Single-quantum terahertz signal detection system and method based on Rydberg atoms

Abstract

The invention provides a single-quantum terahertz signal detection system and method based on Rydberg atoms. Relates to the field of signal detection. The first laser is used for emitting detection laser so as to excite alkali metal atoms from a ground state to a low-energy-level state; the second laser is used for emitting coupled laser so as to excite the alkali metal atoms in the low energy level state to a first excitation state; the third laser is used for emitting Rydberg laser so as to excite the alkali metal atoms in the first excited state to the Rydberg state; the terahertz signal input port is used for receiving a terahertz signal to be detected so as to excite alkali metal atoms in a first excited state to a second excited state; and the single-photon detector is used for detecting fluorescent photons of visible light or infrared light released by the alkali metal atoms when the alkali metal atoms are in spontaneous radiation transition from the second excited state to the low-energy-level state so as to realize detection of the single-quantum terahertz signal.

Description

Technical Field

[0001] This invention relates to the field of signal detection, and in particular to a single-quantum terahertz signal detection system and method based on Rydberg atoms. Background Technology

[0002] Terahertz waves (THz) refer to electromagnetic waves with frequencies between 0.1 THz and 10 THz. They represent a fairly wide range of electromagnetic radiation between millimeter waves and infrared waves, characterized by high information transmission capacity, high detection accuracy, and strong penetration capabilities. Furthermore, due to their very wide spectrum, they can operate outside the bands currently countered by stealth technology, enabling the detection of stealth targets. These advantages of terahertz waves make them promising for applications in fields such as information science, biology, medicine, astronomy, and environmental science.

[0003] The main challenges facing existing terahertz signal detection technologies include:

[0004] 1. Terahertz waves suffer severe atmospheric attenuation, resulting in low source transmission power and insufficient receiver sensitivity, which limits the radar's effective range and makes it difficult to effectively support long-range imaging and detection applications.

[0005] 2. In close-range applications such as terminal guidance, existing detection and imaging systems require aperture accumulation and rely on relative motion, which limits the full realization of the advantages of terahertz radar technology.

[0006] 3. Terahertz radar signals have a large bandwidth and a high sampling frame rate. High-resolution imaging requires a large amount of data, and signal processing is complex and time-consuming.

[0007] The accuracy and sensitivity of existing terahertz detection technologies are no longer sufficient to meet the requirements of today's scientific research and technological applications, and there is an urgent need for new measurement technologies to break through the limitations of existing terahertz measurements. Summary of the Invention

[0008] To address the technical problems existing in the prior art, the present invention aims to provide a single-quantum terahertz signal detection system and method based on Rydberg atoms. It employs five energy levels of Rydberg atoms, is suitable for the detection and reception of high-sensitivity terahertz signals in complex electromagnetic environments, has high sensitivity, and has very good anti-interference capabilities.

[0009] To achieve the above-mentioned objectives, this invention provides a single-quantum terahertz signal detection system based on Rydberg atoms, comprising:

[0010] Atomic gas chamber, used to contain alkali metal atomic vapors;

[0011] A first laser is used to emit a probe laser and incident it into the atomic gas cell to excite alkali metal atoms from the ground state to a lower energy level state;

[0012] A second laser is used to emit a coupling laser and incident it into the atomic gas cell in a direction opposite to the incident direction of the probe laser, so as to excite the alkali metal atoms in the low energy level state to the first excited state.

[0013] A third laser is used to emit a Rydberg laser and incident it into the atomic gas cell in a direction perpendicular to the incident direction of the probe laser, so as to excite the alkali metal atoms in the first excited state to the Rydberg state.

[0014] The terahertz signal input port is used to receive the terahertz signal to be measured and to incident on the atomic gas cell perpendicular to the incident direction of the probe laser, so as to excite the alkali metal atoms in the Rydberg state to the second excited state.

[0015] A single-photon detector is used to detect the fluorescent photons of visible or infrared light emitted when the alkali metal atom spontaneously transitions from the second excited state to a lower energy level, thereby realizing the detection of single quantum terahertz signals.

[0016] According to one technical solution of the present invention, it further includes:

[0017] The signal processor is used to reconstruct the terahertz signal to be measured based on the detected fluorescent photons; and to demodulate the information carried in the terahertz signal to be measured according to a preset terahertz signal modulation mode.

[0018] According to one technical solution of the present invention, the alkali metal is cesium.

[0019] According to one technical solution of the present invention, when the alkali metal is cesium:

[0020] ground state is ;

[0021] low energy level state :

[0022] The first excited state is ;

[0023] Ridburg state ;

[0024] The second excited state is .

[0025] According to one technical solution of the present invention, the wavelength of the detection laser is 852nm; the wavelength of the coupling laser is 1470nm; and the wavelength of the Rydberg laser is 790~980nm.

[0026] This invention also provides a method for detecting single-quantum terahertz signals based on Rydberg atoms, the steps of which are as follows:

[0027] Alkali metal atoms are excited from their ground state to a lower energy level by probing lasers;

[0028] The alkali metal atoms in a low-energy state are excited to a first excited state by a coupling laser; the coupling laser is incident in a direction opposite to the incident direction of the probe laser;

[0029] The alkali metal atoms in the first excited state are excited to the Rydberg state by a Rydberg laser; the Rydberg laser to be tested is incident perpendicular to the incident direction of the probe laser;

[0030] The terahertz signal to be measured excites the alkali metal atoms in the Rydberg state to a second excited state; the terahertz signal to be measured is incident perpendicular to the incident direction of the probe laser;

[0031] The fluorescence photons of visible or infrared light emitted when the alkali metal atom spontaneously transitions from the second excited state to a lower energy level are detected, thereby enabling the detection of single-quantum terahertz signals.

[0032] According to one technical solution of the present invention, it further includes:

[0033] Based on the detected fluorescent photons, the terahertz signal to be measured is reconstructed; and based on the preset terahertz signal modulation mode, the information carried in the terahertz signal to be measured is demodulated.

[0034] According to one technical solution of the present invention, the alkali metal is cesium.

[0035] According to one technical solution of the present invention, when the alkali metal is cesium:

[0036] ground state is ;

[0037] low energy level state :

[0038] The first excited state is ;

[0039] Ridburg state ;

[0040] The second excited state is .

[0041] According to one technical solution of the present invention, the wavelength of the detection laser is 852nm; the wavelength of the coupling laser is 1470nm; and the wavelength of the Rydberg laser is 790~980nm.

[0042] The present invention provides a single-quantum terahertz signal detection system and method based on Rydberg atoms, which has the following beneficial effects:

[0043] 1. By taking advantage of the fact that highly excited electrons in the Rydberg state can easily interact with terahertz signals, a novel method of terahertz signal measurement traceable to a single terahertz quantum is achieved. Furthermore, this process does not involve electromagnetic waves driving free electrons to generate current, resulting in extremely high sensitivity and overcoming the limitations of existing thermal noise limits.

[0044] 2. By utilizing the abundant energy level structure of Rydberg atoms, it is possible to convert terahertz signals into visible or infrared photons, thereby enabling the detection of terahertz signals using mature commercial visible or infrared single-photon detectors, which greatly reduces the cost of terahertz signal detection.

[0045] 3. Furthermore, because Rydberg atoms have abundant energy level structures, they can receive signals with ultra-narrow linewidths. Therefore, using Rydberg atoms to detect terahertz signals has excellent anti-interference capabilities, solving the problem of signal interference in complex electromagnetic environments. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0047] Figure 1 The schematic diagram illustrates the structure of a single-quantum terahertz signal detection system based on Rydberg atoms according to one embodiment of the present invention.

[0048] Figure 2 The schematic diagram illustrates the terahertz signal detection energy level structure in a single-quantum terahertz signal detection system and method based on Rydberg atoms according to an embodiment of the present invention.

[0049] Figure 3 The diagram schematically illustrates a comparison between an existing terahertz signal receiver and the single-quantum terahertz signal detection system of the present invention. Detailed Implementation

[0050] The description of the embodiments in this specification should be taken in conjunction with the accompanying drawings, which should form part of the complete specification. In the drawings, the shape or thickness of the embodiments may be exaggerated and may be indicated in a simplified or convenient manner. Furthermore, parts of the various structures in the drawings will be described separately; it is worth noting that elements not shown in the figures or not described in words are in a form known to those skilled in the art.

[0051] The descriptions of the embodiments herein, including any references to directions and orientations, are for ease of description only and should not be construed as limiting the scope of the invention. The following description of preferred embodiments involves combinations of features, which may exist independently or in combination; the invention is not particularly limited to the preferred embodiments. The scope of the invention is defined by the claims. Figures 1-3 As shown; Specific Implementation Method 1

[0053] This embodiment provides a single-quantum terahertz signal detection system based on Rydberg atoms, such as Figure 1 As shown, it includes:

[0054] Atomic gas chamber 1 is used to contain alkali metal atomic vapors;

[0055] The first laser 2 is used to emit a probe laser and incident it into the atomic gas cell 1 to excite alkali metal atoms from the ground state to a lower energy level state;

[0056] The second laser 4 is used to emit a coupling laser and incident it into the atomic gas cell 1 in a direction opposite to the incident direction of the probe laser, so as to excite the alkali metal atoms in the low energy level state to the first excited state.

[0057] The third laser 5 is used to emit a Rydberg laser and incident it into the atomic gas cell 1 in a direction perpendicular to the incident direction of the probe laser, so as to excite the alkali metal atoms in the first excited state to the Rydberg state.

[0058] The terahertz signal input port is used to receive the terahertz signal to be measured and to incident on the atomic gas cell 1 perpendicular to the incident direction of the probe laser, so as to excite the alkali metal atoms in the Rydberg state to the second excited state.

[0059] The single-photon detector 3 is used to detect the fluorescent photons of visible or infrared light emitted when alkali metal atoms spontaneously transition from the second excited state to a lower energy level, thereby realizing the detection of single quantum terahertz signals.

[0060] In this embodiment, a Rydberg atom refers to an atom with highly excited electron states (principal quantum number n > 10), whose transition energy levels are located in the microwave and terahertz frequency bands. A Rydberg atom with a principal quantum number of n possesses a large electric dipole moment (∝n). 2) and polarizability (∝n 7 It readily couples with terahertz signals and is extremely sensitive to terahertz signal responses. Therefore, it can effectively detect weak terahertz signals.

[0061] The signal detection system integrates the atomic gas chamber 1, the first laser 2, the terahertz signal input port, the second laser 4, the third laser 5, and the single-photon detector 3 into a single receiver through an integrated optical path design. This reduces the complexity of system operation and improves overall reliability. It is also more suitable for deployment on spaceborne platforms, thereby achieving high-sensitivity terahertz signal detection, which is of great significance for future stealth target detection and space communication.

[0062] The probe of the aforementioned single-photon detector 3 is made of non-metallic material, which causes very little interference to the terahertz signal to be measured, and its theoretical measurement accuracy is far higher than that of existing electronic measurement technology.

[0063] This embodiment utilizes a rich energy level structure, selecting five energy levels of the Rydberg atom of an alkali metal to complete the detection of terahertz signals, including the ground state (ground state|1>), the first excited state (excited state|2>), the Rydberg state (excited state|3>), the second excited state (excited state|4>), and the low energy level state (low energy level state|5>).

[0064] In addition to the atomic gas chamber 1, the first laser 2, the second laser 4, the third laser 5, and the single-photon detector 3, the optical path system of the detection system should also include necessary laser frequency stabilization devices, optical lenses (polarizers, lenses, dichroic mirrors), etc.

[0065] like Figure 2 As shown, atomic gas cell 1 is located in the center; the first laser 2 is on the left, and the first laser beam passes from left to right through a polarizer (used to convert the first laser beam into linearly polarized light, ensuring that the polarization state of the laser beam incident on atomic gas cell 1 is consistent, satisfying the specific requirements of atomic energy level transitions for the polarization direction of the incident light) and a first lens (used to collimate or focus the diverging first laser beam, so that the laser beam is incident on atomic gas cell 1 with a uniform and stable beam diameter, improving the interaction efficiency between the laser and alkali metal atoms) before entering atomic gas cell 1; the second laser 4 is on the right, and the second laser beam first hits a dichroic mirror, and then is reflected back to atomic gas cell 1 by the dichroic mirror; the visible light or infrared light emitted by the atomic gas cell is transmitted through the dichroic mirror to reach the single-photon detector 3, and the dichroic mirror reflects and blocks the excess first laser beam that is not absorbed by atomic gas cell 1, preventing it from entering the single-photon detector 3 and interfering with the signal detection. The third laser 5 emits a Rydberg laser from the side in a direction perpendicular to the detection laser, and passes through a polarizer and a lens to enter atomic gas cell 1.

[0066] The aforementioned first laser 2, second laser 4, and third laser 5 primarily emit narrow-linewidth laser beams, forming two opposing laser beams (one for detection and one for coupling) and a vertical laser beam to excite the alkali metal atoms in the atomic gas chamber 1 to the Rydberg state, thereby detecting the terahertz signal. Narrow linewidth refers to a sufficiently narrow spectral linewidth of the laser to resolve and resonantly excite transitions between selected atomic energy levels, avoiding the excitation of neighboring energy levels.

[0067] like Figure 2 As shown, the specific work steps are as follows:

[0068] (1) Frequency stabilization of probe laser, coupled laser, and Rydberg laser is achieved by using the Plesiochronous Digital Hierarchy (PDH) locking technology based on sideband modulation to realize high-precision frequency stabilization of laser.

[0069] (2) After the frequency stabilized probe laser is adjusted by optical components such as polarizer and lens, it enters the atomic gas cell and excites the atoms in the atomic gas cell from the ground state to a low energy level state.

[0070] (3) After the frequency-stabilized coupled laser transmitted in space is adjusted by optical components such as polarizer and lens, it is directed towards the atomic gas cell, exciting the alkali metal atoms in the atomic gas cell from the low energy level state to the first excited state.

[0071] (4) After the frequency stabilized Rydberg laser beam transmitted in space is adjusted by optical components such as polarizer and lens, it is perpendicular to the probe laser and enters the atomic gas cell, exciting the alkali metal atoms in the atomic gas cell from the first excited state to the Rydberg state.

[0072] (5) When the terahertz radiation source is turned on, the terahertz signal irradiates the atomic gas cell, and the alkali metal atoms in the atomic gas cell transition from the Rydberg state to the second excited state under the action of the terahertz signal.

[0073] (6) Alkali metal atoms in the second excited state are extremely unstable. After spontaneously emitting visible light or infrared fluorescent photons, they transition to a lower energy level.

[0074] (7) Fluorescent photons are detected by visible light or infrared single photon detectors. As long as a fluorescent photon is detected, it corresponds to a terahertz single quantum. The detection of single quantum terahertz signals is realized by detecting fluorescent photons.

[0075] like Figure 3As shown, the difference between existing terahertz signal receivers and the atomic-based terahertz signal detection system (receiver) of this embodiment is illustrated. The terahertz signal detection system in this embodiment has the advantages of traceability, large dynamic range, and high sensitivity, and has great application potential in the fields of terahertz detection, terahertz radar, and imaging. Specific Implementation Method Two

[0077] This embodiment is a further explanation of embodiment one. This embodiment also includes:

[0078] The signal processor 6 is used to reconstruct the terahertz signal to be measured based on the detected fluorescent photons; and to demodulate the information carried in the terahertz signal to be measured according to the preset terahertz signal modulation mode.

[0079] In this embodiment, the signal processor 6, the atomic gas chamber 1, the first laser 2, the terahertz signal input port, the second laser 4, the third laser 5, and the single-photon detector 3 can also be integrated into a single receiver through an integrated optical path design.

[0080] Specific usage steps also include:

[0081] (7) The terahertz signal is copied, demodulated and information is obtained by signal processor 6.

[0082] Specifically, the signal processor 6 reconstructs the original terahertz signal waveform by using the timestamp, count rate, or spatial distribution of fluorescent photons, combined with the preset modulation format of the terahertz signal, and through photon count statistics or time correlation analysis, thereby demodulating the information it carries. Specific Implementation Method 3

[0084] This embodiment is a further explanation of Embodiment 1. In this embodiment, the alkali metal is cesium. Specific Implementation Method Four

[0086] This embodiment is a further explanation of embodiment three. In this embodiment, when the alkali metal is cesium:

[0087] ground state is ;

[0088] low energy level state :

[0089] The first excited state is ;

[0090] Ridburg state ;

[0091] The second excited state is . Detailed Implementation Method Five

[0093] This embodiment is a further explanation of one of the embodiments one to four. In this embodiment, the wavelength of the detection laser is 852nm; the wavelength of the coupling laser is 1470nm; and the wavelength of the Rydberg laser is 790~980nm. Specific Implementation Method Six

[0095] This embodiment of the single-quantum terahertz signal detection method based on Rydberg atoms includes the following steps:

[0096] Alkali metal atoms are excited from their ground state to a lower energy level by probing lasers;

[0097] Alkali metal atoms in a low-energy state are excited to the first excited state by a coupling laser; the coupling laser is incident in a direction opposite to the incident direction of the probe laser;

[0098] Alkali metal atoms in the first excited state are excited to the Rydberg state by a Rydberg laser; the Rydberg laser to be tested is incident perpendicular to the incident direction of the probe laser.

[0099] The terahertz signal to be measured excites the alkali metal atoms in the Rydberg state to the second excited state; the terahertz signal to be measured is incident perpendicular to the incident direction of the probe laser;

[0100] The fluorescence photons of visible or infrared light emitted when alkali metal atoms spontaneously transition from the second excited state to a lower energy level can be detected, thereby enabling the detection of single-quantum terahertz signals.

[0101] In this embodiment, it includes

[0102] (1) Initial state preparation: Alkali metal atoms are excited from the ground state to a lower energy level by probe laser;

[0103] (2) Alkali metal atoms in a low-energy state are excited to the first excited state by coupling laser;

[0104] (3) Excite alkali metal atoms in the first excited state to the Rydberg state using a Rydberg laser;

[0105] (4) Alkali metal atoms in the Rydberg state absorb a single quantum terahertz signal and transition to the second excited state;

[0106] (5) Alkali metal atoms in the second excited state are extremely unstable. After spontaneously emitting visible light or infrared fluorescent photons, they transition to a lower energy level.

[0107] (6) Use visible light or infrared single-photon detectors to detect fluorescence signals, thereby realizing the detection of terahertz signals. Detailed Implementation Method Seven

[0109] This embodiment is a further explanation of embodiment six. This embodiment also includes:

[0110] Based on the detected fluorescent photons, the terahertz signal to be measured is reconstructed; and based on the preset terahertz signal modulation mode, the information carried in the terahertz signal to be measured is demodulated. Detailed Implementation Method Eight

[0112] This embodiment is a further explanation of embodiment six. In this embodiment, the alkali metal is cesium. Detailed Implementation Method Nine

[0114] This embodiment is a further explanation of embodiment eight. In this embodiment, when the alkali metal is cesium:

[0115] ground state is ;

[0116] low energy level state :

[0117] The first excited state is ;

[0118] Ridburg state ;

[0119] The second excited state is . Detailed Implementation Method Ten

[0121] This embodiment is a further explanation of one of embodiments six to nine. In this embodiment, the wavelength of the detection laser is 780nm; the wavelength of the coupling laser is 480nm; and the wavelength of the Rydberg laser is 790~980nm.

[0122] The present invention relates to a single-quantum terahertz signal detection system and method based on Rydberg atoms. The system includes: an atomic gas chamber for containing alkali metal atomic vapor; a first laser for emitting a probe laser to excite alkali metal atoms from the ground state to a lower energy level; a second laser for emitting a coupling laser to excite alkali metal atoms in the lower energy level to a first excited state; a third laser for emitting a Rydberg laser to excite alkali metal atoms in the first excited state to a Rydberg state; a terahertz signal input port for receiving a terahertz signal to be measured to excite alkali metal atoms in the first excited state to a second excited state; and a single-photon detector for detecting visible or infrared fluorescent photons released when alkali metal atoms spontaneously transition from the second excited state to a lower energy level, thereby realizing the detection of a single-quantum terahertz signal.

[0123] Furthermore, it should be noted that the present invention can be provided as a method, apparatus, or computer program product. Therefore, embodiments of the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, embodiments of the present invention can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code.

[0124] Embodiments of the present invention are described with reference to flowchart illustrations and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0125] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing terminal equipment to cause a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0126] It should also be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0127] Finally, it should be noted that the above description represents a preferred embodiment of the present invention. It should be pointed out that although preferred embodiments have been described, those skilled in the art, once they understand the basic inventive concept of the present invention, can make various improvements and modifications without departing from the principles described herein. These improvements and modifications should also be considered within the scope of protection of the present invention. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.

Claims

1. A single-quantum terahertz signal detection system based on Rydberg atoms, characterized in that, include: Atomic gas chamber (1) is used to contain alkali metal atomic vapor; A first laser (2) is used to emit a probe laser and incident it into the atomic gas chamber (1) to excite alkali metal atoms from the ground state to a lower energy level state; The second laser (4) is used to emit a coupling laser and incident it into the atomic gas cell (1) in a direction opposite to the incident direction of the probe laser, so as to excite the alkali metal atoms in the low energy level state to the first excited state; The third laser (5) is used to emit a Rydberg laser and incident it into the atomic gas cell (1) in a direction perpendicular to the incident direction of the probe laser, so as to excite the alkali metal atoms in the first excited state to the Rydberg state. The terahertz signal input port is used to receive the terahertz signal to be measured and to be incident on the atomic gas cell (1) perpendicular to the incident direction of the probe laser, so as to excite the alkali metal atoms in the Rydberg state to the second excited state; A single-photon detector (3) is used to detect the visible or infrared fluorescent photons released when the alkali metal atom spontaneously transitions from the second excited state to a low energy level, thereby realizing the detection of single quantum terahertz signals.

2. The single-quantum terahertz signal detection system based on Rydberg atoms according to claim 1, characterized in that, Also includes: The signal processor (6) is used to reconstruct the terahertz signal to be tested based on the detected fluorescent photons; and to demodulate the information carried in the terahertz signal to be tested according to the preset terahertz signal modulation mode.

3. The single-quantum terahertz signal detection system based on Rydberg atoms according to claim 1, characterized in that, The alkali metal is cesium.

4. The single-quantum terahertz signal detection system based on Rydberg atoms according to claim 3, characterized in that, When the alkali metal is cesium: ground state is ; low energy level state : The first excited state is ; Ridburg state ; The second excited state is .

5. The single-quantum terahertz signal detection system based on Rydberg atoms according to any one of claims 1 to 4, characterized in that, The wavelength of the detection laser is 852 nm; the wavelength of the coupling laser is 1470 nm; and the wavelength of the Rydberg laser is 790~980 nm.

6. A method for detecting single-quantum terahertz signals based on Rydberg atoms, characterized in that, The steps are as follows: Alkali metal atoms are excited from their ground state to a lower energy level by probing lasers; The alkali metal atoms in a low-energy state are excited to a first excited state by a coupling laser; the coupling laser is incident in a direction opposite to the incident direction of the probe laser; The alkali metal atoms in the first excited state are excited to the Rydberg state by a Rydberg laser; the Rydberg laser to be tested is incident perpendicular to the incident direction of the probe laser; The terahertz signal to be measured excites the alkali metal atoms in the Rydberg state to a second excited state; the terahertz signal to be measured is incident perpendicular to the incident direction of the probe laser; The fluorescence photons of visible or infrared light emitted when the alkali metal atom spontaneously transitions from the second excited state to a lower energy level are detected, thereby enabling the detection of single-quantum terahertz signals.

7. The method for detecting single-quantum terahertz signals based on Rydberg atoms according to claim 6, characterized in that, Also includes: Based on the detected fluorescent photons, the terahertz signal to be measured is reconstructed; and based on the preset terahertz signal modulation mode, the information carried in the terahertz signal to be measured is demodulated.

8. The method for detecting single-quantum terahertz signals based on Rydberg atoms according to claim 6, characterized in that, The alkali metal is cesium.

9. The method for detecting single-quantum terahertz signals based on Rydberg atoms according to claim 8, characterized in that, When the alkali metal is cesium: ground state is ; low energy level state : The first excited state is ; Ridburg state ; The second excited state is .

10. The method for detecting single-quantum terahertz signals based on Rydberg atoms according to any one of claims 6 to 9, characterized in that, The wavelength of the detection laser is 852 nm; the wavelength of the coupling laser is 1470 nm; and the wavelength of the Rydberg laser is 790~980 nm.

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