CN111948462B - Coaxial structure broadband quantum microwave measuring device and method - Google Patents

Abstract

The invention relates to a broadband quantum microwave measuring device and method. The measurement device has a quantum-microwave interaction physical structure similar to that of a coaxial line, specifically including an inner conductor, an outer conductor, a filling medium, and a quantum sample; in TEM mode, the device is simple and can achieve broadband without changing the physical system With quantum microwave measurement; this method sets a very small quantum sample space in the filling medium, so that the material of the quantum sample carrier is the background material of the microwave field area. This "for me" design strategy can significantly reduce the current quantum microwave Measuring the interference of the quantum sample carrier itself to the microwave signal to be measured will help improve the measurement accuracy; the coaxial structure measurement device can be directly connected to the current microwave transmission system through impedance transformation, making its function analogous to conventional microwave sensors, which is convenient for use Microwave monitoring of microwave transmission systems. In addition, the present invention also has the advantages of traceability, miniaturization and easy expansion.

Description

A Coaxial Structure Broadband Quantum Microwave Measuring Device and Method

technical field

The invention relates to the fields of quantum precision measurement and microwave engineering, in particular to a coaxial structure broadband quantum microwave measurement device and method.

Background technique

Accurate evaluation of microwave field and microwave power has always been a core topic in the fields of microwave engineering, high-precision measuring instruments, and electromagnetic metrology. The rise of quantum technology provides a new solution to this topic. In particular, atoms are used as microwave field sensing substances, and the direct proportional relationship between the atomic transition Rabi frequency and the electric/magnetic field strength (the proportional coefficients are all basic physical constants) in the process of atom-microwave interaction can be used to realize the direct conversion from electromagnetic quantities to atomic frequencies. convert. This new microwave measurement strategy naturally has the advantages of self-calibration and traceability to the International System of Units (ISU), and its theoretical measurement capability can break through traditional limitations. It is expected to be used in the construction of quantum precision microwave measurement instruments and new national electromagnetic standards. The potential is huge.

等“Imaging of microwave fields using ultracold atoms”,Applied Physics Letters,97(5),051101,2010)；2012年美国J.P.Shaffer教授团队演示了自由空间Rydberg原子微波电场探测装置(J.Sedlacek等“Microwave electrometry with Rydberg atoms in avapour cell using bright atomic resonances”,Nature Physics,8,819-824,2012)；2015年和2017年瑞士G.Mileti教授团队和中国电子科技大学团队分别报道了基于不同量子理论的腔基原子微波磁场探测装置(C.Affolderbach等“Imaging microwave and DCmagnetic fields in a vapor-cell Rb atomic clock”,IEEE Transactions onInstrumentation and Measurement,64(12),3629-3637,2015；F.Sun等“Measuringmicrowave cavity response using atomic Rabi resonances”,Applied PhysicsLetters,111(5),051103,2017)；2018年美国NIST团队报道了基于矩形波导的原子微波功率标准(C.Holloway等“A quantum-based power standard:using Rydberg atoms for aSI-traceable radio-frequency power measurement technique in rectangularwaveguides”,Applied Physics Letters,113(9),094101,2018)。Recently, the academic community has carried out a series of highly fruitful research work on the atomic measurement of electricity/magnetic field. For example, in 2010, Dr. P. Treutlein’s team in Switzerland demonstrated an atomic microwave magnetic field detection device based on a coplanar waveguide (P.

etc. "Imaging of microwave fields using ultracold atoms", Applied Physics Letters, 97(5), 051101, 2010); in 2012, the team of Professor JPShaffer in the United States demonstrated a free-space Rydberg atomic microwave electric field detection device (J.Sedlacek et al. "Microwave electrometry with Rydberg atoms in avapour cell using bright atomic resonances”, Nature Physics, 8,819-824,2012); In 2015 and 2017, the team of Professor G. Mileti from Switzerland and the team from the University of Electronic Science and Technology of China reported cavity-based atomic microwaves based on different quantum theories Magnetic field detection device (C.Affolderbach et al. "Imaging microwave and DCmagnetic fields in a vapor-cell Rb atomic clock", IEEE Transactions on Instrumentation and Measurement, 64(12), 3629-3637, 2015; F.Sun et al. "Measuring microwave cavity response using atomic Rabi resonances”, Applied Physics Letters, 111(5), 051103, 2017); in 2018, the NIST team in the United States reported an atomic microwave power standard based on rectangular waveguides (C. Holloway et al. “A quantum-based power standard: using Rydberg atoms for aSI-traceable radio-frequency power measurement technique in rectangular waveguides”, Applied Physics Letters, 113(9), 094101, 2018).

Although quantum microwave measurement has become an international frontier hotspot, based on the current research results, its common problems include (not limited to) the following points:

1. The measurement device is too complicated, and the working bandwidth of the quantum-microwave interaction structure is very limited. It is often necessary to replace the microwave excitation structure to measure signals of different frequencies, which is not suitable for engineering applications;

2. The material properties of the quantum sample carrier (such as the alkali metal atom glass gas cell) are different from the measurement background (such as air), which causes the disturbance of the field to be measured, which in turn leads to inaccurate measurement results;

3. Only application scenarios such as free space, resonant cavity and waveguide are considered, so the developed quantum microwave measurement device cannot be compared to the current general microwave power sensor, which limits its practical application.

Contents of the invention

In order to solve the above-mentioned problems existing in the prior art, the present invention provides a coaxial structure broadband quantum microwave measurement device and method:

A coaxial structure broadband quantum microwave measurement device, including: inner conductor, outer conductor, filling medium and quantum sample;

The outer conductor is sleeved on the inner conductor at a set interval; the set interval is b-a; wherein, a is the radius of the inner conductor and the inner radius of the filling medium, and b is the inner radius of the outer conductor and the filling medium the outer radius of

The filling medium is uniformly densely filled between the outer conductor and the inner conductor;

A sample space is set in the filling medium; a light hole for passing the laser light is opened on the outer conductor, and the light hole is collinearly arranged with the sample space;

The quantum sample is placed in the sample space for sensing microwaves to be measured;

The inner conductor, the outer conductor and the filling medium form a coaxial structure; the coaxial structure works in TEM mode, allowing quantum-based measurement of the microwave signal to be measured with an operating wavelength greater than π(a+b) Evaluate;

确定得到的特性阻抗达到目标阻抗值；其中，Z_c为特性阻抗，ε_r为填充介质的相对介电常数。Both the radius of the inner conductor and the inner radius of the outer conductor are determined according to the frequency of the microwave to be measured, the relative permittivity of the filling medium, and the impedance matching requirements; the impedance matching requirements refer to the formula

Make sure that the obtained characteristic impedance reaches the target impedance value; where Z _c is the characteristic impedance, and ε _r is the relative permittivity of the filling medium.

Preferably, the size of the sample space is equal to the size of the light hole.

Preferably, the shape of the inner conductor is cylindrical; the material of the inner conductor is copper.

Preferably, the outer conductor is a circular tubular structure; the material of the outer conductor is copper or stainless steel.

Preferably, the filling medium is glass or polytetrafluoroethylene.

Preferably, the number of said light holes is one or two;

When the filling medium is polytetrafluoroethylene, the number of the light-through hole is one; an optical fiber channel is provided in the filling medium, and the light-through hole, the optical fiber channel and the sample space are collinearly arranged;

When the filling medium is glass, the number of the light-through holes is two; the two light-through holes are arranged collinearly with the sample space.

A coaxial structure broadband quantum microwave measurement method, applied to the above-mentioned coaxial structure broadband quantum microwave measurement device; the coaxial structure broadband quantum microwave measurement method includes:

Obtain the frequency of the microwave to be measured according to the quantum sample used, and determine the filling medium and its relative permittivity;

确定得到的特性阻抗达到目标阻抗值；其中，Z_c为特性阻抗，a为内导体的半径和填充介质的内半径，b为外导体的内半径和填充介质的外半径，ε_r为填充介质的相对介电常数；Determine the conductor radius in the measuring device according to the frequency of the microwave to be measured, the relative permittivity of the filling medium, and the impedance matching requirements; the conductor radius includes the radius of the inner conductor and the inner radius of the outer conductor; the impedance matching Requirement means according to the formula

Determine that the obtained characteristic impedance reaches the target impedance value; where, _Zc is the characteristic impedance, a is the radius of the inner conductor and the inner radius of the filling medium, b is the inner radius of the outer conductor and the outer radius of the filling medium, and _εr is the filling medium The relative permittivity;

Extraction of quantum transition Rabi frequency through microwave-light-quantum interaction;

Determine the microwave field strength to be measured according to the Rabi frequency; the microwave field strength to be measured is a microwave magnetic field strength amplitude or a microwave electric field strength amplitude;

The microwave power transmitted in the measuring device is determined from the conductor radius, the relative permittivity and the field strength.

Preferably, the determination of the conductor radius in the measuring device according to the frequency of the microwave to be measured, the relative permittivity of the filling medium, and impedance matching requirements specifically includes:

Limit the radius of the conductor according to the frequency of the microwave to be measured, that is, ensure that the microwave measurement is carried out in the TEM mode, and the defined relationship is as follows: f<c/[π(a+b)]; wherein, f=c/λ is to be The frequency of the microwave is measured, λ is the wavelength of the microwave to be measured, and c is the speed of light in vacuum;

Adjusting the radius of the inner conductor and the inner radius of the outer conductor under the aforementioned defined relationship until the impedance matching requirement is met;

The target impedance value is generally the current commonly used coaxial cable impedance value; the commonly used coaxial cable impedance value is 50 ohms or 75 ohms.

Preferably, the determination of the microwave field strength to be measured according to the Rabi frequency specifically includes:

根据所述Rabi频率确定待测微波场强；其中，Ω为Rabi频率，μ为跃迁矩阵元，/>

为普朗克常数，S为场强。use the formula

Determine the microwave field strength to be measured according to the Rabi frequency; where, Ω is the Rabi frequency, μ is the transition matrix element, />

is Planck's constant, and S is the field strength.

Preferably, the calculation of the microwave power transmitted in the measuring device according to the conductor radius, the relative permittivity and the field strength specifically includes:

或/>

根据所述导体半径、所述相对介电常数和所述场强确定测量装置中传输的微波功率；其中，P为测量装置中传输的微波功率，H为微波磁场强度幅值，E为微波电场强度幅值。use the formula

or />

Determine the microwave power transmitted in the measuring device according to the conductor radius, the relative permittivity and the field strength; wherein, P is the microwave power transmitted in the measuring device, H is the microwave magnetic field intensity amplitude, and E is the microwave electric field intensity magnitude.

According to the specific embodiments provided by the invention, the invention discloses the following technical effects:

The invention mainly consists of an inner conductor, an outer conductor, a filling medium and a quantum sample to form a quantum-microwave interaction physical structure similar to a coaxial cable. While simplifying the microwave measurement device and greatly improving the microwave measurement bandwidth, it can realize The direct connection of 50 ohm or 75 ohm impedance microwave transmission system expands the scope of application; the invention not only allows the measurement of microwave magnetic field and microwave power through magnetic dipole quantum transition, but also allows the measurement of microwave electric field and microwave power through electric dipole quantum transition. Measurement of microwave power. The present invention sets a very small quantum sample space in the filling medium, so that the material of the quantum sample carrier is the background material of the microwave field region. This "for my use" design strategy can significantly reduce or even eliminate The quantum sample carrier itself interferes with the microwave signal to be measured, which is beneficial to improve the measurement accuracy.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those skilled in the art, other drawings that implement the idea of the present invention can also be obtained from these drawings without creative work.

Fig. 1 is the structural representation of coaxial structure broadband quantum microwave measuring device provided by the present invention;

Fig. 2 is the longitudinal sectional view of coaxial structure broadband quantum microwave measuring device provided by the present invention;

Fig. 3 is the lateral sectional view when the filling medium is glass in the coaxial structure broadband quantum microwave measuring device provided by the present invention;

Fig. 4 is the cross-sectional view when the filling medium is polytetrafluoroethylene in the coaxial structure broadband quantum microwave measuring device provided by the present invention;

Fig. 5 is the flow chart of coaxial structure broadband quantum microwave measuring method provided by the present invention;

Fig. 6 is the energy level figure of cesium atom in the embodiment of the present invention;

Fig. 7 is a compatible structural diagram of the coaxial wideband quantum microwave measurement device in the embodiment of the present invention and the current common 50 ohm or 75 ohm impedance microwave transmission system.

Symbol Description:

1-inner conductor, 2-outer conductor, 3-filling medium, 4-sample space, 5-first light hole, 6-second light hole, 7-laser, 40-quantum sample, 32-air filling medium , 51-optical hole, 111-the inner conductor of the current common 50 ohm or 75 ohm impedance coaxial transmission line.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

The object of the present invention is to provide a coaxial structure broadband quantum microwave measurement device and method, which has the advantages of simple structure, wide frequency band, good compatibility, accurate measurement and wide application range.

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is a schematic structural view of a coaxial broadband quantum microwave measurement device provided by the present invention, and Fig. 2 is a longitudinal sectional view of the coaxial broadband quantum microwave measurement device provided by the present invention. As shown in FIG. 1 and FIG. 2 , a coaxial broadband quantum microwave measurement device includes: an inner conductor 1 , an outer conductor 2 , a filling medium 3 and a quantum sample 40 .

The outer conductor 2 is sheathed on the inner conductor 1 at a set interval. The set distance is b-a. Wherein, a is the radius of the inner conductor and the inner radius of the filling medium, and b is the inner radius of the outer conductor and the outer radius of the filling medium.

The shape of the inner conductor 1 is preferably cylindrical, and the material is preferably copper. The shape of the outer conductor 2 is preferably tubular (hollow cylindrical), and the material is preferably copper or stainless steel, but not limited thereto.

The filling medium 3 is uniformly densely filled between the outer conductor 2 and the inner conductor 1 . Wherein, the filling medium is glass or polytetrafluoroethylene, but not limited thereto.

The inner conductor 1, the outer conductor 2 and the filling medium 3 form a coaxial structure. The coaxial structure works in TEM mode, allowing quantum-based measurement and evaluation of the microwave signal to be measured with an operating wavelength greater than π(a+b). A sample space 4 is arranged in the filling medium 3, and the sample space 4 is preferably a very small sample space. The outer conductor 2 is provided with a light hole for the laser to pass through, and the light hole and the sample space 4 are collinearly arranged. In order to further improve the measurement accuracy, the size of the sample space 4 is equivalent to the size of the light through hole.

In order to facilitate transition excitation for different quantum samples, the number of the light-through holes is one or two. However, in practical applications, users can expand the specific number of apertures and sample spaces according to actual needs.

Wherein, when the filling medium 3 is polytetrafluoroethylene, the number of the light through hole is one. In addition, a fiber channel 42 is opened in the filling medium 3 , and the optical hole 51 , the fiber channel 42 and the sample space 4 are arranged in line.

When the filling medium 3 is glass, the number of the light through holes is two. And the two light holes 5 and 6 are arranged in line with the sample space 4 .

The quantum sample 40 is placed in the sample space 4 .

Both the radius of the inner conductor 1 and the inner radius of the outer conductor 2 are determined according to the frequency of the microwave to be measured, the relative permittivity of the filling medium 3 and impedance matching requirements.

The broadband quantum microwave measurement method based on the coaxial interaction structure of the present invention is mainly realized by the following steps:

其中ε_r为所述测量装置中所述填充介质的相对介电常数。Step 1, ensure that the microwave measurement is carried out under the following conditions: λ>π(a+b), where λ is the frequency of the microwave field to be measured, and a and b are respectively the coaxial broadband filled with the medium 3 loaded with the quantum sample 40 in the present invention Radius of the inner and outer conductors of the quantum microwave measuring device. At this moment, the coaxial broadband quantum microwave measurement device works in TEM mode, and calculates the characteristic impedance of the measurement device according to the following formula:

Where ε _r is the relative permittivity of the filling medium in the measuring device.

Step 2. Determine the required filling medium 3 and its relative permittivity ε _r according to the selected quantum sample 40, adjust a and b to make the measurement device achieve impedance with the current common 50 ohm or 75 ohm impedance microwave coaxial connector matching, feeding the microwave signal to be measured into the measuring device.

其中，μ为跃迁矩阵元，/>

为普朗克常数，两者均为基本物理常数。Step 3: Inject the laser light 7 through the optical hole 5 or 51 to prepare the quantum state, and the quantum sample 40 prepared in the completed state undergoes a quantum transition under the excitation of the microwave field to realize the state inversion. The quantum transition Rabi frequency Ω is proportional to the microwave field strength S:

Among them, μ is the transition matrix element, />

is Planck's constant, both of which are fundamental physical constants.

Step 4. The quantum transition is detected by the laser to accurately extract the Rabi frequency Ω, and then the field strength S of the microwave signal to be measured is calculated.

(对于磁偶极跃迁，此时S＝H，H为微波磁场强度幅值)或

(对于电偶极跃迁，此时S＝E，E为微波电场强度幅值)，即可实现对待测微波信号功率水平的高精度评估。Step 5, according to the measured field strength S, and the following relationship between transmitted microwave power P and field strength S in the measuring device:

(For the magnetic dipole transition, at this time S=H, H is the amplitude of the microwave magnetic field intensity) or

(For the electric dipole transition, at this time S=E, where E is the amplitude of the microwave electric field intensity), a high-precision evaluation of the power level of the microwave signal to be measured can be realized.

Step 6. Since the measuring device of the present invention works in the TEM mode of the coaxial structure and allows broadband microwave feed-in, it can be realized by mediating specific energy levels or selecting energy level transitions of different frequencies by the three-dimensional strong static magnetic field. Wideband microwave precision measurement based on quantum effects.

The specific implementation cases are provided below to further illustrate the scheme of the present invention. In the specific implementation cases of the present invention, glass or polytetrafluoroethylene is used as an example to illustrate the specific implementation cases. In specific applications, the scheme of the present invention is also applicable to other filling media. Measured technical solutions.

Embodiment one

When the filling medium is glass, as shown in Figure 3, the outer conductor 2 is provided with a first light hole 5 and a second light hole 6 for the laser to pass through, and the first light hole 5 and the second light hole The light hole 6 is arranged in line with the sample space 4 .

The sample space 4 is loaded with an atomic sample 40, and the laser 7 is single-frequency light or double-frequency light.

When the laser 7 is a single-frequency light, it has the dual functions of pumping and detection. At this time, the Rabi frequency Ω corresponding to the microwave magnetic field can be extracted by Rabi resonance or Rabi oscillation, and then the microwave magnetic field in the measuring device can be calculated. and transmit microwave power. When the laser 7 is dual-frequency light, it specifically includes coupled light and probe light transmitted in antiparallel, at this time, the Rabi frequency Ω corresponding to the microwave electric field can be extracted by methods such as EIT and AT splitting of Rydberg atoms, and then can be calculated The microwave electric field and transmitted microwave power in the measurement device.

Specifically, the present invention provides a method for performing broadband quantum microwave measurement relying on the above coaxial structure broadband quantum microwave measurement device. As shown in Figure 5, the broadband quantum microwave measurement method includes:

Step 100: Obtain the frequency of the microwave to be measured and the relative permittivity of the filling medium (also the carrier of the quantum sample) according to the quantum sample used.

Step 101: Determine the radius of the conductor in the measuring device according to the frequency of the microwave to be measured, the relative permittivity of the filling medium, and impedance matching requirements. The conductor radius includes the radius of the inner conductor and the inner radius of the outer conductor. This step specifically includes:

其中，a为内导体的半径和填充介质的内半径，b为外导体的内半径和填充介质的外半径，ε_r为量子样品载体的相对介电常数。Determine the characteristic impedance of the measuring device according to the frequency of the microwave to be measured and the relative permittivity of the quantum sample carrier:

where a is the radius of the inner conductor and the inner radius of the filling medium, b is the inner radius of the outer conductor and the outer radius of the filling medium, and _εr is the relative permittivity of the quantum sample carrier.

Adjust the radius of the inner conductor and the inner radius of the outer conductor, and make the characteristic impedance Z _c be 50 ohms or 75 ohms under the premise of satisfying λ>π(a+b), and the radius of the inner conductor and the outer conductor obtained at this time The inner radius is the conductor radius, where λ is the frequency of the microwave to be measured.

Step 102: extract the Rabi frequency during the quantum transition. Specifically, the sub-transition to be measured is detected by laser to realize accurate extraction of the Rabi frequency Ω.

Step 103: Determine the field strength according to the Rabi frequency. The field strength is the magnitude of the microwave magnetic field strength or the magnitude of the microwave electric field strength.

根据Rabi频率确定场强，其中，Ω为Rabi频率，μ为跃迁矩阵元，/>

为普朗克常数，S为场强。This step 103 preferably adopts the formula

Determine the field strength according to the Rabi frequency, where Ω is the Rabi frequency, μ is the transition matrix element, />

is Planck's constant, and S is the field strength.

Step 104: Calculate the microwave power transmitted by the measuring device according to the conductor radius, relative permittivity and field strength.

Step 104 specifically includes:

或/>

根据导体半径、相对介电常数和场强确定测量装置中传输的微波功率，其中，P为测量装置中传输的微波功率，H为微波磁场强度幅值，E为微波电场强度幅值。use the formula

or />

Determine the microwave power transmitted in the measuring device according to the conductor radius, relative permittivity and field strength, where P is the microwave power transmitted in the measuring device, H is the amplitude of the microwave magnetic field intensity, and E is the amplitude of the microwave electric field intensity.

Based on the aforementioned devices and methods, the present invention uses cesium atoms as quantum samples 40 for sensing microwaves, and uses glass as a filling medium to realize quantum measurement of X-band microwave signals. The transition frequency of the hyperfine ground state F=3→F=4 of the undisturbed cesium atom is 9.192631770 GHz, just in the X-band, and its energy level is shown in Figure 6.

欧。In this embodiment, the inner conductor 1 of the coaxial structure is made of oxygen-free copper material, and is cylindrical, with an outer diameter 2a=1.24mm. The outer conductor 2 of the coaxial structure is an inner hollow cylinder made of stainless steel with an inner diameter of 2b=7mm. The material of the filling medium 3 of the coaxial structure is glass with a relative permittivity ε _r =4.3, in the shape of a cylinder, and its inner diameter and outer diameter are 1.24mm and 7mm respectively. In this way, the inner conductor 1, the outer conductor 2 and the filling medium 3 are closely connected to form the aforementioned coaxial structure, and its impedance

Europe.

Inside the filling medium 3, a very small sample space 4 with a side length of 0.5 mm is set at a distance of 1 mm from the inner conductor 1, and a cesium atom sample is loaded in the sample space 4. The outer conductor 2 is provided with a first light hole 5 and a second light hole 6 with a diameter of 0.5mm for the 852nm laser 7 to pass through. The sample space 4, the first light hole 5 and the second light hole The three optical holes 6 are collinear, and are not on the same level as the inner conductor. The laser 7 is locked on the D2 line of the cesium atom, and is used as the pumping light for the energy state preparation of the cesium atom and the probe light for the hyperfine transition. The coaxial structure and the quantum sample 40 together with the laser 7 constitute the core of the coaxial broadband quantum microwave measurement device of the present invention.

During the working process, the 852nm laser 7 of the D2 line prepares the ground state cesium atoms 40 in the sample space 4 to the energy level of 6 ² S _1/2 F=3, under the excitation of the magnetic field component of the microwave signal to be measured, The ground state cesium atom on the F=3 energy level will jump to the 6 ² S _1/2 F=4 energy level, and once the cesium atom has a layout on the 6 ² S _1/2 F=4 energy level, it will be The laser 7 records, and at this time, the laser 7 acts as a detection light again. The Rabi frequency Ω corresponding to the microwave magnetic field to be measured can be fitted from the recorded information, and then the microwave magnetic field in the coaxial structure broadband quantum microwave measurement device can be calculated by using the coaxial structure broadband quantum microwave measurement method provided by the present invention and transmit microwave power.

欧，(图7所示)。阻抗匹配完成后，电磁波便可经由现行商用同轴线缆低损耗馈入至量子样品段同轴互作用结构。如此，所述本发明提供的同轴结构宽带量子微波测量装置将十分方便适用于现行微波传输链路的微波场和功率的可溯源高精度传感。In order to make the coaxial wideband quantum microwave measurement device provided by the present invention compatible with the current microwave transmission system, the glass-filled coaxial structure can be gradually transitioned to the conventional coaxial interface of the air-filled medium 32 through impedance transformation. Conventional coaxial interface air relative permittivity ε _r = 1, outer conductor 2 inner diameter 2b = 7mm, outer diameter of inner conductor 111 is 3.04mm, characteristic impedance

Europe, (shown in Figure 7). After the impedance matching is completed, the electromagnetic wave can be fed into the coaxial interaction structure of the quantum sample section through the existing commercial coaxial cable with low loss. In this way, the coaxial structure broadband quantum microwave measurement device provided by the present invention will be very convenient and applicable to the traceable high-precision sensing of the microwave field and power of the current microwave transmission link.

Among them, part (a) of Figure 7 is a specific structural diagram of a coaxial broadband quantum microwave measurement device compatible with the current microwave transmission system, and Figure 7 (b) is a coaxial broadband quantum microwave measurement device compatible with the current microwave transmission system A cross-sectional view in .

Embodiment two

When the filling medium is polytetrafluoroethylene commonly used in current microwave transmission lines, as shown in FIG. 4 , the outer conductor 2 is provided with a light hole 51 for passing the laser light, and a fiber channel 42 is provided in the filling medium 3 . The vacuum sample space 4 is located at the top of the fiber channel 42 , and the light hole 51 communicates with the fiber channel 42 . Wherein, the fiber channel 42 is a micron-scale fiber channel.

When the quantum sample 40 loaded in the sample space 4 is a vacuum-loaded atom or an air-loaded NV color center sample, the optical fiber inputs and extracts the laser light through the optical fiber channel 42 and the optical hole 51, including the inner conductor 1 and the outer conductor 2 and the coaxial structure of the filling medium 3. At this time, accurate measurement of the microwave magnetic field, microwave electric field and microwave power in the measuring device can be realized through the same microwave-quantum-laser interaction process as in the first embodiment.

Based on the above settings, the technical solution provided by the present invention has the following advantages over the prior art:

1. Compared with the current complex and narrow-band quantum microwave measurement device, the coaxial quantum-microwave interaction physical structure working in TEM mode proposed by the present invention has the advantages of miniaturization, wide frequency band and compatibility with the current 50 ohm or 75 ohm impedance microwave The advantages of the transmission system are more conducive to practical engineering applications;

2. In the current quantum microwave measurement device, the material of the quantum sample carrier is different from the background material of the microwave field area to be measured, which causes the measured field to be measured to deviate from the real field to varying degrees. The coaxial quantum-microwave interaction structure constructed by the invention confines the microwave field to be measured in the filling medium, and at the same time, the filling medium also acts as a carrier of quantum samples. If the quantum sample is an alkali metal atom in the glass sample space, the present invention selects the same or very similar glass as the filling medium of the coaxial interaction structure. This "for me" design strategy can significantly reduce or even eliminate At present, in the quantum microwave measurement, the quantum sample carrier itself interferes with the microwave signal to be measured, and the measurement accuracy is high;

3. The broadband quantum microwave measurement device with coaxial structure of the present invention can use atoms as quantum samples for sensing microwave fields, or use NV color centers as quantum samples for sensing microwave fields. Its compact physical structure allows the measurement device to be placed in a three-dimensional strong static magnetic field structure with uniform and adjustable field strength. Through the mediation of specific energy levels by the static magnetic field or the selection of energy level transitions at different frequencies, broadband and even Ultra-wideband microwave precision measurement based on quantum effects;

4. When the quantum sample is an atom, the filling medium is glass, and the sample space is loaded with atoms in vacuum. The present invention can realize the traceable measurement of the microwave field and microwave power; when the quantum sample is an NV color center, the filling medium is polytetrafluoroethylene Ethylene, the present invention can use micron-sized hollow-core optical fiber (NV color center sample attached to the head) to be embedded in the filling medium, and there is almost no interference to the microwave signal to be measured.

In summary, the present invention has the advantages of traceability, miniaturization, wide frequency range, high precision and good compatibility.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

In this paper, specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; meanwhile, for those of ordinary skill in the art, according to the present invention Thoughts, there will be changes in specific implementation methods and application ranges. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims (10)

1. A coaxial structure broadband quantum microwave measuring device is characterized by comprising: an inner conductor, an outer conductor, a filling medium and a quantum sample;

the outer conductor is sleeved on the inner conductor according to a set distance; the set distance is b-a; wherein, a is the radius of the inner conductor and the inner radius of the filling medium, and b is the inner radius of the outer conductor and the outer radius of the filling medium;

the filling medium is uniformly and densely filled between the outer conductor and the inner conductor;

a sample space is arranged in the filling medium; the outer conductor is provided with a light through hole for laser to pass through, and the light through hole and the sample space are arranged in a collinear way;

the quantum sample is arranged in the sample space and used for sensing the microwave to be detected;

the inner conductor, the outer conductor and the filling medium form a coaxial structure; the coaxial structure works in a TEM mode, and quantum-based measurement and evaluation are allowed to be carried out on the microwave signal to be measured with the working wavelength larger than pi (a + b);

the radius of the inner conductor and the inner radius of the outer conductor are determined according to the frequency of the microwave to be measured, the relative dielectric constant of the filling medium and the impedance matching requirement; the impedance matching requirement is according to the formula

Determining that the obtained characteristic impedance reaches a target impedance value; wherein Z is _c Is characteristic impedance,. Epsilon _r Is the relative dielectric constant of the fill medium.

2. The broadband quantum microwave measurement device with the coaxial structure according to claim 1, wherein the size of the sample space is equal to the size of the light through hole.

3. The broadband quantum microwave measurement device of claim 1, wherein the inner conductor is cylindrical in shape; the inner conductor is made of copper.

4. The broadband quantum microwave measurement device with the coaxial structure as claimed in claim 1, wherein the outer conductor is a circular tubular structure; the outer conductor is made of copper or stainless steel.

5. The broadband quantum microwave measurement device with the coaxial structure as claimed in claim 1, wherein the filling medium is glass or polytetrafluoroethylene.

6. The broadband quantum microwave measurement device with the coaxial structure according to claim 1, wherein the number of the light passing holes is one or two;

when the filling medium is polytetrafluoroethylene, the number of the light through holes is one; an optical fiber channel is formed in the filling medium, and the light through hole, the optical fiber channel and the sample space are arranged in a collinear manner;

when the filling medium is glass, the number of the light through holes is two; the two light-transmitting holes and the sample space are arranged in a collinear manner.

7. A coaxial structure broadband quantum microwave measuring method is characterized by being applied to the coaxial structure broadband quantum microwave measuring device as claimed in any one of claims 1 to 6; the coaxial structure broadband quantum microwave measurement method comprises the following steps:

acquiring the frequency of the microwave to be detected according to the quantum sample, and determining the filling medium and the relative dielectric constant thereof;

determining the radius of a conductor in the measuring device according to the frequency of the microwave to be measured, the relative dielectric constant of the filling medium and the impedance matching requirement; the conductor radius includes a radius of the inner conductor and an inner radius of the outer conductor; the impedance matching requirement is according to the formula

Determining that the obtained characteristic impedance reaches a target impedance value; wherein Z is _c For the characteristic impedance, a is the radius of the inner conductor and the inner radius of the filling medium, b is the inner radius of the outer conductor and the outer radius of the filling medium, ε _r Is the relative dielectric constant of the fill medium;

extracting quantum transition Rabi frequency through microwave-light-quantum interaction;

determining the microwave field intensity to be detected according to the Rabi frequency; the microwave field intensity to be detected is a microwave magnetic field intensity amplitude or a microwave electric field intensity amplitude;

and determining the microwave power transmitted in the measuring device according to the conductor radius, the relative dielectric constant and the field intensity.

8. The method for measuring broadband quantum microwaves of coaxial structures according to claim 7, wherein the determining the radius of the conductor in the measuring device according to the frequency of the microwaves to be measured, the relative dielectric constant of the filling medium and the impedance matching requirement specifically comprises:

and defining the radius of the conductor according to the frequency of the microwave to be measured, namely ensuring that the microwave measurement is carried out in a TEM mode, wherein the defined relation is as follows: f < c/[ π (a + b) ]; wherein f = c/λ is the frequency of the microwave to be detected, λ is the wavelength of the microwave to be detected, and c is the speed of light in vacuum;

adjusting the radius of the inner conductor and the inner radius of the outer conductor under the aforementioned defined relationship until the impedance matching requirement is met;

the target impedance value is 50 ohms or 75 ohms.

9. The method for measuring broadband quantum microwaves of coaxial structures according to claim 7, wherein the determining the microwave field strength to be measured according to the Rabi frequency specifically comprises:

using a formula

Determining the microwave field intensity to be detected according to the Rabi frequency; wherein omega is the Rabi frequency, mu is the transition matrix element,

is the Planck constant, S is the field strength.

10. The method for microwave measurement of broadband quantum in coaxial structure according to claim 7, wherein the calculating the microwave power transmitted in the measuring apparatus according to the radius of the conductor, the relative dielectric constant and the field strength specifically comprises:

using a formula

Or

Determining the microwave power transmitted in the measuring device according to the conductor radius, the relative dielectric constant and the field intensity; wherein, P is the microwave power transmitted in the measuring device, H is the microwave magnetic field intensity amplitude, and E is the microwave electric field intensity amplitude.

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