Post-emission selection system for quantum radar and use method of post-emission selection system

Abstract

The invention discloses a post-emission selection system for a quantum radar and a use method of the post-emission selection system, and belongs to the field of quantum radar control. The system comprises a quantum post selection filter, and a beam splitter, an ideal conductor, a reflector and a photon number detector which are sequentially arranged along a single photon target detection direction, and the beam splitter is used for receiving single photons emitted by a single photon detection source and sending the single photons into different channels according to a modulation source and a preset operator relationship; the quantum post-selection filter is arranged on the post-selection filtering channel and is used for receiving single photons and calculating global quantum state evolution; the ideal conductor is covered with a wave-absorbing material, and the wave-absorbing material is used for interacting with the single photons in the target detection channel; the reflector is used for receiving the acted single photons and reflecting the single photons to the photon number detector, and the photon number detector is used for calculating the average photon number and the relative photon number gain meeting the precision requirement. According to the invention, the detection precision and anti-interference performance of the quantum radar can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of quantum radar measurement technology, and in particular to a post-launch selection system for quantum radar and a method for using the system. Background Art

[0002] Quantum radar is a new type of radar that uses quantum phenomena to perceive target states and acquire information. It utilizes the correlation characteristics of entangled photon states to enable it to detect targets under low signal-to-noise ratio conditions. Quantum radar is widely used in target detection, target identification and other fields, especially stealth target detection, and plays an irreplaceable role in these applications and research.

[0003] In related technologies, since the reflectivity or transmittance of non-cooperative targets when covered by absorbing materials is extremely low, it is difficult to collect sufficient echo signals and perform effective quantum measurements, resulting in low relative photon number gain and detection accuracy of quantum radar, and it is easily interfered by various factors, which in turn leads to a series of research and applications being carried out inefficiently.

[0004] Based on this, there is an urgent need for a post-launch selection system for quantum radar and its use method to solve the above technical problems. Summary of the Invention

[0005] The present invention provides a post-launch selection system for quantum radar and its use method, which can effectively improve the detection accuracy and anti-interference performance of quantum radar. The technical solution is as follows:

[0006] In one aspect, a post-emission selection system for a quantum radar is provided, the system comprising a quantum post-selection filter and a beam splitter, a perfect conductor, a reflector, and a photon number detector arranged in sequence along a single-photon target detection direction, wherein:

[0007] The beam splitter is used to receive single photons emitted by a single photon detection source, and send the single photons to a target detection channel and a post-selection filter channel respectively according to a modulation source and a preset operator relationship;

[0008] The quantum post-selective filter is provided on the post-selective filter channel, and is used to receive single photons in the post-selective filter channel and calculate the global quantum state evolution according to a preset operator relationship to modulate the detection performance of the photon number detector;

[0009] The ideal conductor is covered with an absorbing material having a preset operator relationship, wherein the absorbing material is used to simulate a target and interact with single photons in the target detection channel;

[0010] The reflector is used to receive the single photons after the action and reflect them to the photon number detector, and the photon number detector is used to calculate the average photon number and the relative photon number gain that meets the accuracy requirements based on the received single photons and quantum state evolution.

[0011] In another aspect, a method for using a post-launch selection system for a quantum radar is provided, the method comprising:

[0012] The beam splitter is used to send single photons into a target detection channel and a post-selection filter channel;

[0013] Processing single photons in a post-selection filter channel using the quantum post-selection filter to determine a global quantum state evolution;

[0014] Utilizing the absorbing material to interact with single photons in a target detection channel to obtain the interacted single photons;

[0015] The photon number detector is used to process the single photons after the interaction to determine the measured average photon number and the relative photon number gain.

[0016] The technical solution provided by the present invention can bring at least the following beneficial effects: through the modulation of the emitted single photons by the quantum post-selective filter, changes in the quantum post-selective filter parameters can affect the average photon number measured by the detector, thereby improving the detection accuracy and anti-interference performance of the quantum radar. Because the quantum post-selective filter modulates the transmission path, the relative photon number gain is independent of the absorbing material, further reducing noise interference and improving system stability. By performing partial post-selection operations on the transmission part to influence the global quantum state, precise control of the quantum state is achieved, thereby improving the relative photon number gain, detection accuracy, and signal-to-noise ratio of the quantum radar, and meeting the research needs of quantum radar to maintain stable and high-precision detection performance in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a structural diagram of a post-launch selection system for quantum radar provided by one embodiment of the present invention;

[0019] Figure 2 This is an embodiment of the present invention provides for |r1| 2=0.5, the relationship between the quantum post-selection filter parameters and the relative photon number gain. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] As mentioned above, in existing schemes, it is difficult to collect sufficient echo signals and perform effective quantum measurements because the reflectivity or transmittance of non-cooperative targets when covered by absorbing materials is extremely low, resulting in low relative photon number gain and detection accuracy of quantum radar.

[0022] Based on this, the concept of the present invention is that through the modulation effect of the quantum post-selective filter on the emitted photons, the change of the quantum post-selective filter parameters can affect the average number of photons measured by the photon number detector, thereby improving the detection accuracy and anti-interference performance of the quantum radar.

[0023] The specific implementation of the above concept is described below.

[0024] Please refer to Figure 1 An embodiment of the present invention provides a post-launch selection system for a quantum radar, the system comprising:

[0025] A quantum post-selective filter and a beam splitter, an ideal conductor, a reflector and a photon number detector are sequentially arranged along the single-photon target detection direction, wherein:

[0026] The beam splitter is used to receive single photons emitted by a single photon detection source, and send the single photons to a target detection channel and a post-selection filter channel respectively according to a modulation source and a preset operator relationship;

[0027] The quantum post-selective filter is provided on the post-selective filter channel, and is used to receive single photons in the post-selective filter channel and calculate the global quantum state evolution according to a preset operator relationship to modulate the detection performance of the photon number detector;

[0028] The ideal conductor is covered with an absorbing material having a preset operator relationship, wherein the absorbing material is used to simulate a target and interact with single photons in the target detection channel;

[0029] The reflector is used to receive the single photons after the action and reflect them to the photon number detector, and the photon number detector is used to calculate the average photon number and the relative photon number gain that meets the accuracy requirements based on the received single photons and quantum state evolution.

[0030] In an embodiment of the present invention, a quantum post-selective filter modulates the emitted single photons. Changes in the filter's parameters can affect the average photon count measured by the detector, improving the detection accuracy and anti-interference performance of the quantum radar. Because the quantum post-selective filter modulates the transmit path, the relative photon gain is independent of the absorbing material, further reducing noise interference and improving system stability. By influencing the global quantum state through partial post-selection operations in the transmit path, precise control of the quantum state is achieved, thereby improving the relative photon gain, detection accuracy, and signal-to-noise ratio of the quantum radar. This meets the research needs of quantum radars that maintain stable and high-precision detection performance in complex environments.

[0031] Specifically, Figure 1 The channel a1 shown is an active detection source for emitting single photons, and the channel a2 is a modulation source in a vacuum state. The beam splitter BS1 divides the incident single photons into multiple channels, of which channel b1 is used as the target detection channel and channel c2 is used as the post-selection filter channel. The post-selection filter channel is connected to the quantum post-selection filter F p , and the global quantum state evolution is determined based on the received emitted photons. Target detection channel b1 interacts with a target simulated by a perfect conductor PEC covered by an absorbing material AM. Channel f1 is the absorbing material noise path, and channel f2 is the absorbing material absorption path. Target reflection path b2 reaches photon number detector D1 through reflector M1.

[0032] The active detection of single photons from a source mainly exploits the correlation properties of entangled quantum states. One branch of the entangled quantum state is used for signal measurement, while the other is used to assist in signal enhancement.

[0033] In an embodiment of the present invention, the purpose of connecting a beam splitter is to divide the incident single photon into two channels, one channel serves as a target detection channel to interact with the target, and the other channel serves as a post-selection filtering channel to determine the global quantum state evolution through a quantum post-selection filter.

[0034] Specifically, the operator relationship of the beam splitter is determined by the following formula:

[0035]

[0036] Among them, <↑|, |↑>, <↓|, |↓> are all beam splitting matrices; Boson generation operator for the photon detection source; is the boson generation operator for the modulation source; Boson generation operator for the target detection channel; is the boson generation operator of the post-selection filter channel; S1 is the SU(2) matrix of the beam splitter, t is the projection parameter, r is the reflection parameter, and the subscript * indicates the conjugate of the parameter.

[0037] In the embodiment of the present invention, the quantum post-selective filter has an adjustable parameter p, which is used to change the average number of photons measured by the detector.

[0038] Specifically, the operator relation F of the quantum post-selection filter is p Determined by the following formula:

[0039]

[0040] Among them, |0> and |1> both represent the Fock state of the photon; is the Fock state of photons in the postselection filter channel; p is a controllable postselection parameter introduced. By setting p to a value between 0 and 1, the average number of photons reaching the photon number detector D1 and the relative photon number gain K can be changed.

[0041] Furthermore, the quantum state evolution is calculated by the following formula:

[0042]

[0043] Where |out> is the quantum state evolution after passing through the quantum post-selection filter. When the filter operator F acts on the entangled state, that is, F|out>, quantum operations on the output state can be realized.

[0044] In the embodiment of the present invention, an ideal conductor module covered with an absorbing material is used to simulate a target and interact with the target detection path. The absorbing material must satisfy the operator relationship shown in the following formula:

[0045]

[0046] Where, Boson generation operator for the target detection channel; f1 is the boson generation operator for the mirror reflection channel; + A boson generation operator for the noise path of the absorbing material; is the boson generation operator of the absorbing material’s absorbing path; S AM is the SU(2) matrix of the absorbing material, α is the projection parameter and β is the reflection parameter.

[0047] In the embodiment of the present invention, the average number of photons measured by the photon number detector is calculated using the following formula:

[0048]

[0049] Where, is the boson generation operator of the mirror reflection channel; b2 is the boson annihilation operator of the mirror reflection channel; Boson generation operator for quantum postselection filter.

[0050] When the parameter p=1, F p＝1 |out>=|out>,

[0051] Furthermore, the relative photon number gain K is calculated by the following formula:

[0052]

[0053] Where r1 is the reflection term parameter in the SU(2) matrix of the beam splitter.

[0054] It is worth noting that the number of photons is related to the absorbing material, but in this embodiment, K is independent of the material because the post-selection here modulates the emission path of the photons.

[0055] The following combination Figure 2 Experimental data are presented for a post-launch selection system for quantum radar.

[0056] Figure 2 Given that when |r1| 2 =0.5, the relationship curve of the relative photon number gain K quantum post-selection filter parameter p. Figure 2 It can be seen that the smaller the post-selection parameter p, the larger the relative photon number gain K. As a reference for adjusting the parameters, in the specific implementation process, the parameter p of the quantum post-selection filter can be adjusted according to actual needs to optimize the detection performance.

[0057] In summary, through the modulation of the transmit path by the quantum post-selective filter, changes in the filter's parameters can affect the average photon count measured by the detector, thereby improving the detection accuracy and anti-interference performance of the quantum radar. Because the quantum post-selective filter modulates the transmit path, the relative photon gain K is independent of the absorbing material, further reducing noise interference and improving system stability. By performing partial post-selection operations on the transmit path to influence the global quantum state, precise control of the quantum state is achieved, thereby improving the relative photon gain, detection accuracy, and signal-to-noise ratio of the quantum radar, meeting the research needs of quantum radar to maintain stable and high-precision detection performance in complex environments.

[0058] An embodiment of the present invention also provides a method for using a post-emission selection system for a quantum radar, applicable to any of the above embodiments, the method comprising: using the beam splitter to distribute single photons into a target detection channel and a post-selection filter channel; using the quantum post-selection filter to process the single photons in the post-selection filter channel to determine the global quantum state evolution; using the absorbing material to interact with the single photons in the target detection channel to obtain the single photons after interaction; using the photon number detector to process the single photons after interaction to determine the measured average photon number and relative photon number gain. Furthermore, the average photon number is changed by adjusting the post-selection parameter of the quantum post-selection filter.

[0059] For the convenience of description, the above system or system is described as being divided into various modules or units according to their functions. Of course, when implementing this application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0060] Through the description of the above embodiments, it can be seen that those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general hardware platform. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in various embodiments of the present application or certain parts of the embodiments.

[0061] Finally, it should be noted that, in this document, relational terms such as first, second, third, and fourth are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0062] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A post-launch selection system for quantum radar, characterized in that: The system includes a quantum post-selective filter and a beam splitter, a perfect conductor, a reflector, and a photon number detector arranged in sequence along the single-photon target detection direction, wherein: The beam splitter is used to receive single photons emitted by a single photon detection source, and send the single photons to a target detection channel and a post-selection filter channel respectively according to a modulation source and a preset operator relationship; The quantum post-selective filter is provided on the post-selective filter channel, and is used to receive single photons in the post-selective filter channel and calculate the global quantum state evolution according to a preset operator relationship to modulate the detection performance of the photon number detector; The ideal conductor is covered with an absorbing material having a preset operator relationship, wherein the absorbing material is used to simulate a target and interact with single photons in the target detection channel; The reflector is used to receive the single photons after the action and reflect them to the photon number detector, and the photon number detector is used to calculate the average photon number and the relative photon number gain that meets the accuracy requirements based on the received single photons and quantum state evolution.

2. The system according to claim 1, wherein The modulation source is set to be vacuum.

3. The system according to claim 1, wherein: The operator relationship of the beam splitter is determined by the following formula: Among them, <↑|, |↑>, <↓|, |↓> are all beam splitting matrices; Boson generation operator for the photon detection source; is the boson generation operator for the modulation source; Boson generation operator for the target detection channel; is the boson generation operator of the post-selection filtering channel; S1 is the SU(2) matrix of the beam splitter.

4. The system according to claim 1, wherein: The operator relation F of the quantum post-selective filter is p Determined by the following formula: Among them, |0> and |1> are both Fock states of photons. is the Fock state of the photon in the post-selection filtering channel; p is the adjustable post-selection parameter.

5. The system according to claim 4, wherein: The quantum state evolution is calculated by the following formula: Where |out> is the quantum state evolution after passing through the quantum post-selection filter.

6. The system according to claim 1, wherein: The operator relationship of the absorbing material is determined by the following formula: Where, Boson generation operator for the target detection channel; f1 is the boson generation operator for the mirror reflection channel; + A boson generation operator for the noise path of the absorbing material; is the boson generation operator of the absorbing material’s absorbing path; S AM is the SU(2) matrix of the absorbing material.

7. The system according to claim 5, wherein: The average photon number is calculated by the following formula: Where, is the boson generation operator of the mirror reflection channel; b2 is the boson annihilation operator of the mirror reflection channel; Boson generation operator for quantum postselection filter.

8. The system according to claim 7, wherein: The relative photon number gain K is calculated by the following formula: Where r1 is the reflection term parameter in the SU(2) matrix of the beam splitter.

9. A method for using a post-launch selection system for a quantum radar, characterized in that: Applied to the system according to any one of claims 1 to 8, the method comprises: The beam splitter is used to send single photons into a target detection channel and a post-selection filter channel; Processing single photons in a post-selection filter channel using the quantum post-selection filter to determine a global quantum state evolution; Utilizing the absorbing material to interact with single photons in a target detection channel to obtain the interacted single photons; The photon number detector is used to process the single photons after the interaction to determine the measured average photon number and the relative photon number gain.

10. The method according to claim 9, wherein The average photon number is changed by adjusting the post-selection parameter of the quantum post-selection filter.

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