WO2018184209A1

WO2018184209A1 - Photon output method and device

Info

Publication number: WO2018184209A1
Application number: PCT/CN2017/079728
Authority: WO
Inventors: 熊春乐; 张翔; 梁恒惠
Original assignee: 华为技术有限公司
Priority date: 2017-04-07
Filing date: 2017-04-07
Publication date: 2018-10-11
Also published as: CN110521144B; CN110521144A

Abstract

The application provides a photon output method and device, which can improve the efficiency of simultaneously outputting a plurality of indistinguishable single photons in a unit of time. The method comprises: after a previous time window ends and when a heralding photon is detected for the first time, determining that a start time of a current time window is a time when the heralding photon is detected for the first time, wherein the heralding photon and a heralded photon appear as a pair, the heralding photon is used to herald the existence of the heralded photon, and the heralding photon and the heralded photon that appear as a pair are generated by the same photon pair source; in the current time window, detecting a heralding photon after the start time; and adjusting a transmission time of all heralded photons corresponding to all detected heralding photons in the current time window, such that all the heralded photons in the time window are output at the same output time.

Description

Photon output method and device

Technical field

The present application relates to the field of communications and, more particularly, to a method and apparatus for photon output.

Background technique

Single photon is the carrier of quantum communication and quantum computing. The emission rate of single photon source directly determines the rate of quantum communication and the speed and scalability of quantum computing systems. Moreover, some specific quantum communication methods and quantum gate operations (such as quantum relay, quantum network, linear optical quantum computing, etc.) require a light source that can simultaneously generate multiple unresolvable photons. The two most common methods in the prior art are two methods of simultaneously generating multiple unresolvable photons, one is to simply combine multiple photon sources, and the other is to generate multiple photons using a cascaded nonlinear process. Very inefficient.

Therefore, how to improve the efficiency of generating multiple unresolvable photons at the same time is an urgent problem to be solved.

Summary of the invention

The present application provides a method and apparatus for photon output that can increase the efficiency of simultaneously generating a plurality of indistinguishable photons.

In a first aspect, the present application provides a method for photon output, including: after the end of a previous time window, when a photon is first detected, determining a start time of the current time window as the first detection of the Declaring a photon, the declaring photon and the declaring photon appear in pairs, the declaring photon being used to announce the existence of the declared photon, the declaring photon and the pair of photons appearing in the same photon by the same photon Generated from the source;

Declaring a photon after the current time window start time in the current time window;

Adjusting the transmission time of all the announced photons corresponding to all the announced photons detected in the current time window, so that all the announced photons in the time window are output at the same output time.

Therefore, in the present application, by the first detection of the declaring photon after the end of the previous time window, the time at which the declaring photon is detected for the first time is determined as the starting time of the current time window, and is currently Detecting the photon after the current time window start time, and adjusting the transmission time of all the announced photons corresponding to all the announced photons, so that the announced photon in the time window is The output at the same output time increases the efficiency of simultaneously outputting photons.

Optionally, in an implementation manner of the first aspect, the same output moment is a first output moment after the end of the current time window in the preset output moment.

Optionally, in an implementation manner of the first aspect, after the end of the previous time window, when the photon is announced, the start time of the time window is determined to be before the time when the photon is announced. The method also includes:

When the detecting is turned on, the time of the first detected photon is detected as the starting time of the first time window;

Declaring a photon after the first time window start time in the first time window;

Adjusting the transmission time of all the announced photons corresponding to all the announced photons detected in the first time window, so that all of the announced photons in the first time window are outputted at the same output time.

Optionally, the adjusting all the announced light corresponding to all the announced photons detected in the current time window The transmission time of the child is such that all of the announced photons in the time window are output at the same output time, including:

Determining, between each of the all announced photons of the time window, a time interval between a time detected by the photon and the same output time;

Adjusting the transmission time of all the announced photons corresponding to all the announced photons detected in the current time window according to the determined time interval between the detected photon detection time and the same output time All of the said photons within the time window are declared to be output at the same output time.

Optionally, in an implementation manner of the first aspect, the time window has a length of 2 ⁿ T, and the T is a period in which the photon pair source generates the announcement photon and the announced photon, n The optical delay optical path is used to adjust the transmission time of the announced photon corresponding to the announcement photon.

Optionally, in an implementation manner of the first aspect, the length of the adjacent preset output moment is 2 ⁿ T, where the T is the photon pair source generating the announcement photon and the announced photon Cycle, n is the number of optical switches used in the optical delay optical path -1.

In a second aspect, the present application provides an apparatus for outputting photons, comprising: a processor, a single photon detector, and an optical delay optical path, the method of any of the optional implementations of the first aspect or the first aspect.

In a third aspect, the present application provides a system for outputting photons, including: a processor, a single photon detector, an optical delay optical path, and a plurality of photon pair sources, the processor being used for the first time after the end of the previous time window When the photon is detected, determining that the starting time of the current time window is the time when the photon is first detected, the declaring photon and the declared photon appearing in pairs, and the declaring photon is used to announce the announced photon. The existence of a photon, the declared photon and the pair of declared photons appearing from the same photon pair source;

The single photon detector is configured to detect the announcement photon within the current time window;

The optical delay optical path is configured to adjust a transmission time of the announced photon corresponding to the announced photon detected in the current time window, so that the announced photon in the time window is outputted at the same output time;

The plurality of photon pair sources are used to generate declarative photons of the same nature and the same declared photons of the same nature.

In a fourth aspect, the present application provides an apparatus for outputting photons, including a memory and a processor, the program storing thereon program code that can be used to indicate execution of the first or any optional implementation thereof, when When the code is executed, the processor can implement means for outputting photons in the method to perform various operations.

In a fifth aspect, the present application provides a computer storage medium having stored therein program code, the program code being operative to indicate execution of any of the foregoing first aspect or any optional implementation of the first aspect Methods.

DRAWINGS

1 is a schematic block diagram of a system for outputting photons and apparatus in accordance with the present application.

2 is a schematic flow chart of a method of outputting photons in accordance with the present application.

3 is a schematic block diagram of adjusting the transmission time of a declared photon in accordance with the present application.

4 is a schematic block diagram of an apparatus for outputting photons in accordance with the present application.

5 is a schematic block diagram of a system for outputting photons in accordance with the present application.

detailed description

The technical solutions in the present application will be described below with reference to the accompanying drawings.

FIG. 1 shows a schematic block diagram of a system 100 for outputting photons that can be applied to the present application.

As shown in FIG. 1, the system 100 includes a photon pair source 110. The photon pair source 110 can include a plurality of photon pair sources. Each photon pair source of the plurality of photon pairs can simultaneously generate a pair of photons, respectively. Photon detector and photon detector; the photon detector 120 includes a plurality of single photon detectors, the plurality of single photon detectors and the plurality of photon pairs are equal in number, and one-to-one correspondence The photon detector is configured to detect whether the photon generates a photon to the source. If the single photon detector detects the photon, the declared photon corresponding to the declaring photon can be generated; the optical delay optical path 130 is used to adjust the declared photon. The transmission time is used by the processor 140 to control the optical delay optical path to adjust the transmission time of the announced photon.

For a better understanding of the present application, the present application will be described below in conjunction with FIGS. 2-5.

FIG. 2 shows a schematic flow diagram of a method 200 of outputting photons of the present application. As shown in FIG. 2, the method 200 includes the following:

In 210, after the end of the previous time window, when the photon is declared for the first time, it is determined that the starting time of the current time window is the time when the photon is detected for the first time, and the photon is declared to be paired with the photon being announced. Appearing, the declaring photon is used to declare the existence of the declared photon, the declaring photon and the pair of photons appearing in the pair are generated by the same photon pair source.

It should be understood that the time window is a time window of a time division multiplexing operation.

Specifically, the photon pairs the source simultaneously to generate two photons with a certain probability. The two photons are time-correlated. In quantum photonics, two photons are defined as declaring photons and declaring photons, and detecting photons predicts that photons are declared. The presence. After the end of the previous time window, the time at which the photon is declared for the first time is determined as the starting time of the current time window.

Optionally, after detecting the photon at the end of the previous time window, determining that the start time of the time window is before the time when the photon is detected, the method further includes: when the detecting is turned on, the first one is The detected time of the announced photon is determined as the starting time of the first time window; in the first time window, the announced photon is detected; and the corresponding photon detected in the first time window is adjusted The transmission time of the photon is declared such that the announced photon in the first time window is output at the same output time.

In 220, within the current time window, the declaring photon after the start time of the time window is detected.

In 230, the transmission time of all the announced photons corresponding to all the announced photons detected in the current time window is adjusted, so that all the announced photons in the time window are outputted at the same output time.

Specifically, when the photon is detected, the photon is converted into an electric signal, and the photon disappears, and the transmission time of the declared photon corresponding to the declaring photon detected in the current time window is adjusted, so that the time window is obtained. The declared photons within the output are output at the same output time.

Optionally, determining a time interval between each of the all announced photons of the time window that announces the photon detection time and the same output time;

Adjusting the transmission time of all the announced photons corresponding to all the announced photons detected in the current time window according to the determined time interval between the time at which each photon is detected and the same output time, so that the time is within the time window All of this is declared to be output at the same output moment.

Specifically, in the time window, when the photon is declared, the time interval between the detected photon photon and the same output time is determined, and according to the time interval, the declared photon corresponding to the declaring photon is adjusted. The transmission time is such that the announced photon is output at the same output time. According to this method, all of the photons in the time window are decimated, so that all of the announced photons in the time window are output at the same output time.

Optionally, the same output moment is the first output after the end of the current time window in the preset output moment time.

Specifically, the photon generates a photon periodically to the source, and the same output moment also appears periodically, and the same output moment is the first output moment after the end of the current time window in the preset output moment.

It should be understood that the same output moment may be determined according to actual conditions, and the same output moment is not the first output moment after the end of the current time window in the preset output moment. For example, the same output moment may also be The second output time after the end of the current time window in the output time set.

Optionally, the length of the time window is 2 ⁿ T, ^where T is the period during which the photon pairs generate the declaring photon and the declared photon, and n is the number of optical switches used in the optical delay optical path -1, the optical The delayed optical path is used to adjust the transmission time of the announced photon corresponding to the announcement photon.

The optical delay optical path is used to adjust the photon transmission time, which is equivalent to how many paths the photon has gone. If the transmission time of the photon in the unit optical delay optical path is T, and the propagation speed of the photon in the optical delay optical path is v, then the length of the optical delay optical path is L (L=T×v). If the time output of the declared photon is 3T is adjusted, then the photon is declared to go a 3L optical delay optical path.

n+1 optical switches, plus a delay line of the appropriate length, can achieve any delay of 2 ⁿ T. For example, if we have optical delay optical paths of three lengths of L, 2L, and 4L, then we can achieve all delays of 0-7T, and three different delay optical paths require four optical switches.

Optionally, the length of the adjacent preset output moment is 2 ⁿ T, ^where T is the period during which the photon pairs generate the declaring photon and the declared photon, and n is the number of optical switches used in the optical delay optical path - 1.

As shown in FIG. 2, the photon pair source 1 and the photon pair source 2 have the same properties, that is, the photon pairs source 1 and the photon pair source 2 generate the same frequency, line width, pulse width, and polarization state of the declared photon. That is, photons are indistinguishable from the declared photons generated by source 1 and photons to source 2. The period of the fixed clock is 4T, and the T2 of each fixed clock period is preset as the output time. The length of the two adjacent output moments is 4T, and the time window is 4T. In FIG. 3, at the time T2, the announcement is detected. In the case of a photon, the time at which the photon is detected is determined as the starting time of the current time window, and the transmission time of the announced photon corresponding to the declaring photon is adjusted to be 4T, so that the declared photon corresponding to the declaring photon is in the time window. The first preset time output after the end, that is, output at time T2; when the photon is detected at the time T1 in the time window, the transmission time of the announced photon corresponding to the announcement photon is adjusted to be T, so that the photon is announced. The corresponding announced photon is output at the first preset time after the end of the time window, that is, at time T2.

After the current time window is over, when the photon is announced, the time at which the photon is detected is determined as the starting time of the current time window. For example, after the end of the previous time window, the photon is detected at time T3. Determining the time at which the photon is detected is determined as the starting time of the current time window, and adjusting the transmission time of the announced photon corresponding to the declaring photon to 7T, so that the announced photon corresponding to the declaring photon is after the end of the time window The first preset time output is outputted at time T2; when the photon is detected at the time T2 in the time window, the transmission time of the announced photon corresponding to the announcement photon is adjusted to 4T, so that the photon corresponding to the announcement photon is The photon is declared to be output at the first preset time after the end of the time window, that is, at the time T2.

It should be understood that the photon pair source 1 and the photon pair source 2 may generate photons at any time in one cycle. The timing of generating photons in the present application is for example only and is not limited thereto.

It should also be understood that photon pair source 1 and photon pair source 2 are by way of example only, and there may be multiple photon pair sources of similar nature.

Therefore, in the present application, by the first detection of the declaring photon after the end of the previous time window, the time at which the declaring photon is detected for the first time is determined as the starting time of the current time window, and Detecting the announcement photon in the current time window, and adjusting the detected photon corresponding to the announced photon The transmission time is such that the announced photons in the time window are output at the same output time, which improves the efficiency of simultaneously outputting photons.

FIG. 4 shows a schematic flow diagram of an apparatus 300 for outputting photons of the present application. As shown in FIG. 4, the apparatus 300 includes:

The processor 310 is configured to determine, when the photon is announced for the first time after the end of the previous time window, the start time of the current time window is the time when the photon is detected for the first time, and the photon and the photo are announced. Declaring the occurrence of photons in pairs, the declaring photons being used to declare the presence of the declared photons, the declaring photons and the paired photons appearing in pairs being generated by the same photon pair source;

a single photon detector 320, configured to detect an announcement photon after a current time window start time in the current time window;

The optical delay optical path 330 is configured to adjust a transmission time of all the announced photons corresponding to all the announced photons detected in the current time window, so that all the announced photons in the time window are outputted at the same output time.

It should be understood that the single photon detector 320 is a plurality of single photon detectors, the number of the single photon detectors being equal to the number of photon pair sources, and the single photon detectors are in one-to-one correspondence with the photon pair sources.

Optionally, the same output moment is the first output moment after the end of the current time window in the preset output moment.

Optionally, the processor is specifically configured to: when the photon is detected for the first time after the end of the previous time window, determine that the start time of the current time window is before the time when the photonic photo is detected, When the detecting is turned on, the time of the first detected photon is detected as the starting time of the first time window;

The single photon detector is specifically used for:

Declaring a photon after the start time of the first time window in the first time window;

The optical delay optical path is specifically used to:

Optionally, the length of the time window is 2 ⁿ T, the T is a period in which the photon pair source generates the announcement photon and the declared photon, and n is the number of optical switches used in the optical delay optical path. -1.

Optionally, the length of the adjacent preset output moment is 2 ⁿ T, where T is the period in which the photon pair source generates the declaring photon and the declared photon, and n is used in the optical delay optical path. The number of optical switches is -1.

It should be understood that the same property means that the photon has the same properties of the declared photon, such as the frequency, line width, pulse width, and polarization state.

Optionally, the system further includes an indication module, the indication module is configured to indicate that the system output is announced photons.

Optionally, the apparatus 300 may further include a memory 340 for storing a program, the program including code.

Optionally, when the code is executed, the processor 310 may control the device for outputting photons in the optical delay optical path implementation method 200 to perform various operations, which are not described herein for brevity.

It should be understood that, in the embodiment of the present application, the processor 310 may be a central processing unit (CPU), and the processor 310 may also be other general-purpose processors, digital signal processors, and application specific integrated circuits. Ready-to-use programmable gate arrays or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware Component components, etc. The general purpose processor may be a microprocessor or the processor or any conventional processor or the like.

The memory 340 can include read only memory and random access memory and provides instructions and data to the processor 310. A portion of the memory 340 may also include a non-volatile random access memory. For example, the memory 340 can also store information of the device type.

In an implementation process, at least one step of the above method may be performed by an integrated logic circuit of hardware in the processor 310, or the integrated logic circuit may perform the at least one step driven by an instruction in a software form. The steps of the method disclosed in connection with the present application may be directly embodied by hardware processor execution or by a combination of hardware and software modules in a processor. The software module can be located in a conventional storage medium such as random access memory, flash memory, read only memory, programmable read only memory or electrically erasable programmable memory, registers, and the like. The storage medium is located in the memory, and the processor 310 reads the information in the memory and completes the steps of the above method in combination with the hardware thereof. To avoid repetition, it will not be described in detail here.

FIG. 5 shows a schematic flow diagram of a system 400 for outputting photons of the present application. As shown in Figure 5, the system 400 includes:

The processor 410 is configured to determine, when the photon is announced for the first time after the end of the previous time window, the start time of the current time window is the time when the photon is first detected, and the photon is Declaring the occurrence of photons in pairs, the declaring photons being used to declare the presence of the declared photons, the declaring photons and the paired photons appearing in pairs being generated by the same photon pair source;

a single photon detector 420, configured to detect the announcement photon within the current time window;

The optical delay optical path 430 is configured to adjust a transmission time of the announced photon corresponding to the announced photon detected in the current time window, so that the announced photon in the time window is outputted at the same output time.

Photon pair source 440, the photon pair source comprising N photon pair sources of the same nature for generating photons.

Optionally, the system 400 for outputting photons further includes an indication module for indicating that the system 400 outputs the declared photons.

Specifically, the indication module sends an indication message to indicate that the system 400 outputs the declared photon. For example, the indication module can be a diode. When the diode is lit, it indicates that the system has multiple photon outputs when the diode is off. When it is indicated, the system outputs an empty pulse.

It should be understood that, in various embodiments of the present application, the size of the serial numbers of the above processes does not mean the order of execution, and the order of execution of each process should be determined by its function and internal logic, and should not be implemented in the present application. The process constitutes any limitation.

A person skilled in the art can clearly understand that for the convenience and brevity of the description, the specific working process of the system, the device and the unit described above can refer to the corresponding process in the foregoing method embodiment, and details are not described herein again.

The foregoing is only a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present application. It should be covered by the scope of protection of this application. Therefore, the scope of protection of the present application should be determined by the scope of the claims.

Claims

A method of photon output, comprising:

After detecting the photon for the first time after the previous time window bundle, determining that the starting time of the current time window is the time when the photon is first detected, the declaring photon and the declared photon appear in pairs. Declaring a photon for announcing the existence of the declared photon, the declaring photon and the pair of photons appearing in the pair being generated by the same photon pair source;

Declaring a photon after the current time window start time in the current time window;

Adjusting the transmission time of all the announced photons corresponding to all the announced photons detected in the current time window, so that all the announced photons in the time window are output at the same output time.
The method according to claim 1, wherein the same output time is a first output time after the end of the current time window in the preset output time.
The method according to claim 1 or 2, wherein, after the end of the previous time window, when the photon is declared for the first time, the start time of the current time window is determined to be that the photon is detected. Before the moment, the method further includes:

When the detection is turned on, determining the time of the first detected announcement photon as the starting time of the first time window;

Declaring a photon after the first time window start time in the first time window;

Adjusting the transmission time of all the announced photons corresponding to all the announced photons detected in the first time window, so that all of the announced photons in the first time window are outputted at the same output time.
The method according to any one of claims 1 to 3, wherein the adjusting the transmission time of all the announced photons corresponding to all the announced photons detected in the current time window is made within the time window All of the said photons are declared to be output at the same output time, including:

Determining, between each of the all announced photons of the time window, a time interval between a time detected by the photon and the same output time;

Adjusting the transmission time of all the announced photons corresponding to all the announced photons detected in the current time window according to the determined time interval between the detected photon detection time and the same output time All of the said photons within the time window are declared to be output at the same output time.
The method according to any one of claims 1 to 4, wherein the time window has a length of 2 n T, and the T is the photon pair source generating the declarative photon and the declared photon The period n is the number of optical switches used in the optical delay optical path -1, and the optical delay optical path is used to adjust the transmission time of the announced photon corresponding to the announcement photon.
The method according to any one of claims 1 to 5, wherein the length of the adjacent preset output time is 2 n T, the T is the photon pair source generating the announcement photon and the The period in which the photon is declared, n is the number of optical switches used in the optical delay optical path -1.
A device for outputting photons, comprising:

a processor, configured to determine, at a time after the end of the previous time window, the first time the photon is announced, the start time of the current time window is the time when the photon is detected for the first time, the announcement photon and the announced Photons appear in pairs, the declaring photons being used to declare the presence of the declared photons, the declaring photons and the pair of proposed photons being produced by the same photon pair source;

a single photon detector for detecting the current time window starting time within the current time window Announcement photon;

The optical delay optical path is configured to adjust a transmission time of all the announced photons corresponding to all the announced photons detected in the current time window, so that all of the announced photons in the time window are outputted at the same output time.
The apparatus according to claim 7, wherein the same output time is a first output time after the end of the current time window in the preset output time.
The device according to claim 7 or 8, wherein the processor is specifically configured to:

After the end of the previous time window, when the photon is declared for the first time, it is determined that the start time of the current time window is before the time when the photon is detected, and when the detection is turned on, the first detected Determining the time of the photon is determined as the starting time of the first time window;

The single photon detector is specifically used for:

Declaring a photon after the start time of the first time window in the first time window;

The optical delay optical path is specifically used to:

Adjusting the transmission time of all the announced photons corresponding to all the announced photons detected in the first time window, so that all of the announced photons in the first time window are outputted at the same output time.
The device according to any one of claims 7 to 9, wherein the processor is specifically configured to:

Determining, between each of the all announced photons of the time window, a time interval between a time detected by the photon and the same output time;

Adjusting the transmission time of all the announced photons corresponding to all the announced photons detected in the current time window according to the determined time interval between the detected photon detection time and the same output time All of the said photons within the time window are declared to be output at the same output time.
The apparatus according to any one of claims 7 to 10, wherein the time window has a length of 2 n T, and the T is the photon pair source generating the declarative photon and the declared photon The period, n is the number of optical switches used in the optical delay optical path -1.
The apparatus according to any one of claims 7 to 11, wherein the length of the adjacent preset output time is 2 n T, the T is the photon pair source generating the announcement photon and the The period in which the photon is declared, n is the number of optical switches used in the optical delay optical path -1.
A system comprising the single photon detector of any one of claims 7 to 12, a processor, an optical delay optical path, and a plurality of photon pair sources of the same nature.
The system of claim 13 wherein said system further comprises an indication module for indicating that said system output is declared photons.