Physical constant traceable atom thermodetector and method based on fluorescence detection

Abstract

The invention relates to a physical constant traceable atom temperature measuring instrument and method based on fluorescence detection, and the method comprises the steps: a low n-state atom radiation field sensor carries out the reverse coincidence propagation of 780 nm detection light and 776 nm decoration light in a rubidium atom steam pool, and forms electromagnetic induction transparency; according to the Rydberg atomic radiation field sensor, 1263 nm coupling light and decoration light are subjected to coincident propagation in the same direction, and three-photon electromagnetic induction transparency is formed; under the induction of black-body radiation, atoms jump to adjacent energy levels and generate fluorescence; the spectral density characteristics of blackbody radiation in a plurality of characteristic wavebands are synchronously extracted to a unified quantum sensing platform through common fluorescence detection of an atom with a high main quantum number and an atom with a low main quantum number. And fitting the absolute temperature of the object directly according to the Planck black body radiation law through the acquired wide-spectrum radiation spectrum density data. The method does not depend on external calibration, and can effectively suppress high-precision absolute temperature measurement influenced by surface emissivity.

Description

Technical Field

[0001] This invention belongs to the field of temperature measurement, specifically relating to an atomic thermometer and method with traceable physical constants based on fluorescence detection. Background Technology

[0002] Precise measurement of the absolute temperature of objects has important applications in industrial process control, scientific experiments, and medical diagnosis. For example, non-contact temperature measurement based on the blackbody radiation law is the main method for measuring the temperature of high-temperature, mobile, or easily contaminated objects, and its core lies in accurately sensing the intensity of electromagnetic waves radiated by the object.

[0003] Traditional radiation thermometry relies on a single classical detector (such as an infrared thermometer and a microwave radiometer) that operates in a specific wavelength band. This leads to inherent limitations: First, the measurement accuracy cannot be traced back to fundamental physical constants, requiring frequent and complex recalibration using a blackbody with a known temperature to combat detector drift. Second, single-band measurement results are severely affected by the unknown emissivity of the object's surface, introducing systematic errors that are difficult to correct. Third, to obtain the blackbody radiation spectrum to invert the true temperature or correct for emissivity effects, existing technologies must integrate multiple independently calibrated detector systems for different wavelength bands. This makes the device complex, costly, and difficult to guarantee consistency between channels.

[0004] Compared to traditional radiation sensors, Rydberg atom-based microwave electric field quantum sensors offer advantages such as high sensitivity, wide bandwidth, resistance to electromagnetic interference, and the ability to be traced back to fundamental physical constants without external calibration, attracting widespread attention in the field of electromagnetic sensing in recent years. Although Rydberg atom-based quantum sensors provide a new approach for self-calibrated absolute radiation measurements, existing methods still have significant limitations. Current research is limited to using a single, highly excited (high n) Rydberg atom for precise microwave measurements, with its sensitive frequency band mainly concentrated in the microwave to millimeter-wave range, corresponding to the extremely low temperature range of blackbody radiation. Furthermore, there is currently no publicly available scheme for directly measuring the temperature of blackbody radiation using a Rydberg atom microwave receiver.

[0005] In 2025, the National Institute of Standards and Technology (NIST) explored a scheme to measure temperature using the intensity of radiative fluorescence induced by blackbody radiation from rubidium atoms with low principal quantum numbers (n). However, this scheme essentially remained a single-point measurement, measuring only the intensity of blackbody radiation at a single wavelength of 12.2 μm, thus failing to capture the shape information of the blackbody radiation energy spectrum. Relying solely on "single-point" measurements in the microwave / millimeter-wave band to invert absolute temperature fundamentally fails to capture the energy peak information of blackbody radiation, thus severely limiting its inversion accuracy and reliability and failing to fully leverage the theoretical advantage of atomic sensors tracing back to fundamental physical constants. Furthermore, existing schemes have not solved the systemic challenge of achieving broadband synchronous radiation measurements on a unified and concise quantum platform, severely limiting their information dimensions and application potential. Summary of the Invention

[0006] To address the technical deficiencies in existing technologies, the present invention aims to provide an atomic thermometer and method based on fluorescence detection with traceable physical constants. This method utilizes a high principal quantum number (high n) atom and a low principal quantum number (low n) atom for co-fluorescence detection, simultaneously extracting the spectral density characteristics of blackbody radiation across multiple characteristic bands (particularly the infrared micrometer band where its energy peak is located and the highly penetrating millimeter wave band) onto a unified quantum sensing platform. At this point, the absolute temperature of the object can be directly fitted according to Planck's blackbody radiation law using the acquired broad-spectrum radiation density data.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention discloses an atomic thermometer with traceable physical constants based on fluorescence detection, the thermometer comprising a low n-state atomic radiation field sensor, a blackbody, a Rydberg atomic radiation field sensor, a photodetector, a fluorescence collection device, and a spectrometer;

[0009] The low n-state atomic radiation field sensor is used to transmit atoms sequentially from the ground state 5S by using 780 nm probe light and 776 nm embellishment light propagating in opposite directions in a rubidium atom vapor cell. 1 / 2 Excited to 5P 3 / 2 Re-excited to 5D 5 / 2 This creates electromagnetic induction transparency;

[0010] A blackbody is used to emit blackbody radiation, which induces 5D... 5 / 2 Atoms move towards neighboring 6, 7, and 8P atoms 3 / 2 Energy level transition, followed by spontaneous emission to the ground state 5S 1 / 2 It produces fluorescence at 420, 360, and 335 nm.

[0011] The high-n-state Rydberg atomic radiation field sensor is used to advance atoms from a 5D atomic radiation field sensor, building upon the low-n-state atomic radiation field sensor. It employs a 1263nm laser as the coupling beam, which propagates in the same direction as the embellishment beam. 5 / 2 Excited to the Rydberg state nF 7 / 2 This results in three-photon electromagnetic induction transparency;

[0012] A blackbody is used to emit blackbody radiation, under the induction of blackbody radiation, atoms move from nF... 7 / 2 Towards the nearest energy level (n+1) or (n+2)D 5 / 2 The transition occurs, and spontaneous emission produces fluorescence at approximately 480 nm.

[0013] The photodetector is used to detect 780-776-1263 three-photon electromagnetic induction transparency;

[0014] A fluorescence collection device is used to focus the divergent fluorescence signal onto the photosensitive surface of a spectrometer;

[0015] A spectrometer is used to perform spectral resolution on the converged fluorescence signal in order to obtain intensity information corresponding to different types of fluorescence radiation.

[0016] The fluorescence intensity information is converted into blackbody radiation spectral density information according to the pre-stored formula, and the blackbody radiation spectrum is fitted to obtain the temperature corresponding to the detected radiation.

[0017] Furthermore, the low n-state atomic radiation field sensor includes a 780 nm laser, a 776 nm laser, a saturable absorption spectroscopy device, a 780-776 nm two-photon EIT spectroscopy device, at least two fiber couplers, and a rubidium atom vapor cell. The 780 nm laser is used to generate 780 nm laser light to drive rubidium atoms in the rubidium atom vapor cell from the ground state 5S. 1 / 2 Excited to the excited state 5P 3 / 2 A 776 nm laser was used to generate 776 nm laser light to drive rubidium atoms in a rubidium atom vapor cell from the excited state 5P. 3 / 2 Excited to the adorned state 5D 5 / 2 A 780 nm laser is used as the probe beam, and a 776 nm laser is used as the embellishment beam. A saturable absorption spectroscopy device is used for frequency locking of the 780 nm laser, and a 780-776 nm two-photon EIT spectroscopy device is used for frequency locking of the 776 nm laser. The 780 nm and 776 nm lasers are respectively positioned on opposite sides of a rubidium atom vapor cell and emit laser light in a direction perpendicular to the cell. An optical fiber coupler is placed on each side of the rubidium atom vapor cell. The 780 nm probe beam and the 776 nm embellishment beam propagate in opposite directions within the rubidium atom vapor cell, causing the rubidium atoms to successively transition from their ground state 5S... 1 / 2 Excited to 5P 3 / 2Re-excited to 5D 5 / 2 This creates electromagnetic induction transparency.

[0018] Furthermore, the probe light is locked at 5 seconds via a saturated absorption spectrum. 1 / 2 Up to 5P 3 / 2 Leap forward.

[0019] Furthermore, the embellishing light is transparently locked at 5P via two-photon electromagnetic induction. 3 / 2 To 5D 5 / 2 Leap forward.

[0020] Furthermore, the high n-state Rydberg atomic radiation field sensor includes a 1263 nm laser that emits light in a direction parallel to the rubidium atom vapor cell. Building upon the low n-state atomic radiation field sensor, the 1263 nm laser is used as the coupling light, propagating in the same direction as the embellishment light, thus propelling atoms from the 5D... 5 / 2 Excited to the Rydberg state nF 7 / 2 This results in three-photon electromagnetic induction transparency.

[0021] Secondly, a method for atomic thermometry based on fluorescence detection with traceable physical constants is provided. This method achieves absolute temperature measurement using an atomic thermometer based on fluorescence detection with traceable physical constants as described in the first aspect of this invention and any optional embodiment thereof. The method includes the following steps:

[0022] S1. A low n-state atomic radiation field sensor is formed by using a 780 nm probe light and a 776 nm embellishment light to propagate in opposite directions in a rubidium atomic vapor cell. A Rydberg atomic radiation field sensor is constructed by using a 1263 nm coupling light and a 780 nm probe light to propagate in opposite directions in a rubidium atomic vapor cell.

[0023] S2. Select the appropriate quantum measurement path according to the wavelength of the blackbody radiation center corresponding to the measured temperature. The quantum measurement path includes the low n-state energy level measurement path and the high n-state Rydberg energy level measurement path.

[0024] S3, Laser System Locking: Based on the selected quantum measurement path, the relevant laser frequency is locked;

[0025] S4. Rubidium atoms in a blackbody radiation vapor cell are induced to adjacent energy levels by blackbody radiation and spontaneously emit fluorescence.

[0026] S5. Collect and detect fluorescence signals, and convert fluorescence intensity into blackbody radiation spectral density information;

[0027] S6. Perform blackbody radiation spectrum fitting to obtain the temperature corresponding to the detected radiation.

[0028] Furthermore, in step S2, for temperatures higher than the first preset temperature, the low n-state energy level measurement path is selected for temperature measurement; for temperatures lower than the second preset temperature, the high n-state Rydberg energy level measurement path is selected for temperature measurement.

[0029] Furthermore, in step S3, the 780 nm laser is locked at 5S. 1 / 2 →5P 3 / 2 In the transition, the 776 nm laser is locked at 5P. 3 / 2 →5D 5 / 2 In the leap, the 1263 nm laser is locked at 5D 5 / 2 →40F 7 / 2 Leap forward.

[0030] Furthermore, in step S3, the 1263 nm laser is turned on and locked only when the high n-state Rydberg state energy level measurement path is selected.

[0031] Furthermore, the relationship between fluorescence intensity and blackbody radiation temperature in step S5 is calculated using the following formula:

[0032] (1)

[0033] Where S is the detected fluorescence intensity; N is the total number of atoms involved in the interaction; η is the detector response efficiency; Γ is the spontaneous emission rate of the energy level that produces fluorescence; and p is the distribution at the corresponding energy level, which is determined by blackbody radiation-induced transitions and is a function of temperature T.

[0034] The beneficial technical effects of this invention are as follows: Based on a hybrid quantum system, a broadband absolute temperature measurement is constructed, enabling the simultaneous sensing of blackbody radiation (BBR) across multiple bands. By acquiring the spectral shape information of the blackbody radiation, a high-precision absolute temperature is directly fitted according to Planck's law, thus overcoming the shortcomings of traditional "single-point" temperature measurement methods, such as sensitivity to emissivity and the need for frequent calibration. Compared to traditional methods that require the integration of multiple independently calibrated detectors to acquire the radiation spectrum, and existing quantum temperature measurement schemes limited to "single-point" measurements of a single atomic energy state, this invention discloses an atomic thermometer with traceable physical constants based on fluorescence detection. For the first time, it integrates the capability of "spectral temperature measurement" into a single atomic system, achieving high-precision absolute temperature measurement that is independent of external calibration and effectively suppresses the influence of surface emissivity. This has significant scientific value and broad industrial application prospects. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the experimental energy levels upon which an atomic thermometer based on fluorescence detection and traceable physical constants is based, as shown in Embodiment 1 of the present invention.

[0036] Figure 2 This is a schematic diagram of the structure of an atomic thermometer with traceable physical constants based on fluorescence detection, as shown in Embodiment 1 of the present invention.

[0037] Figure 3 At 800 K, using low n atoms, the theoretically simulated fluorescence spectrum fitting curve;

[0038] Figure 4 The blackbody radiation spectral density fitting curve after calibration at 800 K, using low-n atoms;

[0039] Figure 5 At 2.7 K, using Rydberg atoms, the theoretically simulated fluorescence spectrum fitting curve;

[0040] Figure 6 At 2.7 K, using Rydberg atoms, the calibrated blackbody radiation spectral density fitting curve;

[0041] Among them: ①-780 nm laser; ②-776 nm laser; ③-1263 nm laser; ④-saturated absorption spectroscopy device; ⑤-780-776 nm two-photon EIT spectroscopy device; ⑥-fiber coupler; ⑦-rubidium atomic vapor cell; ⑧-photodetector; ⑨-fluorescence collection device; ⑩-spectrometer. Detailed Implementation

[0042] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] like Figure 1 As shown, this embodiment of the invention provides an atomic thermometer with traceable physical constants based on fluorescence detection. The thermometer includes a low n-state atomic radiation field sensor, a blackbody, a high n-state Rydberg atomic radiation field sensor, a photodetector (⑧), a fluorescence collection device (⑨), and a spectrometer (⑩).

[0045] The low n-state atomic radiation field sensor includes a 780 nm laser①, a 776 nm laser②, a saturable absorption spectroscopy device④, a 780-776 nm two-photon EIT spectroscopy device⑤, at least two fiber couplers⑥, and a rubidium atom vapor cell⑦ (or cold atoms as the sample). The 780 nm laser① is used to generate 780 nm laser light to drive rubidium atoms from the ground state 5S. 1 / 2 Excited to the excited state 5P 3 / 2 A 776 nm laser ② is used to generate 776 nm laser light to drive rubidium atoms from the excited state 5P. 3 / 2 Excited to the adorned state 5D 5 / 2A 780 nm laser is used as the probe light, and a 776 nm laser is used as the embellishment light. A saturable absorption spectroscopy device ④ is used to frequency-lock the 780 nm laser ① to lock the 780 nm probe light at 5 s. 1 / 2 Up to 5P 3 / 2 The 780-776 nm two-photon EIT spectrometer ⑤ is used for frequency locking of a 776 nm laser ② to lock the 776 nm embellished light at 5P. 3 / 2 To 5D 5 / 2 Leap forward.

[0046] A 780 nm laser ① and a 776 nm laser ② are respectively positioned on either side of a rubidium atomic vapor cell ⑦, emitting laser light in a direction perpendicular to the rubidium atomic vapor cell ⑦. An optical fiber coupler ⑥ is positioned on each side of the rubidium atomic vapor cell ⑦ to guide light into the optical fiber for transmission or to extract parallel light from the optical fiber. The optical fiber coupler ⑥ and the optical fiber are used to adjust the spatial optical path direction. Specifically, the optical fiber coupler ⑥ is positioned between the 780 nm laser ① and the rubidium atomic vapor cell ⑦ to adjust the probe light propagating in a direction perpendicular to the rubidium atomic vapor cell ⑦ to propagate in the direction of the rubidium atomic vapor cell ⑦. Similarly, the optical fiber coupler ⑥ is positioned between the 776 nm laser ② and the rubidium atomic vapor cell ⑦ to adjust the embellishment light propagating in a direction perpendicular to the rubidium atomic vapor cell ⑦ to propagate in the direction of the rubidium atomic vapor cell ⑦.

[0047] Fiber optic coupler ⑥ is a fiber optic coupler used for spatial optical hopping.

[0048] The rubidium atomic vapor cell ⑦ is used to generate atomic excitation and fluorescence radiation. The blackbody is a standard blackbody radiation source that can produce blackbody radiation at around 100°C.

[0049] The 780 nm probe light and the 776 nm decoration light propagate in opposite directions within a rubidium atom vapor cell (or with cold atoms as the sample), causing the atoms to move sequentially from their ground state 5S. 1 / 2 Excited to 5P 3 / 2 Re-excited to 5D 5 / 2 This creates electromagnetically induced transparency (EIT). Subsequently, under the induction of blackbody radiation, 5D... 5 / 2 Atoms move towards neighboring 6, 7, and 8P atoms 3 / 2 Energy level transition, followed by spontaneous emission to the ground state 5S 1 / 2 It produces fluorescence at 420, 360, and 335 nm. The rubidium atomic vapor cell ⑦ allows simultaneous transmission of visible light, near-infrared 780 nm laser, 776 nm laser, micrometer waves (2-6 μm), and millimeter waves. The rubidium atomic vapor cell ⑦ is made of materials such as sapphire.

[0050] The laser parameters are as follows (but not limited to): A 780nm laser ① generating the probe light has a power of 70 microwatts and a diameter of approximately 900 micrometers in the rubidium atom vapor cell ⑦; a 776nm laser ② generating the embellishment light has a power of 7 milliwatts and a diameter of approximately 900 micrometers in the rubidium atom vapor cell ⑦. The laser locking scheme is as follows (but not limited to): the probe light is locked at 5S wavelengths through a saturated absorption spectrum. 1 / 2 Up to 5P 3 / 2 In the transition, the embellished light is locked at 5P via two-photon EIT (electromagnetically induced transparency). 3 / 2 To 5D 5 / 2 Leap forward.

[0051] The high n-state Rydberg atomic radiation field sensor includes a 1263 nm laser ③, which emits laser light in a direction parallel to the rubidium atom vapor cell ⑦. The 1263 nm laser ③ is used to generate 1263 nm laser light to drive rubidium atoms from the 5D-modified state. 5 / 2 Excited to the Rydberg state nF 7 / 2 Building upon the low-n-state atomic radiation field sensor, a 1263 nm laser is used as the coupling light, propagating in the same direction as the embellishment light, to project atoms from a 5D... 5 / 2 Excited to the Rydberg state nF 7 / 2 This forms a three-photon EIT. Subsequently, under the induction of blackbody radiation, atoms move from nF... 7 / 2 Towards the nearest energy level (n+1) or (n+2)D 5 / 2 The transition occurs, and spontaneous emission produces fluorescence at approximately 480 nm.

[0052] In this embodiment of the invention, the coupled light power generated by the 1263 nm laser ③ is 50 milliwatts, and its diameter in rubidium atomic vapor is approximately 1000 micrometers. The locking scheme for the laser emitted by the laser is as follows (but not limited to): the probe light is locked at 5 s Hz through a saturated absorption spectrum. 1 / 2 Up to 5P 3 / 2 During the transition, the embellished light is locked at 5P via two-photon EIT. 3 / 2 To 5D 5 / 2 During the transition, the coupled light is locked at 5D via a three-photon EIT. 5 / 2 To nF 7 / 2 (e.g., 40F) 7 / 2 In the transition, atoms are induced to 41 and 42D by blackbody radiation. 5 / 2 superior.

[0053] The photodetector ⑧, fluorescence collection device ⑨, and spectrometer ⑩ are all located next to the rubidium atom vapor cell ⑦. The photodetector ⑧ is used to detect the 780-776-1263 three-photon EIT; the fluorescence collection device ⑨, composed of a set of convex lenses, is used to focus the diverging fluorescence onto the photosensitive surface of the spectrometer ⑩. The spectrometer ⑩ is used to perform spectral resolution on the focused fluorescence.

[0054] Fluorescence Collection and Detection: A coaxial lens group is used to collect fluorescence signals within a certain solid angle range and image them onto the photosensitive surface of the detector. A high-precision spectrometer is then used to accurately resolve the detected fluorescence signals, obtaining intensity information corresponding to different types of fluorescence radiation. The fluorescence wavelengths generated by the low-n state in the two-photon process are 420.30, 358.81, and 334.96 nm, corresponding to blackbody radiation wavelengths of 5.2, 4.6, and 2.4 μm. The fluorescence wavelength generated by the Rydberg state in the three-photon process is 480 nm, corresponding to the mm-wave band of blackbody radiation. The high-n Rydberg states 41 and 42D are used. 5 / 2 The corresponding fluorescence wavelengths are 480.67 and 480.59 nm, and the corresponding blackbody radiation wavelengths are 8.73 and 4.45 nm.

[0055] Measurement of low n-state fluorescence intensity using blackbody radiation curves: The relationship between the intensity of low n-state fluorescence and the blackbody radiation temperature can be calculated using the following formula:

[0056] (1)

[0057] Where S is the detected fluorescence intensity; N is the total number of interacting atoms; η is the detector's response efficiency; Γ is the spontaneous emission rate of the energy level that produces fluorescence; and p is the distribution at that energy level, determined by blackbody radiation-induced transitions and a function of temperature T. For quantum detection systems operating at constant temperatures, calibration can be performed using the spontaneous emission rates of atoms and the detector's response efficiency. At room temperature, due to the energy level 6P... 3 / 2 Below 5D 5 / 2 The spontaneous emission efficiency is much greater than that of blackbody radiation-induced transitions, and the distribution p(T) is almost unaffected by blackbody radiation. The interaction quantum number N of the system can be calibrated using the ratio of fluorescence intensity at 358.81 and 334.96 nm to that at 420.30 nm, thus converting the fluorescence intensity ratio into an atomic distribution relationship.

[0058] (2)

[0059] Therefore, the ratio of the two fluorescence intensities can be converted into two energy levels, 7 and 8P. 3 / 2 The ratio of atomic populations, and the two energy levels from the same state 5D 5 / 2Excited by blackbody radiation, the distribution of atomic transitions is determined by the intrinsic transition probabilities and dipole moments (and calculation programs exist to achieve this at different temperatures). After calibration of the atomic transition probabilities, two temperature-dependent points in the μm band of the blackbody radiation curve can be obtained, which can be used for fitting the blackbody radiation curve, especially in the range from near room temperature to hundreds of degrees Celsius. Note that when fitting, the blackbody radiation spectral density formula needs to be used because stimulated atomic transitions are considered.

[0060] Figure 3 and Figure 4 The theoretically simulated fluorescence spectrum and the calibrated radiation spectral density fitting curves for 800 K blackbody irradiation are presented. For room temperature (approximately 300 K), the radiation center deviates further by 2.4 μm, requiring a more precise detector to achieve spectral resolution.

[0061] Measurement of fluorescence intensity of high n-state Rydberg state in blackbody radiation curve: The starting point of the energy level of the high n-state Rydberg state is different from that of the low n-state, but the fluorescence intensity can be calculated using formula (1), where p(T) becomes the population of the Rydberg state. By continuously scanning a 1263 nm laser, the Rydberg energy level nF can be excited to different principal quantum numbers n, such as 38, 39, 40, etc. Subsequently, the fluorescence intensity of 480 nm generated by the radiation of the corresponding energy level is detected. The fluorescence wavelengths differ by more than 0.05 nm, which can be distinguished using a spectrometer of corresponding precision.

[0062] Using the same scheme in formula (2), the system is calibrated with the detector's corresponding efficiency and spontaneous emission rate to obtain the blackbody radiation curve in the millimeter wave range. At this time, the corresponding temperature is about 2 K, which can be used for aerospace and cosmic microwave background radiation measurement.

[0063] Figure 5 and Figure 6 The theoretically simulated fluorescence spectrum and calibrated radiation spectral density fitting curves for blackbody irradiation at 2.7 K are presented. For Rydberg atoms, the radiation is concentrated in the millimeter-wave band, which can be used to measure blackbody radiation temperatures down to the level of the cosmic microwave background radiation. In addition, by using higher Rydberg states (n+3, n+4, etc.), the measured temperature can be increased, showing promising applications in ultra-low temperature fields such as aerospace and cryogenic experiments.

[0064] Example 2

[0065] This invention provides an atomic thermometry method based on fluorescence detection and traceable physical constants. The method achieves absolute temperature measurement based on an atomic thermometer based on fluorescence detection and traceable physical constants provided in Embodiment 1 of this invention. The method includes the following steps:

[0066] S1. A low n-state atomic radiation field sensor is formed by using a 780 nm probe light and a 776 nm embellishment light to propagate in opposite directions in a rubidium atomic vapor cell. A Rydberg atomic radiation field sensor is constructed by using a 1263 nm coupling light and a 780 nm probe light to propagate in opposite directions in a rubidium atomic vapor cell.

[0067] S2. Select the appropriate quantum measurement path according to the wavelength of the blackbody radiation center corresponding to the measured temperature. The quantum measurement path includes the low n-state energy level measurement path and the high n-state Rydberg energy level measurement path.

[0068] The appropriate quantum measurement system is selected based on the wavelength of the blackbody radiation center corresponding to the measured temperature. For higher temperatures (typically above 300 K), the radiation wavelength is generally on the order of μm, and the low n-state energy level is chosen for measurement. For lower temperature systems (typically below 20 K), the radiation is generally on the order of mm waves or hundreds of μm, and the high n-state Rydberg state is chosen for measurement. For temperatures between 20 K and 300 K, both systems can be used for measurement, but temperature fitting using the edge of the curve is not optimal. Both the low n-state energy level measurement path and the high n-state Rydberg state energy level measurement path can detect several points in the temperature curve. By selecting the appropriate quantum measurement path based on the wavelength of the blackbody radiation center corresponding to the measured temperature, the "optimal" blackbody radiation temperature range can be determined, improving the accuracy of temperature measurement. However, in practice, both can be used for measurements across the entire range.

[0069] S3, Laser System Locking: Based on the selected quantum measurement path, the relevant laser frequency is locked;

[0070] Based on the chosen quantum measurement path, the relevant laser frequency is locked. The 780 nm laser is locked at 5 s using a saturated absorption spectrum (or another reference such as an ultrastable cavity). 1 / 2 →5P 3 / 2 For the transition, the 776 nm laser is locked at 5P using a 780-776 two-photon EIT spectrum (or other references such as an ultrastable cavity). 3 / 2 →5D 5 / 2 For the transition, the 1263 nm laser is locked at 5D using a 780-776-1263 three-photon EIT spectrum (or other references such as an ultrastable cavity). 5 / 2 →40F 7 / 2 Transition up (only turn on and lock the 1263 nm laser when selecting the Rydberg state measurement path).

[0071] S4. Rubidium atoms in a blackbody radiation vapor cell are induced to adjacent energy levels by blackbody radiation and spontaneously emit fluorescence.

[0072] Point the side of the rubidium cell directly at the blackbody radiation source so that the radiation acts on the atoms in the rubidium cell (or use a microwave cavity to enhance the radiation and then act on the rubidium cell). The atoms are induced to adjacent energy levels by the blackbody radiation and spontaneously emit fluorescence.

[0073] S5. Collect and detect fluorescence signals, and convert fluorescence intensity into blackbody radiation spectral density information;

[0074] Fluorescence is collected by a lens assembly onto the photosensitive surface of the detector. The detector in the spectrometer is then turned on to ensure that a fluorescence signal is received, thus detecting that blackbody radiation has successfully acted on the atoms.

[0075] The fluorescence signal received by the detector is analyzed and resolved using a spectrometer for both intensity and wavelength (or by using a high-precision detector such as a filter array with sufficient filtering effect and a photomultiplier tube to achieve wavelength and intensity resolution). For low n-state detection paths, sufficient intensity resolution is required, especially since the intensity difference between 420.30 and 358.81 fluorescence can be as high as 106 times. For Rydberg state detection paths, sufficiently fine wavelength resolution is required. For principal quantum numbers n < 50, a wavelength resolution exceeding 0.05 nm is generally needed, while for 50 < n < 60, a wavelength resolution exceeding 0.02 nm is typically required. A high-precision spectrometer can be used to obtain the intensity distribution of the fluorescence spectrum at different wavelengths.

[0076] By using existing open-source energy level calculation formulas or by referring to existing spectral measurement values, the radiation rate and transition rate of the selected energy level can be obtained. Then, the detection efficiency of the detector (such as a spectrometer) can be found. Based on formula (2), the fluorescence intensity and wavelength information can be calibrated using the corresponding spontaneous emission rate and detector effect efficiency to obtain the population ratio of different energy levels. The population ratio and the branching ratio of different energy levels calculated by the CJ coefficient can be used to calibrate the blackbody radiation spectral density ratio corresponding to the resonance frequency between different energy levels.

[0077] S6. Perform blackbody radiation spectrum fitting to obtain the temperature corresponding to the detected radiation.

[0078] Using the blackbody radiation spectral density information obtained in the previous step, a blackbody radiation curve and temperature are obtained by fitting the formula for blackbody radiation spectral density. Since the blackbody radiation spectral density distribution is only related to temperature, the spectral density distribution curve at a specific temperature can be obtained using the blackbody radiation spectral density distribution at two points, and thus the temperature corresponding to the detected radiation can be obtained.

[0079] As can be seen from the above embodiments, the atomic thermometer and method disclosed in this invention, which utilizes the energy level transitions of atoms within the blackbody radiation range, obtains the intensity ratio of blackbody radiation in different wavelength bands by detecting the induced fluorescence signal, and then fits the blackbody radiation curve to determine the temperature distribution of the system. Compared with traditional infrared detectors and other methods, atomic detection has the advantage of being traceable to fundamental physical constants, enabling absolute temperature measurement. Compared with existing single-frequency atomic thermometry schemes, the device disclosed in this invention can obtain a complete blackbody radiation curve, especially in high-temperature and extremely low-temperature environments, exhibiting higher measurement accuracy.

[0080] The apparatus and method described in this invention are not limited to the embodiments described in the specific implementation. Other implementation methods derived by those skilled in the art based on the technical solution of this invention also fall within the scope of technical innovation of this invention.

Claims

1. An atomic thermometer with traceable physical constants based on fluorescence detection, characterized in that: The thermometer includes a low n-state atomic radiation field sensor, a blackbody, a Rydberg atomic radiation field sensor, a photodetector, a fluorescence collection device, and a spectrometer. The low n-state atomic radiation field sensor is used to transmit atoms sequentially from the ground state 5S by using 780 nm probe light and 776 nm embellishment light propagating in opposite directions in a rubidium atom vapor cell. 1 / 2 Excited to 5P 3 / 2 Re-excited to 5D 5 / 2 This creates electromagnetic induction transparency; A blackbody is used to emit blackbody radiation, which induces 5D... 5 / 2 Atoms move towards neighboring 6, 7, and 8P atoms 3 / 2 Energy level transition, followed by spontaneous emission to the ground state 5S 1 / 2 It produces fluorescence at 420, 360, and 335 nm. The high-n-state Rydberg atomic radiation field sensor is used to advance atoms from a 5D atomic radiation field sensor, building upon the low-n-state atomic radiation field sensor. It employs a 1263nm laser as the coupling beam, which propagates in the same direction as the embellishment beam. 5 / 2 Excited to the Rydberg state n F 7 / 2 This results in three-photon electromagnetic induction transparency; A blackbody is used to emit blackbody radiation, under the induction of blackbody radiation, atoms move from nF... 7 / 2 Towards the nearest energy level (n+1) or (n+2)D 5 / 2 The transition occurs, and spontaneous emission produces fluorescence at approximately 480 nm. The photodetector is used to detect 780-776-1263 three-photon electromagnetic induction transparency; A fluorescence collection device is used to focus the divergent fluorescence signal onto the photosensitive surface of a spectrometer; A spectrometer is used to perform spectral resolution on the converged fluorescence signal in order to obtain intensity information corresponding to different types of fluorescence radiation. The fluorescence intensity information is converted into blackbody radiation spectral density information according to the pre-stored formula, and the blackbody radiation spectrum is fitted to obtain the temperature corresponding to the detected radiation.

2. The atomic thermometer with traceable physical constants based on fluorescence detection according to claim 1, characterized in that: The low n-state atomic radiation field sensor includes a 780 nm laser, a 776 nm laser, a saturable absorption spectroscopy device, a 780-776 nm two-photon EIT spectroscopy device, at least two fiber couplers, and a rubidium atom vapor cell. The 780 nm laser is used to generate 780 nm laser light to drive rubidium atoms in the rubidium atom vapor cell from the ground state 5S. 1 / 2 Excited to the excited state 5P 3 / 2 A 776 nm laser was used to generate 776 nm laser light to drive rubidium atoms in a rubidium atom vapor cell from the excited state 5P. 3 / 2 Excited to the adorned state 5D 5 / 2 A 780 nm laser is used as the probe beam, and a 776 nm laser is used as the embellishment beam. A saturable absorption spectroscopy device is used for frequency locking of the 780 nm laser, and a 780-776 nm two-photon EIT spectroscopy device is used for frequency locking of the 776 nm laser. The 780 nm and 776 nm lasers are respectively positioned on opposite sides of a rubidium atom vapor cell and emit laser light in a direction perpendicular to the cell. An optical fiber coupler is placed on each side of the rubidium atom vapor cell. The 780 nm probe beam and the 776 nm embellishment beam propagate in opposite directions within the rubidium atom vapor cell, causing the rubidium atoms to successively transition from their ground state 5S... 1 / 2 Excited to 5P 3 / 2 Re-excited to 5D 5 / 2 This creates electromagnetic induction transparency.

3. The atomic thermometer with traceable physical constants based on fluorescence detection according to claim 2, characterized in that: The probe light is locked at 5 seconds by a saturated absorption spectrum. 1 / 2 Up to 5P 3 / 2 Leap forward.

4. An atomic thermometer with traceable physical constants based on fluorescence detection according to claim 2, characterized in that: The embellishing light is transparently locked at 5P through two-photon electromagnetic induction. 3 / 2 To 5D 5 / 2 Leap forward.

5. An atomic thermometer with traceable physical constants based on fluorescence detection according to claim 1, characterized in that: The high n-state Rydberg atomic radiation field sensor includes a 1263 nm laser that emits light parallel to the rubidium atom vapor cell. Building upon the low n-state atomic radiation field sensor, the 1263 nm laser is used as the coupling light, propagating in the same direction as the embellishment light, to project atoms from a 5D... 5 / 2 Excited to the Rydberg state nF 7 / 2 This results in three-photon electromagnetic induction transparency.

6. A method for atomic thermometry with traceable physical constants based on fluorescence detection, characterized in that: The method achieves absolute temperature measurement using an atomic thermometer with traceable physical constants based on fluorescence detection, as described in any one of claims 1-5. The method includes the following steps: S1. A low n-state atomic radiation field sensor is formed by using 780 nm probe light and 776 nm embellishment light to propagate in opposite directions in a rubidium atomic vapor cell. A Rydberg atomic radiation field sensor is constructed by using 1263 nm coupling light and 780 nm probe light to propagate in opposite directions in a rubidium atomic vapor cell. S2. Select the appropriate quantum measurement path according to the wavelength of the blackbody radiation center corresponding to the measured temperature. The quantum measurement path includes the low n-state energy level measurement path and the high n-state Rydberg energy level measurement path. S3, Laser System Locking: Based on the selected quantum measurement path, the relevant laser frequency is locked; S4. Rubidium atoms in a blackbody radiation vapor cell are induced to adjacent energy levels by blackbody radiation and spontaneously emit fluorescence. S5. Collect and detect fluorescence signals, and convert fluorescence intensity into blackbody radiation spectral density information; S6. Perform blackbody radiation spectrum fitting to obtain the temperature corresponding to the detected radiation.

7. The atomic thermometry method based on fluorescence detection with traceable physical constants according to claim 6, characterized in that: In step S2, for temperatures higher than the first preset temperature, the low n-state energy level measurement path is selected for temperature measurement; for temperatures lower than the second preset temperature, the high n-state Rydberg energy level measurement path is selected for temperature measurement.

8. The atomic thermometry method based on fluorescence detection with traceable physical constants according to claim 7, characterized in that: In step S3, the 780 nm laser is locked for 5 seconds. 1 / 2 →5P 3 / 2 In the transition, the 776 nm laser is locked at 5P. 3 / 2 →5D 5 / 2 In the leap, the 1263 nm laser is locked at 5D 5 / 2 →40F 7 / 2 Leap forward.

9. The atomic thermometry method based on fluorescence detection with traceable physical constants according to claim 7, characterized in that: In step S3, the 1263 nm laser is turned on and locked only when the high n-state Rydberg state energy level measurement path is selected.

10. A method for atomic thermometry based on fluorescence detection with traceable physical constants, as described in any one of claims 6 to 9, characterized in that: The relationship between fluorescence intensity and blackbody radiation temperature in step S5 is calculated using the following formula: （1） Where S is the detected fluorescence intensity; N is the total number of atoms involved in the interaction; η is the detector response efficiency; Γ is the spontaneous emission rate of the energy level that produces fluorescence; and p is the distribution at the corresponding energy level, which is determined by blackbody radiation-induced transitions and is a function of temperature T.

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