A dual-side input type Rydberg atom terahertz mixer and detection system

Abstract

The application provides a dual-side input type Rydberg atom terahertz mixer and a detection system, relates to the technical field of terahertz wave detection, and efficiently couples terahertz waves in a waveguide to a Rydberg atom gas chamber of the dual-side input type Rydberg atom terahertz mixer; a local signal is transmitted to the Rydberg atom gas chamber and a terahertz wave cavity through a local signal end waveguide; a measured terahertz wave is mixed with the local signal; a mixing result is reflected on light intensity after detection light passes through the Rydberg atom gas chamber and the terahertz wave cavity, and is detected by a photodetector; superheterodyne detection of the terahertz wave is realized; the detection sensitivity is improved; the terahertz electric field intensity and the phase are obtained; and an efficient detection method is provided for the application of terahertz technology.

Description

Technical Field

[0001] This invention belongs to the field of terahertz wave detection technology, specifically relating to a dual-input type Rydberg atom terahertz mixer and detection system. Background Technology

[0002] Terahertz waves refer to electromagnetic waves with frequencies between 0.1 THz and 10 THz, falling between the infrared and microwave bands in the electromagnetic spectrum. This band of electromagnetic waves possesses several unique properties: First, it can penetrate non-polar materials such as clothing, paper, and wood; second, many substances exhibit characteristic absorption peaks in the terahertz band; third, water strongly absorbs terahertz waves, with water molecules displaying multiple characteristic absorption peaks in this band; fourth, compared to microwaves and millimeter waves, its higher frequency band facilitates the development of high-bandwidth communication systems; and fifth, compared to infrared and visible light, it penetrates adverse weather conditions such as rain, snow, and fog. Due to the unique position of terahertz waves in the electromagnetic spectrum and these special physical properties, it possesses unique application value and broad market prospects in many fields, including public safety, biomedicine, communications, and non-destructive testing. However, in the field of terahertz technology, both basic research and engineering applications lag far behind other bands in the electromagnetic spectrum.

[0003] One major reason limiting the application of terahertz technology is the immaturity of terahertz detection technology. Currently common terahertz detection methods, such as frequency mixing detection, direct detection, or optical guide antennas, have significant shortcomings in detecting weak terahertz signals.

[0004] In recent years, radio frequency electric field detection technology based on the Rydberg atomic quantum effect has been continuously developing, achieving fruitful research results in the field of microwave detection. The Rydberg atom is a highly excited-state atom with a relatively large principal quantum number. Compared with the ground-state atom, it has a larger orbital radius, longer radiation lifetime, and higher polarizability, making it very suitable for sensing and measuring weak electromagnetic fields. Furthermore, the resonant transition frequencies between Rydberg energy levels happen to fall within the microwave and terahertz frequency bands.

[0005] The basic theory of radio frequency electric field detection in the Rydberg atom is as follows: Figure 1 As shown, a Rydberg atom gas cell 103 filled with alkali metal vapor is used as the sensing element. A probe light signal 104 excites the alkali metal atoms from their ground state to a certain intermediate excited state, and a coupling light signal 105 excites the alkali metal atoms from the intermediate excited state to a specific highly excited Rydberg state, thus forming a ladder-type three-level system of Rydberg atoms. This produces an electromagnetically induced transparency phenomenon, which manifests as the optical properties of the Rydberg atom gas changing from absorbing the probe light to being transparent to the probe light.

[0006] An external radio frequency electric field is then applied to the Rydberg atoms. The applied electric field at a specific frequency couples to some higher-energy Rydberg states, generating quantum coherence and causing the resonance peaks of the electromagnetically induced transparent spectrum to split, a phenomenon known as the Autler-Townes effect (AT splitting). The size of the AT splitting varies depending on the electric field strength; a stronger electric field results in a larger split. The strength of the applied electric field can be measured by measuring the spacing of the AT splits.

[0007] Since the strength of the external electric field is proportional to the spacing of the AT splits, the above measurement method is no longer effective when the external electric field is so weak that the AT splits are indistinguishable. In this case, a frequency mixing detection method can be used, that is, a signal with a slight frequency difference from the measured signal is used as the local oscillator signal 101, and the local oscillator signal 101 and the measured signal 102 are simultaneously irradiated onto the Rydberg atomic gas cell 103, such as... Figure 1 As shown. At this time, the Rydberg atom acts as a mixer, converting the measured signal into an intermediate frequency (IF) signal with a frequency equal to the difference between the local oscillator signal and the measured signal. This is reflected in the output intensity of the probe light signal 104 after passing through the Rydberg atom gas cell. The intensity oscillates with the difference frequency between the local oscillator signal and the measured signal, thereby obtaining the electric field intensity of the measured radio frequency signal. Summary of the Invention

[0008] To address the current limitations in terahertz technology development and application due to insufficient terahertz detection techniques, this invention proposes a terahertz mixer detector based on the Rydberg atomic quantum effect. Building upon existing Rydberg atomic radio frequency electric field detection theory, this invention proposes a terahertz mixer detector structure that enables the realization of a terahertz mixer detector based on the Rydberg atomic quantum effect.

[0009] A dual-input Rydberg atom terahertz mixer includes: a local oscillator signal end flange, a local oscillator signal end waveguide, a local oscillator signal end waveguide air cell transition structure, a Rydberg atom air cell that also serves as a terahertz wave cavity, a waveguide air cell transition structure for the signal under test, and a waveguide for the signal under test and a flange for the signal under test.

[0010] The local oscillator signal terminal flange is connected to the local oscillator signal terminal waveguide for receiving the local oscillator signal;

[0011] The local oscillator signal end waveguide gas chamber transition structure transitions the local oscillator signal to the Rydberg atomic gas chamber and terahertz wave cavity;

[0012] The flange of the signal under test is connected to the waveguide of the signal under test, and is used to receive the terahertz wave under test.

[0013] The waveguide gas chamber transition structure at the signal under test end transitions the measured terahertz wave to the Rydberg atomic gas chamber and terahertz wave cavity, forming a stable terahertz electromagnetic field within the sealed cavity.

[0014] The Rydberg atomic gas chamber and terahertz wave cavity is a hollow sealed cavity with a light-transmitting window, which is filled with alkali metal atomic gas. Coupled light and probe light pass through the light-transmitting window.

[0015] The local oscillator signal and the measured terahertz wave form a standing wave in the Rydberg air cell and terahertz wave cavity. The position of the light transmission window coincides with the antinode of the standing wave, so that the position of the antinode of the standing wave coincides with the propagation position of the probe light and the coupling light beam, thereby achieving the optimal detection efficiency.

[0016] The present invention also proposes a terahertz mixing detection system, comprising: a dichroic mirror, a photodetector, and a terahertz mixer;

[0017] The dichroic mirror is positioned on the optical path before the coupled light enters the light-transmitting window, and is used to transmit the coupled light and reflect the probe light.

[0018] The photodetector is positioned directly opposite the dichroic mirror and is used to measure the intensity of the probe light reflected by the dichroic mirror.

[0019] The photodetector outputs a sine wave, the amplitude of which is proportional to the amplitude of the measured terahertz wave, and the frequency of which is the frequency difference between the local oscillator signal and the measured terahertz wave.

[0020] Furthermore, the Rydberg atom gas chamber and terahertz wave cavity of the terahertz mixer is filled with alkali metal atom gas. The probe light excites the alkali metal atoms from the ground state to the intermediate state, and the coupling light excites the alkali metal atoms from the intermediate state to the Rydberg state. The Rydberg state atoms transition to the adjacent Rydberg state under the action of the local oscillator signal and the measured terahertz wave.

[0021] Furthermore, the Rydberg state determines the wavelength of the coupled light, the energy level difference between the Rydberg state and the adjacent Rydberg state determines the frequency of the measured terahertz wave, the principal quantum number of the Rydberg atom is selected according to the frequency of the measured terahertz wave, and the wavelength of the coupled light is selected according to the energy level difference between the intermediate state and the Rydberg state.

[0022] The present invention also proposes a terahertz superheterodyne detection system, comprising: a first terahertz mixer, a second terahertz mixer, a first reflector, a second reflector, a first beam splitter, a second beam splitter, a first terahertz power divider, a second terahertz power divider, a terahertz 90° phase shifter, a first photodetector, and a second photodetector.

[0023] Alkali metal atom gas is filled into the Rydberg atomic gas chamber and terahertz wave cavity of the first and second terahertz mixers.

[0024] The coupling light is split into a first coupling light and a second coupling light by the second beam splitter, and the probe light is split into a first probe light and a second probe light by the first beam splitter.

[0025] The first coupling light and the first probe light excite the alkali metal atoms to the Rydberg state in the first terahertz mixer, and the second coupling light and the second probe light excite the alkali metal atoms to the Rydberg state in the second terahertz mixer.

[0026] The local oscillator signal is divided into a first local oscillator signal and a second local oscillator signal by the first terahertz power divider. The first local oscillator signal enters the Rydberg atomic gas cell and terahertz wave cavity through the local oscillator signal waveguide of the first terahertz mixer. The second local oscillator signal is shifted by 90° after passing through the terahertz 90° phase shifter, and then enters the Rydberg atomic gas cell and terahertz wave cavity through the local oscillator signal waveguide of the second terahertz mixer.

[0027] The terahertz wave under test is split into a first terahertz wave and a second terahertz wave by the second terahertz power divider. The first terahertz wave enters the Rydberg atomic gas cell and terahertz wave cavity through the waveguide of the measured signal end of the first terahertz mixer. The second terahertz wave enters the Rydberg atomic gas cell and terahertz wave cavity through the waveguide of the measured signal end of the second terahertz mixer.

[0028] The first local oscillator signal and the first terahertz wave under test are mixed in the first terahertz mixer. The mixing result is reflected in the light intensity of the first probe light after passing through the Rydberg atomic gas cell and terahertz wave cavity of the first terahertz mixer, and is detected by the first photodetector.

[0029] The second local oscillator signal and the second measured terahertz wave are mixed in the second terahertz mixer. The mixing result is reflected in the light intensity of the second probe light after passing through the Rydberg atomic gas cell and terahertz wave cavity of the second terahertz mixer, and is detected by the second photodetector.

[0030] Furthermore, the output of the first photodetector is the light intensity of the first probe light after passing through the Rydberg atomic gas cell / terahertz wave cavity. This light intensity is the mixed signal of the first local oscillator signal and the first measured terahertz wave, and is the in-phase component I. The output of the second photodetector is the light intensity of the second probe light after passing through the Rydberg atomic gas cell / terahertz wave cavity. This light intensity is the mixed signal of the second local oscillator signal after a 90° phase shift and the second measured terahertz wave, and is the quadrature component Q. The amplitude and phase of the measured terahertz wave are obtained by using the IQ demodulation method.

[0031] Furthermore, the Rydberg atom gas chambers and terahertz wave cavities of the first and second terahertz mixers are filled with alkali metal atom gas. The first and second probe beams excite the alkali metal atoms from the ground state to the intermediate state, and the first and second coupling beams excite the alkali metal atoms from the intermediate state to the Rydberg state. The Rydberg state atoms transition to the adjacent Rydberg state under the action of the local oscillator signal and the measured terahertz wave.

[0032] Compared with the prior art, the present invention has the following beneficial technical effects:

[0033] Current common terahertz detection methods, such as mixing detection, direct detection, or optical antennas, have significant limitations in detecting weak terahertz signals. This invention proposes a terahertz mixing detection technique based on the Rydberg atomic quantum effect. The main feature is the proposed coupling structure between the terahertz wave and the Rydberg atomic gas cell. Compared to terahertz waves irradiating the Rydberg atomic gas cell from free space, this structure significantly improves the coupling efficiency. Based on this coupling structure, a dual-input Rydberg atomic terahertz mixer is implemented, enabling superheterodyne detection of terahertz waves. This improves detection sensitivity while obtaining the two most important physical quantities: terahertz electric field intensity and phase. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A schematic diagram illustrating the basic theory of existing Rydberg atom radio frequency electric field detection technology;

[0036] Figure 2 This is a schematic diagram of the dual-input type Rydberg atom terahertz mixer of the present invention;

[0037] Figure 3 This is a structural diagram of the Rydberg atomic gas chamber and terahertz wave cavity of the present invention;

[0038] Figure 4 This is a schematic diagram of the terahertz mixing detection system of the present invention;

[0039] Figure 5 This is a schematic diagram of the terahertz superheterodyne detection system of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] In the accompanying drawings of specific embodiments of the present invention, in order to better and more clearly describe the working principle of each component in the system and show the connection relationship of each part in the device, only the relative positional relationship between each component is clearly distinguished. It does not constitute a limitation on the signal transmission direction, connection sequence, or size, dimension, and shape of each part within the component or structure.

[0042] In existing applications of Rydberg atom detection of electromagnetic wave electric fields, electromagnetic waves are emitted through an antenna and directed to a Rydberg atomic gas cell. Because the electromagnetic waves radiated by the antenna are divergent, the Rydberg atomic gas cell, including the laser beam, occupies only a small portion of this divergent region, significantly reducing detection efficiency. Therefore, this invention proposes a waveguide-to-Rydberg atomic gas cell coupling structure to efficiently couple terahertz waves from the waveguide to the Rydberg atomic gas cell, greatly improving detection efficiency. Based on this coupling structure, a Rydberg terahertz mixer is constructed to achieve superheterodyne detection of terahertz waves. While improving detection sensitivity, this method also obtains the two most important physical quantities: terahertz electric field strength and phase, providing an efficient detection method for terahertz technology applications.

[0043] like Figure 2 The diagram shows the structure of the dual-input Rydberg atom terahertz mixer of the present invention. The dual-input Rydberg atom terahertz mixer includes: a local oscillator signal end flange 1, a local oscillator signal end waveguide 2, a local oscillator signal end waveguide gas chamber transition structure 3, a Rydberg atom gas chamber / terahertz wave cavity 4, a measured signal end waveguide gas chamber transition structure 5, a measured signal end waveguide 6, and a measured signal end flange 7. A light-transmitting window 8 is provided on the Rydberg atom gas chamber / terahertz wave cavity 4 to allow coupling light 9 and probe light 10 to pass through.

[0044] The local oscillator signal terminal flange 1 adopts a standard flange of the terahertz band and is connected to the local oscillator signal terminal waveguide 2 for receiving the local oscillator signal.

[0045] The local oscillator signal waveguide 2 adopts a standard waveguide in the terahertz band for transmitting the local oscillator signal.

[0046] The local oscillator signal waveguide gas cell transition structure 3 is a pyramidal horn structure that transitions the local oscillator signal in the waveguide to the Rydberg atomic gas cell and terahertz wave cavity 4. The optimized transition structure can smoothly couple the terahertz wave in the waveguide to the Rydberg atomic gas cell cavity, thereby reducing return loss.

[0047] The waveguide gas cell transition structure 5 at the signal under test end is a pyramidal horn structure, which transitions the signal under test in the waveguide to the Rydberg atomic gas cell and terahertz wave cavity 4. The optimized transition structure can smoothly couple the terahertz wave in the waveguide to the Rydberg atomic gas cell cavity, thereby reducing return loss.

[0048] The waveguide 6 at the signal under test uses a standard waveguide in the terahertz band to transmit the terahertz wave under test.

[0049] The flange 7 of the signal under test adopts a standard flange in the terahertz band and is used to connect to the waveguide 6 of the signal under test to receive the terahertz wave.

[0050] Regarding the materials of each part of the aforementioned dual-input Rydberg atomic terahertz mixer, except for the parts already described, all are made of gold-plated copper, which has excellent corrosion resistance and terahertz wave reflection performance.

[0051] The Rydberg atomic gas chamber / terahertz wave cavity 4 is a rectangular hollow sealed cavity filled with alkali metal atomic gas, the specific structure of which is as follows: Figure 3 As shown.

[0052] The outer end face 4-1 is the end face connecting the Rydberg atomic gas cell and terahertz wave cavity to the local oscillator signal end waveguide gas cell transition structure 3. It is made of optical glass, and the local oscillator signal can reach the Rydberg atomic gas cell and terahertz wave cavity through the outer end face 4-1.

[0053] The inner end face 4-2 is the end face connecting the Rydberg atomic gas cell and terahertz wave cavity to the waveguide gas cell of the signal under test. It is made of optical glass, and the signal under test can reach the Rydberg atomic gas cell and terahertz wave cavity through the inner end face 4-2.

[0054] The left light-transmitting window 8-1 and the right light-transmitting window 8-2 are made of optical glass (ITO glass) with an indium tin oxide film on the surface. They are used to allow the coupling light 9 and the probe light 10 to enter the Rydberg atomic gas cell and terahertz wave cavity, while also being able to reflect terahertz waves.

[0055] The wall portion 4-3, the left light-transmitting window 8-1 and the right light-transmitting window 8-2, the inner end face 4-2 and the outer end face 4-1 together constitute the sealed cavity. The wall portion 4-3 is a copper-plated gold structure, which has excellent corrosion resistance and terahertz wave reflection performance, and is used to form a stable terahertz electromagnetic field within the sealed cavity.

[0056] In one embodiment of the present invention, a terahertz mixing detection system based on the Rydberg atomic quantum effect is proposed, such as... Figure 4 As shown, Figure 4 This is a schematic diagram of a terahertz mixing and detection system based on the Rydberg atomic quantum effect. The terahertz mixing and detection system includes: a dual-input Rydberg atomic terahertz mixer, a dichroic mirror 11, and a photodetector 12.

[0057] Dichroic mirror 11 is used to transmit coupling light 9 and reflect probe light 10; photodetector 12 is used to measure the intensity of probe light 10. Local oscillator signal 13 and the measured terahertz wave 14 are input from both ends of the Rydberg atom terahertz mixer.

[0058] When performing terahertz wave measurements using a terahertz mixing detection system based on the Rydberg atomic quantum effect, an alkali metal atom gas is filled into the Rydberg atomic gas chamber / terahertz wave cavity 4. Taking rubidium atoms as an example, a probe light with a wavelength of 780.24 nm is used to detect the rubidium atoms from their ground state (5S). 1 / 2 ) excited to the intermediate state (5P) 3 / 2 Then, using coupled light, rubidium atoms are moved from the intermediate state (5P) 3 / 2 ) Excited to the Rydberg state (nD) 5 / 2 ). Ridburg state (nD) 5 / 2 The atom transitions to the adjacent Rydberg state (n+1P) under the influence of the local oscillator signal and the measured terahertz wave. 3 / 2 ), where n is the principal quantum number of the Rydberg atom.

[0059] Specific Rydberg states (nD) 5 / 2 The wavelength of the coupled light is determined by the adjacent Rydberg states (nD). 5 / 2 ) and (n+1P 3 / 2 The energy level difference between the two terahertz waves determines the frequency of the measured terahertz wave. For example, when n=20, the wavelength of the coupled light is 486.41nm, and the frequency of the measurable terahertz wave is 0.309THz.

[0060] In practical applications, the principal quantum number of the Rydberg atom is first selected based on the frequency of the terahertz being measured, and then the intermediate state (5P) is selected based on... 3 / 2 ) and Ridberg state (nD) 5 / 2 The energy level difference selects the wavelength of the coupled light.

[0061] During the measurement, the local oscillator signal 13 in the waveguide is transmitted to the Rydberg atomic gas cell / terahertz cavity 4 via the local oscillator signal end waveguide 2. The measured terahertz wave 14 in the waveguide is transmitted to the Rydberg atomic gas cell / terahertz cavity 4 via the measured signal end waveguide 6. The coupling light 9 and the probe light 10 enter the Rydberg atomic gas cell / terahertz cavity 4 through the light transmission window 8. The local oscillator signal 13 and the measured terahertz wave 14 are mixed in the Rydberg atomic gas cell / terahertz cavity 4. The mixing result is reflected in the light intensity of the probe light 10 after passing through the Rydberg atomic gas cell / terahertz cavity 4, and is detected by the photodetector 12.

[0062] The output of photodetector 12 is a sine wave, the amplitude of which is proportional to the amplitude of the measured terahertz wave, and the frequency is the frequency difference between the local oscillator signal 13 and the measured terahertz wave 14. The amplitude of the measured terahertz wave can be obtained by measuring the sine wave signal output by photodetector 12.

[0063] This system can also use other alkali metal Depberg atoms, such as cesium atom gas.

[0064] In another embodiment, the present invention also proposes a terahertz superheterodyne detection system based on the Rydberg atomic quantum effect, as shown in the figure below. Figure 5 As shown. The terahertz superheterodyne detection system includes: a first terahertz mixer 20-1, a second terahertz mixer 20-2, a first reflector 15-1, a second reflector 15-2, a first beam splitter 16-1, a second beam splitter 16-2, a first terahertz power divider 17-1, a second terahertz power divider 17-2, a terahertz 90° phase shifter 18, a first photodetector 12-1, and a second photodetector 12-2.

[0065] The structures of the first terahertz mixer 20-1 and the second terahertz mixer 20-2 are both as follows: Figure 2 As shown, for the specific structure, please refer to the previous section. Figure 2 The explanatory section.

[0066] This embodiment employs two terahertz mixers based on the Rydberg atomic quantum effect for superheterodyne mixing. The coupling beam 9 is split into two beams by the second beam splitter 16-2: a first coupling beam 9-1 and a second coupling beam 9-2. The probe beam 10 is also split into two beams by the first beam splitter 16-1: a first probe beam 10-1 and a second probe beam 10-2. The first coupling beam 9-1 and the first probe beam 10-1 excite the atoms to the Rydberg state in the first terahertz mixer 20-1. The second coupling beam 9-2 and the second probe beam 10-2 excite the atoms to the Rydberg state in the second terahertz mixer 20-2.

[0067] The local oscillator signal 13 is split into two paths by the first terahertz power divider 17-1, namely the first local oscillator signal 13-1 and the second local oscillator signal 13-2. The first local oscillator signal 13-1 enters the Rydberg atomic gas cell and terahertz wave cavity through the local oscillator signal end waveguide of the first terahertz mixer 20-1. The second local oscillator signal 13-2 is phase-shifted by 90° after passing through the terahertz 90° phase shifter 18, and enters the Rydberg atomic gas cell and terahertz wave cavity through the local oscillator signal end waveguide of the second terahertz mixer 20-2.

[0068] The measured terahertz wave 14 is split into two paths by the second terahertz power divider 17-2, namely the first measured terahertz wave 14-1 and the second measured terahertz wave 14-2. The first measured terahertz wave 14-1 enters the Rydberg atomic gas cell / terahertz wave cavity through the waveguide of the measured signal end of the first terahertz mixer 20-1, and the second measured terahertz wave 14-2 enters the Rydberg atomic gas cell / terahertz wave cavity through the waveguide of the measured signal end of the second terahertz mixer 20-2.

[0069] The first local oscillator signal 13-1 and the first measured terahertz wave 14-1 are mixed in the first terahertz mixer 20-1. The mixing result is reflected in the light intensity of the first probe light 10-1 after passing through the first terahertz mixer 20-1, and is detected by the first photodetector 12-1.

[0070] The second local oscillator signal 13-2 and the second measured terahertz wave 14-2 are mixed in the second terahertz mixer 20-2. The mixing result is reflected in the light intensity of the second probe light 10-2 after passing through the second terahertz mixer 20-2, and is detected by the second photodetector 12-2.

[0071] The output of the first photodetector 12-1 is the light intensity of the first probe light 10-1 after passing through the Rydberg atomic gas cell / terahertz wave cavity. This light intensity is the mixed signal of the first local oscillator signal 13-1 and the first measured terahertz wave 14-1, i.e., the in-phase component I. The output of the second photodetector 12-2 is the light intensity of the second probe light 10-2 after passing through the Rydberg atomic gas cell / terahertz wave cavity. This light intensity is the mixed signal of the second local oscillator signal 13-2 after a 90° phase shift and the second measured terahertz wave 14-2, i.e., the quadrature component Q. By using the IQ demodulation method, the amplitude and phase of the measured terahertz wave can be obtained.

[0072] This embodiment uses two Rydberg atom-based terahertz mixers for superheterodyne mixing, directly obtaining the amplitude and phase of the measured terahertz wave, the two most important physical quantities, in a single measurement.

[0073] This invention proposes a coupling structure between terahertz waves and a Rydberg atom gas cell. Compared to terahertz waves irradiating the Rydberg atom gas cell from free space, this structure significantly improves the coupling efficiency. Based on this coupling structure, a Rydberg atom terahertz mixer is implemented, enabling superheterodyne detection of terahertz waves. This improves detection sensitivity while obtaining the two most important physical quantities: terahertz electric field intensity and phase.

[0074] The key feature of this invention is that the Rydberg atomic gas chamber also functions as a terahertz wave cavity. The structure, material selection, and assembly of its various components into the final cavity structure simultaneously serve as both a Rydberg atomic gas chamber and a terahertz wave cavity. This ensures perfect overlap between the measured signal (terahertz wave) and the sensor (Rydberg atomic gas), significantly improving detection efficiency.

[0075] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).

[0076] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A dual-input type Rydberg atom terahertz mixer, characterized in that, include: Local oscillator signal end flange, local oscillator signal end waveguide, local oscillator signal end waveguide air chamber transition structure, Rydberg atomic air chamber and terahertz wave cavity, waveguide air chamber transition structure of the signal under test, waveguide of the signal under test and flange of the signal under test. The local oscillator signal terminal flange is connected to the local oscillator signal terminal waveguide for receiving the local oscillator signal; The local oscillator signal end waveguide gas chamber transition structure transitions the local oscillator signal to the Rydberg atomic gas chamber and terahertz wave cavity; The flange of the signal under test is connected to the waveguide of the signal under test, and is used to receive the terahertz wave under test. The waveguide gas chamber transition structure at the signal under test end transitions the measured terahertz wave to the Rydberg atomic gas chamber and terahertz wave cavity, forming a stable terahertz electromagnetic field within the sealed cavity. The Rydberg atomic gas chamber and terahertz wave cavity is a hollow sealed cavity with a light-transmitting window, which is filled with alkali metal atomic gas, and the coupling light and probe light pass through the light-transmitting window; The local oscillator signal and the measured terahertz wave form a standing wave in the Rydberg air cell and terahertz wave cavity. The position of the light transmission window coincides with the antinode of the standing wave, so that the position of the antinode of the standing wave coincides with the propagation position of the probe light and the coupling light beam, thereby achieving the optimal detection efficiency.

2. A terahertz mixing detection system, characterized in that, include: Dichroic mirror, photodetector, and dual-input Rydberg atomic terahertz mixer as described in claim 1; The local oscillator signal is transmitted to the Rydberg atomic gas cell and terahertz wave cavity via the local oscillator signal end waveguide, and the measured terahertz wave is transmitted to the Rydberg atomic gas cell and terahertz wave cavity via the measured signal end waveguide, where it is mixed with the local oscillator signal. The dichroic mirror is positioned in the optical path before the coupled light enters the light-transmitting window, and is used to transmit the coupled light and reflect the probe light emitted from the light-transmitting window; the photodetector is positioned opposite the dichroic mirror and is used to measure the light intensity of the probe light reflected by the dichroic mirror. The photodetector outputs a sine wave, the amplitude of which is proportional to the amplitude of the measured terahertz wave, and the frequency of which is the frequency difference between the local oscillator signal and the measured terahertz wave.

3. The terahertz mixing detection system according to claim 2, characterized in that, The Rydberg atom gas chamber and terahertz wave cavity of the dual-input Rydberg atom terahertz mixer is filled with alkali metal atom gas. The probe light excites the alkali metal atoms from the ground state to the intermediate state, and the coupling light excites the alkali metal atoms from the intermediate state to the Rydberg state. The Rydberg state atoms transition to the adjacent Rydberg state under the action of the local oscillator signal and the measured terahertz wave.

4. The terahertz mixing detection system according to claim 3, characterized in that, The Rydberg state determines the wavelength of the coupled light, the energy level difference between the Rydberg state and the adjacent Rydberg state determines the frequency of the measured terahertz wave, the principal quantum number of the Rydberg atom is selected according to the frequency of the measured terahertz wave, and the wavelength of the coupled light is selected according to the energy level difference between the intermediate state and the Rydberg state.

5. A terahertz superheterodyne detection system, characterized in that, include: First terahertz mixer, second terahertz mixer, first reflector, second reflector, first beam splitter, second beam splitter, first terahertz power divider, second terahertz power divider, terahertz 90° phase shifter, first photodetector and second photodetector. The first and second terahertz mixers are dual-input type Rydberg atom terahertz mixers as described in claim 1, wherein the Rydberg atom gas chamber and terahertz wave cavity of the first and second terahertz mixers are filled with alkali metal atom gas. The coupling light is split into a first coupling light and a second coupling light by the second beam splitter, and the probe light is split into a first probe light and a second probe light by the first beam splitter. The first coupling light and the first probe light excite the alkali metal atoms to the Rydberg state in the first terahertz mixer, and the second coupling light and the second probe light excite the alkali metal atoms to the Rydberg state in the second terahertz mixer. The local oscillator signal is divided into a first local oscillator signal and a second local oscillator signal by the first terahertz power divider. The first local oscillator signal enters the Rydberg atomic gas cell and terahertz wave cavity through the local oscillator signal waveguide of the first terahertz mixer. The second local oscillator signal is shifted by 90° after passing through the terahertz 90° phase shifter, and then enters the Rydberg atomic gas cell and terahertz wave cavity through the local oscillator signal waveguide of the second terahertz mixer. The terahertz wave under test is split into a first terahertz wave and a second terahertz wave by the second terahertz power divider. The first terahertz wave enters the Rydberg atomic gas cell and terahertz wave cavity through the waveguide of the measured signal end of the first terahertz mixer. The second terahertz wave enters the Rydberg atomic gas cell and terahertz wave cavity through the waveguide of the measured signal end of the second terahertz mixer. The first local oscillator signal and the first terahertz wave under test are mixed in the first terahertz mixer. The mixing result is reflected in the light intensity of the first probe light after passing through the Rydberg atomic gas cell and terahertz wave cavity of the first terahertz mixer, and is detected by the first photodetector. The second local oscillator signal and the second measured terahertz wave are mixed in the second terahertz mixer. The mixing result is reflected in the light intensity of the second probe light after passing through the Rydberg atomic gas cell and terahertz wave cavity of the second terahertz mixer, and is detected by the second photodetector.

6. The terahertz superheterodyne detection system according to claim 5, characterized in that, The output of the first photodetector is the light intensity of the first probe light after passing through the Rydberg atomic gas cell / terahertz wave cavity. This light intensity is the mixed signal of the first local oscillator signal and the first measured terahertz wave, and is the in-phase component I. The output of the second photodetector is the light intensity of the second probe light after passing through the Rydberg atomic gas cell / terahertz wave cavity. This light intensity is the mixed signal of the second local oscillator signal after a 90° phase shift and the second measured terahertz wave, and is the quadrature component Q. The amplitude and phase of the measured terahertz wave are obtained by using the IQ demodulation method.

7. The terahertz superheterodyne detection system according to claim 6, characterized in that, Alkali metal atom gas is filled into the Rydberg atom gas chamber and terahertz wave cavity of each of the first and second terahertz mixers. The first and second probe lights excite the alkali metal atoms from the ground state to the intermediate state, and the first and second coupling lights excite the alkali metal atoms from the intermediate state to the Rydberg state. The Rydberg state atoms transition to the adjacent Rydberg state under the action of the local oscillator signal and the measured terahertz wave.

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