Shimming device and magnetic field equipment for a small quantum computer based on non-magnetic-loss heating

Abstract

The present invention discloses a shimming device and a magnetic field device for a small quantum computer based on non-magnetic loss heating. The shimming device includes a probe frame and two shimming plates. The two shimming plates are arranged at intervals and installed on the probe frame. The probe frame is used to carry a test sample located between the two shimming plates. On the inner surface of each shimming plate facing the test sample, there is a shimming coil, and on the outer surface of each shimming plate facing away from the test sample, there is a heating coil. The heating coil is fabricated by the target field method, and the magnetic field intensity generated by the heating coil in the area where the test sample is located is less than a preset value. The heating coil integrated on the shimming plate is used to replace the traditional heating resistor attached to the surface of the magnetic yoke, and the current control module for supplying power to the heating resistor is removed, which is beneficial to the miniaturization of the nuclear magnetic quantum computer. At the same time, a new type of heating coil designed by the target field method is adopted to avoid affecting the homogeneous magnetic field environment of the target field.

Description

Technical Field

[0001] The present invention belongs to the technical field of quantum computers, and more specifically, relates to a shimming device and a magnetic field device for a small quantum computer based on non-magnetic loss heating. Background Art

[0002] Among many new computer architectures, quantum computing is considered to be the next-generation architecture that is expected to subvert the existing computing system because it has exponential acceleration in solving many problems. Among the current physical experimental platforms for realizing quantum computing, nuclear magnetic resonance is the system with the earliest start, the most perfect development, and the most quantum algorithms implemented.

[0003] Existing large nuclear magnetic resonance quantum computers use superconducting coils to generate strong magnetic fields. The superconducting coils work in a cryogenic environment and require daily addition of liquid helium and liquid nitrogen to maintain the low-temperature environment. These instruments are expensive and relatively large in size, and need to be installed in a space several meters high.

[0004] Existing desktop nuclear magnetic resonance quantum computers use neodymium iron boron permanent magnets as strong magnetic field generating devices, and are equipped with a shimming module to compensate for the magnetic field generated by the permanent magnets to make the magnetic field more uniform. The shimming module includes: a shimming power supply and a shimming plate. The shimming plate is connected to the shimming power supply and is placed on a magnetic yoke. At the same time, a temperature control module is equipped to keep the permanent magnet in a stable temperature environment. The temperature control module includes components such as a power resistor for heating, a thermistor for temperature measurement, and a current control module for controlling the heating current, which occupy a certain space position in the nuclear magnetic resonance quantum computer.

[0005] In some other ways, the temperature control module uses a heating coil to provide heat. However, existing heating coils (such as induction cooker coils) are usually "mosquito coil"-shaped helical coils. Although they can produce good heating effects, due to the wiring not being designed and corrected by the target field method, due to the electromagnetic induction effect, they will generate a first-order magnetic field component (usually the Z component), which will destroy the shimming environment of the target field. Summary of the Invention

[0006] (I) Technical Problems to be Solved by the Present Invention

[0007] The technical problem solved by the present invention is: how to reduce the occupied space of the heat preservation module of the shimming device in a miniaturized quantum computer and maintain the shimming environment of the target field.

[0008] (II) Technical Solutions Adopted by the Present Invention

[0009] A shimming device for a small quantum computer based on non-magnetic loss heating, the shimming device includes a probe frame and two shimming plates, the two shimming plates are arranged at intervals and installed on the probe frame, the probe frame is used to carry a test sample located between the two shimming plates, and each shimming plate has a shimming coil on the inner surface facing the test sample, and each shimming plate has a heating coil on the outer surface facing away from the test sample, wherein the heating coil is manufactured by the target field method, and the magnetic field intensity generated by the heating coil in the area where the test sample is located is less than a preset value.

[0010] Preferably, the manufacturing process of the heating coil by the target field method is as follows:

[0011] Construct a double-plane coil model, the double-plane coil model includes a spherical target field and a pair of heating coils with undetermined wire layouts symmetrically arranged on both sides of the spherical target field;

[0012] Determine the relationship between the current density of a pair of the heating coils and the magnetic field intensity at any point in the space of the spherical target field;

[0013] According to the spatial coordinates and target magnetic field intensity of several predetermined points in the space of the set spherical target field, inversely solve the relationship to obtain the number of Fourier expansion terms corresponding to the current density of the heating coil;

[0014] Calculate the heating coil plane stream function according to the current density of the heating coil and the number of Fourier expansion terms;

[0015] Construct a three-dimensional model of the heating coil with a determined wire layout according to the heating coil plane stream function, the preset conductivity of the heating coil, and the preset resistance value of the heating coil;

[0016] Manufacture the heating coil according to the three-dimensional model of the heating coil.

[0017] Preferably, the method for determining the relationship between the current density of a pair of the heating coils and the magnetic field intensity at any point in the space of the spherical target field includes:

[0018] Perform a Fourier transform on the current density of the heating coil to obtain the radial current density component and the circumferential current density component when the order of the magnetic field intensity generated by the heating coil is zero;

[0019] Calculate the magnetic field intensity generated by a pair of heating coils at any point in the space of the spherical target field according to the Biot-Savart law;

[0020] Obtain the relationship according to the radial current density component, the circumferential current density component, and the magnetic field intensity generated by a pair of heating coils at any point in the space of the spherical target field.

[0021] Preferably, the method for calculating the planar stream function of the heating coil based on the current density of the heating coil and the number of Fourier expansion terms includes:

[0022] Calculating the planar stream function of the heating coil based on the radial current density component and the circumferential current density component when the order of the magnetic field intensity generated by the heating coil is zero, and the number of Fourier expansion terms, where the planar stream function of the heating coil characterizes the relationship between the circuit density of each point of the heating coil and the polar coordinates.

[0023] Preferably, the method for constructing a three-dimensional model of the heating coil with a determined wiring layout based on the planar stream function of the heating coil, the preset conductivity of the heating coil, and the preset resistance value of the heating coil includes:

[0024] Determining the planar current density contour lines according to the planar stream function of the heating coil as the wiring layout of the heating coil;

[0025] Determining the length and cross-sectional area of the heating coil according to the preset conductivity of the heating coil and the preset resistance value of the heating coil;

[0026] Determining the number of turns and the spacing of the heating coil according to the wiring layout of the heating coil and the length of the heating coil;

[0027] Constructing a three-dimensional model of the heating coil according to the length, cross-sectional area, number of turns, spacing, and wiring layout of the heating coil.

[0028] Preferably, the shimming plate is detachably mounted on the probe frame.

[0029] The present application also discloses a magnetic field device for a small quantum computer based on non-magnetic-loss heating, including two permanent magnets and the shimming device for the small quantum computer based on non-magnetic-loss heating as described above. The shimming device is arranged between the two permanent magnets, and the heating coil is attached to the permanent magnet.

[0030] Preferably, the magnetic field device further includes a housing made of a magnetic conductive material, and the permanent magnet and the shimming device are installed in the housing.

[0031] Preferably, the probe frame of the shimming device is detachably connected to the inner side wall of the housing.

[0032] (III) Beneficial effects

[0033] The present invention discloses a shimming device and a magnetic field device for a small quantum computer based on non-magnetic-loss heating. Compared with the prior art, it has the following technical effects:

[0034] The heating coil integrated on the shimming plate is used to replace the traditional heating resistor attached to the surface of the magnetic yoke iron, and the current control module for powering the heating resistor is removed, which is beneficial to the miniaturization of the nuclear magnetic quantum computer. At the same time, a new type of heating coil designed by the target field method is adopted to avoid affecting the magnetic field environment of the target field. Brief Description of the Drawings

[0035] Figure 1 Schematic diagram of the shimming device of the small quantum computer based on non-magnetic loss heating in the first embodiment of the present invention;

[0036] Figure 2 Schematic diagram of constructing a double-plane coil model in the first embodiment of the present invention;

[0037] Figure 3 Schematic diagram of electromagnetic simulation of the heating coil in the first embodiment of the present invention;

[0038] Figure 4 Graph of the fitting result of the magnetic field intensity of the heating coil in the first embodiment of the present invention;

[0039] Figure 5 Graph of the simulation result of the magnetic field intensity non-uniformity of the heating coil in the first embodiment of the present invention;

[0040] Figure 6 Schematic diagram of the magnetic field device of the small quantum computer based on non-magnetic loss heating in the first embodiment of the present invention. Detailed Description of the Invention

[0041] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] Before describing the various embodiments of the present application in detail, the technical concept of the present application will be briefly described first: In the prior art, some temperature control modules in quantum computers use resistive heating modules, which occupy a relatively large space position, and another part uses conventional coil heating modules, which will damage the shimming environment of the target field. For this reason, the present application provides a shimming device for a small quantum computer based on non-magnetic loss heating. Heating coils made by the target field method are respectively arranged on the outer surfaces of two shimming plates. While realizing the heat preservation function, the heating coils generate a very small magnetic field intensity in the area where the test sample is located, so as not to damage the shimming environment of the target field. On the other hand, since a layer of heating coil is attached to the outer surface of the shimming plate, the occupied space of the temperature control module is greatly reduced.

[0043] Specifically, as Figure 1As shown in the figure, the shimming device of the small quantum computer based on non-magnetic loss heating in the first embodiment includes a probe frame 10 and two shimming plates 20. The two shimming plates 20 are arranged at intervals and installed on the probe frame 10. The probe frame 10 is used to carry a test sample located between the two shimming plates 20. Each shimming plate 20 has a shimming coil on the inner surface facing the test sample, and a heating coil 21 on the outer surface facing away from the test sample. The heating coil is fabricated by the target field method, and the magnetic field intensity generated by the heating coil 21 in the area where the test sample is located is less than a preset value.

[0044] The following focuses on the fabrication process of the heating coil. The target field method includes the following steps:

[0045] Step S10: Construct a double-plane coil model, which includes a spherical target field and a pair of heating coils with undetermined wire layouts symmetrically arranged on both sides of the spherical target field.

[0046] Specifically, in the nuclear magnetic quantum computer architecture, the heating coils on the two shimming plates form a double-plane structure, as Figure 2 shown. During design, the heating coils are placed at Z = a and Z = -a respectively, and it is set that the radius of the heating coil satisfies ρ min ≤ρ≤ρ max , where ρ min and ρ max are the minimum radius and maximum radius of the heating coil respectively, which limits the layout position of the heating coil on the plane. The sphere at the center represents the magnetic field intensity investigation range generated by the heating coil, that is, the spherical target field. Take any point P(x, y, z) on the sphere surface and any point S(ρ, φ) on the heating coil.

[0047] Step S10: Determine the relationship between the current density of a pair of heating coils and the magnetic field intensity at any point in the space of the spherical target field.

[0048] First, the current density of the heating coil is processed by using the Fourier transform of trigonometric functions to obtain the radial current density component and the circumferential current density component of the heating coil:

[0049]

[0050] In the above formula, , is the Fourier expansion term coefficient of the heating coil current density series, is the order of the expansion term, is the order of the magnetic field intensity generated by the heating coil.

[0051] In the first embodiment, the magnetic field intensity order Set to 0, the above formula is simplified to:

[0052]

[0053] Furthermore, according to the Biot-Savart law, the magnetic field strength generated by the current in the heating coil at any point P(x, y, z) in the space of the spherical target field can be calculated as:

[0054]

[0055] In the above formula, is the vacuum permeability, which is a constant , is the current density at the source point S on the heating coil, is the length vector from the source point S on the heating coil to point P in the central sphere space. In this embodiment, the heating coil is a set of double-plane coils, and the magnetic field strength they jointly generate at point P is:

[0056]

[0057] In the formula,

[0058] When the order of the magnetic field strength is 0, the radial current density component and the circumferential current density component, the magnetic field strength generated by a pair of heating coils at any point in the space of the spherical target field is, that is, the relationship between the current density of a pair of heating coils and the magnetic field strength at any point in the space of the spherical target field:

[0059]

[0060] Step S20: According to the spatial coordinates and target magnetic field strength of several predetermined points in the space of the set spherical target field, inversely solve the relational formula to obtain the Fourier expansion term number corresponding to the current density of the heating coil.

[0061] Take Q predetermined points in the central sphere space of the target field, set the spatial coordinates and target magnetic field strength of each predetermined point, that is , let , that is, the magnetic field strength generated by the heating coil at each point in the target field has only a very small gradient and approaches a constant.

[0062] Substitute the spatial coordinates of each predetermined point and the target magnetic field strength into the relational formula, and inversely solve to obtain the Fourier expansion term number corresponding to the current density of the heating coil.

[0063] Step S20: Calculate the flow function of the heating coil plane based on the current density of the heating coil and the number of Fourier expansion terms.

[0064] Introduce a flow function in the heating coil plane :

[0065]

[0066] Calculate the flow function of the heating coil plane based on the radial current density component and the circumferential current density component at the zero order of the magnetic field intensity generated in the heating coil and the number of Fourier expansion terms:

[0067]

[0068] Step S30: Construct a three-dimensional model of the heating coil with a determined wire layout based on the flow function of the heating coil plane, the preset conductivity of the heating coil, and the preset resistance value of the heating coil;

[0069] Among them, the flow function of the heating coil plane characterizes the relationship between the circuit density of each point of the heating coil and the polar coordinates Use the Matlab data processing software to draw the contour lines of the plane current density represented by the flow function of the heating coil plane The contour lines represent the wire layout of the heating coil.

[0070] Furthermore, determine the length and cross-sectional area of the heating coil according to the preset conductivity ρ of the heating coil and the preset resistance value R of the heating coil, according to the following formula:

[0071]

[0072] Determine the number of turns and the spacing of the heating coil according to the wire layout of the heating coil and the length of the heating coil.

[0073] Determine the number of turns N of the heating coil through the heating coil length L and the average radius of the coil ; Determine the heating coil spacing d through the heating coil width a and the heating coil radius limit , according to the following formula:

[0074]

[0075] Construct a three-dimensional model of the heating coil according to the length, cross-sectional area, number of turns, spacing, and wire layout of the heating coil.

[0076] Step S40: Manufacture the heating coil according to the three-dimensional model of the heating coil.

[0077] The body of the shimming plate 20 is a PCB board. After designing the three-dimensional model of the heating coil, first, the contour of the three-dimensional model of the heating coil is converted into a two-dimensional plane contour line. Then, the two-dimensional plane contour line is imported into the PCB drawing software, and it is designed into a file used by the PCB manufacturing factory in the PCB drawing software. The design data is exported and a PCB board with a heating coil is manufactured by a professional board factory.

[0078] As Figure 3 shown, after constructing the three-dimensional model of the heating coil, the magnetic field intensity and distribution generated by the double-plane heating coil within the spherical target field space range are simulated and calculated. The magnetic field intensity within the -5 to 5 mm three-dimensional range at the center of the space of the coil is exported in the simulation software, and the fitting components and non-uniformity of the magnetic field are calculated using the Matlab data software. As Figure 4 shown, the magnetic field intensity generated by the heating coil is fitted with each order term. The results show that the heating coil has a strong constant order term and a relatively weak first-order y term, and no other term components. As Figure 5 shown, the magnetic field uniformity generated by the heating coil in the spherical target field is very small, only 0.1 ppm, so the magnetic field interference is very small.

[0079] Among them, in order to facilitate the replacement of the shimming plate 20 with different heating powers, the shimming plate 20 is installed on the probe frame 10 in a detachable manner. At the same time, the shimming device also includes a pin header and socket 30 for connecting two shimming plates 20 and a female terminal block 40 for connecting to an external power supply.

[0080] Furthermore, as Figure 6 shown, the magnetic field device of the small quantum computer based on non-magnetic loss heating in the second embodiment includes two relatively arranged permanent magnets 50 and the shimming device in the first embodiment. The shimming device is arranged between the two permanent magnets 50, and the heating coil 21 is attached to the permanent magnet 50.

[0081] Specifically, the magnetic field device of the small quantum computer based on non-magnetic loss heating further includes a housing 60 made of a magnetic conductive material. The permanent magnet 50 and the shimming device are installed inside the housing 60. Among them, the probe frame 10 of the shimming device is detachable from the inner side wall of the housing 60, which facilitates the replacement of the shimming plate 20 with different heating powers. At the same time, a layer of copper foil can be added between the heating coil 21 and the converging magnetic pole head 51 of the permanent magnet 50 to improve the uniform heat conduction between the heating coil 21 and the converging magnetic pole head 51.

[0082] When the magnetic field device of the small quantum computer based on non-magnetic loss heating is working, the shimming plate 20 is in close contact with the converging magnetic pole head 51. The two shimming plates are connected by pin headers 30. The horn female socket 40 is connected to the external shimming voltage source. First, adjust the output voltage value of the shimming voltage source to make the input voltage values of the heating coil 21 arranged on the surface layer of the shimming plate 20 and the shimming coil in the inner layer reach the maximum value, so that the heating power of each coil reaches the maximum, and full-power operation is achieved. After heating the permanent magnet 50 to the set temperature, adjust the output voltage value of the shimming voltage source, turn off the input voltage value of the shimming coil, and make the power of the heating coil 21 balance with the power of the permanent magnet 50 dissipating heat outward. Then turn on the input voltage of the shimming coil in the inner layer of the shimming plate 20 to compensate for the strong magnetic field generated by the permanent magnet 50.

[0083] The magnetic field device of the small quantum computer based on non-magnetic loss heating disclosed in this embodiment uses the heating coil integrated on the shimming plate to replace the traditional heating resistor attached to the surface of the magnetic yoke, removing the current control module for supplying power to the heating resistor, which is beneficial to the miniaturization of the nuclear magnetic quantum computer. At the same time, a new type of heating coil designed by the target field method is adopted to avoid affecting the magnetic field environment of the target field.

[0084] The specific implementation manners of the present invention have been described in detail above. Although some embodiments have been shown and described, those skilled in the art should understand that these embodiments can be modified and improved without departing from the principles and spirits of the present invention defined by the claims and their equivalents, and these modifications and improvements should also be within the protection scope of the present invention.

Claims

1. A shimming device for a small quantum computer based on non-magnetic loss heating, characterized in that The shimming device includes a probe frame and two shimming plates. The two shimming plates are arranged at intervals and installed on the probe frame. The probe frame is used to carry a test sample located between the two shimming plates. Each inner surface of the shimming plates facing the test sample is provided with a shimming coil, and each outer surface of the shimming plates facing away from the test sample is provided with a heating coil. The heating coil is manufactured by the target field method, and the magnetic field intensity generated by the heating coil in the area where the test sample is located is less than a preset value.

2. The shimming device of the small quantum computer based on non-magnetic-loss heating according to claim 1, wherein The manufacturing process of the heating coil by the target field method is as follows: Construct a double-plane coil model, which includes a spherical target field and a pair of heating coils with undetermined wire layouts symmetrically arranged on both sides of the spherical target field; Determine the relationship between the current density of a pair of heating coils and the magnetic field intensity at any point in the space of the spherical target field; According to the spatial coordinates and target magnetic field intensity of several predetermined points in the space of the set spherical target field, inversely solve the relationship to obtain the number of Fourier expansion terms corresponding to the current density of the heating coil; Calculate the heating coil plane stream function according to the current density of the heating coil and the number of Fourier expansion terms; Construct a three-dimensional model of the heating coil with a determined wire layout according to the heating coil plane stream function, the preset conductivity of the heating coil, and the preset resistance value of the heating coil; Manufacture the heating coil according to the three-dimensional model of the heating coil.

3. The shimming device of the small quantum computer based on non-magnetic-loss heating according to claim 2, wherein The method for determining the relationship between the current density of a pair of heating coils and the magnetic field intensity at any point in the space of the spherical target field includes: Perform a Fourier transform on the current density of the heating coil to obtain the radial current density component and the circumferential current density component when the order of the magnetic field intensity generated by the heating coil is zero; Calculate the magnetic field intensity generated by a pair of heating coils at any point in the space of the spherical target field according to the Biot-Savart law; obtain the relationship according to the radial current density component, the circumferential current density component, and the magnetic field intensity generated by a pair of heating coils at any point in the space of the spherical target field.

4. The shimming device for a small quantum computer based on non-magnetic-loss heating according to claim 3, wherein The method for calculating the heating coil plane stream function according to the current density of the heating coil and the number of Fourier expansion terms includes: Calculate the heating coil plane stream function according to the radial current density component and the circumferential current density component when the order of the magnetic field intensity generated by the heating coil is zero and the number of Fourier expansion terms, where the heating coil plane stream function characterizes the relationship between the circuit density of each point of the heating coil and the polar coordinates.

5. The shimming device for a small quantum computer based on non-magnetic loss heating according to claim 4, characterized in that, The method for constructing a three-dimensional model of the heating coil with a determined wire layout according to the heating coil plane stream function, the preset conductivity of the heating coil, and the preset resistance value of the heating coil includes: Determine the plane current density contour according to the heating coil plane stream function as the wire layout of the heating coil; Determine the length and cross-sectional area of the heating coil according to the preset conductivity of the heating coil and the preset resistance value of the heating coil; Determine the number of turns and the spacing of the heating coil according to the layout of the heating coil wire routing and the length of the heating coil; Construct a three-dimensional model of the heating coil according to the length, cross-sectional area, number of turns, spacing, and wire routing layout of the heating coil.

6. The shimming device for a small quantum computer based on non-magnetic-loss heating according to claim 1, wherein The shim plate is detachably mounted on the probe frame.

7. A magnetic field device for a small quantum computer based on non-magnetic loss heating, characterized in that, It includes two permanent magnets and the shimming device of the small quantum computer based on non-magnetic-loss heating according to any one of claims 1 to 6. The shimming device is arranged between the two permanent magnets, and the heating coil is in contact with the permanent magnets.

8. The magnetic field device of the small quantum computer based on non-magnetic loss heating according to claim 7, characterized in that, The magnetic field device further includes a housing made of a magnetic conductive material, and the permanent magnets and the shimming device are installed in the housing.

9. The magnetic field device of the small quantum computer based on non-magnetic-loss heating according to claim 8, characterized in that, The probe frame of the shimming device is detachably connected to the inner side wall of the housing.

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