Field polarization measurement method of Rydberg radio frequency receiving system

Abstract

The invention provides a field polarization measurement method of a Rydberg radio frequency receiving system, and belongs to the field of quantum microwave measurement. According to the field polarization measurement method, a dual-frequency polarization reconfigurable metasurface is introduced on the basis of the principle that a linearly polarized wave at any angle can be decomposed into two mutually perpendicular linearly polarized waves which are superposed, and the metasurface selectively penetrates through an x-direction component or a y-direction component of a to-be-measured linearly polarized field through switching of the switching state of a PIN tube, so that the to-be-measured linearly polarized field is obtained. Measuring an x-direction component electric field and a y-direction component electric field through a Rydberg radio frequency receiving system, and reversely deducing the total electric field intensity and the polarization angle of the linear polarization field to be measured. The polarization angle is obtained by measuring the electric field intensity in the x direction and the y direction of the field to be measured, the problem that calibration is needed in an existing polarization angle distinguishing method is solved, the application range is wide, the proposed dual-frequency polarization reconfigurable metasurface can work at two frequency points, the cross-band characteristic of a Rydberg atom antenna is met, the structure is simple, and the cost is low. And the cross-band response consistency is high.

Description

Technical Field

[0001] This invention belongs to the field of quantum microwave measurement and relates to a field polarization measurement method for a Rydberg radio frequency receiving system. Background Technology

[0002] Radio frequency receiving systems based on Rydberg atoms have become an important direction for breaking through classical limits due to their unique physical advantages. Rydberg atoms possess enormous polarizability (~n). 7 ) and transition dipole moment (~n 2 Rydberg atoms are extremely sensitive to external electric fields, and their energy level structure naturally covers the MHz to THz frequency band, enabling strong coupling with microwave fields through multiphoton resonance. Sensors based on Rydberg atoms possess advantages such as high sensitivity, wide bandwidth, fast response, no need for demodulation, and strong anti-interference capabilities. They can also achieve electric field measurements traceable to the International System of Units (SI), demonstrating great potential to replace traditional antenna systems. In practical electromagnetic sensing applications, electric field polarization information is a crucial parameter describing the propagation characteristics and information carrying capacity of electromagnetic waves, playing a key role in signal recognition, target detection, and communication demodulation. Therefore, how to accurately detect the electric field polarization angle in a Rydberg atom receiving system has become one of the key technical problems urgently needing to be solved in this field.

[0003] In existing research, the polarization resolution of linearly polarized fields of Rydberg atom pairs mainly relies on the phenomenon that the AT (Autler-Townes) splitting spectral characteristics change with the angle between the applied electric field and the laser polarization direction. Specifically, when the polarization direction of the external electric field changes relative to the laser direction, it causes changes in the AT splitting peak shape, peak intensity, and splitting characteristics. By establishing a pre-defined mapping relationship between the electric field polarization angle and the corresponding spectral characteristics, the measurement of unknown electric field polarization angles can be achieved.

[0004] However, the above-mentioned polarization angle measurement method based on spectral feature calibration still has limitations in practical applications: on the one hand, the response of spectral features to polarization angle is usually nonlinear and multivalued, and the resolution is limited in a specific angle range, resulting in a limited range of available polarization detection; on the other hand, this method usually depends on specific atomic energy level structures and laser configurations, and is difficult to apply universally in different frequency bands, different atomic transition schemes or complex electromagnetic environments, which limits the applicability and engineering promotion of Rydberg atomic polarization angle resolution technology.

[0005] A metasurface is a planar artificial structure material composed of subwavelength-scale (typically smaller than the operating wavelength) artificial atoms (superatoms) arranged in a two-dimensional or quasi-two-dimensional manner. By carefully designing the geometry and arrangement of each subwavelength unit, it achieves precise control over the amplitude, phase, polarization, and mode characteristics of incident electromagnetic waves (light waves, microwaves, etc.). Currently, related research and patents have introduced metasurfaces into Rydberg radio frequency receiving systems. For example, Chinese invention patent (application number 202210856298.0) proposes an atomic gas cell probe loaded with a metasurface lens. Compared to traditional atomic receiving antennas, this invention utilizes a metasurface lens for microwave focusing, placing the atomic gas cell at its focal point, thereby increasing the detection sensitivity of the atomic receiving antenna. However, these inventions primarily focus on using metasurfaces to improve detection sensitivity and do not utilize them for auxiliary polarization measurements.

[0006] Therefore, the Rydberg receiving system urgently needs a new field polarization measurement method to overcome the problems of existing technologies, such as strong dependence on spectral calibration, limited applicability, and insufficient stability, and to achieve high-precision, wide-applicability, and high-stability detection of electric field polarization. Summary of the Invention

[0007] To address the calibration requirements of current field polarization measurement methods for Rydberg RF receiving systems, this invention proposes a new method for measuring field polarization in Rydberg RF receiving systems. This method is based on the principle that a linearly polarized wave at any angle can be decomposed into the superposition of two mutually perpendicular linearly polarized waves. It introduces a dual-frequency polarization reconfigurable metasurface designed in this invention. By switching the PIN diode, the metasurface selectively transmits either the x-direction or y-direction component of the linearly polarized field under test. The field strength of the x-direction and y-direction components is then measured using the Rydberg RF receiving system, allowing the total electric field strength and polarization angle of the measured linearly polarized field to be deduced. Furthermore, to preserve the cross-band characteristics of the Rydberg RF receiving system, this polarization reconfigurable metasurface can operate at multiple frequencies.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for measuring the field polarization of a Rydberg radio frequency receiving system, the method comprising the following steps: The first step is to design a dual-frequency polarization reconfigurable metasurface. The dual-frequency polarization reconfigurable metasurface designed in this invention can achieve the decomposition of linearly polarized waves at arbitrary angles. It is composed of multiple metasurface units with identical structures. The specific structure of each metasurface unit includes a dielectric substrate and metal structures and PIN diodes disposed on the upper and lower sides of the dielectric substrate. Specifically: The upper surface of the dielectric substrate is provided with a first thin metal line, a first long metal line, a first short metal line, a first PIN tube, and a second short metal line. The longitudinal direction of the dielectric substrate is defined as the length direction of each structure on the upper surface, and the lateral edge is defined as the width direction. The longitudinal direction of the dielectric substrate is defined as the width direction of each structure on the lower surface, and the lateral edge is defined as the length direction. The first thin metal line comprises two identical metal strips symmetrically distributed along the longitudinal edges of both sides of the dielectric substrate, used to improve the polarization selectivity of the dual-frequency polarized reconfigurable metasurface. The first long metal line comprises two identical narrow metal strips symmetrically placed along the longitudinal centerline of the dielectric substrate, with the edges of the two metal strips aligned with the lateral edges of the dielectric substrate, and a gap between the two metal strips. The first short metal line comprises two identical metal strips located within the gap between the first long metal lines, respectively positioned adjacent to the two sides of the gap. A gap is also maintained between the two first short metal lines for mounting the first PIN tube. The first PIN tube is located between the gaps of the first short metal lines and is connected to the two strips of the first short metal line. The second short metal line comprises four identical metal strips, regularly distributed in two interval regions defined by the first thin metal line and the first long metal line. Specifically, in each interval region, four metal strips are symmetrically arranged along the extension direction of the first long metal line, with two strips in each interval region. The length and width of the first long metal line determine the low-frequency operating frequency, and the length and width of the second short metal line determine the high-frequency operating frequency.

[0009] The lower surface of the dielectric substrate is provided with a second thin metal line, a second long metal line, a third short metal line, a second PIN diode, and a fourth short metal line. The second thin metal line comprises two identical narrow metal strips symmetrically distributed along the lateral edges of the dielectric substrate, used to improve the polarization selectivity of the dual-frequency polarized reconfigurable metasurface. The second long metal line comprises two identical metal strips placed along the lateral centerline of the dielectric substrate, with the edges of the metal strips aligned with the longitudinal edges of the dielectric substrate, and a gap between the two metal strips. The third short metal line comprises two identical metal strips located within the gap between the second long metal lines, respectively positioned adjacent to the two lateral edges of the gap. A gap is also maintained between the two third short metal lines for mounting the second PIN diode. The second PIN diode is located between the gaps of the third short metal lines and is connected to the two strips of the third short metal line. The fourth metal short line comprises four identical metal strips, regularly distributed in the two interval regions defined by the second metal thin line and the second metal long line. Specifically, in each interval region, four metal strips are symmetrically arranged along the extension direction of the second metal long line, with two strips in each interval region. The length and width of the second metal long line determine the low-frequency operating frequency, and the length and width of the second metal short line determine the high-frequency operating frequency.

[0010] Furthermore, when the dual-frequency polarized reconfigurable metasurface needs to be in the x-polarization wave selection state, a DC bias voltage is applied to the first PIN diode on the upper side of the dielectric substrate to make the first PIN diode in the conducting state; at the same time, no DC bias voltage is applied to the second PIN diode on the lower side of the dielectric substrate to make the second PIN diode in the cut-off state.

[0011] Furthermore, when the dual-frequency polarized reconfigurable metasurface needs to be in the y-polarized wave selection state, no DC bias voltage is applied to the first PIN diode on the upper side of the dielectric substrate, so that the first PIN diode is in the cut-off state; at the same time, a DC bias voltage is applied to the second PIN diode on the lower side of the dielectric substrate, so that the second PIN diode is in the conducting state.

[0012] Furthermore, the dielectric substrate is used to support the metal periodic array and active devices, and its material type does not constitute a limitation on the present invention. The dielectric substrate can be any dielectric material that meets the requirements of electromagnetic wave transmission and device fabrication, including but not limited to polytetrafluoroethylene high-frequency copper-clad laminate, epoxy resin substrate, ceramic substrate, flexible dielectric substrate, or combinations thereof. As long as the dielectric substrate can support the arrangement of the metal periodic array and PIN diodes, and ensure the electromagnetic response characteristics of the dual-frequency polarized reconfigurable metasurface, the technical effects of the present invention can be achieved.

[0013] Furthermore, the active device used to realize the polarization reconfigurability function is preferably a PIN diode, but the specific model, package form, and electrical parameters of the active device do not constitute a limitation of the present invention. Without departing from the technical concept of the present invention, the first PIN diode and the second PIN diode can be replaced with any active or controllable device capable of switching between equivalent on and off states under DC bias control, including but not limited to RF switching diodes, varactor diodes, MEMS switches, field-effect transistors, or equivalent devices thereof. As long as the active device can change the equivalent electromagnetic parameters of the metal periodic array under the action of an external control signal, thereby realizing the switching of the polarization selection state, it should fall within the protection scope of the present invention.

[0014] The second step involves constructing a coupling system between a dual-frequency polarized reconfigurable metasurface and a Rydberg atom radio frequency receiving system. The dual-frequency polarized reconfigurable metasurface is located between the horn antenna and the first atomic gas cell of the Rydberg atom radio frequency receiving system, ultimately completing the detection of the radio frequency signal. Specifically: The Rydberg atomic radio frequency receiving system involved in this invention includes a detection optical path, a coupling optical path, a first atomic gas cell, a radio frequency module, and a signal detection module, specifically: The probe light is generated by the probe light source and passes through the first optical isolator, the first half-wave plate, and the first polarizing beam splitter in sequence before being split into two beams: one beam enters the probe light frequency-locking module, which is used to stabilize the output wavelength of the probe light source, wherein the probe light frequency-locking module is a known structure; the other beam is deflected by the first reflector and passes through the fourth half-wave plate, the fourth polarizing beam splitter, the fifth half-wave plate, the beam shifter, and the first dichroic mirror in sequence before finally entering the first atomic gas cell.

[0015] The coupled light path is generated by the coupled light source and passes through the second optical isolator, the second half-wave plate, and the third polarization beam splitter in sequence before being split into two beams: one beam enters the coupled light frequency-locking module, which is used to stabilize the output wavelength of the coupled light source. The coupled light frequency-locking module is a known structure. The other beam is deflected by the second mirror and passes through the seventh half-wave plate, the fifth polarization beam splitter, the sixth half-wave plate, and the second dichroic mirror in sequence before finally entering the first atomic gas cell.

[0016] Within the first atomic gas chamber, the probe light path and the coupling light path propagate in opposite directions along the same optical axis, achieving optical path overlap. The probe light path is used to excite atoms from the ground state |1> to the intermediate state |2>, while the coupling light path is used to excite atoms from the intermediate state |2> to the Rydberg state |3>. The probe light transmitted through the first atomic gas chamber passes through the second dichroic mirror, enters the balanced detector, is converted into an electrical signal, and is observed by an oscilloscope.

[0017] The radio frequency module is used to generate the radio frequency signal to be tested. The radio frequency signal to be tested is generated by a signal generator, radiated by a horn antenna, and then filtered by the dual-frequency polarized reconfigurable metasurface designed in this invention. Finally, it acts on the atoms in the first atomic gas chamber, coupling the Rydberg states |3> and |4> of the atoms. Finally, the radio frequency signal is detected by the signal detection module.

[0018] Furthermore, in the second step, the horn antenna is positioned in front of the dual-frequency polarized reconfigurable metasurface, and the first atomic gas chamber is located behind the dual-frequency polarized reconfigurable metasurface.

[0019] The third step is to adjust the wavelengths of the probe and coupling optical paths according to the frequency of the first test field until the EIT (Electromagnetically Induced Transparency) effect is observed on the oscilloscope. Since the dual-frequency polarized reconfigurable metasurface can operate at two frequencies, when there are two test fields with different frequencies, one test field is selected and defined as the first test field, and the other test field is defined as the second test field. Fourth, based on the coupling system constructed in the second step, the dual-frequency polarized reconfigurable metasurface is made to work in the y-polarized wave selection state. By placing the dual-frequency polarized reconfigurable metasurface between the horn antenna and the first atomic gas cell, the y-direction component of the first field to be measured is obtained, as shown in formula (1): (1) Where E1 represents the y-direction component of the first field to be measured; Represents the reduced Planck constant; The transition dipole moment between Rydberg states |3> and |4> is represented by the ARC (AlkaliRydbergCalculator) software package, which is obtained by means of the ARC. The AT splitting interval is represented by the AT splitting image recorded under the first test field using an oscilloscope, and then fitted to the AT splitting image. .

[0020] Fifth, based on the coupling system constructed in the second step, the dual-frequency polarization reconfigurable metasurface is made to work in the x-polarization wave selection state. By placing the dual-frequency polarization reconfigurable metasurface between the horn antenna and the first atomic gas cell, the x-direction component of the first field to be measured is obtained, as shown in formula (2): (2) Where E2 represents the x-direction component of the first field to be measured; The AT splitting interval is represented by the AT splitting image recorded under the first test field using an oscilloscope, and then fitted to the AT splitting image. .

[0021] Step 6: Calculate the total electric field strength and the polarization angle of the total electric field relative to the x-axis of the first field to be measured; The formula for calculating the total electric field strength is: ; The formula for calculating the polarization angle of the total electric field relative to the x-axis is: .

[0022] Step 7: Adjust the wavelengths of the probe and coupling optical paths according to the frequency of the second test field until the EIT effect is observed on the oscilloscope. Repeat steps 3 to 6 to obtain the total electric field strength and polarization angle of the total electric field relative to the x-axis of the second test field.

[0023] The above steps constitute the field polarization measurement method for the Rydberg radio frequency receiving system proposed in this invention. By following the above steps, the electric field strength and polarization angle of two fields to be measured at different frequencies can be measured.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The dual-frequency polarization reconfigurable frequency selectable surface proposed in this invention can operate at two frequency points, which matches the cross-band characteristics of the Rydberg atomic antenna.

[0025] (2) The dual-frequency polarization reconfigurable frequency selective surface designed in this invention has a simple structure, good dual-frequency response consistency, does not require recalibration, and does not require additional feeders, which can effectively reduce the negative impact of the power supply system on the frequency selective surface.

[0026] (3) The present invention obtains the polarization angle by measuring the electric field intensity in the x and y directions of the field to be measured, which avoids the problem of calibration required by the existing polarization angle resolution method and has a wider range of applications. Attached Figure Description

[0027] Figure 1 A schematic diagram of a unit cell for a dual-frequency polarized reconfigurable metasurface; Figure 1 (a) in the figure represents the upper structure of the dual-frequency polarized reconfigurable metasurface unit; Figure 1 (b) in the figure represents the lower layer structure of the dual-frequency polarized reconfigurable metasurface unit; Figure 2 For the Reedburg radio frequency receiving system; Figure 3 Schematic diagram of a dual-frequency polarized reconfigurable metasurface; Figure 4 The electromagnetic wave transmission coefficients of the dual-frequency polarized reconfigurable metasurface for x-polarized and y-polarized waves under different states are plotted. Figure 4 In the figure, (a) represents the electromagnetic wave transmission coefficient of the dual-frequency polarized reconfigurable metasurface when it is operating in the x-polarization wave selection state; Figure 4 In the figure, (b) represents the electromagnetic wave transmission coefficient of the dual-frequency polarized reconfigurable metasurface operating in the y-polarized wave-selective state. Figure 5 This is a schematic diagram of AT splitting when the test field is 3.2 GHz; Figure 5 (a) is a schematic diagram of AT splitting of a linearly polarized wave after passing through the y-polarized wave selection state of a metasurface; Figure 5 (b) is a schematic diagram of AT splitting of a linearly polarized wave after passing through the x-polarized wave selection state of a metasurface; In the diagram: 1 First thin metal wire; 2 First long metal wire; 3 First short metal wire; 4 First PIN tube; 5 Second short metal wire; 6 Second thin metal wire; 7 Second long metal wire; 8 Third short metal wire; 9 Second PIN tube; 10 Fourth short metal wire; 11 Probe light source; 12 Coupled light source; 13 First optical isolator; 14 Second optical isolator; 15 First half-wave plate; 16 Second half-wave plate; 17 Third half-wave plate; 18 Fourth half-wave plate; 19 Fifth half-wave plate; 20 Sixth half-wave plate; 21 Seventh half-wave plate; 22 First polarization beam splitter; 23 Second polarization beam splitter; 24 Third polarization beam splitter. 25. Polarization beam splitter, 26. Fifth polarization beam splitter, 27. Probe light frequency-locking module, 28. Coupled light frequency-locking module, 29. Half-reflector, 30. Second atomic gas cell, 31. Third atomic gas cell, 32. First atomic gas cell, 33. First photodetector, 34. Second photodetector, 35. First reflector, 36. Second reflector, 37. Beam shifter, 38. First dichroic mirror, 39. Second dichroic mirror, 40. Third dichroic mirror, 41. Fourth dichroic mirror, 42. Signal generator, 43. Horn antenna, 44. Dual-frequency polarized reconfigurable metasurface, 45. Balanced detector, 46. Oscilloscope. Detailed Implementation

[0028] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings and technical solutions.

[0029] A method for measuring the field polarization of a Rydberg radio frequency receiving system, the method comprising the following steps: The first step is to design a dual-frequency polarized reconfigurable metasurface 44. The dual-frequency polarized reconfigurable metasurface 44 designed in this embodiment can achieve the decomposition of linearly polarized waves at arbitrary angles. It is composed of multiple metasurface units with identical structures. Each metasurface unit includes a dielectric substrate and metal structures and PIN diodes respectively disposed on the upper and lower sides of the dielectric substrate. The unit period is p, and the dielectric substrate thickness is h. Specifically: like Figure 1As shown in (a), the upper surface of the dielectric substrate is provided with a first thin metal line 1, a first long metal line 2, a first short metal line 3, a first PIN tube 4, and a second short metal line 5. The longitudinal direction of the dielectric substrate is defined as the length direction of each structure provided on the upper surface, and the lateral edge is defined as the width direction. The longitudinal direction of the dielectric substrate is defined as the width direction of each structure provided on the lower surface, and the lateral edge is defined as the length direction. The first thin metal line 1 includes two identical metal strips, symmetrically distributed on both sides of the longitudinal edge of the dielectric substrate, with length and width of l1 and w1. The first long metal line 2 includes two identical narrow metal strips, with length and width of l2 and w2, placed along the longitudinal centerline of the dielectric substrate. The edges of the metal strips are aligned with the edges of the dielectric substrate, and a gap is left between the two metal strips. The first short metal line 3 includes two identical metal strips, with length and width of l3 and w3, located in the gap between the first long metal lines 2, and respectively disposed adjacent to the two sides of the gap. A gap with length d1 is also left between the two first short metal lines 3. The first PIN tube 4 is located between the gaps of the first short metal wires 3 and is connected to two strips of the first short metal wires 3 respectively. The second short metal wire 5 includes four identical metal strips with lengths and widths of l4 and w4, regularly distributed in two interval regions defined by the first thin metal wire 1 and the first long metal wire 2. Specifically, in the interval regions, four metal strips are symmetrically arranged along the extension direction of the first long metal wire 2, with two strips in each interval region. The distance between two metal strips is d2, and the distance from the first long metal wire 2 is d3. The length and width of the first long metal wire 2 determine the low-frequency operating frequency, and the length and width of the second short metal wire 5 determine the high-frequency operating frequency.

[0030] like Figure 1As shown in (b), the upper surface of the dielectric substrate is provided with a second thin metal line 6, a second long metal line 7, a third short metal line 8, a second PIN tube 9, and a fourth short metal line 10. The second thin metal line 6 comprises two identical narrow metal strips symmetrically distributed on both sides of the dielectric substrate's transverse edge, with lengths and widths of l1 and w1. The second long metal line 7 comprises two identical metal strips with lengths and widths of l2 and w2, placed along the transverse centerline of the dielectric substrate, with the edges of the metal strips aligned with the edges of the dielectric substrate, and a gap between the two metal strips. The third short metal line 8 comprises two identical metal strips with lengths and widths of l3 and w3, located within the gap between the second long metal lines 7, and respectively positioned adjacent to the two sides of the gap. A gap with a length of d1 is also maintained between the two third short metal lines 8. The second PIN tube 9 is located between the gaps of the third short metal lines 8 and is connected to the two strips of the third short metal line 8. The fourth metal short line 10 comprises four identical metal strips, with lengths and widths of l4 and w4, respectively. These strips are regularly distributed in two interval regions defined by the second metal thin line 6 and the second metal long line 7. Specifically, within each interval region, four metal strips are symmetrically arranged along the extension direction of the second metal long line 7, with two strips in each interval region. The distance between two metal strips is d2, and the distance from the second metal long line 7 is d3. The thickness of each metal strip is tm. The length and width of the second metal long line 7 determine the low-frequency operating frequency, while the length and width of the fourth metal short line 10 determine the high-frequency operating frequency.

[0031] In this embodiment, the length of the first metal wire 1 is the same as the length of the dielectric substrate. The width of the second metal wire 6 is the same as the width of the dielectric substrate.

[0032] The embodiment described is a dual-frequency polarized reconfigurable metasurface 44 with polarization selection frequencies of 3.2 GHz and 15.35 GHz. The dielectric material used is F4B with a relative permittivity of 2.2 and a loss tangent of 0.001. The PIN diode used is an ARCHIWAVEARW3172. Other structural parameters are shown in Table 1 (unit: mm).

[0033] Table 1: Structural parameters of dual-frequency polarized reconfigurable metasurfaces

[0034] In this embodiment, when the dual-frequency polarized reconfigurable metasurface needs to be in the x-polarization wave selection state, a DC bias voltage is applied to the first PIN diode 4 on the upper side of the dielectric substrate to make the PIN diode in the conducting state; at the same time, no DC bias voltage is applied to the second PIN diode 9 on the lower side of the dielectric substrate to make the PIN diode in the cut-off state.

[0035] In this embodiment, when the dual-frequency polarized reconfigurable metasurface needs to be in the y-polarized wave selection state, no DC bias voltage is applied to the first PIN diode 4 on the upper side of the dielectric substrate, so that the PIN diode is in the cut-off state; at the same time, a DC bias voltage is applied to the second PIN diode 9 on the lower side of the dielectric substrate, so that the PIN diode is in the conduction state.

[0036] In this embodiment, the dual-frequency polarized reconfigurable metasurface 44, as shown... Figure 3 As shown, the upper layer positively biases the first metal lines 2 applied to each unit on one side edge of the upper surface of the dual-frequency polarized reconfigurable metasurface 44, and the upper layer negatively biases the first metal lines 2 applied to each unit on the other side edge of the upper surface of the dual-frequency polarized reconfigurable metasurface 44; the lower layer positively biases the second metal lines 7 applied to each unit on one side edge of the lower surface of the dual-frequency polarized reconfigurable metasurface 44, and the lower layer negatively biases the second metal lines 7 applied to each unit on the other side edge of the lower surface of the dual-frequency polarized reconfigurable metasurface 44. The electromagnetic wave transmission coefficient of the dual-frequency polarized reconfigurable metasurface 44 in the x-polarization wave selection state is as follows: Figure 4 As shown in (a), the transmission coefficients of x-polarized waves at 3.2 GHz and 15.35 GHz are -0.13 dB and -0.26 dB, respectively, while those of y-polarized waves are -15.70 dB and -24.81 dB, respectively. This indicates that the metasurface in this state allows x-polarized waves to pass through while blocking y-polarized waves. The electromagnetic wave transmission coefficients of the dual-frequency polarized reconfigurable metasurface 44 in the y-polarized wave selective state are as follows: Figure 4 As shown in (b), the transmission coefficients of y-polarized waves at 3.2 GHz and 15.35 GHz are -0.13 dB and -0.26 dB, respectively, while those of x-polarized waves at 3.2 GHz and 15.35 GHz are -15.70 dB and -24.81 dB, respectively. This indicates that the metasurface can transmit y-polarized waves and block x-polarized waves in this state.

[0037] The second step involves constructing a coupling system between a dual-frequency polarized reconfigurable metasurface and a Rydberg atom radio frequency receiver system, such as... Figure 2 As shown; the Rydberg atomic radio frequency receiving system includes a detection optical path, a coupling optical path, an atomic gas cell, a radio frequency module, and a signal detection module. Specifically: The detection light path is generated by the detection light source 11, and after passing through the first optical isolator 13, the first half-wave plate 15, and the first polarization beam splitter 22, it is split into two beams: one beam enters the detection light frequency-locking module 27, which is used to stabilize the output wavelength of the detection light source 11, wherein the detection light frequency-locking module 27 is a known structure; the other beam is deflected by the first reflector 35, and after passing through the fourth half-wave plate 18, the fourth polarization beam splitter 25, the fifth half-wave plate 19, the beam shifter 37, and the first dichroic mirror 38, it finally enters the first atomic gas cell 32. In the detection light frequency-locking module 27 of this embodiment: the detection light path passes through the third half-wave plate 17 and the second polarization beam splitter 23, and is split into two beams: one beam passes through the second atomic gas cell 30, is reflected by the half-reflector 29, and after passing through the second atomic gas cell 30 and the second polarization beam splitter 23, it finally enters the first photodetector 33; the other beam enters the coupling light frequency-locking module 28.

[0038] The coupled light path is generated by the coupled light source 12, and after passing through the second optical isolator 14, the second half-wave plate 16, and the third polarization beam splitter 24, it is also split into two beams: one beam enters the coupled light frequency locking module 28, which is used to stabilize the output wavelength of the coupled light source 12, wherein the coupled light frequency locking module 28 is a known structure; the other beam is deflected by the second reflector 36, and after passing through the seventh half-wave plate 21, the fifth polarization beam splitter 26, the sixth half-wave plate 20, and the second dichroic mirror 39, it finally enters the first atomic gas cell 32. In the coupled light frequency locking module 28 of this embodiment: the probe light path passes through the third dichroic mirror 40, the third atomic gas cell 31, and the fourth dichroic mirror 41 in sequence, and finally enters the second photodetector 34. The coupled light path passes through the fourth dichroic mirror 41, the third atomic gas cell 31, and the third dichroic mirror 40 in sequence.

[0039] Within the first atomic gas chamber 32, the probe light path and the coupling light path propagate in opposite directions along the same optical axis, achieving optical path overlap. The probe light path is used to excite atoms from the ground state |1> to the intermediate state |2>, and the coupling light path is used to excite atoms from the intermediate state |2> to the Rydberg state |3>. The probe light transmitted through the first atomic gas chamber 32 passes through the second dichroic mirror 39, enters the balanced detector 45, is converted into an electrical signal, and is observed by the oscilloscope 46.

[0040] The radio frequency module is used to generate the radio frequency signal to be tested. The radio frequency signal to be tested is generated by the signal generator 42, radiated by the horn antenna 43, and filtered by the dual-frequency polarized reconfigurable metasurface 44 designed in this invention. Finally, it acts on the atoms in the first atomic gas chamber 32, coupling the Rydberg state |3> and Rydberg state |4> of the atom. Finally, the radio frequency signal is detected by the signal detection module.

[0041] Furthermore, in the second step, the horn antenna 43 is arranged in front of the dual-frequency polarized reconfigurable metasurface 44, and the first atomic gas chamber 32 is located behind the dual-frequency polarized reconfigurable metasurface 44.

[0042] Third, since the dual-frequency polarized reconfigurable metasurface 44 can operate at two frequency points, when there are two test fields with different frequencies, one test field can be selected and defined as the first test field, and the other test field can be defined as the second test field. In this embodiment, the first atomic gas chamber 32 contains cesium atoms. The wavelength of the detection optical path is 852 nm, the wavelength of the coupling optical path is 510 nm, the frequency of the first test field is 3.2 GHz, and the frequency of the second test field is 15.35 GHz. When the test field is 3.2 GHz, the atomic states corresponding to |1>, |2>, |3>, and |4> are 6S1 / 2, 6P3 / 2, 60D5 / 2, and 61P3 / 2, respectively. When the test field is 15.35 GHz, the atomic states corresponding to |1>, |2>, |3>, and |4> are 6S1 / 2, 6P3 / 2, 75D5 / 2, and 77P3 / 2, respectively.

[0043] Adjust the wavelengths of the probe optical path and the coupling optical path according to the frequency of the first test field until the EIT effect is observed on the oscilloscope 46. Fourth step: Based on the coupling system constructed in the second step, the dual-frequency polarization reconfigurable metasurface 44 is made to work in the y-polarization wave selection state. The dual-frequency polarization reconfigurable metasurface 44 is placed between the horn antenna 43 and the first atomic gas cell 32 to obtain the y-direction component of the first field to be measured, as shown in formula (1): (1) Where E1 represents the y-direction component of the first field to be measured; Represents the reduced Planck constant; The transition dipole moment between Rydberg states |3> and |4> is represented by the ARC software package; The AT splitting interval is represented by recording the corresponding AT splitting image under the first test field using an oscilloscope 46, and then fitting these images using software to calculate the AT splitting interval. .

[0044] In this embodiment, , , The AT splitting image obtained by the dual-frequency polarized reconfigurable metasurface 44 operating in the y-polarization wave-selective state and the calculated... As shown in Figure 5(a).

[0045] Fifth, based on the coupling system constructed in the second step, the dual-frequency polarization reconfigurable metasurface is made to work in the x-polarization wave selection state. By placing the metasurface between the horn antenna 43 and the first atomic gas cell 32, the x-direction component of the first field to be measured is obtained, as shown in formula (2): (2) Where E2 represents the x-direction component of the first field to be measured; The AT splitting interval is represented by recording the corresponding AT splitting image under the first test field using an oscilloscope 46, and then fitting these images using software to calculate the AT splitting interval. .

[0046] In this embodiment, , The AT splitting image obtained by the dual-frequency polarized reconfigurable metasurface 44 operating in the x-polarization wave-selective state and the calculated... like Figure 5 As shown in (b) of the diagram.

[0047] Step 6: Calculate the total electric field strength and the polarization angle of the total electric field relative to the x-axis of the first field to be measured; The formula for calculating the total electric field strength is: ; The formula for calculating the polarization angle of the total electric field relative to the x-axis is: .

[0048] Step 7: Adjust the wavelengths of the probe light and coupling light according to the frequency of the second test field until the EIT effect is observed on oscilloscope 46. Repeat steps 3 to 6 to obtain the total electric field strength and the polarization angle of the total electric field relative to the x-axis of the second test field.

[0049] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for measuring the field polarization of a Rydberg radio frequency receiving system, characterized in that, The field polarization measurement method includes the following steps: The first step is to design a dual-frequency polarization reconfigurable metasurface to achieve the decomposition of linearly polarized waves at arbitrary angles. It is composed of multiple metasurface units with the same structure. The specific structure of each metasurface unit includes a dielectric substrate and metal structures and PIN tubes disposed on the upper and lower sides of the dielectric substrate. The second step involves constructing a coupling system between a dual-frequency polarized reconfigurable metasurface and a Rydberg atom radio frequency receiving system. The dual-frequency polarized reconfigurable metasurface is located between the horn antenna (43) and the first atomic gas cell (32) of the Rydberg atom radio frequency receiving system, ultimately completing the detection of the radio frequency signal. Specifically: In the third step, the dual-frequency polarized reconfigurable metasurface (44) operates at two frequency points. When there are two test fields with different frequencies, one test field is selected and defined as the first test field, and the other test field is defined as the second test field. The wavelengths of the probe optical path and the coupling optical path are adjusted according to the frequency of the first test field until the electromagnetic induced transparency effect is observed on the oscilloscope (46). The fourth step is to make the dual-frequency polarization reconfigurable metasurface (44) work in the y-polarization wave selection state based on the coupling system constructed in the second step. By placing the dual-frequency polarization reconfigurable metasurface (44) between the horn antenna (43) and the first atomic gas cell (32), the y-direction component of the first field to be measured is obtained. Fifth step: Based on the coupling system constructed in the second step, the dual-frequency polarization reconfigurable metasurface (44) is made to work in the x-polarization wave selection state. By placing the dual-frequency polarization reconfigurable metasurface (44) between the horn antenna (43) and the first atomic gas cell (32), the x-direction component of the first field to be measured is obtained. Step 6: Calculate the total electric field strength and the polarization angle of the total electric field relative to the x-axis of the first field to be measured; The formula for calculating the total electric field strength is: ; The formula for calculating the polarization angle of the total electric field relative to the x-axis is: ; Step 7: Adjust the wavelengths of the probe optical path and the coupling optical path according to the frequency of the second test field until the electromagnetic induced transparency effect is observed on the oscilloscope (46); repeat steps 3 to 6 to obtain the total electric field strength and the polarization angle of the total electric field relative to the x-axis of the second test field.

2. The field polarization measurement method for a Rydberg radio frequency receiving system according to claim 1, characterized in that, In the first step, the specific structure of the dual-frequency polarized reconfigurable metasurface is as follows: The upper surface of the dielectric substrate is provided with a first thin metal line (1), a first long metal line (2), a first short metal line (3), a first PIN tube (4), and a second short metal line (5), and the longitudinal direction of the dielectric substrate is defined as the length direction and the transverse edge is defined as the width direction; the first thin metal line (1) includes two identical metal strips, symmetrically distributed on both sides of the longitudinal edge of the dielectric substrate; the first long metal line (2) includes two identical narrow metal strips, symmetrically placed along the longitudinal center line of the dielectric substrate, the edges of the two metal strips are respectively aligned with the transverse edge of the dielectric substrate, and a gap is left between the two metal strips; the first short metal line (3) includes two identical metal strips, located in the gap between the first long metal lines (2), and respectively set close to the two sides of the gap; a gap is also left between the two first short metal lines (3) for installing the first PIN tube (4); the second short metal line (5) includes four identical metal strips, regularly distributed in the two interval areas defined by the first thin metal line (1) and the first long metal line (2); The lower surface of the dielectric substrate is provided with a second thin metal line (6), a second long metal line (7), a third short metal line (8), a second PIN tube (9), and a fourth short metal line (10); the second thin metal line (6) includes two identical narrow metal strips, symmetrically distributed on both sides of the transverse edge of the dielectric substrate; the second long metal line (7) includes two identical metal strips, placed along the transverse center line of the dielectric substrate, with the edges of the metal strips aligned with the longitudinal edge of the dielectric substrate, and a gap between the two metal strips; the third short metal line (8) includes two identical metal strips, located in the gap between the second long metal lines (7), and respectively disposed adjacent to the two sides of the gap; a gap is also reserved between the two third short metal lines (8) for installing the second PIN tube (9); the fourth short metal line (10) includes four identical metal strips, regularly distributed in the two interval areas defined by the second thin metal line (6) and the second long metal line (7).

3. The field polarization measurement method for a Rydberg radio frequency receiving system according to claim 2, characterized in that, In the dual-frequency polarized reconfigurable metasurface: In the spaced region on the upper surface of the dielectric substrate, four metal strips are symmetrically arranged along the extension direction of the first long metal line (2), with two strips in each spaced region; the length and width of the first long metal line (2) determine the low-frequency operating frequency, and the length and width of the second short metal line (5) determine the high-frequency operating frequency. In the spaced region on the lower surface of the dielectric substrate, four metal strips are symmetrically arranged along the extension direction of the second long metal line (7) in the spaced region, with two strips in each spaced region; the length and width of the second long metal line (7) determine the low-frequency operating frequency, and the length and width of the second short metal line (5) determine the high-frequency operating frequency.

4. The field polarization measurement method for a Rydberg radio frequency receiving system according to claim 3, characterized in that, In the dual-frequency polarized reconfigurable metasurface: The dielectric substrate can be any dielectric material that meets the requirements of electromagnetic wave transmission and device processing, including polytetrafluoroethylene high-frequency copper clad laminate, epoxy resin substrate, ceramic substrate, flexible dielectric substrate or a combination thereof. The first PIN diode (4) and the second PIN diode (9) are replaced with any active or controllable device that can achieve equivalent switching between conduction and cutoff states under DC bias control, including RF switching diodes, varactor diodes, MEMS switches, field-effect transistors or their equivalent devices.

5. The field polarization measurement method for a Rydberg radio frequency receiving system according to claim 4, characterized in that, In the field polarization measurement method: When the dual-frequency polarized reconfigurable metasurface needs to be in the x-polarization wave selection state, a DC bias voltage is applied to the first PIN tube (4) on the upper side of the dielectric substrate to make the first PIN tube (4) in the conducting state; at the same time, no DC bias voltage is applied to the second PIN tube (9) on the lower side of the dielectric substrate to make the second PIN tube (9) in the cut-off state. When the dual-frequency polarized reconfigurable metasurface needs to be in the y-polarized wave selection state, no DC bias voltage is applied to the first PIN tube (4) on the upper side of the dielectric substrate, so that the first PIN tube (4) is in the cut-off state; at the same time, a DC bias voltage is applied to the second PIN tube (9) on the lower side of the dielectric substrate, so that the second PIN tube (9) is in the conduction state.

6. The field polarization measurement method for a Rydberg radio frequency receiving system according to claim 5, characterized in that, In the second step, the Rydberg atomic radio frequency receiving system includes a detection optical path, a coupling optical path, a first atomic gas cell (32), a radio frequency module, and a signal detection module, specifically: The probe light is generated by the probe light source (11), and after passing through the first optical isolator (13), the first half-wave plate (15) and the first polarization beam splitter (22) in sequence, it is split into two beams: one beam enters the probe light frequency-locking module (27); the other beam is turned by the first reflector (35), and after passing through the fourth half-wave plate (18), the fourth polarization beam splitter (25), the fifth half-wave plate (19), the beam shifter (37) and the first dichroic mirror (38) in sequence, it finally enters the first atomic gas cell (32); The coupled light path is generated by the coupled light source (12), and after passing through the second optical isolator (14), the second half-wave plate (16) and the third polarization beam splitter (24) in sequence, it is also split into two beams: one beam enters the coupled light frequency-locking module (28); the other beam is turned by the second reflector (36), and after passing through the seventh half-wave plate (21), the fifth polarization beam splitter (26), the sixth half-wave plate (20) and the second dichroic mirror (39) in sequence, it finally enters the first atomic gas cell (32); Inside the first atomic gas chamber (32), the probe light path and the coupling light path propagate in opposite directions along the same optical axis, achieving optical path overlap; the probe light transmitted through the first atomic gas chamber (32) passes through the second dichroic mirror (39), enters the balanced detector (45) and is converted into an electrical signal, which is then observed by the oscilloscope (46); The radio frequency signal to be tested generated by the radio frequency module is generated by the signal generator (42), radiated by the horn antenna (43), filtered by the dual-frequency polarized reconfigurable metasurface (44), and then applied to the atoms in the first atomic gas chamber (32). Finally, the radio frequency signal is detected by the signal detection module.

7. The field polarization measurement method for a Rydberg radio frequency receiving system according to claim 6, characterized in that, In the second step, the horn antenna (43) is arranged in front of the dual-frequency polarized reconfigurable metasurface (44), and the first atomic gas chamber (32) is located behind the dual-frequency polarized reconfigurable metasurface (44).

8. The field polarization measurement method for a Rydberg radio frequency receiving system according to claim 7, characterized in that, In the fourth step, the formula for calculating the y-direction component of the first field to be measured is: （1） Where E1 represents the y-direction component of the first field to be measured; Represents the reduced Planck constant; This represents the transition dipole moment between Rydberg states |3> and |4>. The AT splitting interval is represented by the AT splitting image corresponding to the first test field recorded using an oscilloscope (46), and the AT splitting image is fitted to obtain the result. .

9. The field polarization measurement method for a Rydberg radio frequency receiving system according to claim 8, characterized in that, In the fourth step, the formula for calculating the x-direction component of the first field to be measured is: （2） Where E2 represents the x-direction component of the first field to be measured; The AT splitting interval is represented by the AT splitting image corresponding to the first test field recorded using an oscilloscope (46), and the AT splitting image is fitted to obtain the result. .

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