Method and device for determining magnetic field model

Abstract

A method for determining a magnetic field model of a magnetic field established by at least one magnet arrangement (2) is specified, comprising:-providing first information characterizing a magnetic field value in a predetermined region (4) spaced apart from the magnet arrangement (2) in which the magnet arrangement (2) is in an environment having a first temperature,-providing second information characterizing a magnetic field value in a predetermined region (4) spaced apart from the magnet arrangement (2) in which the magnet arrangement (2) is in an environment having a second temperature, the magnet arrangement (2) is in an environment having a second temperature, and-determining a magnetic field model, which characterizes a temperature-dependent behavior of the magnetic field of the at least one magnet arrangement (2), from the first information and the second information. In addition, a device (1) for carrying out the method is specified.

Description

[0001] This disclosure relates to methods and apparatus for determining a magnetic field model established by an arrangement of at least one magnet.

[0002] Typically, the magnetic field distribution of a magnet changes according to its temperature. Specifically, the magnetic field distribution at room temperature is usually different from that at low temperatures.

[0003] The objective is to provide a method for improving the magnetic field distribution. Furthermore, an apparatus for performing this method is to be provided.

[0004] This objective is achieved through the subject matter of the independent claims. Advantageous embodiments, implementations, and further developments are the subject matter of the corresponding dependent claims.

[0005] A method for determining a magnetic field model, wherein the magnetic field is established by an arrangement of at least one magnet and provided to an ion trap, is described. Exemplarily, the arrangement of at least one magnet comprises at least two magnets spaced apart from each other. Specifically, the arrangement of at least one magnet is configured to establish a magnetic field (exemplarily, to establish a gradient in the magnitude of the magnetic field) within a predetermined region. Exemplarily, the magnetic field of the magnet arrangement has a magnitude that differs from each other at different locations within the predetermined region.

[0006] Specifically, the magnitude gradient of the magnetic field established by the magnet arrangement is at least 0.5 T / m and at most 500 T / m. Specifically, the magnitude gradient of the magnetic field in the predetermined region is at least 50 T / m and at most 250 T / m, exemplarily 150 T / m.

[0007] At least one magnet arrangement may include at least one permanent magnet (particularly including at least two permanent magnets) and / or at least one solenoid (particularly including at least two solenoids). Exemplarily, the permanent magnets do not require an external magnetic field to maintain magnetic properties such as magnetization. Furthermore, the permanent magnets are particularly configured to provide a magnetic field without being supplied with an electric current. Exemplarily, the solenoids are particularly configured to provide a magnetic field due to an electric current applied to the solenoid.

[0008] According to at least one embodiment of the method, first information is provided, which characterizes a magnetic field value in a predetermined region spaced apart from a magnet arrangement, wherein the magnet arrangement is in an environment having a first temperature. Exemplarily, the environment is the physical space in which the magnet arrangement is arranged. Specifically, the temperature of the magnet arrangement in the environment having the first temperature is within a range of at most 50% of the first temperature plus or minus the first temperature.

[0009] The predetermined region extends, for example, in the lateral direction and in the vertical direction perpendicular to the lateral direction. Specifically, the predetermined region surrounds a three-dimensional region in space, which is particularly displaced relative to the arrangement of the magnet.

[0010] According to at least one embodiment of the method, second information is provided, which characterizes the magnetic field value in a predetermined region, wherein the magnet arrangement is situated in an environment having a second temperature. Specifically, the temperature of the environment in which the magnet is situated is within a range of at most 50% of the second temperature plus or minus a second temperature. Exemplarily, the second temperature is less than the first temperature.

[0011] The first and second information, for example, each characterize the measurement results of the magnetic field sensor device. Exemplarily, the magnetic field sensor device is spaced apart from a predetermined area. Specifically, the magnetic field sensor device is used to provide a measurement result of a magnetic field established by a magnet arranged in the predetermined area, wherein the measured magnetic field is the first information when the magnet is in an environment having a first temperature, and the measured magnetic field is the second information when the magnet is in an environment having a second temperature.

[0012] For example, magnetic field sensor devices include at least one of the following: Hall sensor devices, fluxgate sensor devices, and superconducting quantum interference devices.

[0013] According to at least one embodiment of the method, a magnetic field model is determined based on first and second information. This magnetic field model characterizes the temperature-dependent behavior of a magnetic field arranged in at least one magnet, including at least one permanent magnet. Exemplarily, the magnetic field model includes multiple components for different spatial points in a predetermined region, such as at least one of magnetic field strength and magnetic field direction. Specifically, the magnetic field strength is represented by magnetic flux density or magnetic field intensity.

[0014] In particular, the temperature-dependent behavior of the magnetic field in the predetermined region characterizes the change of the magnetic field in the predetermined region within a temperature range between a first temperature and a second temperature.

[0015] Typically, the magnetic field established by an arrangement of magnets depends on the temperature of the magnet arrangement. When the temperature is relatively high, the magnetic domains of the permanent magnets may become disordered, resulting in a decrease in the magnitude of the magnetic field. When the temperature is relatively low, the magnetic domains of the permanent magnets can align more uniformly, resulting in an increase in the magnitude of the magnetic field. In particular, the magnetic field established by an arrangement of magnets including a solenoid depends on the fluctuations in the current applied to the solenoid. These fluctuations in current are particularly dependent on the temperature of the solenoid.

[0016] Therefore, it is desirable to know as accurately as possible how the magnetic field acts in a predetermined region at different temperatures, such as at a first temperature after the permanent magnet is magnetized and at a second temperature during operation of the permanent magnet, or, for example, at a first temperature when the solenoid is operated with a first current and at a second temperature during operation of the solenoid with a first current.

[0017] One concept is to define a magnetic field model that characterizes the temperature-dependent behavior of the magnetic field of at least one magnet arrangement. In this way, devices with a magnet arrangement advantageously possessing a precisely tailored magnetic field pattern within a predetermined region can be provided and / or manufactured. Specifically, the magnet arrangement can also be advantageously implemented on demand according to the magnetic field model, allowing for minimal or even no recalibration of the magnet arrangement when operating at a second temperature.

[0018] For example, the magnet arrangement can be produced according to a magnetic field model, since the magnetic field model can be used to advantageously predict changes in the magnetic field in a predetermined region from a first temperature to a second temperature. Furthermore, it is advantageous to magnetize and / or remagnetize permanent magnets according to the magnetic field model. Similarly, it is advantageous to operate solenoids according to the magnetic field model. Therefore, the magnet arrangement can be adjusted according to the magnetic field model to achieve a predetermined magnetic field pattern in the predetermined region.

[0019] Exemplarily, the methods described above are performed in the indicated order. Exemplarily, the methods described herein are computer-implemented methods.

[0020] According to at least one embodiment of the method, the provision of first information and the provision of second information are alternately repeated. Specifically, magnetic field values ​​are measured at a first temperature and a second temperature, and then the measurement of magnetic field values ​​at the first temperature and the second temperature is repeated at least once more. Exemplarily, after each repetition from the first temperature to the second temperature, the magnetic field model is determined and updated.

[0021] The repetition of the method is advantageous for obtaining the components of the magnetic field model more accurately, so as to predict the change from the first temperature to the second temperature more precisely.

[0022] According to at least one embodiment of the method, when the magnet arrangement is in an environment characterized by a temperature between a first temperature and a second temperature, at least one additional piece of information is provided, which characterizes the magnetic field value in a predetermined region. Specifically, a magnetic field model is additionally determined based on the additional information.

[0023] For example, multiple additional pieces of information are provided, each of which represents a magnetic field value in a predetermined region. In particular, an additional temperature is associated with each of the additional pieces of information, said additional temperature being between a first temperature and a second temperature.

[0024] By performing several additional measurement steps while cooling the magnet arrangement from a first temperature to a second temperature, the magnetic field model can be determined more advantageously and with particular precision.

[0025] According to at least one embodiment of the method, the first temperature is higher than the second temperature. For example, the first temperature is at least four times the second temperature. For example, the first temperature is at most 40°C or at most 25°C and / or at least 0°C or at least 10°C. The second temperature is at most 70 K, at most 30 K or at most 15 K, and at least 0.3 K or at least 4 K.

[0026] Specifically, the magnet arrangement is cooled to a second temperature, for example, by a cryostat.

[0027] According to at least one embodiment of the method, a target magnetization and / or target position of at least one magnet arrangement is determined based on a magnetic field model. Specifically, according to the magnetic field model, the target magnetization and / or target position of the magnet arrangement is determined such that the magnetic field at a second temperature corresponds to a desired magnetic field. In particular, the at least one magnet arrangement produced has the target magnetization and / or target position such that the magnetic field at the second temperature corresponds to the desired magnetic field.

[0028] According to at least one embodiment of the method, when the magnet arrangement is in an environment having a first temperature, at least one magnet arrangement including at least one permanent magnet is magnetized. Exemplarily, a target magnetization and / or target location can be determined for other devices having at least one permanent magnet, which are magnetized and / or positioned at the first temperature.

[0029] Typically, a permanent magnet is magnetized by using an external magnetic field to align the magnetic domains within the material of the permanent magnet along a preferred direction. If the magnetic moments align to a predetermined portion, the permanent magnet establishes a magnetic field. The strength of the magnetization of the permanent magnet arrangement depends on the strength of the external magnetic field.

[0030] According to at least one embodiment of the method, the magnetization of at least one permanent magnet is monitored during magnetization.

[0031] According to at least one embodiment of the method, at least one permanent magnet, including at least one permanent magnet, is magnetized and / or positioned such that when the permanent magnet is arranged in an environment having a second temperature, the magnitude of the magnetic field is zero at a predetermined point in a predetermined region.

[0032] Specifically, at least one permanent magnet is magnetized at a first temperature according to a magnetic field model. During magnetization, the strength of an external magnetic field is adjusted according to the magnetic field model, such that the permanent magnet in an environment with a second temperature establishes a magnetic field of zero magnitude at a predetermined point in a predetermined region. For this purpose, magnetization is specifically monitored.

[0033] According to at least one embodiment of the method, at least one permanent magnet, including at least one permanent magnet, is magnetized and / or positioned such that when the permanent magnet is in an environment having a second temperature, the gradient of the magnitude of the magnetic field is maximized in a predetermined region.

[0034] During the magnetization of at least one permanent magnet, the strength of an external magnetic field is adjusted according to a magnetic field model such that the permanent magnet in an environment with a second temperature establishes a gradient of the magnitude of the magnetic field in a predetermined region (e.g., along the axis). For this purpose, magnetization is specifically monitored.

[0035] According to at least one embodiment of the method, at least one magnetic arrangement is part of an ion trap. The ion trap can be a polo trap, a linear ion trap, a surface ion trap, and / or a multilayer ion trap. For example, an radio frequency (RF) voltage is applied to at least some electrodes of the ion trap, thereby providing a time-varying electric field configured to confine and / or manipulate ions. Specifically, the ions are located within a processing region that serves as a predetermined area.

[0036] Specifically, at least one magnet arrangement is configured to establish a gradient in the magnitude of the magnetic field of the magnet arrangement within the processing region (e.g., along the capture axis). Specifically, the magnetic field of the magnet arrangement has a magnitude that differs from one another for different locations within the processing region (and particularly for different locations along the capture axis). Advantageously, the resonant frequency of each ion at the processing region is unique for each ion in the processing region (i.e., each captured ion), and the gradient in the magnitude of the magnetic field of the magnet arrangement acts on that processing region.

[0037] According to at least one embodiment of the method, the ion trap includes at least one magnetic field sensor device or at least two magnetic field sensor devices configured to measure the magnetic field of at least one magnet arranged in a predetermined region.

[0038] According to at least one embodiment of the method, at least one magnetic field sensor device or at least two magnetic field sensor devices are spaced apart from the predetermined area in the lateral direction and / or in the vertical direction.

[0039] For example, the magnetic field sensor device is configured to sense the magnetic field of a magnet arrangement at at least two specific locations, each specific location corresponding to a position where the magnetic field sensor device is arranged in an ion trap. By combining the sensing of at least two magnetic field sensor devices at at least two specific locations, the magnetic field in a predetermined region can be determined, and first information and second information can be provided.

[0040] According to at least one embodiment of the method, the ion trap includes at least two registers. Each register includes a predetermined region (i.e., a processing region).

[0041] According to at least one embodiment of the method, at least one magnet arrangement is associated with each of at least two registers. Additionally, at least one magnetic field sensor device and / or at least two magnetic field sensor devices are associated with each of the at least two registers.

[0042] According to at least one implementation of the method, a magnetic field model is determined for each register in the register.

[0043] According to at least one embodiment of the method, the magnetization and / or position of each of at least two magnet arrangements is determined independently of each other.

[0044] In this way, ion traps with precisely customized magnetic field patterns can be generated, allowing for minimal or even no recalibration when operating at a second temperature. This advantageously simplifies the operation of scalable architectures involving a large number of qubit registers and processing regions, each with a customized magnetic field distribution. A combination of modeling and feedback during magnetization of the permanent magnet is advantageously implemented to generate the desired magnetic field in a predetermined region (i.e., the processing region). A combination of modeling and feedback during solenoid operation is also advantageously implemented to generate the desired magnetic field in the predetermined region (i.e., the processing region).

[0045] Furthermore, an apparatus (preferably an ion trap) for performing the method described above is specified. Therefore, the features described in conjunction with the apparatus also apply to the method, and vice versa. According to at least one embodiment, the apparatus includes at least one magnet arrangement configured to establish a magnetic field in a predetermined region, and at least one magnetic field sensor device spaced apart from the predetermined region. According to at least one embodiment of the apparatus, at least one magnetic field sensor device is arranged within the apparatus, and at least one magnetic field sensor device is configured to provide a magnetic field value in the predetermined region.

[0046] The ion trap and method are described in more detail below with reference to exemplary embodiments and associated drawings.

[0047] Figure 1A flowchart of a method according to an exemplary implementation is shown.

[0048] Figure 2 An apparatus for performing a method according to an exemplary embodiment is shown.

[0049] In the accompanying drawings, identical, similar, or equivalent elements are given the same reference numerals. The scale of the drawings and the elements shown in them should not be considered as drawn to scale. Rather, individual elements may be exaggerated for better representation and / or better understanding.

[0050] exist Figure 1 In step S1 of the method, first information is provided, which characterizes the magnetic field value in a predetermined region 4 spaced apart from the magnet arrangement 2, wherein the magnet arrangement 2 is in an environment having a first temperature.

[0051] Specifically, the magnet arrangement 2 is part of the ion trap 6. The magnet arrangement 2 exemplarily includes at least two magnets spaced apart from each other. The at least two magnets are specifically configured to establish a magnetic field in the processing region (particularly the predetermined region 4) of the ion trap 6. Specifically, in method step S1, the ion trap 6 having the magnet arrangement 2 is in an environment having a first temperature. In method step S1, the temperature of the ion trap 6 having the magnet arrangement 2 substantially corresponds to the first temperature.

[0052] The magnetic field value of the first information is provided, for example, by a magnetic field sensor. The magnetic field sensor device 3 is specifically spaced apart from the predetermined region 4. Specifically, in method step S1, the magnetic field sensor device 3 is used to provide the magnetic field established in the predetermined region 4 by the magnet arrangement 2 at a first temperature.

[0053] For example, the first temperature characterizes typical room temperature.

[0054] Subsequently, in method step S2, second information is provided, which characterizes the magnetic field value in the predetermined region 4, wherein the magnet arrangement 2 is in an environment with a second temperature.

[0055] Specifically, in method step S2, the ion trap 6 having the magnet arrangement 2 is in an environment having a second temperature. In method step S2, the temperature of the ion trap 6 having the magnet arrangement 2 approximately corresponds to the second temperature.

[0056] The magnetic field value of the second information is provided, for example, by a magnetic field sensor. Specifically, in method step S2, the magnetic field sensor device 3 is used to provide the magnetic field established by the magnet arrangement 2 in a predetermined region 4 at a second temperature.

[0057] The magnetic field sensor device 3 is configured to sense the magnetic field of the magnet arrangement 2 at a specific location, which corresponds to the position where the magnetic field sensor device 3 is arranged in the ion trap. By sensing the magnetic field of the magnet arrangement 2 at the specific location, the magnetic field in a predetermined region 4 can be determined, and first information and second information can be provided.

[0058] For example, the second temperature characterizes a typical low temperature.

[0059] For example, the same magnetic field sensor in ion trap 6 is used to provide (especially measure) magnetic field values ​​at the first and second temperatures.

[0060] Subsequently, in method step S3, a magnetic field model is determined based on the first information and the second information. This magnetic field model characterizes the temperature-dependent behavior of the magnetic field of at least one magnet arrangement 2.

[0061] For example, when the magnet arrangement 2 is in an environment with a first temperature, at least one magnet arrangement 2, including at least one permanent magnet (particularly mounted in the ion trap 6), is magnetized. Based on the temperature-dependent behavior of the magnetic field of the permanent magnet 2 as a magnetization behavior (i.e., according to the magnetic field model), the permanent magnet is magnetized such that, for example, when the magnet arrangement 2 is in an environment with a second temperature, the magnitude of the magnetic field is zero at a predetermined point in the predetermined region 4.

[0062] Alternatively or additionally, at least one permanent magnet is magnetized at a first temperature according to a magnetic field model, such that when the permanent magnet arrangement 2 is in an environment with a second temperature, the gradient of the magnitude of the magnetic field is maximized in a predetermined region 4.

[0063] The magnetization of the permanent magnet can be monitored during magnetization, allowing for particularly precise setting of the magnetization.

[0064] If the ion trap 6 includes at least two registers, a predetermined region 4 (i.e., a processing region) is allocated to each register. Additionally, each register is provided with at least two magnetic field sensor devices 3. Advantageously, a magnetic field model is determined (particularly independently of each other) for each register.

[0065] Advantageously, each magnet arrangement 2 assigned to one of the registers can be individually magnetized according to its respective magnetic field model. Specifically, a desired magnetic field can be formed differently for each register in a corresponding predetermined region 4.

[0066] according to Figure 2 The device 1 includes a magnet arrangement 2 configured to establish a magnetic field in a predetermined region 4 and a magnetic field sensor device 3 spaced apart from the predetermined region 4. In particular, the magnet arrangement 2 is also spaced apart from the predetermined region 4.

[0067] Preferably, device 1 is an ion trap 6.

[0068] A magnetic field sensor 3 is disposed within the device 1 and is configured to provide a magnetic field value in a predetermined region 4. The magnet arrangement 2 and the magnetic field sensor 3 are disposed on a substrate 5 or a carrier.

[0069] Figure Labels

[0070] 1 device

[0071] 2. Magnet Arrangement

[0072] 3. Magnetic field sensor device

[0073] 4. Pre-selected area

[0074] 5 substrate

[0075] 6 Ion traps

[0076] S1..S3 Method Steps

Claims

1. A method for determining a magnetic field model, said magnetic field being established by at least one magnet arrangement (2) and provided to an ion trap (6), comprising: - Provide first information, which characterizes the magnetic field value in a predetermined region (4) spaced apart from the magnet arrangement (2), wherein the magnet arrangement (2) is in an environment having a first temperature. - Provide second information, which characterizes the magnetic field value in the predetermined region (4), wherein the magnet arrangement (2) is in an environment having a second temperature, and - Determine the magnetic field model based on the first information and the second information, the magnetic field model characterizing the temperature-dependent behavior of the magnetic field of the at least one magnet arrangement (2).

2. The method according to claim 1, wherein, - Alternately repeat the provision of the first information and the provision of the second information.

3. The method according to claim 1 or 2, wherein, - When the magnet arrangement (2) is in an environment characterized by a temperature between the first temperature and the second temperature, at least one additional piece of information is provided, which characterizes the magnetic field value in the predetermined region (4).

4. The method according to at least one of claims 1 to 3, wherein, - The first temperature is higher than the second temperature.

5. The method according to any one of claims 1 to 4, wherein, - Determine the target magnetization and / or target location of the at least one magnet arrangement (2) based on the magnetic field model.

6. The method according to any one of claims 1 to 5, wherein, - When the magnet arrangement (2) is in an environment having the first temperature, the at least one magnet arrangement (2), including at least one permanent magnet, is magnetized.

7. The method according to claim 6, wherein, - Monitor the magnetization of the at least one magnet arrangement (2) during magnetization.

8. The method according to any one of claims 1 to 6, wherein, - The at least one magnet arrangement (2), including at least one permanent magnet, is magnetized and / or positioned such that when the magnet arrangement (2) is in an environment having the second temperature, the magnitude of the magnetic field is zero at a predetermined point in the predetermined region (4).

9. The method according to any one of claims 1 to 8, wherein, - The at least one magnet arrangement (2), including at least one permanent magnet, is magnetized and / or positioned such that when the magnet arrangement (2) is in an environment having the second temperature, the gradient of the magnitude of the magnetic field is maximized in the predetermined region (4).

10. The method according to any one of claims 1 to 9, wherein, - The at least one magnet arrangement (2) is part of the ion trap (6), and - The ion trap (6) includes at least one magnetic field sensor device or at least two magnetic field sensor devices (3), which are configured to measure the magnetic field of the at least one magnet arrangement (2) in the predetermined region (4).

11. The method according to claim 10, wherein, - The at least one magnetic field sensor device or the at least two magnetic field sensor devices (3) are spaced apart from the predetermined area (4).

12. The method according to any one of claims 10 or 11, wherein, - The ion trap (6) includes at least two registers - At least one magnet arrangement (2) is associated with each of the at least two registers, and - Determine the magnetic field model for each register in the register.

13. The method according to claim 12, wherein, - Determine the magnetization and / or position of each of the at least two magnet arrangements (2) independently.

14. An apparatus (1) for performing the method according to any one of claims 1 to 13, comprising: - At least one magnet arrangement (2), said at least one magnet arrangement being configured to establish a magnetic field in a predetermined region (4), and - At least one magnetic field sensor device (3), said at least one magnetic field sensor device (3) being spaced apart from the predetermined region (4), wherein, - The at least one magnetic field sensor device (3) is arranged within the device (1), and - The at least one magnetic field sensor device (3) is configured to provide a magnetic field value in the predetermined region (4).

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