Long-wave time service signal receiving method based on quantum antenna

Abstract

The invention discloses a long-wave time service signal receiving method based on a quantum antenna, and belongs to the technical field of quantum measurement. The core of the method is that Rydberg atoms are used as quantum antennas to receive signals; the method comprises the following steps: firstly, preparing cesium atoms into a highly excited state in a two-photon excitation mode of 852 nm and 509 nm laser; then, applying a direct-current electric field as a local oscillation field in the atomic gas chamber through an electrode plate; when a long-wave time service signal (such as a Roland-C signal) with the frequency of 100kHz arrives, superheterodyne frequency mixing is generated with a direct-current electric field in the atomic gas chamber based on an AC Stark effect, and a frequency mixing signal easy to detect is generated; and finally, the signal is detected through a photoelectric detector and an oscilloscope, and receiving of the time service signal is completed. The atomic system is used for replacing a traditional metal antenna, and the system has the remarkable advantages of high sensitivity, high anti-interference capability, small probe size, easiness in system integration and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of quantum measurement, and particularly relates to a long-wave time signal receiving method based on a quantum antenna. BACKGROUND

[0002] Time service is a widely used behavior of transmitting standard time, and the main function of a time service system is to transmit standard time information and standard frequency signals to users through various communication means. The time service system is one of the most important national infrastructures. The size of a long-wave time signal receiver is mainly related to the size of its receiving antenna. Domestic time signal receivers still have the shortcomings of insufficient bandwidth and low signal-to-noise ratio. In the new planning, China requires the construction of an enhanced Loran navigation system in the next five years, and it is more urgent to optimize the miniaturized long-wave receiver to meet the requirements of bandwidth, signal-to-noise ratio and other indicators. In view of the demand for continuous improvement of the service capacity of long-wave time signal transmitting stations, the Rydberg atom long-wave time signal receiver uses high-energy state atoms as antennas to respond to time signals with high sensitivity, achieving a receiving sensitivity that exceeds that of traditional receivers. Rydberg atoms have extremely high electric field measurement sensitivity, which can solve the signal-to-noise ratio bottleneck of traditional receivers in long-distance or interference environments, and avoid the problem of large volume and difficult deployment of traditional long-wave antennas. SUMMARY

[0003] Therefore, the application provides a long-wave time signal receiving method based on a quantum antenna, which has the advantages of high sensitivity, long receiving distance, probe size not affected by antenna gain, and easy integration of atomic receivers compared with traditional radio receivers.

[0004] The technical scheme of the application is as follows: A long-wave time signal receiving method based on a quantum antenna, comprising the following steps: Preparation of Rydberg atoms in an atomic cell to a high-energy state by a two-photon excitation method; Applying a direct current electric field through an electrode plate arranged in the atomic cell as a local oscillator field for heterodyne reception; When a long-wave time signal with a frequency of 100 kHz reaches the atomic cell, a mixing signal is generated by mixing based on the AC Stark effect between the long-wave time signal and the direct current electric field; The mixing signal is detected by a photoelectric detector and an oscilloscope to complete the reception of the long-wave time signal.

[0005] Further, the two-photon excitation method is specifically as follows: The 852nm probe light and the 509nm coupling light are adjusted by an optical system to be parallel and coincident to the cesium atom cell, and the Rydberg atom is excited to 63D 5 / 2 state or 65D 3 / 2 state.

[0006] Further, the optical system performs the following operations: The 852nm probe light is divided into two linearly polarized lights with perpendicular polarization states by a polarization beam splitter; The 509nm coupling light is divided into two beams by a beam splitter, one of which is used for electromagnetic induced transparency frequency stabilization, and the other is adjusted in polarization to make its polarization state parallel to that of the two 852nm linearly polarized lights, and to ensure that they are parallel and coincident to the atom cell.

[0007] Further, the mixing signal is a superheterodyne mixing signal, whose signal amplitude is proportional to the amplitude of the long-wave time signal and the amplitude of the direct current electric field, and whose signal frequency is 100kHz.

[0008] Further, the long-wave time signal is a Loran-C pulse signal.

[0009] Further, the electrode plate is connected to an external direct current power supply for generating the direct current electric field in the atom cell.

[0010] Advantages: 1. The present application uses Rydberg atom as quantum antenna, which has much higher response sensitivity to electric field than traditional metal antenna. Through the direct interaction between atomic state and external electric field, and using the superheterodyne mixing mechanism based on AC Stark effect, the weak far-field long-wave time signal can be effectively detected, thereby breaking the bottleneck of low signal-to-noise ratio of traditional receiver in long distance or complex electromagnetic environment.

[0011] 2. The traditional long-wave receiver relies on a physical antenna with a wavelength comparable to the size, resulting in a large device and difficult deployment. The atom cell probe used in the present application is no longer limited by the wavelength of electromagnetic wave, realizing the miniaturization of the receiving front end. The atomic system is easy to integrate with optical elements, laying a technical foundation for developing high-precision, chip-level portable long-wave time signal receiving equipment.

[0012] 3. The method of the present application performs signal down-conversion by electro-optic effect instead of traditional electronic circuit, and the mixing process is completed in the atom, avoiding the problems of nonlinear distortion and noise introduction of analog circuit. At the same time, the Rydberg atom has inherent wideband response characteristics to specific frequency band microwave signals, combined with a tunable laser preparation system, so that the receiving method has good frequency adaptability and system stability while maintaining high measurement accuracy. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the timing signal reception according to the present invention. Detailed Implementation

[0014] This invention provides a method for receiving long-wavelength timing signals based on a quantum antenna, such as... Figure 1 As shown, the steps for using Rydberg atoms for timing reception are to first prepare Rydberg atoms to 63D using two-photon excitation. 5 / 2 The atomic probe employs an internal electrode plate, applying a DC electric field to the Rydberg atoms via an external DC power supply. When a 100kHz Rowland pulse signal arrives, the signal to be measured and the DC electric field will produce a mixing effect in the atomic gas cell. The amplitude of the mixed signal is proportional to the amplitude of the measured signal (i.e., the Rowland signal) and the amplitude of the DC electric field. The frequency of the mixed signal is 100kHz. By connecting the detector to an oscilloscope, the time-domain signal of the Rowland pulse signal group can be detected, thus completing the reception of long-wavelength time signals.

[0015] First, Rydberg atoms are prepared using two-photon excitation. The probe light generated by an 852 nm laser is wavelength-locked to around 852.358 nm by a saturable absorber. After passing through a half-wave plate, it generates linearly polarized light with tunable polarization. This linearly polarized light is then converted into two beams of mutually perpendicular polarization by a polarization beam splitter (PBD). These beams then pass parallel to each other through a dichroic mirror into the Cs atom gas cell. The dichroic mirror reflects 509 nm light and transmits 852 nm light. Subsequently, the two 852 nm laser beams passing through the atom gas cell pass through the dichroic mirror and then through a polarization beam splitter (PBS) into two photodetectors (PDs) to detect the EIT signal. The coupled light generated by the 509nm laser is wavelength-locked at 509.00691nm by an external reference EIT device. This laser is then split into two beams of equal power via a splitter fiber. One beam is used for EIT frequency stabilization, while the other beam is converted into spatial light via a fiber coupler. After passing through a half-wave plate, it generates linearly polarized light with tunable polarization. The polarization states of this linearly polarized light are parallel to the polarization states of the two linearly polarized beams from the 852nm laser after passing through the PBD. By adjusting the directions of the two 509nm laser beams, they are ensured to enter the Cs atom gas cell parallel, opposite, and overlapping to the two 852nm laser beams, respectively, thus realizing the Cs atom 6P... 3 / 2 F=5 to 65D 3 / 2 transition states and 6P 3 / 2 F=5 to 63D 5 / 2The transition state of the atom probe adopts the form of built-in electrode plates, a DC electric field is applied to the Rydberg atom through the electrode plates by an external DC power supply, when a Loran pulse signal with a frequency of 100 KHz arrives, the to-be-detected signal and the DC electric field will generate a mixing effect in the atom chamber, the amplitude of the mixing signal is proportional to the ratio of the amplitude of the to-be-detected signal, i.e. the Loran signal, and the amplitude of the DC electric field, and the frequency of the mixing signal is 100 KHz. The detector is connected with an oscilloscope, and the time domain signal of the Loran pulse signal group can be detected, and the reception of the long-wave time signal is completed.

[0016] The DC electric field is applied as the local oscillator field of the heterodyne signal, the to-be-detected signal is a Loran-C signal, and the principle of generating the mixing effect is as follows: In the superheterodyne wideband sweep measurement technology based on the AC Stark effect, there are two microwave fields irradiating the atom chamber, which are the local oscillator microwave field with known parameters and the signal microwave field to be received. In the case that the local oscillator microwave field and the signal microwave field irradiate the atom chamber at the same time, the Rydberg atom plays a role of a spatial frequency mixer. When the unknown signal microwave field to be detected and the local oscillator microwave field act on the same Rydberg atom at the same time, the two are coherently superimposed, and through the nonlinear response of the electromagnetically induced transparency spectrum, the interference signal of the two will finally be generated in the transmission of the probe light. The interference term in the transmission of the probe light is a sinusoidal oscillation, and the oscillation amplitude is proportional to the Rabi frequency of the unknown signal microwave field, and the frequency and phase of the oscillation depend on the relative frequency and relative phase between the local oscillator microwave field and the signal microwave field.

[0017] The expression of the signal microwave field is E S cos[ωt+φ L (t)], and the expression of the local oscillator field is E L , i.e. a DC signal with a frequency of 0, ω is a microwave carrier frequency, φ L (t) is a phase difference of the local oscillator field relative to the signal field. When the local oscillator field exists, the square of the total electric field is Taking a long-time average, we have

[0018] The detector can detect the signal of , i.e. the Loran pulse signal.

[0019] In conclusion, the above is only a preferred embodiment of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for receiving long wave time signal based on quantum antenna, characterized in that, The method comprises the following steps: Preparation of Rydberg atoms in a high excited state in an atomic cell by means of two-photon excitation; Application of a direct current electric field by means of an electrode plate arranged in the atomic cell as a local oscillator field of heterodyne reception; When a long-wave time signal with a frequency of 100 kHz reaches the atomic cell, a mixing frequency signal is generated by mixing the direct current electric field based on AC Stark effect; Detection of the mixing frequency signal by means of a photoelectric detector and an oscilloscope to complete reception of the long-wave time signal.

2. The method of claim 1, wherein, The two-photon excitation mode is specifically as follows: The probe light with a wavelength of 852 nm and the coupling light with a wavelength of 509 nm are adjusted by an optical system to be parallel and coincident to each other and then are incident into a cesium atomic cell to excite the Rydberg atom to 63D 5 / 2 or 65D 3 / 2 state.

3. The method of claim 2, wherein, The optical system performs the following operations: The 852 nm probe light is divided into two linearly polarized lights with perpendicular polarization states by means of a polarization beam splitter; The 509 nm coupling light is divided into two beams by means of a beam splitter, one of which is used for electromagnetic induced transparency frequency stabilization, and the other one is adjusted in polarization state so as to be parallel to the polarization states of the two 852 nm linearly polarized lights, and to ensure that they are parallel and opposite and coincide into the atomic cell.

4. The method of claim 1, wherein, The mixing frequency signal is a superheterodyne mixing frequency signal, the signal amplitude of which is proportional to the amplitudes of the long-wave time signal and the direct current electric field, and the signal frequency thereof is 100 kHz.

5. The method of claim 1, wherein, The long-wave time signal is a Loran-C pulse signal.

6. The method according to any one of claims 1 to 5, characterized in that, The electrode plate is connected with an external direct current power supply for generating the direct current electric field in the atomic cell.

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