Molecular clock for realizing long-term stability of high-frequency signal and working method thereof

Abstract

The invention discloses a molecular clock for realizing long-term stability of a high-frequency signal and a working method of the molecular clock. According to the molecular clock, the working gas chamber is used for storing high-purity carbonyl sulfide gas by adopting a cylinder, the pressure intensity is maintained through the vacuum pump, and two-way transmission of microwave signals is realized by utilizing the antenna coupler; the Moku: Pro generates a TTL time sequence signal, controls a high-speed switch to switch gas excitation and signal acquisition, and integrates filtering and phase locking functions to generate an error signal; and the mixer mixes the gas response signal with the local oscillator source, outputs a direct current error signal after filtering and phase locking, feeds back the direct current error signal to the voltage-controlled crystal oscillator, and outputs a long-term stable signal after 8 frequency division. The long-term stability of a high-frequency signal is remarkably improved through the high stability of the rotation transition frequency of carbonyl sulfide molecules and a closed-loop feedback mechanism.

Description

Technical Field

[0001] This invention belongs to the field of quantum clock technology, and in particular relates to a molecular clock for achieving long-term stability of high-frequency signals and its operating method. Background Technology

[0002] The emergence of quantum clocks has solved the problems of low frequency stability and poor accuracy in ultra-high precision clock applications, and they have been widely used in military, communications, measurement, and radio astronomy. While traditional quantum clocks have been commercialized, their large size and complex structure limit their development scale and application requirements. However, the rapid development of semiconductor technology and microelectronics processes in recent decades has led to remarkable progress in the development of miniature precision measurement devices that utilize quantum energy level transition signals as references. The first all-electronic commercial-grade chip-scale molecular clock (CSMC) uses the rotational absorption transition spectral line of the OCS (carbonyl sulfide) molecule at 231.061 GHz as its time reference, achieving performance similar to CSAC while being smaller and consuming less power, representing a new breakthrough in time base products in the terahertz field.

[0003] Despite the significant progress made in chip-scale quantum clocks, the development of novel quantum clocks to further reduce size, power consumption, and cost remains crucial in the face of increasingly complex and volatile environments. Emission-type molecular clocks offer a fresh perspective for this type of quantum clock development. These clocks induce a transient response signal from carbonyl sulfide (OCS) molecules at the excitation frequency through external coherent detection. Heterodyne detection is then used to convert this signal into a usable reference signal, which is combined with a phase-locked loop to servo the voltage-controlled oscillator, outputting a highly stable frequency signal with microscopic quantum properties. Summary of the Invention

[0004] The purpose of this invention is to provide a molecular clock and its operating method for achieving long-term stability of high-frequency signals, and to achieve long-term stability of voltage-controlled crystal oscillators.

[0005] To achieve the objectives of this invention, in one aspect, this invention provides a molecular clock for achieving long-term stability of high-frequency signals, comprising a microwave frequency source, a high-speed switch, a working gas chamber, a low-noise amplifier, a mixer, a Moku:Pro, a voltage-controlled crystal oscillator, and a frequency divider;

[0006] The microwave frequency source is used to generate an emission source that excites the gas in the working chamber, and also serves as a local oscillator source for mixing with the gas signal excited in the working chamber; and receives the Moku:Pro control signal for signal modulation and frequency sweeping functions.

[0007] The working gas chamber is used to store frequency reference source gas and to excite the high-speed switch to switch between gas excitation and signal acquisition within the working gas chamber.

[0008] The low-noise amplifier is used to amplify the gas excitation signal;

[0009] The mixer is used to mix the local oscillator signal with the amplified signal.

[0010] The Moku:Pro is used to generate a timing TTL signal to control the generation of microwave pulses and the reception time of response signals.

[0011] The voltage-controlled crystal oscillator is used to connect with the frequency divider to output a low-frequency signal and receive error DC signal correction in real time to achieve long-term stability of the high-frequency signal.

[0012] The frequency divider is used to reduce the high-frequency output signal of the voltage-controlled crystal oscillator by an integer or fractional ratio to generate a low-frequency signal.

[0013] The working gas chamber includes a vacuum gauge, a gas chamber, and a coupler;

[0014] The vacuum gauge is used to monitor the vacuum level of the gas chamber to ensure that a vacuum environment filled with polar gas molecules can be provided.

[0015] The gas chamber is cylindrical to store polar gas phase and provide its excitation environment, and is placed horizontally during testing;

[0016] The coupler includes a transmitter coupler and a receiver coupler; the transmitter coupler is used to feed the microwave pulse detection signal from the emission source into the gas chamber; the receiver coupler is used to send the pulsed molecular response signal into a high-speed switch.

[0017] The transmitter coupler and receiver coupler are respectively disposed on the two bottom surfaces of the cylindrical gas chamber.

[0018] The coupler uses an L-shaped antenna.

[0019] The polar gaseous molecule is carbonyl sulfide with a purity of 99% and three molecular rotational transition frequencies of 12.162979 GHz, 24.325927 GHz, and 36.488813 GHz.

[0020] The vacuum gauge is equipped with a vacuum pump to ensure that the gas pressure in the chamber is within the allowable range.

[0021] The gas pressure range in the chamber is 1 to 7 Pa.

[0022] The Moku:Pro has a built-in filter and phase-locked loop;

[0023] The filter is used to perform low-pass filtering on the mixed signal to remove high-frequency noise.

[0024] The phase-locked loop is used to phase-lock the filtered signal, generate an error DC signal, and correct the output signal of the voltage-controlled crystal oscillator.

[0025] The voltage-controlled crystal oscillator is an 80MHz voltage-controlled crystal oscillator with an 8-fold frequency divider, which reduces the signal to 10MHz.

[0026] On the other hand, the present invention also provides a method for operating a molecular clock to achieve long-term stability of high-frequency signals, comprising the following steps:

[0027] Step 1: Connect the Moku:Pro output signal to the microwave transmitter, microwave local oscillator, and single-pole double-throw switch to achieve timing control of each instrument;

[0028] Step 2: The microwave transmitter generates a frequency-modulated signal, which enters the working gas chamber through a high-speed switch to excite the working gas and generate a gas excitation signal.

[0029] Step 3: The gas excitation signal is acquired by a high-speed switch and amplified by a low-noise amplifier;

[0030] Step 4: Mix the amplified signal with the microwave local oscillator through a mixer to obtain a signal containing gas excitation frequency information;

[0031] Step 5: Input the mixed signal into the filter and phase-locked loop of Moku:Pro to obtain the DC error signal;

[0032] Step 6: Connect the DC error signal to the voltage-controlled crystal oscillator (VCO) control signal to control the output of the VCO.

[0033] Step 7: Connect the output of the voltage-controlled crystal oscillator to the external reference of the Moku:Pro, microwave transmitter, and microwave local oscillator to complete the loop closure.

[0034] Compared with the prior art, the significant progress of the present invention is that: the present invention uses the rotational transition emission spectral lines of polar gas phase molecules as the frequency standard, pushing the frequency to low frequency ranges such as 36GHz, 24GHz, and 12GHz, thereby reducing the cost of the signal source and improving the output frequency stability of the voltage-controlled crystal oscillator. After testing, it has been proven that the solution has practical application significance.

[0035] To more clearly illustrate the functional characteristics and structural parameters of the present invention, further explanation is provided below in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0036] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0037] Figure 1 This is a schematic diagram of the molecular clock device of the present invention;

[0038] Figure 2 This is a schematic diagram of the kilometer frequency stability of the voltage-controlled crystal oscillator in an embodiment of the present invention;

[0039] Figure 3 This is the absorption spectrum curve of gas molecules at 36.488813 GHz during molecular transition in an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of the kilometer frequency stability of the high-frequency signal realized by the molecular clock device in this embodiment of the invention;

[0041] Figure 5 This is a schematic diagram of the working air chamber in an embodiment of the present invention;

[0042] Figure 6 This is a schematic diagram of the reference signals of each instrument connected in series in an embodiment of the present invention. Detailed Implementation

[0043] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] The present invention provides a molecular clock for achieving long-term stability of high-frequency signals, combined with Figure 1 It includes a microwave frequency source, a high-speed switch, a working gas chamber, a low-noise amplifier, a mixer, a multi-functional Moku:Pro, a voltage-controlled crystal oscillator, and a frequency divider;

[0045] The microwave frequency source is used to generate an emission source that excites the gas in the working chamber, and also serves as a local oscillator source for mixing with the gas signal excited in the working chamber; and receives the Moku:Pro control signal for signal modulation and frequency sweeping functions.

[0046] The working gas chamber is used to store frequency reference source gas and to excite the high-speed switch to switch between gas excitation and signal acquisition within the working gas chamber.

[0047] The low-noise amplifier is used to amplify the gas excitation signal;

[0048] The mixer is used to mix the local oscillator signal with the amplified signal.

[0049] The Moku:Pro is used to generate a timing TTL signal to control the generation of microwave pulses and the reception time of response signals.

[0050] The voltage-controlled crystal oscillator (VCXO) is used to connect with the frequency divider to output a low-frequency signal and receive error DC signal correction in real time to achieve long-term stability of the high-frequency signal.

[0051] The frequency divider is used to reduce the high-frequency output signal of the voltage-controlled crystal oscillator by an integer or fractional ratio to generate a low-frequency signal.

[0052] Combination Figure 5 The working gas chamber includes a vacuum gauge, a gas chamber, and a coupler;

[0053] The vacuum gauge is used to monitor the vacuum level of the gas chamber to ensure that a vacuum environment filled with polar gas molecules can be provided.

[0054] The gas chamber is cylindrical to store polar gas phase and provide its excitation environment, and is placed horizontally during testing;

[0055] The coupler includes a transmitter coupler and a receiver coupler; the transmitter coupler is used to feed the microwave pulse detection signal from the emission source into the gas chamber; the receiver coupler is used to send the pulsed molecular response signal into a high-speed switch.

[0056] The transmitter coupler and receiver coupler are respectively disposed on the two bottom surfaces of the cylindrical gas chamber.

[0057] The coupler uses an L-shaped antenna.

[0058] The polar gaseous molecule is carbonyl sulfide (OCS) with a purity of 99% and molecular rotational transition frequencies of 12.162979 GHz, 24.325927 GHz, and 36.488813 GHz.

[0059] The vacuum gauge is equipped with a vacuum pump to ensure that the gas pressure in the chamber is within the allowable range.

[0060] The gas pressure range in the chamber is 1 to 7 Pa.

[0061] The Moku:Pro has a built-in filter and phase-locked loop;

[0062] The filter is used to perform low-pass filtering on the mixed signal to remove high-frequency noise.

[0063] The phase-locked loop is used to phase-lock the filtered signal, generate an error DC signal, and correct the output signal of the voltage-controlled crystal oscillator.

[0064] The voltage-controlled crystal oscillator is an 80MHz voltage-controlled crystal oscillator with an 8-fold frequency divider, which reduces the signal to 10MHz.

[0065] The method for operating a molecular clock to achieve long-term stability of high-frequency signals, as described above, is characterized by the following steps:

[0066] Step 1: Connect the Moku:Pro output signal to the microwave transmitter, microwave local oscillator, and single-pole double-throw switch to achieve timing control of each instrument;

[0067] Step 2: The microwave transmitter generates a frequency-modulated signal, which enters the working gas chamber through a high-speed switch to excite the working gas and generate a gas excitation signal.

[0068] Step 3: The gas excitation signal is acquired by a high-speed switch and amplified by a low-noise amplifier;

[0069] Step 4: Mix the amplified signal with the microwave local oscillator through a mixer to obtain a signal containing gas excitation frequency information;

[0070] Step 5: Input the mixed signal into the filter and phase-locked loop of Moku:Pro to obtain the DC error signal;

[0071] Step 6: Connect the DC error signal to the voltage-controlled crystal oscillator (VCO) control signal to control the output of the VCO.

[0072] Step 7: Connect the output of the voltage-controlled crystal oscillator to the external reference of the Moku:Pro, microwave transmitter, and microwave local oscillator to complete the loop closure.

[0073] Example

[0074] Combination Figure 6 Simulation tests were conducted on the above scheme:

[0075] First, connect the 10MHz signal output of the voltage-controlled crystal oscillator to a frequency counter for frequency counting. Then, use the frequency data to plot the kilometer-second Allan variance stability graph, as shown below. Figure 2 As shown, without molecular clock correction, the stability of the voltage-controlled crystal oscillator is approximately in the range of 7×10⁻⁸ to 1.5×10⁻⁷.

[0076] Next, the voltage-controlled crystal oscillator is connected to the molecular clock device for loop feedback. Based on the above principle, the microwave signal source is first controlled using Moku:Pro to achieve a frequency sweep mode. The carbonyl sulfide gas absorption spectrum is obtained by processing the oscilloscope readings, such as... Figure 3 As shown, a curve positively correlated with frequency and voltage appears near the molecular excitation frequency, proving that the molecular clock device is working normally. Then, the frequency source sweep mode is turned off, and the molecular clock device is set to the molecular excitation frequency by fixing the emission module. The polar gas phase molecular carbonyl sulfide generates a response signal in a short time, and the molecular clock device enters the working state. The DC error signal obtained through the phase-locked loop is used to adjust the voltage-controlled crystal oscillator.

[0077] Finally, the 10MHz output of the voltage-controlled crystal oscillator was counted using a frequency counter, and then an Allan variance stability plot was plotted using the frequency data, as shown below. Figure 4 As shown, the output of the voltage-controlled crystal oscillator is greatly improved in the loop feedback mode. Compared to the above... Figure 2 The result shows that the long-term stability of the emission molecular clock is improved by more than an order of magnitude.

[0078] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0079] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A molecular clock for achieving long-term stability of high-frequency signals, characterized in that, Includes microwave frequency source, high-speed switch, working gas chamber, low-noise amplifier, mixer, Moku:Pro, voltage-controlled crystal oscillator and frequency divider; The microwave frequency source is used to generate an emission source that excites the gas in the working chamber, and also serves as a local oscillator source for mixing with the gas signal excited in the working chamber; and receives the Moku:Pro control signal for signal modulation and frequency sweeping functions. The working gas chamber is used to store frequency reference source gas and to excite the high-speed switch to switch between gas excitation and signal acquisition within the working gas chamber. The low-noise amplifier is used to amplify the gas excitation signal; The mixer is used to mix the local oscillator signal with the amplified signal. The Moku:Pro is used to generate a timing TTL signal to control the generation of microwave pulses and the reception time of response signals. The voltage-controlled crystal oscillator is used to connect with the frequency divider to output a low-frequency signal and receive error DC signal correction in real time to achieve long-term stability of the high-frequency signal. The frequency divider is used to reduce the high-frequency output signal of the voltage-controlled crystal oscillator by an integer or fractional ratio to generate a low-frequency signal.

2. A molecular clock for achieving long-term stability of high-frequency signals according to claim 1, characterized in that, The working gas chamber includes a vacuum gauge, a gas chamber, and a coupler; The vacuum gauge is used to monitor the vacuum level of the gas chamber to ensure that a vacuum environment filled with polar gas molecules can be provided. The gas chamber is cylindrical to store OCS gas and provide its excitation environment, and is placed horizontally during testing; The coupler includes a transmitter coupler and a receiver coupler; the transmitter coupler is used to feed the microwave pulse detection signal from the transmitter source into the gas chamber; the receiver coupler; Used to send pulsed molecular response signals into high-speed switches; The transmitter coupler and receiver coupler are respectively disposed on the two bottom surfaces of the cylindrical gas chamber.

3. A molecular clock for achieving long-term stability of high-frequency signals according to claim 2, characterized in that, The coupler uses an L-shaped antenna.

4. A molecular clock for achieving long-term stability of high-frequency signals according to claim 2, characterized in that, The polar gaseous molecule is carbonyl sulfide with a purity of 99% and three molecular rotational transition frequencies of 12.162979 GHz, 24.325927 GHz, and 36.488813 GHz.

5. A molecular clock for achieving long-term stability of high-frequency signals according to claim 2, characterized in that, The vacuum gauge is equipped with a vacuum pump to ensure that the gas pressure in the chamber is within the allowable range.

6. A molecular clock for achieving long-term stability of high-frequency signals according to claim 5, characterized in that, The gas pressure range in the chamber is 1 to 7 Pa.

7. A molecular clock for achieving long-term stability of high-frequency signals according to claim 1, characterized in that, The Moku:Pro has a built-in filter and phase-locked loop; The filter is used to perform low-pass filtering on the mixed signal to remove high-frequency noise. The phase-locked loop is used to phase-lock the filtered signal, generate an error DC signal, and correct the output signal of the voltage-controlled crystal oscillator.

8. A molecular clock for achieving long-term stability of high-frequency signals according to claim 1, characterized in that, The voltage-controlled crystal oscillator is an 80MHz voltage-controlled crystal oscillator with an 8-fold frequency divider, which reduces the signal to 10MHz.

9. A method for operating a molecular clock to achieve long-term stability of high-frequency signals according to any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Connect the Moku:Pro output signal to the microwave transmitter, microwave local oscillator, and single-pole double-throw switch to achieve timing control of each instrument; Step 2: The microwave transmitter generates a frequency-modulated signal, which enters the working gas chamber through a high-speed switch to excite the working gas and generate a gas excitation signal. Step 3: The gas excitation signal is acquired by a high-speed switch and amplified by a low-noise amplifier; Step 4: Mix the amplified signal with the microwave local oscillator through a mixer to obtain a signal containing gas excitation frequency information; Step 5: Input the mixed signal into the filter and phase-locked loop of Moku:Pro to obtain the DC error signal; Step 6: Connect the DC error signal to the voltage-controlled crystal oscillator (VCO) control signal to control the output of the VCO. Step 7: Connect the output of the voltage-controlled crystal oscillator to the external reference of the Moku:Pro, microwave transmitter, and microwave local oscillator to complete the loop closure.

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