 202310658685 A CN202310658685 A CN 202310658685A CN 116609983 A CN116609983 A CN 116609983A
- Authority
- CN
- China
- Prior art keywords
- beam splitter
- output
- pulse
- entangled
- sub
- 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.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 70
- 239000013078 crystal Substances 0.000 claims abstract description 37
- 238000001208 nuclear magnetic resonance pulse sequence Methods 0.000 claims abstract description 31
- 238000006243 chemical reaction Methods 0.000 claims abstract description 11
- 230000002269 spontaneous effect Effects 0.000 claims abstract description 10
- 230000003287 optical effect Effects 0.000 claims description 58
- 230000005540 biological transmission Effects 0.000 claims description 12
- 238000001514 detection method Methods 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 3
- 230000001105 regulatory effect Effects 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 12
- 239000013307 optical fiber Substances 0.000 description 7
- 238000004891 communication Methods 0.000 description 4
- 125000004122 cyclic group Chemical group 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000010287 polarization Effects 0.000 description 4
- 238000012545 processing Methods 0.000 description 2
- 230000000750 progressive effect Effects 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- QBLDFAIABQKINO-UHFFFAOYSA-N barium borate Chemical compound [Ba+2].[O-]B=O.[O-]B=O QBLDFAIABQKINO-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- WYOHGPUPVHHUGO-UHFFFAOYSA-K potassium;oxygen(2-);titanium(4+);phosphate Chemical compound [O-2].[K+].[Ti+4].[O-]P([O-])([O-])=O WYOHGPUPVHHUGO-UHFFFAOYSA-K 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/3515—All-optical modulation, gating, switching, e.g. control of a light beam by another light beam
- G02F1/3517—All-optical modulation, gating, switching, e.g. control of a light beam by another light beam using an interferometer
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/355—Non-linear optics characterised by the materials used
- G02F1/3551—Crystals
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/365—Non-linear optics in an optical waveguide structure
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
The application discloses a time entangled two-photon generating system and a generating method, wherein the generating system comprises a laser source, an equal-arm MZ interferometer, a circulating waveguide, an upper computer, a controller, a second-order nonlinear crystal and a light splitting module, the equal-arm MZ interferometer consists of a first beam splitter, a second beam splitter and a phase modulator, the upper computer calculates the light intensity percentage of a sub-pulse output by the laser source after modulating the light pulse by the phase modulator and calculates the light intensity percentage of the sub-pulse output by the second beam splitter after modulating the sub-pulse in each cycle by the phase modulator, the controller correspondingly modulates the phase modulator based on each light intensity percentage, so that the sub-pulse sequence output after multiple cycles is output from the output lower port of the second beam splitter in corresponding light intensity proportion, and the sub-pulse sequence output after multiple cycles generates entangled two-photons through spontaneous parametric down-conversion process by the second-order nonlinear crystal.
Description
Technical Field
The application belongs to the technical field of quantum information, and particularly relates to a time-entangled two-photon generation system and a generation method.
Background
The quantum entanglement is a core resource in the quantum information system, plays a vital role in the performance of the quantum information system, and is widely applied to the subdivision fields of quantum key distribution, quantum secure communication, quantum invisible state transmission, quantum precise measurement, quantum cryptography and the like. In general, quantum entanglement can be achieved by physical systems based on nonlinear processes, such as by using conservation of energy, conservation of linear momentum, and conservation of angular momentum in nonlinear processes, and quantum entanglement can be established on different degrees of freedom of photons, such as polarization state entanglement, path entanglement, time entanglement, orbital angular momentum entanglement, and the like. The polarization entangled photon source and the time entangled photon source are suitable for the field of quantum communication.
Currently, the communication field mainly uses optical fibers as carriers for information transmission. The polarization entangled photons are transmitted in the optical fiber, and external environment changes such as optical fiber disturbance have great influence on polarization entanglement degree, so that the transmission distance of the entangled photons is limited. The time entangled photon pair is entangled in time relation, and the entanglement degree is not affected by the transmission distance, so that the long-distance communication is realized, and the method is a coding mode which is most widely applied to actual quantum key distribution.
A current common method of generating time entangled photon pairs is a down conversion technique, as shown in fig. 1, using a system of lasers, unequal arm MZ interferometers, nonlinear materials, beam splitters, and couplers to generate entangled photons. The pump light is provided by a laser, and the unequal arm MZ interferometer usually adopts an optical fiber coding optical path to perform time-splitting on the pump light to form early pulse and late pulse, and then performs early pulse and late pulse pumping. The temporally entangled photon pairs are generated using nonlinear materials and then split and coupled into optical fibers by beam splitters and couplers. However, this solution can only generate a pair of two-dimensional time entangled photon pairs, and to achieve quantum time entanglement with higher dimensions, more devices and delay paths are required, which may lead to problems of large occupied space, high resource consumption, high cost, and the like.
Disclosure of Invention
In order to solve the problems, the application provides a time entangled two-photon generation system and a generation method, wherein the optical pulse output by a laser source circularly forms a sub-pulse sequence on an equal-arm MZ interferometer and a circulating waveguide for a plurality of times, and the sub-pulse sequence generates time entangled two photons after being input into a second-order nonlinear crystal, so that the system has a simple structure and saves resources and space. The specific scheme is as follows:
In a first aspect, the application discloses a time-entangled two-photon generation system, which comprises a laser source, an equal-arm MZ interferometer, a circulating waveguide, an upper computer, a controller, a second-order nonlinear crystal and a light splitting module;
the laser source is used for outputting optical pulses;
the equal-arm MZ interferometer and the circulating waveguide form a circulating loop, and the circulating loop is used for time-splitting the optical pulse and forming a sub-pulse sequence; the equal-arm MZ interferometer consists of a first beam splitter, an interference upper arm, an interference lower arm, a phase modulator and a second beam splitter, wherein two ends of the interference upper arm are respectively connected with an output upper port of the first beam splitter and an input upper port of the second beam splitter, two ends of the interference lower arm are respectively connected with an output lower port of the first beam splitter and an input lower port of the second beam splitter, the phase modulator is arranged on the interference upper arm, and an input lower port of the first beam splitter is used for receiving light pulses output by the laser source; the two ends of the circulating waveguide are respectively connected with the input upper port of the first beam splitter and the output upper port of the second beam splitter, and are used for inputting the beam splitting optical pulse output from the output upper port of the second beam splitter to the input upper port of the first beam splitter; the output lower port of the second beam splitter is used for outputting the sub-pulse sequence;
The upper computer is used for inputting parameters for generating entangled two photons and calculating the light intensity percentage R of the sub-pulse output from the lower port output by the second beam splitter after the light pulse output by the laser source is modulated by the phase modulator based on the parameters 0 Calculating the light intensity percentage of sub-pulses output from the lower port of the second beam splitter after the light splitting light pulses in each cycle are modulated by the phase modulator, and respectivelyCorresponding to R 1 、R 2 …R N The method comprises the steps of carrying out a first treatment on the surface of the Wherein the light intensity percentage is the light intensity of the sub-pulse output from the lower port output by the second beam splitter/the pulse light intensity input from the lower port input or the upper port input by the first beam splitter, and N is the cycle number;
the controller is respectively connected with the phase modulator and the upper computer and is used for receiving the light intensity percentages R output by the upper computer 0 、R 1 、R 2 …R N And based on R 0 、R 1 、R 2 …R N Sequentially modulating the phase modulator accordingly;
the second-order nonlinear crystal is connected with the output lower port of the second beam splitter and is used for generating spontaneous parametric down-conversion process of the sub-pulse sequence and generating entangled two photons;
the light splitting module is connected with the second-order nonlinear crystal and is used for separating the entangled two photons.
Further, the parameters include: preset cycle number N, probability amplitude a 0 、a 1 、a 2 …a N The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the subpulse outputted from the lower port outputted from the second beam splitter after the optical pulse outputted from the laser source is modulated by the phase modulator is named as the 0 th subpulse, the subpulse outputted from the lower port outputted from the second beam splitter in each cycle is respectively named as the 1 st subpulse, the 2 nd subpulse … … nth subpulse, the 0 th subpulse, the 1 st subpulse, the 2 nd subpulse … … nth subpulse form the subpulse sequence, then a 0 Representing a probability amplitude of detection of entangled photon pairs in the 0 th sub-pulse time position; a, a 1 Representing the probability amplitude of detection of entangled photon pairs in the 1 st sub-pulse time position, and so on, a N Representing the probability amplitude of the entangled photon pair detected in the nth sub-pulse time position.
Further, the controller is connected with the laser source, when the laser source generates light pulses based on the driving electric signal, the driving electric signal is fed back to the controller by the laser source at the same time, and the controller starts to perform time sequence modulation on the phase modulator based on the driving electric signal.
Further, the system further comprises a third beam splitter and a photoelectric detector, wherein the input end of the third beam splitter is connected with the laser source, one output end of the third beam splitter is connected with the photoelectric detector, the other output end of the third beam splitter is connected with the input lower port of the first beam splitter, the photoelectric detector is connected with the controller, the third beam splitter is used for splitting the light pulse output by the laser source and transmitting part of the split light pulse to the photoelectric detector, and the photoelectric detector is used for converting the received light pulse into an electric pulse signal and transmitting the electric pulse signal to the controller, and the controller starts to perform time sequence modulation on the phase modulator based on the electric pulse signal.
Preferably, the optical splitting module is an arrayed waveguide grating or a wavelength division multiplexer.
Further, the system also includes a filter disposed between the second-order nonlinear crystal and the spectroscopic module for filtering out noise photons output from the second-order nonlinear crystal that are different in frequency from the entangled two-photons.
Further, the system also comprises an adjustable attenuator, wherein the adjustable attenuator is arranged on a transmission path of the laser source and the input lower port of the first beam splitter and is connected with the controller, and is used for attenuating the intensity of the light pulse output by the laser source.
In a second aspect, the present application discloses a time-entangled two-photon generation method, which is applied to the above-mentioned time-entangled two-photon generation system, the method comprising:
the upper computer inputs parameters for generating entangled two photons, calculates the light intensity percentage R of the sub-pulse output by the lower port output by the second beam splitter after the light pulse output by the laser source is modulated by the phase modulator based on the input parameters 0 Calculating the light intensity percentage R of the sub-pulse output from the lower port of the second beam splitter after the light splitting light pulse in each cycle is modulated by the phase modulator 1 、R 2 …R N ；
The laser source inputs an optical pulse to the input lower port of the first beam splitter, and the controller controls the optical intensity according to the percentage R 0 Adjusting the phase modulator to make the light pulse output by the laser source be R 0 Is output from the output lower port of the second beam splitter in 1-R 0 The light intensity proportion of the first beam splitter is output to the first circulating loop from the output upper port of the second beam splitter; the controller is according to R 1 Adjusting the phase modulator to make the light-splitting pulse entering the first circulation loop in R 1 Is output from the output lower port of the second beam splitter in 1-R 1 The light intensity proportion of the first beam splitter is output to a first circulating loop from an output upper port of the first beam splitter; with this loop … …, the controller is based on R N The phase modulator is regulated, so that all the light splitting light pulses entering the Nth circulation loop are output from the output lower port of the second beam splitter, and the time sequence modulation of the phase modulator by the controller in the entangled state generation period is completed;
a plurality of sub-pulses output from the lower port of the second beam splitter output form a sub-pulse sequence, and the sub-pulse sequence generates spontaneous parametric down-conversion process through a second-order nonlinear crystal and generates entangled two photons;
the entangled two photons are separated and output after passing through the light splitting module.
Further, when the controller is connected to the laser source, the method further comprises:
when the laser source generates light pulses based on the driving electric signal, the laser source simultaneously feeds back the driving electric signal to the controller, and the controller starts to perform time sequence modulation on the phase modulator based on the driving electric signal.
Further, when the system further includes a third beam splitter, an input end of the third beam splitter is connected to the laser source, one output end of the third beam splitter is connected to the photodetector, and another output end of the third beam splitter is connected to the input port of the first beam splitter, and the photodetector is connected to the controller, the method further includes:
the third beam splitter splits the optical pulse output by the laser source and transmits a part of the split optical pulse to the photoelectric detector, the photoelectric detector converts the received optical pulse into an electric pulse signal and transmits the electric pulse signal to the controller, and the controller starts to perform time sequence modulation on the phase modulator based on the electric pulse signal.
In general, the above technical solutions conceived by the present application, compared with the prior art, enable the following beneficial effects to be obtained:
The application provides a time entangled two-photon generating system and a generating method, wherein the generating system comprises a laser source, an equal-arm MZ interferometer, a circulating waveguide, an upper computer, a controller, a second-order nonlinear crystal and a light splitting module, the equal-arm MZ interferometer consists of a first beam splitter, a second beam splitter and a phase modulator arranged between the two beam splitters, the upper computer calculates the light intensity percentage R of a sub-pulse output by the laser source after the light pulse output by the laser source is modulated by the phase modulator based on the input parameters 0 Calculating the light intensity percentage R of the sub-pulse output from the second beam splitter after the light splitting light pulse in each cycle is modulated by the phase modulator 1 、R 2 …R N The controller correspondingly time-sequence modulates the phase modulator based on the light intensity percentages, so that the light splitting light pulse entering the circulation loop is output from the output lower port of the second beam splitter in a corresponding light intensity proportion, a plurality of sub-pulses output from the output lower port of the second beam splitter form a sub-pulse sequence after multiple times of circulation, and the sub-pulse sequence generates spontaneous parametric down-conversion process through the second-order nonlinear crystal and generates entangled two photons. According to the application, the entanglement state of the time entangled photon pair with corresponding dimension is obtained by modulating the phase modulator on the equal-arm MZ interferometer in each process according to the preset circulation times and the preset probability amplitude of each process to form the sub-pulse, the number of the equal-arm MZ interferometers is not depended, the advantage of adaptability adjustment is achieved, and the circulation loop structure of the application saves resources and space.
Drawings
In order to more clearly illustrate this embodiment or the technical solutions of the prior art, the drawings that are required for the description of the embodiment or the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a prior art structure of the present application;
FIG. 2 is a schematic diagram of a time-entangled two-photon generation system according to an embodiment of the present application;
FIG. 3 is a timing diagram of a sub-pulse sequence of the output of the second splitter output lower port in one embodiment of the application;
FIG. 4 is a timing diagram of a sub-pulse sequence of the output of the lower port of the second splitter according to another embodiment of the present application;
FIG. 5 is a schematic diagram of a time-entangled two-photon generation system according to another embodiment of the present application;
FIG. 6 is a schematic diagram of a time-entangled two-photon generation system according to another embodiment of the present application;
FIG. 7 is a schematic diagram of a time-entangled two-photon generation system according to another embodiment of the present application;
FIG. 8 is a schematic diagram of a time-entangled two-photon generation system according to another embodiment of the present application;
FIG. 9 is a schematic diagram of a time-entangled two-photon generation system according to the present application based on the embodiments shown in FIGS. 7 and 8;
fig. 10 is a schematic structural diagram of a time-entangled two-photon generation system according to the present application provided based on fig. 6 and 9.
Detailed Description
In order that the above-recited objects, features and advantages of the present application will become more readily apparent, a more particular description of embodiments of the application will be rendered by reference to the appended drawings and appended drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, but the present application may be practiced in other ways other than those described herein, and persons skilled in the art will readily appreciate that the present application is not limited to the specific embodiments disclosed below.
In order to facilitate understanding and explanation of the technical solutions provided by the embodiments of the present application, the following description will first explain the background art of the present application.
A current common method of generating time entangled photon pairs is a down conversion technique, as shown in fig. 1, using a system of lasers, unequal arm MZ interferometers, nonlinear materials, beam splitters, and couplers to generate entangled photons. The pump light is provided by a laser, and the unequal arm MZ interferometer usually adopts an optical fiber coding optical path to perform time-splitting on the pump light to form early pulse and late pulse, and then performs early pulse and late pulse pumping. The temporally entangled photon pairs are generated using nonlinear materials and then split and coupled into optical fibers by beam splitters and couplers. However, this solution can only generate a pair of two-dimensional time entangled photon pairs, and to achieve quantum time entanglement with higher dimensions, more devices and delay paths are required, which may lead to problems of large occupied space, high resource consumption, high cost, and the like.
Based on the above, the application provides a time-entangled two-photon generation system, as shown in fig. 2, comprising a laser source, a constant arm MZ interferometer, a circulating waveguide, an upper computer, a controller, a second-order nonlinear crystal and a light splitting module.
The laser source is used to output pulses of light. Specifically, the laser source may be a free space laser source device such as a distributed feedback laser, a distributed Bragg reflector laser, a semiconductor laser diode, or an on-chip integrated laser source device such as a hybrid integrated III-V semiconductor laser diode or a vertical cavity surface emitting laser.
The equal arm MZ interferometer and the circulating waveguide form a circulating loop for time-splitting the optical pulses and forming a sub-pulse train. Specifically, the equal-arm MZ interferometer consists of a first beam splitter, an interference upper arm, an interference lower arm, a phase modulator and a second beam splitter, wherein two ends of the interference upper arm are respectively connected with an output upper port of the first beam splitter and an input upper port of the second beam splitter, two ends of the interference lower arm are respectively connected with an output lower port of the first beam splitter and an input lower port of the second beam splitter, the phase modulator is arranged on the interference upper arm, and the input lower port of the first beam splitter is used for receiving light pulses output by a laser source; the two ends of the circulating waveguide are respectively connected with an input upper port of the first beam splitter and an output upper port of the second beam splitter, and are used for inputting the beam splitting optical pulse output from the output upper port of the second beam splitter to the input upper port of the first beam splitter; the output lower port of the second beam splitter is used for outputting the sub-pulse train.
For convenience of distinction and understanding, it is known from the above that the pulse output from the output upper port of the second beam splitter is named as a spectroscopic pulse, and the pulse output from the output lower port of the second beam splitter is named as a sub pulse. Specifically, the sub-pulse output from the lower port of the second beam splitter output after the optical pulse output by the laser source is modulated by the phase modulator is named as the 0 th sub-pulse, and the sub-pulse output from the lower port of the second beam splitter output in each cycle is named as the 1 st sub-pulse, the 2 nd sub-pulse … … nth sub-pulse, and the 0 th sub-pulse, the 1 st sub-pulse and the 2 nd sub-pulse … … nth sub-pulse respectively form a sub-pulse sequence.
The upper computer is used for inputting parameters for generating entangled two photons and calculating the light intensity percentage R of the sub-pulses output from the lower port output by the second beam splitter after the light pulses output by the laser source are modulated by the phase modulator based on the parameters 0 Calculating the light intensity percentage of sub-pulses output from the lower port of the second beam splitter after the light splitting light pulses in each cycle are modulated by the phase modulator, wherein the sub-pulses respectively correspond to R 1 、R 2 …R N The method comprises the steps of carrying out a first treatment on the surface of the Wherein the light intensity percentage is the light intensity of the sub-pulse output from the lower port of the second beam splitter/the light intensity of the pulse input from the lower port or the upper port of the first beam splitter, and N is the cycle number.
Specifically, the light intensity percentage R 0 To output the lower port from the second beam splitterThe light intensity of the 0 th sub-pulse is output/the light intensity input from the first beam splitter input lower port. Percentage of light intensity R 1 The light intensity of the 1 st sub-pulse is output from the second beam splitter output lower port in the first cycle/the light intensity of the spectroscopic light pulse input from the first beam splitter input upper port in the first cycle. Percentage of light intensity R 2 For the light intensity of the 2 nd sub-pulse output from the second beam splitter output lower port in the second cycle/the light intensity of the beam splitting light pulse input from the first beam splitter input upper port in the second cycle, and so on, the light intensity percentage R N The light intensity of the nth sub-pulse is output from the second beam splitter output lower port in the nth cycle/the light intensity of the spectroscopic light pulse input from the first beam splitter input upper port in the nth cycle.
The parameters for generating entangled two photons in the present application include a preset number of cycles N, probability amplitude a 0 、a 1 、a 2 …a N Wherein a is 0 Representing a probability amplitude of detection of entangled photon pairs in the 0 th sub-pulse time position; a, a 1 Representing the probability amplitude of detection of entangled photon pairs in the 1 st sub-pulse time position, and so on, a N Representing the probability amplitude of the entangled photon pair detected in the nth sub-pulse time position. Note that, for the probability amplitude a 0 、a 1 、a 2 …a N Some values may be set to 0 as desired, e.g. set a 1 When the value is 0, the spectrum light pulse in the first cycle is modulated by the phase modulator and is output from the output upper port of the second beam splitter into the second cycle, while the sub-pulse is not output from the output lower port of the second beam splitter, namely the 1 st sub-pulse is not output, and obviously the corresponding R 1 Is 0.
In the application, the upper computer comprises a parameter setting module, a data processing module and a data transmission module which are connected in sequence, wherein the parameter setting module is used for inputting parameters for generating entangled two photons, such as the number of times of circulation N and the probability amplitude a 0 、a 1 、a 2 …a N . The data processing module calculates the optical pulse output by the laser source based on the set parameter calculation, modulates the optical pulse by the phase modulator and outputs the optical pulse from the second beam splitter output lower portIntensity percentage R of sub-pulse 0 Calculating the light intensity percentage of sub-pulses output from the lower port of the second beam splitter after the light splitting light pulses in each cycle are modulated by the phase modulator, wherein the sub-pulses respectively correspond to R 1 、R 2 …R N . The data transmission module is used for transmitting R 0 、R 1 、R 2 …R N And transmitted to the controller.
The controller is respectively connected with the phase modulator and the upper computer and is used for receiving the light intensity percentages R output by the upper computer 0 、R 1 、R 2 …R N And based on R 0 、R 1 、R 2 …R N The phase modulator is time-sequentially modulated accordingly.
Each light intensity percentage R based on upper computer feedback by controller 0 、R 1 、R 2 …R N And completing the phase modulation of the phase modulator one by one according to the time sequence. Specifically, the controller passes through each light intensity percentage R 0 、R 1 、R 2 …R N And calculating and acquiring the initial process of outputting sub-pulses from the lower port output by the second beam splitter by the optical pulse output by the laser source and the modulation voltage or current of the phase modulator corresponding to each subsequent cyclic process, and sequentially completing the initial process and the phase modulation of each cyclic process by the controller according to a preset phase modulation period (the retention time of each modulation voltage or current).
The specific process is as follows: the light pulse output by the laser source is input from the input lower port of the first beam splitter, and the controller modulates the driving voltage or current of the phase modulator to make the light pulse output by the laser source take R 0 Is output from the output lower port of the second beam splitter, then correspondingly outputs the light intensity ratio of 1-R 0 The light intensity ratio of the beam splitter is input into a first circulation loop from the output upper port of the second beam splitter, the beam splitting light pulse entering the first circulation loop is transmitted to the input upper port of the first beam splitter through a circulation waveguide and then is transmitted to the equal-arm MZ interferometer, and in the first circulation loop, the controller modulates the driving voltage or current of the phase modulator to enable the beam splitting light pulse entering the first circulation loop to be in R 1 From the light intensity ratio of (1)The output of the output lower port of the two beam splitters is correspondingly 1-R 1 Is output from the output upper port of the second beam splitter into the second circulation loop. The split-beam pulse entering the second circulation loop is transmitted to the input upper port of the first beam splitter through the circulation waveguide and then enters the equal-arm MZ interferometer for transmission, and in the second circulation loop, the controller modulates the driving voltage or current of the phase modulator to enable the split-beam pulse entering the second circulation loop to be in R 2 Is output from the output lower port of the second beam splitter, then correspondingly outputs the light intensity ratio of 1-R 2 Is output from the output upper port of the second beam splitter into the third circulation loop. And the time sequence modulation of the phase modulator is performed by a preset circulation process in the entangled state generation period.
The second-order nonlinear crystal is connected with the output lower port of the second beam splitter and is used for generating spontaneous parametric down-conversion process of the sub-pulse sequence and generating entangled two photons. The second-order nonlinear crystal can be any one of periodically polarized lithium niobate, periodically polarized potassium titanyl phosphate, periodically polarized barium metaborate and other nonlinear crystals, and can generate spontaneous parameters under the action of the sub-pulse sequence to generate entangled two photons. The entangled state that produces entangled two photons is expressed as:
|φ>＝a 0 |00>+a 1 |11>+a 2 |22>+…+a N |NN>
Assuming that the probability of generating entangled two photons by a single sub-pulse in the sub-pulse sequence through the second-order nonlinear crystal is P, the probability of generating entangled photon pairs by each sub-pulse in the sub-pulse sequence through the second-order nonlinear crystal is P n ＝P n ，P n Is a minimum value that is negligible, i.e., the probability that each sub-pulse in the sequence of sub-pulses will produce entangled photon pairs through the second-order nonlinear crystal is negligible. In addition, if a certain m sub-pulses (m is more than or equal to 2) in the sub-pulse sequence generate a plurality of entangled two photons at the same time, the entangled two photons can be screened out in the post-selection process, and only the process that only one entangled two photon is generated in the sub-pulse sequence in one entangled state generation period is selected.
In one embodiment of the application, the preset cycle is set 3 times, and the probability amplitude corresponds to a 0 、a 1 、a 2 、a 3 Specifically, a is 0 And a 2 Are all set to 0.a, a 0 Setting to 0 indicates that all optical pulses output by the laser source enter the first circulation loop from the output upper port of the second beam splitter after being modulated by the phase modulator, and no 0 th sub-pulse is output from the output lower port of the second beam splitter; a, a 2 Setting to 0 indicates that all the split light pulses entering the second circulation loop enter the third circulation loop from the output upper port of the second beam splitter after being modulated by the phase modulator, and the 2 nd sub-pulse is not output from the output lower port of the second beam splitter, and the entangled state of generating entangled two photons under the condition of setting parameters is expressed as follows: phi >＝a 1 |11>+a 3 |33>The corresponding sub-pulse sequence timing diagram is shown in FIG. 3, at t 0 No 0 th sub-pulse is generated in the phase modulation period corresponding to the time period, and at t 2 No sub-pulse 2 is generated in the phase modulation period corresponding to the time period, and at t 1 And t 3 And outputting the 1 st sub-pulse and the 3 rd sub-pulse correspondingly in the phase modulation period corresponding to the time period. The probability amplitude of the 1 st sub-pulse for generating entangled two photons through a second-order nonlinear crystal is a 1 The probability amplitude of the entangled two photons generated by the 3 rd sub-pulse through the second-order nonlinear crystal is a 3 。
In another embodiment of the present application, the preset cycle is set 4 times, and the probability amplitude corresponds to a 0 、a 1 、a 2 、a 3 、a 4 And none of these five probability magnitudes is 0. The entangled state based on this set parameter condition to generate entangled two photons is expressed as:
|φ>＝a 0 |00>+a 1 |11>+a 2 |22>+a 3 |33>+a 4 |44>
the corresponding sub-pulse sequence timing diagram is shown in FIG. 4, at t 0 、t 1 、t 2 、t 3 、t 4 The 0 th sub pulse, the 1 st sub pulse and the 1 st sub pulse are respectively and correspondingly output in the phase modulation period corresponding to the time period2 sub-pulses, 3 sub-pulses and 4 sub-pulses. The probability amplitude of the 0 th sub-pulse, the 1 st sub-pulse, the 2 nd sub-pulse, the 3 rd sub-pulse and the 4 th sub-pulse for generating entangled two photons through the second-order nonlinear crystal respectively corresponds to a 0 、a 1 、a 2 、a 3 、a 4 。
The light splitting module is connected with the second-order nonlinear crystal and is used for separating entangled two photons. Specifically, the optical splitting module is an arrayed waveguide grating or a wavelength division multiplexer.
The laser source outputs a pulse of light during the pulse period. When the pulse period of the laser source is greater than or equal to the entangled state generation period, only one optical pulse is ensured to be input to the input lower port of the first beam splitter in one entangled state generation period, so that the pulse frequency of the laser source is required to be modulated or an optical switch is arranged on a transmission path of the laser source and the input lower port of the first beam splitter, and the opening and the connection of the optical switch are regulated and controlled, so that only one optical pulse is ensured to be input to the input lower port of the first beam splitter in one entangled state generation period.
In the present application, in order to obtain the time when the laser source outputs the light pulse and the time when the controller starts modulating the phase modulator, the controller is connected to the laser source, as shown in fig. 5, when the laser source generates the light pulse based on the driving electric signal, the laser source simultaneously feeds back the driving electric signal to the controller, and the controller starts to perform time sequence modulation on the phase modulator based on the driving electric signal, that is, uses the time when the controller receives the driving electric signal as the modulation start point of the phase modulator, and then sequentially completes the initial process and the phase modulation of each cycle process according to the preset phase modulation period.
In order to obtain the time when the controller starts to modulate the phase modulator more accurately, and reduce errors, in another embodiment of the present application, a third beam splitter and a photo detector are further arranged in the time-entangled two-photon generating system, as shown in fig. 6, an input end of the third beam splitter is connected to the laser source, an output end of the third beam splitter is connected to the photo detector, another output end of the third beam splitter is connected to an input lower port of the first beam splitter, the photo detector is connected to the controller, the third beam splitter is used for splitting an optical pulse output by the laser source and transmitting a part of the split optical pulse to the photo detector, the photo detector is used for converting the received optical pulse into an electrical pulse signal and transmitting the electrical pulse signal to the controller, and the controller starts to perform time sequence modulation on the phase modulator based on the electrical pulse signal.
It should be noted that in this embodiment, in order to input most of the energy of the laser source output light pulse into the equal arm MZ interferometer, the beam splitting ratio of the third beam splitter is preferably set to 90:10. The method comprises the steps that an optical pulse output by a laser source is divided by energy of a third beam splitter, 10 parts of energy optical pulse is input to a photoelectric detector, 90 parts of energy optical pulse is input to an equal-arm MZ interferometer, the photoelectric detector converts the received optical pulse into an electric pulse signal and transmits the electric pulse signal to a controller, the controller starts to perform time sequence modulation on the phase modulator based on the electric pulse signal, namely, the time when the controller receives the electric pulse signal is used as a modulation starting point of the phase modulator, and then the initial process and the phase modulation of each cycle process are sequentially completed according to a preset phase modulation period.
In order to reduce noise interference, in one embodiment of the present application, the time-entangled two-photon generation system further includes a filter, as shown in fig. 7, disposed between the second-order nonlinear crystal and the spectroscopic module, for filtering out noise photons output from the second-order nonlinear crystal that are different in frequency from entangled two-photons.
The entangled two-photon is a signal photon and an idler photon respectively, a noise photon with different frequency from the entangled two-photon may exist in the entangled two-photon generated by the second-order nonlinear crystal, such as a sub-pulse, and the noise photon is filtered from the entangled two-photon by a filter.
In another embodiment of the present application, the time-entangled two-photon generating system further includes an adjustable attenuator, as shown in fig. 8, disposed on the transmission path of the laser source and the input lower port of the first beam splitter and connected to the controller for attenuating the intensity of the light pulse output from the laser source.
The adjustable attenuator is connected with the controller, specifically, the adjusting parameters of the adjustable attenuator can be set on the upper computer, the upper computer feeds back the intensity adjusting parameters to the controller, and the controller controls the adjustable attenuator to attenuate the light pulse output by the laser source to the proper intensity based on the received intensity adjusting parameters so as to reduce the noise output by the second-order nonlinear crystal.
Based on fig. 7 and 8, the embodiment of the application further provides a time-entangled two-photon generating system, as shown in fig. 9, wherein the time-entangled two-photon generating system comprises an adjustable attenuator and a filter, the adjustable attenuator is arranged on a transmission path of a laser source and an input lower port of a first beam splitter and is connected with a controller, and the filter is arranged between a second-order nonlinear crystal and a beam splitting module.
Based on fig. 6 and 9, another time-entangled two-photon generating system is provided according to an embodiment of the present application, as shown in fig. 10, the time-entangled two-photon generating system includes a third beam splitter, a photo detector, an adjustable attenuator, and a filter, an optical pulse output from a laser source is input to the third beam splitter to split the beam, the adjustable attenuator is disposed between the third beam splitter and the first beam splitter, the photo detector and the adjustable attenuator are both connected to a controller, a part of the optical pulse split by the third beam splitter is transmitted to the photo detector, and the photo detector converts the received optical pulse into an electrical pulse signal and transmits the electrical pulse signal to the controller; the other part of the light pulse is attenuated by the adjustable attenuator and then transmitted to the first beam splitter. The filter is arranged between the second-order nonlinear crystal and the light splitting module.
The above schemes can show that the upper computer calculates the light intensity percentage R of the sub-pulse output by the laser source after the light pulse output by the laser source is modulated by the phase modulator 0 Calculating the light intensity percentage R of the sub-pulse output from the second beam splitter after the light splitting light pulse in each cycle is modulated by the phase modulator 1 、R 2 …R N The controller correspondingly time-sequence modulates the phase modulator based on each light intensity percentage to ensure that the light splitting light pulse entering the circulation loop is output from the output lower port of the second beam splitter according to the corresponding light intensity proportion, and the light splitting light pulse is output from the first beam splitter after multiple times of circulationThe two beam splitters output a plurality of sub-pulses output by the lower port to form a sub-pulse sequence, and the sub-pulse sequence generates spontaneous parametric down conversion process through the second-order nonlinear crystal and generates entangled two photons. According to the application, the entanglement state of the time entangled photon pair with corresponding dimension is obtained by modulating the phase modulator on the equal-arm MZ interferometer in each process according to the preset circulation times and the preset probability amplitude of each process to form the sub-pulse, the number of the equal-arm MZ interferometers is not depended, the advantage of adaptability adjustment is achieved, and the circulation loop structure of the application saves resources and space.
Based on the time-entangled two-photon generation system provided by the embodiment of the application, the embodiment of the application also correspondingly provides a time-entangled two-photon generation method, which comprises the following steps:
s11: the upper computer inputs parameters for generating entangled two photons, calculates the light intensity percentage R of the sub-pulse output by the lower port output by the second beam splitter after the light pulse output by the laser source is modulated by the phase modulator based on the input parameters 0 Calculating the light intensity percentage R of the sub-pulse output from the lower port of the second beam splitter after the light splitting light pulse in each cycle is modulated by the phase modulator 1 、R 2 …R N 。
In S11, inputting parameters that generate entangled two photons includes: preset cycle number N, probability amplitude a 0 、a 1 、a 2 …a N The upper computer inputs a 0 、a 1 、a 2 …a N Calculating and obtaining the light intensity percentage R of the sub-pulse output from the lower port of the second beam splitter in each process 0 、R 1 、R 2 …R N . Each light intensity percentage R based on upper computer feedback by controller 0 、R 1 、R 2 …R N The phase modulator is time-sequentially modulated accordingly, as in step S12.
S12: the laser source inputs an optical pulse to the input lower port of the first beam splitter, and the controller controls the optical intensity according to the percentage R 0 Adjusting the phase modulator to make the light pulse output by the laser source be R 0 Is the ratio of the light intensity of (2)For example, output from the output lower port of the second beam splitter, 1-R 0 The light intensity proportion of the first beam splitter is output to the first circulating loop from the output upper port of the second beam splitter; the controller is according to R 1 Adjusting the phase modulator to make the light-splitting pulse entering the first circulation loop in R 1 Is output from the output lower port of the second beam splitter in 1-R 1 The light intensity proportion of the first beam splitter is output to a first circulating loop from an output upper port of the first beam splitter; with this loop … …, the controller is based on R N And adjusting the phase modulator to enable all the light splitting pulses entering the Nth circulation loop to be output from the output lower port of the second beam splitter, and completing the time sequence modulation of the phase modulator by the controller in the entangled state generation period.
In S12, the controller feeds back the respective light intensity percentages R based on the upper computer 0 、R 1 、R 2 …R N And completing the phase modulation of the phase modulator one by one according to the time sequence. Specifically, the controller passes through each light intensity percentage R 0 、R 1 、R 2 …R N Calculating and obtaining the initial process of outputting sub-pulses from the lower port output by the laser source through the second beam splitter and the modulation voltage or current of the phase modulator corresponding to each subsequent cyclic process, wherein the modulation voltage or current corresponding to each process is kept for a certain time, the time is a preset phase modulation period, and the controller sequentially completes the initial process and the phase modulation of each cyclic process according to the preset phase modulation period.
S13: the plurality of sub-pulses output from the lower port of the second beam splitter output form a sub-pulse sequence, and the sub-pulse sequence undergoes a spontaneous parametric down-conversion process through a second-order nonlinear crystal and generates entangled two photons.
S14: the entangled two photons are separated and output after passing through the light splitting module.
Based on the time-entangled two-photon generation method provided by the embodiment of the application, when the controller is connected with the laser source, the method further comprises:
when the laser source generates light pulses based on the driving electric signal, the laser source simultaneously feeds back the driving electric signal to the controller, and the controller starts to perform time sequence modulation on the phase modulator based on the driving electric signal.
The laser source outputs optical pulses under the action of the driving electric signals, the frequency of the driving electric signals is consistent with that of the optical pulses output by the laser source, and the driving electric signals are fed back to the controller by the laser source. The laser source only outputs one optical pulse in one period, and only one optical pulse is input to the input lower port of the first beam splitter in one entangled state generation period by modulating the pulse frequency of the laser source or setting an optical switch. The controller starts to perform time sequence modulation on the phase modulator based on the driving electric signal, namely the controller takes the moment when the driving electric signal is received as a modulation starting point of the phase modulator, and then sequentially completes the initial process and the phase modulation of each cycle process according to a preset phase modulation period.
Based on the time-entangled two-photon generation method provided by the embodiment of the application, further, the time-entangled two-photon generation system further includes a third beam splitter and a photoelectric detector, an input end of the third beam splitter is connected with the laser source, one output end of the third beam splitter is connected with the photoelectric detector, the other output end is connected with an input lower port of the first beam splitter, and when the photoelectric detector is connected with the controller, the method further includes:
the third beam splitter splits the optical pulse output by the laser source and transmits a part of the split optical pulse to the photoelectric detector, the photoelectric detector converts the received optical pulse into an electric pulse signal and transmits the electric pulse signal to the controller, and the controller starts to perform time sequence modulation on the phase modulator based on the electric pulse signal.
In this embodiment, the controller takes the time when the electric pulse signal is received as a modulation start point for the phase modulator, and then sequentially completes the initial process and the phase modulation of each cycle process according to a preset phase modulation period.
In this specification, each embodiment is described in a progressive manner, or a parallel manner, or a combination of progressive and parallel manners, and each embodiment focuses on the differences from other embodiments, and the same similar parts between the embodiments are referred to each other.
Moreover, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in an article or apparatus that comprises such element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The time entangled two-photon generation system is characterized by comprising a laser source, an equal-arm MZ interferometer, a circulating waveguide, an upper computer, a controller, a second-order nonlinear crystal and a light splitting module;
the laser source is used for outputting optical pulses;
the equal-arm MZ interferometer and the circulating waveguide form a circulating loop, and the circulating loop is used for time-splitting the optical pulse and forming a sub-pulse sequence; the equal-arm MZ interferometer consists of a first beam splitter, an interference upper arm, an interference lower arm, a phase modulator and a second beam splitter, wherein two ends of the interference upper arm are respectively connected with an output upper port of the first beam splitter and an input upper port of the second beam splitter, two ends of the interference lower arm are respectively connected with an output lower port of the first beam splitter and an input lower port of the second beam splitter, the phase modulator is arranged on the interference upper arm, and an input lower port of the first beam splitter is used for receiving light pulses output by the laser source; the two ends of the circulating waveguide are respectively connected with the input upper port of the first beam splitter and the output upper port of the second beam splitter, and are used for inputting the beam splitting optical pulse output from the output upper port of the second beam splitter to the input upper port of the first beam splitter; the output lower port of the second beam splitter is used for outputting the sub-pulse sequence;
The upper computer is used for inputting parameters for generating entangled two photons and calculating the light intensity percentage R of the sub-pulse output from the lower port output by the second beam splitter after the light pulse output by the laser source is modulated by the phase modulator based on the parameters 0 Calculating the light intensity percentage of sub-pulses output from the lower port of the second beam splitter after the light splitting light pulses in each cycle are modulated by the phase modulator, wherein the sub-pulses respectively correspond to R 1 、R 2 …R N The method comprises the steps of carrying out a first treatment on the surface of the Wherein the light intensity percentage is the light intensity of the sub-pulse output from the lower port output by the second beam splitter/the pulse light intensity input from the lower port input or the upper port input by the first beam splitter, and N is the cycle number;
the controller is respectively connected with the phase modulator and the upper computer and is used for receiving the light intensity percentages R output by the upper computer 0 、R 1 、R 2 …R N And based on R 0 、R 1 、R 2 …R N Sequentially modulating the phase modulator accordingly;
the second-order nonlinear crystal is connected with the output lower port of the second beam splitter and is used for generating spontaneous parametric down-conversion process of the sub-pulse sequence and generating entangled two photons;
the light splitting module is connected with the second-order nonlinear crystal and is used for separating the entangled two photons.
2. A time-entangled two-photon generation system according to claim 1, characterized in that the parameters include: preset cycle number N, probability amplitude a 0 、a 1 、a 2 …a N The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the subpulse outputted from the lower port outputted from the second beam splitter after the optical pulse outputted from the laser source is modulated by the phase modulator is named as the 0 th subpulse, the subpulse outputted from the lower port outputted from the second beam splitter in each cycle is respectively named as the 1 st subpulse, the 2 nd subpulse … … nth subpulse, the 0 th subpulse, the 1 st subpulse, the 2 nd subpulse … … nth subpulse form the subpulse sequence, then a 0 Representing a probability amplitude of detection of entangled photon pairs in the 0 th sub-pulse time position; a, a 1 Representing the probability amplitude of detection of entangled photon pairs in the 1 st sub-pulse time position, and so on, a N Representing the probability amplitude of the entangled photon pair detected in the nth sub-pulse time position.
3. The time-entangled two-photon generation system according to claim 1, wherein the controller is connected to the laser source, and when the laser source generates light pulses based on a driving electric signal, the laser source simultaneously feeds back the driving electric signal to the controller, and the controller starts time-series modulation of the phase modulator based on the driving electric signal.
4. The time-entangled two-photon generation system according to claim 1 further comprising a third beam splitter having an input connected to the laser source and an output connected to the photodetector and another output connected to the input lower port of the first beam splitter, and a photodetector connected to the controller, the third beam splitter being configured to split an optical pulse output from the laser source and transmit a portion of the split optical pulse to the photodetector, the photodetector being configured to convert the received optical pulse into an electrical pulse signal and transmit the electrical pulse signal to the controller, the controller beginning to time-sequence modulate the phase modulator based on the electrical pulse signal.
5. The time-entangled two-photon generation system according to claim 1 wherein the light splitting module is an arrayed waveguide grating or a wavelength division multiplexer.
6. A time entangled two photon generation system according to any of claims 1-5 further comprising a filter disposed between the second order nonlinear crystal and the spectroscopic module for filtering out noise photons output from the second order nonlinear crystal that are different in frequency from the entangled two photons.
7. A time entangled two photon generation system according to any of claims 1-5 further comprising an adjustable attenuator disposed in the transmission path of the laser source and the input lower port of the first beam splitter and connected to the controller for attenuating the intensity of the light pulses output by the laser source.
8. A time-entangled two-photon generation method, characterized in that the method is applied to the time-entangled two-photon generation system according to any one of claims 1 to 7, the system comprising: the device comprises an upper computer, a laser source, a controller, an equal-arm MZ interferometer, a circulating waveguide, a second-order nonlinear crystal and a light splitting module, wherein the equal-arm MZ interferometer and the circulating waveguide form a circulating loop, the equal-arm MZ interferometer consists of a first beam splitter, an interference upper arm, an interference lower arm, a phase modulator and a second beam splitter, two ends of the interference upper arm are respectively connected with an output upper port of the first beam splitter and an input upper port of the second beam splitter, two ends of the interference lower arm are respectively connected with an output lower port of the first beam splitter and an input lower port of the second beam splitter, and the phase modulator is arranged on the interference upper arm;
The method comprises the following steps:
the upper computer inputs parameters for generating entangled two photons, calculates the light intensity percentage R of the sub-pulse output by the lower port output by the second beam splitter after the light pulse output by the laser source is modulated by the phase modulator based on the input parameters 0 Calculating the light intensity percentage R of the sub-pulse output from the lower port of the second beam splitter after the light splitting light pulse in each cycle is modulated by the phase modulator 1 、R 2 …R N ；
The laser source inputs an optical pulse to the input lower port of the first beam splitter, and the controller controls the optical intensity according to the percentage R 0 Adjusting the phase modulator to make the light pulse output by the laser source be R 0 Is output from the output lower port of the second beam splitter in 1-R 0 The light intensity proportion of the first beam splitter is output to the first circulating loop from the output upper port of the second beam splitter; the controller is according to R 1 Adjusting the phase modulator to make the light-splitting pulse entering the first circulation loop in R 1 Is output from the output lower port of the second beam splitter in 1-R 1 The light intensity proportion of the first beam splitter is output to a first circulating loop from an output upper port of the first beam splitter; with this loop … …, the controller is based on R N The phase modulator is regulated, so that all the light splitting light pulses entering the Nth circulation loop are output from the output lower port of the second beam splitter, and the time sequence modulation of the phase modulator by the controller in the entangled state generation period is completed;
A plurality of sub-pulses output from the lower port of the second beam splitter output form a sub-pulse sequence, and the sub-pulse sequence generates spontaneous parametric down-conversion process through a second-order nonlinear crystal and generates entangled two photons;
the entangled two photons are separated and output after passing through the light splitting module.
9. The time-entangled two-photon generation method according to claim 8, characterized in that when the controller is connected to the laser source, the method further comprises:
when the laser source generates light pulses based on the driving electric signal, the laser source simultaneously feeds back the driving electric signal to the controller, and the controller starts to perform time sequence modulation on the phase modulator based on the driving electric signal.
10. The time-entangled two-photon generation method according to claim 8 wherein when the system further comprises a third beam splitter and a photodetector, the input of the third beam splitter is connected to the laser source, one output of the third beam splitter is connected to the photodetector, the other output is connected to the input lower port of the first beam splitter, and the photodetector is connected to the controller, the method further comprises:
the third beam splitter splits the optical pulse output by the laser source and transmits a part of the split optical pulse to the photoelectric detector, the photoelectric detector converts the received optical pulse into an electric pulse signal and transmits the electric pulse signal to the controller, and the controller starts to perform time sequence modulation on the phase modulator based on the electric pulse signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310658685.8A CN116609983A (en) | 2023-06-06 | 2023-06-06 | Time entangled two-photon generation system and generation method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310658685.8A CN116609983A (en) | 2023-06-06 | 2023-06-06 | Time entangled two-photon generation system and generation method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116609983A true CN116609983A (en) | 2023-08-18 |
Family
ID=87681678
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310658685.8A Pending CN116609983A (en) | 2023-06-06 | 2023-06-06 | Time entangled two-photon generation system and generation method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116609983A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117367578A (en) * | 2023-12-08 | 2024-01-09 | 合肥硅臻芯片技术有限公司 | Photon number resolution detector and detection method thereof |
-
2023
- 2023-06-06 CN CN202310658685.8A patent/CN116609983A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117367578A (en) * | 2023-12-08 | 2024-01-09 | 合肥硅臻芯片技术有限公司 | Photon number resolution detector and detection method thereof |
| CN117367578B (en) * | 2023-12-08 | 2024-02-23 | 合肥硅臻芯片技术有限公司 | Photon number resolution detector and detection method thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Silberhorn et al. | Generation of continuous variable Einstein-Podolsky-Rosen entanglement via the Kerr nonlinearity in an optical fiber | |
| JP5963869B2 (en) | Method and apparatus for synchronizing entanglement generation sources in a quantum communication network | |
| CN110504613A (en) | Fourier mode locking optical-electronic oscillator | |
| Takesue | Single-photon frequency down-conversion experiment | |
| US4817206A (en) | Optical-fiber transmission system with polarization modulation and heterodyne coherent detection | |
| CN109656078A (en) | A kind of Energy-Time tangles two-photon production method | |
| CN116609983A (en) | Time entangled two-photon generation system and generation method | |
| CN113178775A (en) | Coherent Itanium machine based on-chip whispering gallery mode optical microcavity | |
| Fernández-Pousa et al. | Fundamental SNR limits imposed by ASE in frequency-shifting loops | |
| CN102725926A (en) | Light source device and communication device | |
| EP4113897B1 (en) | Method and system of executing coherent optical communication using continuous-variable quantum cryptography and a remote cv laser source | |
| EP3971638A1 (en) | Method for generating heralded single-photons | |
| CN210839600U (en) | Quantum key distribution device and system | |
| US5390042A (en) | High sensitivity optical receiver suitable for single optical signal with high speed modulation | |
| CN109639364B (en) | Optical generating device and method for multi-channel arbitrary system phase coding signals | |
| CN114614903B (en) | Photon signal generator and generation method | |
| Joshi et al. | Hong-Ou-Mandel interference in the frequency domain | |
| CN113992323B (en) | Chip-based measuring equipment independent quantum key distribution system and method | |
| Tseng et al. | Photonic Generation of Linearly Chirped Microwave Signals Using Period-One Dynamics of Semiconductor Lasers | |
| CN112269270B (en) | Echo state network system based on dual polarization states of vertical cavity surface emitting laser | |
| CN115241718A (en) | Microwave generating device and method | |
| CN114337824A (en) | Polarization insensitive microwave photon link system and implementation method | |
| WO2023144868A1 (en) | Optical pulse generation device and generation method | |
| CN114696914B (en) | Solution to coherent i Xin Ji and combinatorial optimization problem | |
| CN115225155B (en) | System and method for realizing multichannel common carrier frequency phase coding based on array structure |
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 |