Method, system and medium for realizing active shimming and quantum computing

Abstract

The present invention discloses a method, system and medium for realizing active shimming and quantum computing based on a built-in single sample. The sample used for quantum computing is built-in inside a nuclear magnetic resonance probe. The sample is not replaced, and the same sample is used for active shimming (adjusting the current in the shimming coils of each order) and quantum computing. This processing scheme, since a small amount of sample is sealed inside the nuclear magnetic resonance probe, the probe can be completely sealed, reducing the noise with the same frequency as the nuclear magnetic signal received from the surrounding space, and improving the signal-to-noise ratio. More importantly, the heat is cut off from being transferred between the room temperature and the magnet insulation cavity through the sample tube, which can greatly reduce the influence of room temperature fluctuation on the magnet temperature control, thereby obtaining a very uniform and stable magnetic field, avoiding the problem that when using a permanent magnet as a magnetic field source, replacing the sample tube and leaving part of the sample tube outside the probe will cause the temperature of the magnet to be unstable, thereby causing the shimming and spectral resolution to decrease.

Description

[0001] This case is a divisional application of the prior application with application number: 202110143221.4 and title: Methods, systems and media for realizing active field shimming and quantum computing. Technical Field

[0002] The present invention relates to the field of quantum computer technology, and in particular to a method, system and medium for realizing active field shimming and quantum computing based on a built-in single sample. Background Art

[0003] Quantum computers are physical devices that follow the laws of quantum mechanics to perform high-speed mathematical and logical operations, store and process quantum information. The nuclear magnetic resonance (NMR) quantum computing system can implement a variety of quantum computing algorithms at room temperature and pressure, has mature radio frequency measurement and control technology, and simple experimental conditions. The premise of nuclear magnetic resonance is that magnetic nuclei are excited by radio frequency electromagnetic waves with the same transition frequency in a uniform static magnetic field, producing resonance, and the receiving coil can receive the induction attenuation signal. The same atomic nucleus exhibits different resonance frequencies under different static magnetic fields. If all atomic nuclei are to exhibit the same resonance characteristics, an extremely uniform magnetic field is required. The uniformity of a general permanent magnet can reach about 30ppm. If a magnetic field uniformity of the order of 0.1ppm is required, an active shimming coil is required. Active shimming adjusts the static magnetic field by appropriately adjusting the current intensity of each coil in the shimming coil array, and uses the shimming coil to produce changes in the local magnetic field to improve the overall magnetic field uniformity. Generally, H2O, 10% H2O + 90% D2O mixture or TMS are used as shim standard samples in NMR spectroscopy or NMR imaging. 1 The H NMR signal signal-to-noise ratio and the broadening of the sample nuclear magnetic spectrum are relatively good. However, when switching experimental samples, the magnetic susceptibility of different samples is different, which may cause the uniformity of the magnetic field to change, so that the magnetic field uniformity is not in the best state when testing the experimental samples. At the same time, due to the need to switch samples, the sample tube cannot be sealed inside the probe, and a part of it must be left outside the probe, which will cause the probe coil to receive RF noise from the external environment. The temperature drift of the permanent magnet neodymium iron boron material is 1K, and the intensity of the magnetic field will change by about 1200ppm. Therefore, in order to obtain a stable and highly uniform magnetic field, it is necessary to keep the magnet warm so that the magnet temperature is uniform and stable. When using a permanent magnet as a magnetic field source, replacing the sample tube and leaving part of the sample tube outside the probe will cause the temperature of the magnet to be unstable, which will lead to a decrease in the uniform field and spectral resolution. Summary of the invention

[0004] The main purpose of the present invention is to provide a method, system and medium for realizing active field shimming and quantum computing based on a built-in single sample, so as to avoid the problem that when a permanent magnet is used as a magnetic field source, replacing the sample tube and leaving part of the sample tube outside the probe will cause the temperature of the magnet to be unstable, thereby causing the field shimming and the reduction of spectral resolution.

[0005] To achieve the above object, the present invention proposes a method for realizing active shimming and quantum computing based on a built-in single sample, the method comprising the following steps:

[0006] Select a sample for active shimming and quantum computing, and seal the sample inside a nuclear magnetic resonance probe;

[0007] Without turning on active shimming, the sample 1 H NMR signal;

[0008] During the active shimming process, the current in each order of shimming coils is adjusted to observe the 1 Changes in H NMR signals, recording the peak height, half-height width, and width at 20% of the peak height of the spectrum at different currents;

[0009] Comparing the percentage of peak height change, half-height width and 20% peak height width change before and after the current is changed, measuring whether the magnetic field is more uniform after the current is changed according to these three percentage changes, and obtaining the active shimming parameters corresponding to the most uniform state of the magnetic field found using the sample;

[0010] Under the most uniform magnetic field condition, the sample was observed again. 1 H NMR signal;

[0011] The two atomic nuclei directly coupled in the NMR signal of the sample are respectively manipulated by radio frequency electromagnetic field, the nuclear magnetic moments of the two atomic nuclei are used to perform quantum computing gate operations, and the final states of the two atomic nuclei are read to obtain quantum computing parameters.

[0012] Among them, the comparison of the percentage of peak height change, half-height width and 20% peak height width change before and after the current is changed, and measuring whether the magnetic field is more uniform after the current is changed according to these three percentage changes include:

[0013] The percentage changes in peak height, half-height width and 20% peak height width before and after the current is changed are compared, and the weighted sum of these three change percentages is used to measure whether the magnetic field is more uniform after the current is changed.

[0014] Among them, the more uniform the magnetic field is, the higher the peak height of the spectrum line is, and the half-height width and the width at 20% of the peak height are smaller.

[0015] The step of selecting a sample for active shimming and quantum computing and sealing the sample inside a nuclear magnetic resonance probe comprises:

[0016] A sample for active field shimming and quantum computing is selected, and the sample is directly sealed inside a nuclear magnetic resonance probe; or, a sample for active field shimming and quantum computing is selected, and the sample is sealed in a standard nuclear magnetic resonance test tube, and the standard nuclear magnetic resonance test tube containing the sealed sample is sealed inside the nuclear magnetic resonance probe.

[0017] The standard NMR test tube is a standard NMR test tube with a diameter of 5 mm.

[0018] When performing two-bit quantum computing in a nuclear magnetic resonance system, a standard sample is used to even the field, and then other samples are used as physical bit carriers.

[0019] In the two-bit quantum calculation, dimethyl phosphite is selected as the sample, as the physical bit carrier of active shimming or quantum calculation.

[0020] In the active shimming, H2O, a mixture of 10% H2O+90% D2O or TMS is used as a shimming standard sample.

[0021] The present invention also proposes a system for realizing active field shimming and quantum computing based on a built-in single sample, comprising: a nuclear magnetic resonance probe, in which a sample used for active field shimming and quantum computing is sealed, the system also includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the method for realizing active field shimming and quantum computing based on a built-in single sample as described above is realized.

[0022] The present invention also provides a computer storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for realizing active field shimming and quantum computing based on a built-in single sample as described above is implemented.

[0023] The method, system and medium for realizing active shimming and quantum computing based on a built-in single sample proposed in the embodiment of the present invention, the sample used for quantum computing is built-in inside the nuclear magnetic resonance probe, and the sample is not replaced, and the same sample is used for active shimming (adjusting the current in the shimming coils of each order) and quantum computing. This processing scheme, because a small amount of sample is sealed inside the nuclear magnetic resonance probe, the probe can be completely sealed, reducing the noise with the same frequency as the nuclear magnetic signal received from the surrounding space, and improving the signal-to-noise ratio. More importantly, the heat is cut off from being transferred between the room temperature and the magnet insulation cavity through the sample tube, which can greatly reduce the influence of room temperature fluctuations on the magnet temperature control, thereby obtaining a very uniform and stable magnetic field, avoiding the problem that when using a permanent magnet as a magnetic field source, replacing the sample tube and leaving part of the sample tube outside the probe will cause the temperature of the magnet to be unstable, thereby causing the shimming and spectral resolution to decrease. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of the method for realizing active shimming and quantum computing based on a built-in single sample according to the present invention;

[0025] Figure 2 The molecular structure diagram of dimethyl phosphite in the scheme of the present invention;

[0026] Figure 3 Dimethyl phosphite 1 H NMR spectrum without active shimming;

[0027] Figure 4 Dimethyl phosphite 1 H NMR spectrum after active shimming. DETAILED DESCRIPTION

[0028] 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.

[0029] The technical terms involved in the present invention are:

[0030]

[0031] The present invention takes into account that when a permanent magnet is used as a magnetic field source to perform quantum calculation in a nuclear magnetic resonance system, there are higher requirements for the stability of the magnetic field, so a very stable temperature control is required, for example, a temperature drift of less than 1mK. At the same time, since there are great differences between using the nuclear magnetic resonance principle to perform quantum calculation and performing nuclear magnetic spectroscopy analysis, the former focuses on the result of the nuclear magnetic moment of the nucleus under the manipulation of the radio frequency field, and the latter focuses on the nuclear magnetic spectroscopy characteristics of different substances. Based on this, the present invention proposes to embed the sample used for quantum calculation inside the nuclear magnetic resonance probe, without replacing the sample, and use the same sample to perform active shimming (adjusting the current in each order of shimming coil) and quantum calculation. Although this increases the difficulty of active shimming to a certain extent, since a small amount of sample is sealed inside the nuclear magnetic resonance probe, the probe can be completely sealed, reducing the noise received from the surrounding space with the same frequency as the nuclear magnetic signal, and improving the signal-to-noise ratio. More importantly, the heat is cut off from the sample tube at room temperature and the magnet insulation cavity. This can greatly reduce the influence of room temperature fluctuations on the magnet temperature control, and then obtain a very uniform and stable magnetic field.

[0032] Specifically, refer to Figure 1 The present invention proposes a method for realizing active shimming and quantum computing based on a built-in single sample, the method comprising the following steps:

[0033] S1, selecting a sample for active shimming and quantum computing, and sealing the sample inside a nuclear magnetic resonance probe;

[0034] A sample for active field shimming and quantum computing is selected, and the sample is directly sealed inside a nuclear magnetic resonance probe; or, a sample for active field shimming and quantum computing is selected, and the sample is sealed in a standard nuclear magnetic resonance test tube, and the standard nuclear magnetic resonance test tube containing the sealed sample is sealed inside the nuclear magnetic resonance probe.

[0035] The standard NMR test tube is a standard NMR test tube with a diameter of 5 mm.

[0036] One of the schemes is to use standard samples to shim the field when performing two-bit quantum computing in a nuclear magnetic resonance system, and then use other samples as physical bit carriers.

[0037] In one of the schemes, in two-bit quantum computing, dimethyl phosphite can be selected as the sample, as a physical bit carrier for active field shimming or quantum computing.

[0038] In active shimming, conventional H2O, a mixture of 10% H2O+90% D2O or TMS may be used as a shimming standard sample.

[0039] S2, without turning on active shimming, observe the sample 1H NMR signal;

[0040] S3, in the process of active shimming, adjust the current in each order of shimming coils and observe the 1 Changes in H NMR signals, recording the peak height, half-height width, and width at 20% of the peak height of the spectrum at different currents;

[0041] S4, comparing the percentage of peak height change, half-height width and 20% peak height width change before and after the current is changed, and measuring whether the magnetic field is more uniform after the current is changed according to these three percentage changes, and obtaining the active shimming parameters corresponding to the most uniform state of the magnetic field found by using the sample;

[0042] Among them, comparing the percentage of peak height change, half-height width and 20% peak height width change before and after the current is changed, and measuring whether the magnetic field is more uniform after the current is changed according to these three change percentages may include:

[0043] The percentage changes in peak height, half-height width and 20% peak height width before and after the current is changed are compared, and the weighted sum of these three change percentages is used to measure whether the magnetic field is more uniform after the current is changed.

[0044] Among them, under normal circumstances, the more uniform the magnetic field is, the higher the peak height of the spectrum line is, and the half-height width and the width at 20% of the peak height are smaller.

[0045] S5, in the most uniform magnetic field state, observe the sample again 1 H NMR signal;

[0046] S6, respectively manipulating the samples by radio frequency electromagnetic field 1 The two atomic nuclei directly coupled in the H NMR signal are used to perform quantum computing gate operations using the nuclear magnetic moments of the two atomic nuclei, and the final states of the two atomic nuclei are read to obtain quantum computing parameters.

[0047] The scheme of the present invention seals a small amount of sample inside the nuclear magnetic resonance probe, so that the probe can be completely sealed, reducing the noise with the same frequency as the nuclear magnetic signal received from the surrounding space, and improving the signal-to-noise ratio. More importantly, the heat transfer between the room temperature and the magnet insulation cavity through the sample tube is cut off, which can greatly reduce the influence of room temperature fluctuations on the magnet temperature control, thereby obtaining a very uniform and stable magnetic field.

[0048] The scheme of the present invention is described in detail below:

[0049] The present invention selects a sample that can be used for both active shimming and quantum computing. Active shimming requires a strong nuclear magnetic signal, which is generally selected 1 H NMR signal, because 1H has a high natural abundance and a strong NMR signal. If it is to be used for quantum computing, the sample needs to have atomic nuclei that can be independently controlled and coupled to each other. Generally, two different atomic nuclei are selected for the convenience of measurement and control.

[0050] like Figure 2 As shown, Figure 2 The molecular structure of dimethyl phosphite is shown in the figure. It can be seen from the molecular structure that there are 7 H atoms and 1 P atom in the molecule. The P nucleus in this molecule is directly coupled to an H nucleus, so the nuclear magnetic moment of this P nucleus and the H nucleus coupled to it can be used as the carrier of two physical bits of quantum computing. Because there are 3 H atoms connected to each of the two C atoms in this molecule, a large number of H atoms can be used as active shimming.

[0051] The dimethyl phosphite sample is sealed in a 5mm standard NMR tube, so that there is a single sample that can be used for both automatic field shimming and two-bit quantum computing.

[0052] Place the sealed dimethyl phosphite sample in the center of the nuclear magnetic probe to seal the entire nuclear magnetic probe. This reduces the noise received from the surrounding space that is at the same frequency as the nuclear magnetic signal, and improves the signal-to-noise ratio. More importantly, it cuts off the transfer of heat between the room temperature and the magnet insulation cavity through the sample tube, which can greatly reduce the influence of room temperature fluctuations on the magnet temperature control, thereby obtaining a very uniform and stable magnetic field.

[0053] Observation of dimethyl phosphite samples 1 H NMR signal, when active shimming is not turned on, Figure 3 As shown. Figure 3 It can be seen from the NMR spectrum that although the magnetic field uniformity is not very good, the half-width of the spectrum line is relatively large and the signal-to-noise ratio is relatively poor, the NMR spectrum of H nuclei can be seen. Such spectrum lines and signal-to-noise ratio can be used for active field shimming.

[0054] In the process of active shimming, adjust the current in each order of shimming coils and observe Figure 3 middle 1 Changes in H NMR signals. Three parameters are considered here: the peak height, the half-width, and the width at 20% of the peak height.

[0055] The more uniform the magnetic field is, the higher the peak height of the spectrum line is, and the smaller the half-height width and the width at 20% of the peak height are. Record the current peak height, half-height width and 20% peak height width; change the active shim current, and record the peak height, half-height width and 20% peak height width again; compare the percentage of peak height increase before and after the current change, and the percentage of half-height width and 20% peak height width decrease; weighted sum of these three change percentages to measure whether the magnetic field is more uniform after the current change.

[0056] The purpose of weighted summation is to be able to freely define which spectrum line corresponds to a more uniform magnetic field. Ideally, the more uniform the magnetic field, the higher the peak height of the spectrum line, and the smaller the half-width and the width at 20% of the peak height. But in reality, the peak height becomes higher after the current is changed, but the half-width and the width at 20% of the peak height become larger, and the other three parameters do not change consistently. At this time, it is necessary to define the weights between the three parameters according to the specific situation. For example, if the weight of the peak height is 1, and the weight of the half-width and the width at 20% of the peak height are 0, then the adjustment of the uniform field current only refers to the peak height parameter.

[0057] The currents of each order of shimming are continuously adjusted, and the active shimming parameters corresponding to the most uniform state of the magnetic field are found using dimethyl phosphite samples.

[0058] The dimethyl phosphite sample was observed again under the most uniform magnetic field parameters. 1 H NMR signals such as Figure 4 shown.

[0059] exist Figure 4 In the figure, peaks 1 and 4 are NMR signals of H atoms directly coupled to P atoms in the dimethyl phosphite molecule. Peaks 2 and 3 are NMR signals of 6 H nuclei connected to C atoms in the dimethyl phosphite molecule.

[0060] In the process of field uniformity, the NMR signals of the six H nuclei in peaks 2 and 3 are used. Since there are more H nuclei in each dimethyl phosphite molecule, the signal is relatively strong. Even when the magnet field uniformity is not good and the half-width at half-height of the spectrum line is very wide, the NMR signal can still be seen.

[0061] In the process of quantum computing, the NMR signals of H nuclei in peaks 1 and 4 are used. The NMR signals of peaks 1 and 4 both come from H atoms directly coupled with P. The reason why one H atom sees two split peaks 1 and 4 is that the H nuclei are coupled with the P nuclei and split.

[0062] In this way, by separately manipulating the directly coupled H nucleus and P nucleus through the radio frequency electromagnetic field, their nuclear magnetic moments can be used to perform quantum computing gate operations and read their final states.

[0063] At this point, the built-in single sample has been achieved, and the built-in single sample is used for active field shimming and quantum computing.

[0064] Compared with the known prior art, the present invention replaces the standard sample used for active shimming in nuclear magnetic resonance with a single sample that can be used for both active shimming and quantum computing. In two-bit quantum computing, dimethyl phosphite can be selected as the physical bit carrier for active shimming or quantum computing. In addition, the sample used for active shimming and quantum computing can be sealed inside the probe in the nuclear magnetic resonance quantum computing system.

[0065] In addition, traditional H2O, 10% H2O + 90% D2O mixture or TMS can be used as standard samples for shimming; standard samples are used for shimming when performing two-bit quantum computing in the NMR system, and then other samples are used as physical bit carriers.

[0066] In addition, standard 5mm NMR tubes can be used to replace samples at any time instead of sealing the samples directly inside the NMR probe.

[0067] In addition, the present invention also proposes a system for realizing active field shimming and quantum computing based on a built-in single sample, comprising: a nuclear magnetic resonance probe, in which a sample used for active field shimming and quantum computing is sealed, the system also includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the method for realizing active field shimming and quantum computing based on a built-in single sample as described above is implemented.

[0068] In addition, the present invention also proposes a computer storage medium, on which a computer program is stored. When the computer program is executed by a processor, the method for realizing active field shimming and quantum computing based on a built-in single sample as described above is implemented.

[0069] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Equivalent structures or equivalent process changes made by the scheme using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for realizing active shimming and quantum computing, characterized in that: The method comprises the following steps: Selecting samples for active shimming and quantum computing, wherein H2O, a mixture of 10% H2O+90% D2O or TMS is used as a shimming standard sample for active shimming, and dimethyl phosphite is selected as a sample for quantum computing; Without turning on active shimming, the sample 1 H NMR signal; During the active shimming process, the current in each order of shimming coils is adjusted to observe the 1 Changes in H NMR signals, recording the peak height, half-height width, and width at 20% of the peak height of the spectrum at different currents; Comparing the percentage of peak height change, half-width and 20% peak height width before and after the current is changed, defining the weights between the three parameters according to the specific conditions of the three parameters of the peak height, half-width and 20% peak height of the spectrum line, taking the weighted sum of the three change percentages to measure whether the magnetic field is more uniform after the current is changed, and obtaining the active shimming parameters corresponding to the most uniform state of the magnetic field found by using the shimming standard sample; When the magnetic field is in the most uniform state, the uniform field standard sample is observed again. 1 H NMR signal; The two atomic nuclei directly coupled in the NMR signal of the quantum computing sample are respectively manipulated by radio frequency electromagnetic field, the nuclear magnetic moments of the two atomic nuclei are used to perform quantum computing gate operation, and the final state of the two atomic nuclei is read to obtain quantum computing parameters.

2. The method for realizing active shimming and quantum computing according to claim 1, characterized in that: The more uniform the magnetic field is, the higher the peak height of the spectrum line is, and the smaller the half-height width and the width at 20% of the peak height are.

3. A system for realizing active shimming and quantum computing, characterized in that: include: The system includes a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the method for realizing active shimming and quantum computing according to any one of claims 1 to 2 is realized.

4. A computer storage medium, characterized in that: The computer storage medium stores a computer program, and when the computer program is executed by the processor, the method for realizing active shimming and quantum computing according to any one of claims 1 to 2 is realized.

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