Quantum signal parametric amplification system and method

Abstract

The invention discloses a quantum signal parametric amplification system and method.A laser light source module in the quantum signal parametric amplification system outputs a first path of laser and a third path of laser, and a signal modulation module modulates the first path of laser according to communication information to obtain conjugate symmetric quantum signals; the coupler mixes the third path of laser and the conjugate symmetric quantum signal to obtain a mixed signal, and the amplification module carries out parametric amplification on the mixed signal. According to the invention, the first path of laser and the third path of laser which have the same frequency are obtained, the first path of laser is modulated, and then the third path of laser is used as the pump light for parametric amplification, so that synchronous amplification of communication information carried in conjugate symmetric quantum signals and conjugate copies of the communication information can be realized, and thus the influence of noise can be resisted; interference of noise on quantum signals is reduced, and safety and efficiency of quantum applications such as quantum communication are guaranteed. The method is widely applied to the technical field of quantum communication.

Description

Technical Field

[0001] The present invention relates to the field of quantum communication technology, and in particular to a quantum signal parameter amplification system and method. Background Art

[0002] Classical optical communication can cover distances from 10 km at short distances to thousands of kilometers at long distances, with communication rates ranging from 40 Gbps to 1 Tbps, and receiver bandwidths typically between 20 and 60 GHz. Compared with classical optical communication, the transmission distance and bandwidth of quantum communication are limited due to the weak characteristics of quantum signals. These limitations are mainly attributed to the lack of efficient quantum repeaters and high-efficiency, low-noise high-speed photodetectors. Quantum repeaters are a key constraint for various quantum communication systems. At the same time, there is a trade-off between the efficiency and rate of semiconductor photodetectors, and it is difficult to meet the requirements of both at the same time. For example, in the continuous variable quantum key distribution (CVQKD) system, its security depends largely on whether the photodetector can reach the quantum noise limit (Shot Noise Limit, SNL), but the high-speed photodetectors currently on the market are difficult to meet this. Traditional high-speed photodetectors are suitable for classical optical communication, but are not suitable for the quantum noise limit detection required for CVQKD, because their low detection efficiency reduces the transmission distance, and the high noise level limits the security key rate.

[0003] Although preamplifiers can be used to parametrically amplify quantum signals, thereby reducing the impact of noise and compensating for the shortcomings of existing quantum communication systems, the amplifiers used in currently used communication systems are not suitable for quantum communication. For example, in classical optical communication systems, erbium doped fiber amplifiers (EDFA) are widely used as preamplifiers for signal light to enhance signal strength. However, since EDFA has a high noise coefficient, if EDFA is used in quantum communication, such as using EDFA to parametrically amplify quantum signals, the high noise may interfere with the quantum signal, thereby affecting the security and efficiency of the system. Therefore, the use of EDFA in quantum communication systems will be limited. Summary of the invention

[0004] In view of the technical problems such as the lack of suitable quantum signal amplification technology in current quantum applications such as quantum communication, the purpose of the present invention is to provide a quantum signal parameter amplification system and method.

[0005] In one aspect, an embodiment of the present invention includes a quantum signal parametric amplification system, the quantum signal parametric amplification system including:

[0006] Laser light source module; the laser light source module is used to output a first laser and a third laser; the first laser and the third laser have the same single frequency;

[0007] A signal modulation module; the signal modulation module is used to receive the first laser, modulate the first laser according to the communication information to obtain a conjugate symmetric quantum signal, and output the conjugate symmetric quantum signal;

[0008] A coupler; the coupler is used to receive the third laser and the conjugate symmetric quantum signal and mix them to obtain a mixed signal, and output the mixed signal;

[0009] Amplification module: The amplification module is used to receive the mixed signal and perform parametric amplification on the mixed signal.

[0010] Furthermore, the amplification module comprises:

[0011] A third-order nonlinear unit; the third-order nonlinear unit is used to receive the mixed signal, synchronously amplify the mixed signal through the four-wave mixing effect to obtain a parametrically amplified quantum signal, and output the parametrically amplified quantum signal.

[0012] Furthermore, the laser light source module is also used to output a fourth laser; the fourth laser and the third laser have the same single frequency.

[0013] Furthermore, the quantum signal parametric amplification system further comprises:

[0014] Laser processing module: The laser processing module is used to receive the parametrically amplified quantum signal and process the parametrically amplified quantum signal.

[0015] Furthermore, the laser processing module comprises:

[0016] A balanced detection unit; the balanced detection unit is used to receive the parametrically amplified quantum signal and the fourth laser, perform balanced detection on the parametrically amplified quantum signal and the fourth laser to obtain a detection signal, and output the detection signal.

[0017] Furthermore, the laser processing module comprises:

[0018] A communication application unit; the communication application unit is used to receive the detection signal and use the detection signal to perform quantum communication applications.

[0019] Further, the balanced detection unit is used to perform homodyne detection or heterodyne detection when performing balanced detection;

[0020] The communication application unit is used to perform quantum key distribution or quantum teleportation when executing quantum communication applications.

[0021] Furthermore, the laser light source module comprises:

[0022] A first laser light source unit; the first laser light source unit is used to output original laser light;

[0023] A second beam splitter; the second beam splitter is used to receive the original laser, split the original laser into the first laser and the second laser for output;

[0024] The first beam splitter is used to receive the second laser beam, split the second laser beam into the third laser beam and the fourth laser beam for output.

[0025] Furthermore, the laser light source module comprises:

[0026] A first laser light source unit; the first laser light source unit is used to output the first laser;

[0027] A second laser light source unit; the second laser light source unit is used to output a second laser; the second laser has the same single frequency as the first laser;

[0028] The first beam splitter is used to receive the second laser beam, split the second laser beam into the third laser beam and the fourth laser beam for output.

[0029] On the other hand, an embodiment of the present invention further includes a quantum signal parameter amplification method, the quantum signal parameter amplification method comprising:

[0030] Acquire a first laser and a third laser; wherein the first laser and the third laser have the same single frequency;

[0031] Modulating the first laser according to the communication information to obtain a conjugate symmetric quantum signal;

[0032] Mixing the third laser and the conjugate symmetric quantum signal to obtain a mixed signal;

[0033] The mixed signal is parametrically amplified.

[0034] The beneficial effects of the present invention are as follows: the quantum signal parametric amplification system and method in the embodiment, by obtaining two lasers of the same frequency, a first laser and a third laser, modulating the first laser and then performing parametric amplification using the third laser as pump light, can achieve synchronous amplification of the communication information itself and its conjugated copy carried in the conjugated symmetric quantum signal, thereby being able to counteract the influence of noise, reduce the interference of noise on quantum signals, and ensure the security and efficiency of quantum applications such as quantum communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of the quantum signal parameter amplification system in the embodiment;

[0036] Figure 2 Schematic diagram of frequency domain expression of conjugate symmetric quantum signal in the embodiment;

[0037] Figure 3 Schematic diagram of the structure of a quantum signal parametric amplification system provided with a laser processing module in an embodiment;

[0038] Figure 4 and Figure 5 It is a schematic diagram of the structure of the laser light source module and the laser processing module in the embodiment;

[0039] Figure 6 Schematic diagram of the steps of the quantum signal parameter amplification method in the embodiment. DETAILED DESCRIPTION

[0040] In view of the difficulty in realizing low-noise amplifiers for quantum signals in quantum applications such as quantum communication, this embodiment proposes a conjugate symmetric quantum signal amplification scheme based on a third-order nonlinear unit, focusing on realizing efficient amplification of conjugate symmetric quantum signals. This scheme realizes parametric amplification of quantum signals by effectively coupling high-intensity pump light with conjugate symmetric quantum signals and utilizing the four-wave mixing process of the third-order nonlinear unit.

[0041] Specifically, this embodiment proposes a quantum signal parameter amplification system, the structure of which is as follows: Figure 1 See Figure 1 ,The quantum signal parametric amplification system includes laser source module, signal modulation module, coupler and amplification module and other components. Figure 1 In the process, different modules (units) can be connected through communication optical fibers to transmit laser signals.

[0042] Reference Figure 1 The laser light source module generates a first laser and a third laser. The first laser and the third laser have a single frequency (wavelength), and the frequency (wavelength) of the first laser and the third laser are the same.

[0043] Reference Figure 1 The first laser generated by the laser light source module is input into the signal modulation module through the communication optical fiber. The signal modulation module obtains the communication information (specifically, the communication information can be read from the inside or received from the outside. The communication information can be the information to be transmitted when performing quantum applications such as quantum communication). The first laser is modulated according to the communication information to obtain a conjugate symmetric quantum signal.

[0044] In this embodiment, the conjugate symmetric quantum signal can be expressed as:

[0045] Time domain expression:

[0046]

[0047] Frequency domain expression:

[0048]

[0049] The frequency domain expression of the conjugate symmetric quantum signal is as follows Figure 2 See Figure 2 The conjugate symmetric quantum signal consists of the signal light and its conjugate symmetric signal (conjugate copy), and the subcarrier frequencies of the two are symmetrically distributed relative to the main carrier, where X n is the communication information itself, is the conjugate copy of the communication information, w sn 、w in is the subcarrier frequency, w p Indicates the main carrier frequency, which is the same as the pump light (first laser) frequency, and has 2w p =w sn +w in , n is a positive integer.

[0050] Reference Figure 1 The conjugate symmetric quantum signal output by the signal modulation module and the third laser generated by the laser light source module are respectively input into the coupler through the communication optical fiber. The third laser is used as pump light and is mixed with the conjugate symmetric quantum signal in the coupler to obtain a mixed signal.

[0051] Reference Figure 1 The mixed signal output by the coupler is input to the amplification module through the communication optical fiber, and the amplification module amplifies the mixed signal.

[0052] In this embodiment, a third-order nonlinear unit can be used as an amplification module. After the mixed signal is input into the third-order nonlinear unit, a third-order nonlinear process will occur. Specifically, based on the interpretation of quantum states, in the third-order nonlinear unit, through the four-wave mixing effect, every two pump light photons in the third laser (pump light) in the mixed signal are annihilated, and a photon pair that is consistent with the signal itself and the conjugate copy of the conjugate symmetric quantum signal (that is, a pair of signal light photons corresponding to the signal itself in the conjugate symmetric quantum signal and a pair of idler light photons corresponding to the conjugate copy in the conjugate symmetric quantum signal are generated, and a total of four photons are generated), so a four-photon mixing process occurs in the third-order nonlinear unit, thereby realizing the signal itself X n and its conjugate counterpart The synchronous amplification of the quantum signal is realized, thereby achieving the parametric amplification of the quantum signal and finally outputting the parametric amplified quantum signal. The parametric amplified quantum signal carries the encoded quantum information and is amplified relative to the conjugate symmetric quantum signal.

[0053] The four-wave mixing process in the third-order nonlinear unit satisfies 2w p =w sn +w in , n is a positive integer, which is interpreted as the frequency w p The pump light excites two symmetrical sidebands (denoted by w s and w i ), w s The high-frequency sideband and the symmetrical low-frequency sideband w i They are called Stokes light and anti-Stokes light respectively. Stokes light is also called signal light, and anti-Stokes light is called idler light. The law of conservation of energy is satisfied in this process.

[0054] In this embodiment, by obtaining two lasers of the same frequency, namely a first laser and a third laser, modulating the first laser and using the third laser as pump light for parametric amplification, it is possible to achieve synchronous amplification of the communication information itself and its conjugated copy carried in the conjugated symmetric quantum signal, thereby counteracting the influence of noise, reducing the interference of noise on quantum signals, and ensuring the security and efficiency of quantum applications such as quantum communication.

[0055] The application scenario of the quantum signal parametric amplification system in this embodiment can be the receiving end in quantum communication or the relay section of the transmission link. Figure 3 The quantum signal parametric amplification system can be connected to an external laser processing module via a communication optical fiber, or the laser processing module can be used as a component of the quantum signal parametric amplification system to provide the laser processing module with a parametrically amplified quantum signal for processing.

[0056] Specifically, refer to Figure 3 The laser light source module also outputs a fourth laser. The fourth laser, like the third laser, has a single frequency (wavelength) as the first laser, and the first laser has the same frequency (wavelength) as the fourth laser. The fourth laser can be provided as local oscillator light to the laser processing module to process the parametric amplification quantum signal.

[0057] In this embodiment, a structure of the laser light source module is as follows: Figure 4 See Figure 4 The laser light source module includes a first laser light source unit, a first beam splitter and a second beam splitter. The first laser light source unit emits a laser beam (original laser), and the first beam splitter and the second beam splitter split the original laser into a first laser, a third laser and a fourth laser for output.

[0058] Specifically, refer to Figure 4 The original laser output by the first laser light source unit is input to the second beam splitter through the communication optical fiber, and the second beam splitter splits the original laser into two laser beams (a first laser beam and a second laser beam) for output, wherein the first laser beam can be directly output outside the laser light source module, and the second laser beam is input to the first beam splitter through the communication optical fiber, and the first beam splitter splits the second laser beam into two laser beams (a third laser beam and a fourth laser beam) and outputs them outside the laser light source module.

[0059] In this embodiment, another structure of the laser light source module is as follows Figure 5 See Figure 5 The laser light source module includes a first laser light source unit, a second laser light source unit and a first beam splitter. The first laser light source unit emits a laser beam (a first laser beam), the second laser light source unit emits a laser beam (a second laser beam), and the first beam splitter splits the second laser beam into a third laser beam and a fourth laser beam for output.

[0060] Figure 5 In the embodiment, the first laser light source unit and the second laser light source unit are two independent laser sources, and the frequencies of their laser emission are consistent.

[0061] In this embodiment, the structure of the laser processing module is as follows: Figure 4 and Figure 5 See Figure 4 and Figure 5 The laser processing module includes a balance detection unit and a communication application unit. The balance detection unit is used to detect the parametrically amplified quantum signal, and the communication application unit is used to perform quantum communication applications according to the detection results of the balance detection unit.

[0062] Specifically, refer to Figure 4 and Figure 5The parametrically amplified quantum signal output by the amplification module (third-order nonlinear unit) is input into the balanced detection unit through the communication optical fiber. The fourth laser output by the laser light source module is also input into the balanced detection unit as the local oscillator light through the communication optical fiber. The balanced detection unit performs balanced detection on the parametrically amplified quantum signal and the fourth laser.

[0063] In this embodiment, the balanced detection performed by the balanced detection unit is specifically homodyne detection or heterodyne detection. The balanced detection unit outputs a detection signal according to the detection result, and the detection signal is input to the communication application unit through the communication optical fiber.

[0064] In this embodiment, the communication application unit may execute a quantum communication application according to the detection signal output by the balance detection unit. Specifically, the quantum communication application executed by the communication application unit may be quantum key distribution or quantum teleportation.

[0065] By setting up a balanced detection unit, the detection signal required for executing quantum communication applications can be provided to the communication application unit. By setting up a communication application unit, specific quantum communication applications such as quantum key distribution or quantum teleportation can be executed using parametrically amplified quantum signals. Since parametrically amplified quantum signals are obtained through a low-noise amplification process, they are conducive to realizing high-quality quantum communication applications.

[0066] In this embodiment, by running the quantum signal parameter amplification system, a quantum signal parameter amplification method can be performed. As shown in the figure, the quantum signal parameter amplification method includes:

[0067] S1. Obtain a first laser and a third laser; the first laser and the third laser have the same single frequency;

[0068] S2. modulating the first laser according to the communication information to obtain a conjugate symmetric quantum signal;

[0069] S3. Mixing the third laser and the conjugate symmetric quantum signal to obtain a mixed signal;

[0070] S4. Perform parametric amplification on the mixed signal.

[0071] Specifically, step S1 can be performed by the laser light source module in the quantum signal parametric amplification system, step S2 can be performed by the signal modulation module, step S3 can be performed by the coupler, and step S4 can be performed by the amplification module. By executing the quantum signal parametric amplification method, the function of the quantum signal parametric amplification system can be realized, thereby achieving the effects of low-noise amplification of conjugate symmetric quantum signals, etc.

[0072] It should be noted that, unless otherwise specified, when a feature is referred to as being "fixed" or "connected" to another feature, it may be directly fixed or connected to the other feature, or it may be indirectly fixed or connected to the other feature. In addition, the descriptions of up, down, left, right, etc. used in the present disclosure are only relative to the relative positional relationship of the components of the present disclosure in the accompanying drawings. The singular forms of "a", "" and "the" used in the present disclosure are also intended to include the plural forms, unless the context clearly indicates other meanings. In addition, unless otherwise defined, all technical and scientific terms used in this embodiment have the same meaning as those generally understood by those skilled in the art. The terms used in the specification of this embodiment are only for describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this embodiment includes any combination of one or more related listed items.

[0073] It should be understood that, although the term first, second, third etc. may be adopted to describe various elements in the present disclosure, these elements should not be limited to these terms. These terms are only used to distinguish the same type of elements from each other. For example, without departing from the scope of the present disclosure, the first element may also be referred to as the second element, and similarly, the second element may also be referred to as the first element. The use of any and all examples or exemplary language ("for example", "such as" etc.) provided by the present embodiment is only intended to better illustrate embodiments of the present invention, and unless otherwise required, the scope of the present invention will not be limited.

[0074] It should be appreciated that embodiments of the present invention may be implemented or enforced by computer hardware, a combination of hardware and software, or by computer instructions stored in a non-transitory computer-readable memory. The method may be implemented in a computer program using standard programming techniques - including a non-transitory computer-readable storage medium configured with a computer program, wherein the storage medium so configured causes the computer to operate in a specific and predefined manner - according to the methods and drawings described in the specific embodiments. Each program may be implemented in a high-level procedural or object-oriented programming language to communicate with a computer system. However, if desired, the program may be implemented in assembly or machine language. In any case, the language may be a compiled or interpreted language. In addition, the program may be run on a programmed dedicated integrated circuit for this purpose.

[0075] In addition, the operations of the process described in this embodiment may be performed in any suitable order, unless otherwise indicated in this embodiment or otherwise clearly contradicted by the context. The process described in this embodiment (or variations and / or combinations thereof) may be performed under the control of one or more computer systems configured with executable instructions, and may be implemented as a code (e.g., executable instructions, one or more computer programs, or one or more applications) executed on one or more processors in common, by hardware or a combination thereof. A computer program includes a plurality of instructions that may be executed by one or more processors.

[0076] Further, the method can be implemented in any type of computing platform that is operably connected to a suitable computer, including but not limited to a personal computer, a minicomputer, a mainframe, a workstation, a network or distributed computing environment, a separate or integrated computer platform, or in communication with a charged particle tool or other imaging device, etc. Various aspects of the present invention can be implemented in machine-readable code stored on a non-transitory storage medium or device, whether removable or integrated into a computing platform, such as a hard disk, an optical read and / or write storage medium, a RAM, a ROM, etc., so that it can be read by a programmable computer, and when the storage medium or device is read by the computer, it can be used to configure and operate the computer to perform the process described herein. In addition, the machine-readable code, or part thereof, can be transmitted via a wired or wireless network. When such media includes instructions or programs that implement the above steps in conjunction with a microprocessor or other data processor, the invention of this embodiment includes these and other different types of non-transitory computer-readable storage media. When programmed according to the methods and techniques of the present invention, the present invention also includes the computer itself.

[0077] The computer program can be applied to input data to perform the functions of the present embodiment, thereby converting the input data to generate output data stored in a non-volatile memory. The output information can also be applied to one or more output devices such as a display. In a preferred embodiment of the present invention, the converted data represents a physical and tangible object, including a specific visual depiction of the physical and tangible object produced on the display.

[0078] The above are only preferred embodiments of the present invention. The present invention is not limited to the above embodiments. As long as the technical effects of the present invention are achieved by the same means, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention. Within the scope of protection of the present invention, its technical solutions and / or implementation methods may have various modifications and changes.

Claims

1. A quantum signal parameter amplification system, characterized in that: The quantum signal parameter amplification system comprises: Laser light source module; the laser light source module is used to output a first laser and a third laser; the first laser and the third laser have the same single frequency; A signal modulation module; the signal modulation module is used to receive the first laser, modulate the first laser according to the communication information to obtain a conjugate symmetric quantum signal, and output the conjugate symmetric quantum signal; A coupler; the coupler is used to receive the third laser and the conjugate symmetric quantum signal and mix them to obtain a mixed signal, and output the mixed signal; Amplification module: The amplification module is used to receive the mixed signal and perform parametric amplification on the mixed signal.

2. The quantum signal parametric amplification system according to claim 1, characterized in that: The amplification module comprises: A third-order nonlinear unit; the third-order nonlinear unit is used to receive the mixed signal, synchronously amplify the mixed signal through the four-wave mixing effect to obtain a parametrically amplified quantum signal, and output the parametrically amplified quantum signal.

3. The quantum signal parametric amplification system according to claim 2, characterized in that: The laser light source module is also used to output a fourth laser; the fourth laser and the third laser have the same single frequency.

4. The quantum signal parametric amplification system according to claim 3, characterized in that: The quantum signal parameter amplification system also includes: Laser processing module: The laser processing module is used to receive the parametrically amplified quantum signal and process the parametrically amplified quantum signal.

5. The quantum signal parametric amplification system according to claim 4, characterized in that: The laser processing module comprises: A balanced detection unit; the balanced detection unit is used to receive the parametrically amplified quantum signal and the fourth laser, perform balanced detection on the parametrically amplified quantum signal and the fourth laser to obtain a detection signal, and output the detection signal.

6. The quantum signal parametric amplification system according to claim 5, characterized in that: The laser processing module comprises: A communication application unit; the communication application unit is used to receive the detection signal and use the detection signal to perform quantum communication applications.

7. The quantum signal parametric amplification system according to claim 6, characterized in that: The balanced detection unit is used to perform homodyne detection or heterodyne detection when performing balanced detection; The communication application unit is used to perform quantum key distribution or quantum teleportation when executing quantum communication applications.

8. The quantum signal parametric amplification system according to any one of claims 3 to 7, characterized in that: The laser light source module comprises: A first laser light source unit; the first laser light source unit is used to output original laser light; A second beam splitter; the second beam splitter is used to receive the original laser, split the original laser into the first laser and the second laser for output; The first beam splitter is used to receive the second laser beam, split the second laser beam into the third laser beam and the fourth laser beam for output.

9. The quantum signal parametric amplification system according to any one of claims 3 to 7, characterized in that: The laser light source module comprises: A first laser light source unit; the first laser light source unit is used to output the first laser; A second laser light source unit; the second laser light source unit is used to output a second laser; the second laser has the same single frequency as the first laser; The first beam splitter is used to receive the second laser beam, split the second laser beam into the third laser beam and the fourth laser beam for output.

10. A method for quantum signal parameter amplification, characterized in that: The quantum signal parameter amplification method comprises: Acquire a first laser and a third laser; wherein the first laser and the third laser have the same single frequency; Modulating the first laser according to the communication information to obtain a conjugate symmetric quantum signal; Mixing the third laser and the conjugate symmetric quantum signal to obtain a mixed signal; The mixed signal is parametrically amplified.

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