High-gain closed-loop resonant structure applied to Rydberg atoms and dielectric measurement method

Abstract

The invention relates to a high-gain closed-loop resonant structure applied to Rydberg atoms and a dielectric measurement method. The high-gain closed-loop resonant structure provided by the invention is made of a high-conductivity metal material (such as copper), and the whole high-gain closed-loop resonant structure is a rectangular closed loop. The transverse size of the resonant structure is a, the longitudinal size is b, the width of the metal ring line is w, and the thickness of the resonant ring is t. A pair of parallel metal plates is arranged in an internal opening area of the resonant structure, the size of the metal plates is h * h, and the distance between the two parallel metal plates is d. The metal ring and the parallel metal plate form a closed-loop resonant cavity with a specific resonant frequency, and the resonant frequency of the structure and the enhancement rate of a radio frequency electric field can be accurately regulated and controlled by optimizing size parameters (including a, b, w, d, h and t) of the closed-loop resonant cavity. According to the invention, the electric field enhancement rate is obviously improved; the detection sensitivity and the measurement precision of the radio frequency sensor are improved; and the high-precision measurement of the dielectric constant is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of designing quantum sensing and electromagnetic materials, and particularly relates to a closed-loop resonant structure applied to Rydberg atom radio frequency sensing and a method for measuring dielectric constant. Background Art

[0002] Radio frequency (RF) electric field sensing technology has broad application prospects in many fields such as modern communication, radar detection, medical detection, and electromagnetic environment monitoring. In recent years, the RF electric field sensing technology based on Rydberg atoms has become a research hotspot in the field of electromagnetic field precision measurement due to its extremely high electric field sensitivity, wide detection frequency band, and excellent stability. Rydberg atoms have a high principal quantum number and a large electric dipole moment, and are extremely sensitive to external electric fields. By utilizing the electromagnetically induced transparency (EIT) effect, high-precision measurement of RF electric fields can be achieved.

[0003] In the existing RF electric field sensing methods based on Rydberg atoms, measurement is mainly carried out by directly interacting a bare atomic vapor cell with the RF field. However, due to the limited coupling strength between the RF electric field and Rydberg atoms, the detection ability for weak RF signals is insufficient, and the sensitivity measurement is low. To overcome the above deficiencies, a method of enhancing the local RF electric field by introducing a split-ring resonator (SRR) structure has been proposed in current research. Although the existing single-aperture SRR structure has improved the electric field strength to a certain extent, its electric field enhancement factor is limited, and it is difficult to meet the high-sensitivity detection requirements for weak RF signals in practical applications. In addition, existing resonant structures are mostly limited to the enhancement of the RF electric field itself, and the potential application in measuring the electromagnetic parameters of materials has not been further explored in combination with the Rydberg atom system.

[0004] Therefore, there is an urgent need for a new resonant enhancement structure that can significantly increase the RF electric field strength while maintaining simple design and convenient manufacturing, and realize high-sensitivity and high-precision measurement of the dielectric parameters of materials in combination with the Rydberg atom system.

[0005] After retrieval, the application publication number CN114976557A proposed a tunable open resonator enhancement device applied to a Rydberg atom detection system. Its core structure is an open resonator ring, which changes the resonance frequency by adjusting the distance between the plates and can enhance the radio frequency electric field to a certain extent. After analysis, it is found that the patent structure adopts a single-open design, with limited electric field enhancement magnification and no closed-loop structure involved. In addition, the patent does not involve the specific method and application of dielectric measurement. The present invention innovatively proposes a closed-loop resonance structure, which can achieve an electric field enhancement magnification of about 168 times (about 44.5 dB) in the 1.4 GHz frequency band, about 30% higher than that of the single-open resonance structure. At the same time, the present invention first proposes a high-precision dielectric constant measurement method based on the Rydberg atom EIT effect, expanding the application field of Rydberg atom sensing, and having obvious novelty and creativity. Summary of the Invention

[0006] The present invention aims to solve the above problems of the prior art. A high-gain closed-loop resonance structure and a dielectric measurement method applied to Rydberg atom sensing are proposed. The technical solution of the present invention is as follows:

[0007] A high-gain closed-loop resonance structure applied to Rydberg atom sensing, which includes:

[0008] - A resonance loop: made of a highly conductive metal material, having a specific transverse dimension a, a longitudinal dimension b, and a metal loop width w;

[0009] - Parallel metal plates: arranged inside the resonance ring, with a size of h×h and a spacing of d, used to jointly form a resonance cavity with the resonance loop;

[0010] - An atomic gas cell: located between the two parallel metal plates, filled with cesium atoms inside, serving as a medium for the interaction between Rydberg atoms and radio frequency electric fields.

[0011] Further, the metal material is selected from copper, silver or aluminum, where the thickness t of the metal ring is 0.5 mm and the metal loop width w is 1 mm, so as to ensure the high Q value and strong electric field enhancement effect of the structure. The transverse dimension a of the resonance structure is 26 mm, and the longitudinal dimension b is 40.6 mm.

[0012] Further, the size h of the metal plate is 12 mm×12 mm, and the spacing d between the two parallel copper plates is 10.03 mm.

[0013] Further, the position of the resonance ring is offset downward by about 1 mm relative to the center of the parallel copper plate, forming a channel for the laser to pass through.

[0014] Further, a square atomic gas cell (12) is installed in the gap between the parallel copper plates. The outer diameter of the gas cell is 10 mm, and it is made of quartz glass. It is filled with gaseous cesium atoms, which are used to detect the laser and the coupling laser to excite cesium atoms to the Rydberg state and form a Rydberg atom EIT three-level system.

[0015] Further, the RF signal source (16) is vertically incident above the atomic gas cell. The frequency of the incident RF signal is 1.4 GHz. The closed-loop resonant structure (11) generates a resonant effect at this frequency, and significantly enhances the local RF electric field strength in the region of the atomic gas cell (12).

[0016] A method for measuring the dielectric constant using the structure described in any one of the above, comprising the following steps:

[0017] Step 1. Construct a closed-loop resonant structure: Construct a resonant structure according to the structural parameters;

[0018] Step 2. RF signal excitation: Excite the closed-loop resonant structure with an RF signal through a specific polarization mode and direction, so that an enhanced RF electric field is generated in the atomic gas cell;

[0019] Step 3. Probe laser and coupling laser excitation: Use the probe laser and the coupling laser to propagate coaxially and in opposite directions along the axis of the atomic gas cell to excite Rydberg atoms to produce the EIT effect;

[0020] Step 4. Photoelectric detection: Measure the transmitted laser intensity through the atomic gas cell, and analyze the AC Stark frequency shift and spectral line splitting;

[0021] Step 5. Measurement of the dielectric constant of the material: Place the material to be measured in the gap between the parallel metal plates of the closed-loop resonant structure or above the atomic gas cell, observe the frequency shift of the RF electric field, and determine the dielectric constant of the material in combination with the frequency-dielectric constant relationship model of the resonant structure.

[0022] Further, the material to be measured is placed in the gap region between the two parallel metal plates or above the atomic gas cell. By adjusting the relative position between the material to be measured and the closed-loop resonant structure, the electric field enhancement effect can be further improved, making the measurement result more accurate.

[0023] Further, the cesium atomic pressure filled in the atomic gas cell ranges from 0.1 Pascal to 5 Pascals, so as to obtain a stable EIT effect under different RF electric field strengths.

[0024] Further, the design of the resonant structure also includes a temperature compensation mechanism.

[0025] The advantages and beneficial effects of the present invention are as follows:

[0026] (1) Significantly improve the electric field enhancement ratio: Compared with the traditional single-open resonator structure, the closed-loop resonator structure of the present invention achieves an electric field enhancement ratio of 168 times (44.5 dB) at a frequency of 1.4 GHz, and the electric field enhancement performance is improved by 30%.

[0027] (2) Enhance the detection sensitivity and measurement accuracy of RF sensors: The enhanced RF electric field makes the response of Rydberg atoms to weak RF signals more significant, improving the detection sensitivity and measurement accuracy of RF electric field sensors and enabling effective detection of ultra-weak RF signals.

[0028] (3) Achieve high-precision measurement of dielectric constants: Combining with the Rydberg atom EIT spectroscopy measurement technology, the dielectric parameters of the material to be measured can be accurately measured, expanding the practical application fields of Rydberg atom sensing technology.

[0029] (4) Simple structure, easy to implement and promote: The closed-loop resonator structure proposed by the present invention has a simple design, mature manufacturing process and low cost, and has good practical application value and promotion prospects.

[0030] The innovative technical points of the present invention are mainly reflected in the following aspects: First, a new type of closed-loop resonator structure design is proposed, which is different from the traditional single-open structure, and the electric field enhancement ratio of the RF electric field is increased to 168 times in the 1.4 GHz frequency band, effectively improving the detection sensitivity; Second, the closed-loop resonator structure is combined with the Rydberg atom EIT spectroscopy measurement technology to achieve high-precision measurement of the dielectric constant of the material. This technical solution combining the closed-loop structure and the quantum effect effectively expands the application fields of Rydberg atom sensing technology, reflecting the synergistic advantages of structural innovation and measurement method innovation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 are the schematic diagram and working principle diagram of the closed-loop resonator structure provided by the preferred embodiment of the present invention.

[0032] Figure 2 are the schematic diagram of the electric field distribution and the corresponding EIT spectrum under the bare atomic gas cell (a1-a3) and the closed-loop resonator structure (b1-b3).

[0033] Figure 3 are the schematic diagrams of the EIT spectrum contour lines under different dielectric constants. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and detailedly described in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only a part of the embodiments of the present invention.

[0035] The technical solution for the present invention to solve the above technical problems is:

[0036] AsFigure 1 As shown, in this embodiment, the closed-loop resonant structure 11 is made of a highly conductive copper material with a thickness t of 0.5 mm, and the overall structure is in the form of a rectangular closed loop. The transverse dimension a of the resonant structure is 26 mm, the longitudinal dimension b is 40.6 mm, and the width w of the metal loop is 1 mm. A pair of parallel copper plates with dimensions of 12 mm × 12 mm (dimension h × h) are installed in the internal opening area of the closed-loop resonant structure. The distance d between the two parallel copper plates is 10.03 mm. To facilitate the coaxial counter-propagation of the probe laser and the coupling laser, the position of the resonant ring is offset downward by about 1 mm relative to the center of the parallel copper plates, forming a channel for the laser to pass through. A square atomic gas cell 12 is installed in the gap between the parallel copper plates. The outer diameter of the gas cell is 10 mm, which is made of quartz glass and filled with gaseous cesium atoms inside, for the probe laser and the coupling laser to excite cesium atoms to the Rydberg state and form a Rydberg atom EIT three-level system.

[0037] In this embodiment, a probe laser 14 with a wavelength of 852 nm and a coupling laser (number 15 in the figure) with a wavelength of 510 nm are used. The two lasers propagate coaxially in opposite directions along the axis of the atomic gas cell 12 to construct the electromagnetically induced transparency (EIT) state of cesium atoms to achieve highly sensitive detection of the radio frequency field. The radio frequency signal source 16 is incident vertically above the atomic gas cell, and the frequency of the incident radio frequency signal is 1.4 GHz. The closed-loop resonant structure 11 generates a resonant effect at this frequency, significantly enhancing the local radio frequency electric field intensity in the area of the atomic gas cell 12. Through experimental verification, the enhancement factor of the electric field intensity reaches about 168 times (about 44.5 dB) that of the bare atomic gas cell structure.

[0038] Figure 2 The simulation results of the structure of the present invention are shown. Among them, (a1 - a3) represent the bare atomic gas cell structure, and (b1 - b3) represent the situation after adopting the closed-loop resonant structure of the present invention. (a1) and (b1) are respectively the curves of the radio frequency electric field intensity varying with frequency for the bare atomic gas cell and the closed-loop resonant structure. (a2) and (b2) are respectively the distribution diagrams of the electric field intensity at the position of the atomic gas cell at the resonant frequency (1.4 GHz) for the two situations. (a3) and (b3) are the Rydberg EIT spectral curves corresponding to the two situations. It can be seen that the closed-loop resonant structure significantly enhances the radio frequency electric field intensity at the position of the atomic gas cell (12) by using its specific resonance frequency (1.4 GHz). Compared with the situation of the bare atomic gas cell, the enhancement factor of the electric field of the structure of the present invention reaches about 168 times (about 44.5 dB), which is about 30% higher than that of the traditional single-opening resonator structure. The significantly enhanced radio frequency electric field strongly interacts with the Rydberg atoms, resulting in obvious AC Stark frequency shift and spectral line splitting of the Rydberg energy levels, as Figure 2As shown by the EIT spectrum in (b3). After the probe laser (14) passes through the atomic gas cell (12), the transmitted laser signal is received by a photodetector, and the frequency shift and splitting of the EIT spectrum are analyzed by a spectrum analyzer or a spectrometer, enabling highly sensitive and high-precision measurement of the intensity and frequency of ultra-weak radio frequency signals.

[0039] Furthermore, the structure of this embodiment can also be used for high-precision measurement of the dielectric constant of materials. As Figure 3 shown, when a material under test (13) with a thickness of 1 mm is placed in the gap of the closed-loop resonant structure (11) above the atomic gas cell (12), since the change in the dielectric constant of the material under test (13) will affect the total capacitance of the closed-loop resonant structure, thereby causing a shift in the resonant frequency. Figure 3 Shows the contour maps of the Rydberg atom EIT spectra corresponding to different dielectric constants of the materials under test. By analyzing the measured frequency shift of the EIT spectral lines and combining with the pre-established relationship model between the resonant frequency and the dielectric constant, the dielectric constant of the material under test (13) can be determined with high precision.

[0040] In addition, by adjusting the specific dimensions (such as a, b, d, etc.) of the closed-loop resonant structure (11), the resonant frequency of the structure can be precisely controlled, thereby meeting the requirements of radio frequency sensing and material measurement applications in different frequency bands. It should be noted that although reducing the size of the resonant structure can increase the resonant frequency, it may reduce the electric field enhancement effect. Therefore, it is necessary to reasonably balance the relationship between frequency tuning and electric field enhancement during the design process.

[0041] The systems, devices, modules, or units illustrated in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions.

[0042] It should also be noted that the term "including", "comprising", or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, commodity, or device including a series of elements not only includes those elements but also includes other elements not explicitly listed, or elements inherent to such process, method, commodity, or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, commodity, or device including the said element.

[0043] The above embodiments should be understood as being only for illustrative purposes of the present invention and not for limiting the protection scope of the present invention. After reading the content recorded in the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims

1. A high-gain closed-loop resonant structure applied to Rydberg atom sensing, characterized in that, Including: - A resonant loop: Made of a highly conductive metal material, having specific lateral dimension a, longitudinal dimension b, and metal loop width w; - Parallel metal plates: Arranged inside the resonant loop, with dimensions h×h and a spacing d, for jointly forming a resonant cavity with the said resonant loop; - An atomic gas cell: Located between the two parallel metal plates, filled with cesium atoms inside, serving as the medium for the interaction between Rydberg atoms and the radio frequency electric field.

2. The high-gain closed-loop resonant structure according to claim 1, wherein The metal material is selected from copper, silver, or aluminum. The thickness t of the metal loop is 0.5 mm, and the metal loop width w is 1 mm, thereby ensuring a high Q value and a strong electric field enhancement effect of the structure. The lateral dimension a of the resonant structure is 26 mm, and the longitudinal dimension b is 40.6 mm.

3. The high-gain closed-loop resonant structure according to claim 1, wherein The size h of the metal plates is 12 mm×12 mm, and the spacing d between the two parallel copper plates is 10.03 mm.

4. The high-gain closed-loop resonant structure according to claim 1, characterized in that, The position of the resonant loop is offset downward by about 1 mm relative to the center of the parallel copper plates, forming a channel for the laser to pass through.

5. The high-gain closed-loop resonant structure according to claim 1, wherein A square atomic gas cell (12) is installed in the gap between the parallel copper plates. The outer diameter of the gas cell is 10 mm, made of quartz glass material, filled with gaseous cesium atoms inside, for detecting the laser and coupling the laser to excite cesium atoms to the Rydberg state and form a Rydberg atom EIT three-level system.

6. The high-gain closed-loop resonant structure according to claim 5, characterized in that The radio frequency signal source (16) is incident vertically above the atomic gas cell. The frequency of the incident radio frequency signal is 1.4 GHz, and the closed-loop resonant structure (11) generates a resonant effect at this frequency, significantly enhancing the local radio frequency electric field intensity in the region of the atomic gas cell (12).

7. A method for measuring dielectric constant using the structure according to any one of claims 1-6, characterized in that Including the following steps: Step 1. Construct a closed-loop resonant structure: Construct the resonant structure according to the structural parameters; Step 2. Radio frequency signal excitation: Excite the closed-loop resonant structure with the radio frequency signal through a specific polarization mode and direction, so as to generate an enhanced radio frequency electric field in the atomic gas cell; Step 3. Probe laser and coupling laser excitation: Use the probe laser and the coupling laser to propagate coaxially and in opposite directions along the axis of the atomic gas cell to excite the Rydberg atoms to produce the EIT effect; Step 4. Photoelectric detection: Measure the transmitted laser intensity passing through the atomic gas cell, and analyze the AC Stark frequency shift and spectral line splitting; Step 5. Material dielectric constant measurement: Place the material to be measured in the gap between the parallel metal plates of the closed-loop resonant structure or above the atomic gas cell, observe the frequency shift of the radio frequency electric field, and determine the dielectric constant of the material in combination with the frequency dielectric constant relationship model of the resonant structure.

8. The method for measuring dielectric constant according to claim 7, characterized in that, The material to be measured is placed in the gap region between the two parallel metal plates or above the atomic gas cell. By adjusting the relative position between the material to be measured and the closed-loop resonant structure, the electric field enhancement effect can be further improved, making the measurement result more accurate.

9. The method for measuring the dielectric constant according to claim 8, characterized in that The cesium atom pressure filled in the atomic gas cell ranges from 0.1 Pascal to 5 Pascals, so as to obtain a stable EIT effect under different radio frequency electric field intensities.

10. The dielectric constant measurement method according to claim 7, characterized in that, The design of the resonant structure also includes a temperature compensation mechanism.

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