Ion Trap and Quantum Computing System

Abstract

An ion trap (1) is provided, comprising the following - a first permanent magnet (2), and - a second permanent magnet (3) which is spaced apart in lateral directions from the first permanent magnet (2), wherein - the thickness (4) of the first permanent magnet (2) and the thickness (4) of the second permanent magnet (3) are equal to each other, - the first permanent magnet (2) and the second permanent magnet (3) are configured to generate a gradient of magnetic field magnitudes along a capture axis (5), - the capture axis (5) is arranged in a vertical direction above the first permanent magnet (2) and the second permanent magnet (3), and - the first permanent magnet (2) and the second permanent magnet (3) each have a principal extension direction in lateral directions perpendicular to the capture axis (5). In addition, a quantum computer system (11) is provided.

Description

[0001] The present disclosure relates to an ion trap and a quantum computing system.

[0002] The document US 2022 / 0 374 756 A1 describes a device, an arrangement, a system, and a sensor for processing quantum information. The document US 2017 / 0 358 437 A1 describes a Fourier transform ion cyclotron resonance mass spectrometry.

[0003] One challenge to be solved is to provide an ion trap that can confine and / or modify ions particularly well and / or is particularly space-efficient. Furthermore, a quantum computer system with such an ion trap is to be developed.

[0004] The problem is solved by the subject matter of the independent claims. Advantageous embodiments, implementations, and further developments are the subject matter of the respective dependent claims.

[0005] The ion trap is described. In particular, the ion trap is designed to confine at least one ion and / or to change an electronic state of the at least one ion, in particular to perform a quantum calculation.

[0006] The ion trap can be a Paul trap, a linear ion trap, a surface ion trap, and / or a multilayer ion trap. The ion trap comprises, for example, a set of electrodes. A radiofrequency voltage is applied to the electrodes, for example, to provide a time-varying electric field designed to confine and / or modify the ion. In particular, the ion or ions are arranged along a capture axis. For example, the ion, in particular each of the ions, overlaps the capture axis and / or oscillates around the capture axis. For example, the ions are arranged in an ion chain along the capture axis.

[0007] The ion trap comprises a first permanent magnet and a second permanent magnet spaced apart from the first permanent magnet in lateral directions. The permanent magnets each have a top surface and a bottom surface opposite the top surface. The top surface and the bottom surface are connected by a side surface arranged perpendicular to the top surface and the bottom surface. Both the top and bottom surfaces extend in lateral directions.

[0008] The permanent magnets are, in particular, planar permanent magnets. This means, in particular, that the top surface of the first permanent magnet and the top surface of the second permanent magnet lie in a common plane, and that the bottom surface of the first permanent magnet and the bottom surface of the second permanent magnet lie in a common plane. The common planes are spaced apart from each other in the vertical direction perpendicular to the lateral directions.

[0009] For example, the first permanent magnet is spaced from the second permanent magnet by a certain distance in lateral directions. The distance is the minimum dimension between the side surfaces of the permanent magnets in lateral directions. The distance is at least 10 micrometers and at most 1 mm, approximately 150 micrometers.

[0010] Typically, a permanent magnet, such as the first permanent magnet and the second permanent magnet, is designed to permanently maintain magnetization. In particular, a permanent magnet does not require an external magnetic field to maintain magnetic properties such as magnetization. Furthermore, a permanent magnet is typically designed to generate a magnetic field without the need for an electric current. A permanent magnet typically comprises a material from a category of hard magnets, which have a comparatively high coercive force. In particular, a permanent magnet is typically magnetized by comparatively strong external magnetic fields or by aligning magnetic domains.

[0011] The first permanent magnet and / or the second permanent magnet comprise or consist of at least one of the following materials: neodymium-iron-boron (NdFeB), samarium-cobalt (SmCo), aluminum-nickel-cobalt (AlNiCo).

[0012] The thickness of the first permanent magnet and the thickness of the second permanent magnet are equal. In particular, the thickness of the first permanent magnet is equal to the thickness of the second permanent magnet. "Equal" here means that the thicknesses can differ by a maximum of 5% or a maximum of 1% due to manufacturing tolerances. The thickness is defined along the vertical direction. The thickness is at least 1 micrometer and at most 500 micrometers, approximately 10 micrometers.

[0013] The first permanent magnet and the second permanent magnet are configured to generate a gradient of magnetic field magnitudes along the capture axis. This means that the external magnetic field has different magnitudes for different positions on the capture axis. Thus, the magnetic field magnitudes for different positions on the capture axis are characteristic of a magnetic field gradient along the capture axis. Advantageously, a resonant frequency of each of the ions at the capture axis, which is subject to the magnetic field gradient, is unique for each captured ion due to the magnetic field gradient.

[0014] The capture axis is arranged vertically above the first permanent magnet and the second permanent magnet. In particular, the capture axis is arranged vertically above the top surfaces of the first permanent magnet and the second permanent magnet.

[0015] For example, the vertical distance between the common plane of the top surface and the capture axis is at least one or at least two orders of magnitude larger than the specified thickness of the permanent magnets. For example, the distance between the common plane of the top surface and the capture axis is at least 20 micrometers and at most 1 mm, approximately 100 micrometers.

[0016] The first permanent magnet and the second permanent magnet each have a main extension direction in lateral directions perpendicular to the capture axis. In particular, each permanent magnet extends along a length in lateral directions along the main extension direction. In particular, each permanent magnet extends along a width in lateral directions perpendicular to the main extension direction. For example, the length is greater than the width, in particular by at least 20% or at least 40%.

[0017] One idea of ​​the method described here is, among other things, to use a first permanent magnet and a second permanent magnet to generate the gradient of magnetic field magnitudes along the capture axis, wherein the gradient is maximized because the permanent magnets have a shape in the lateral directions described here.

[0018] For example, the shapes of the first permanent magnet and the second permanent magnet are determined using variational calculus and Euler-Lagrange equations with at least one condition to optimize the shapes of the first permanent magnet and the second permanent magnet to achieve a maximum gradient. A first condition is characteristic that the magnetic field vanishes at a predetermined point, which is characteristic of a point on the capture axis located between the two permanent magnets, and an optional second condition is characteristic of a predetermined maximum extension of the two permanent magnets in lateral directions.

[0019] According to at least one embodiment of the ion trap, the magnitude of the magnetic field is zero for a point located laterally between the first permanent magnet and the second permanent magnet and vertically above the first permanent magnet and the second permanent magnet. The point is located, in particular, on the trapping axis. Furthermore, the point is located in a central region between the first permanent magnet and the second permanent magnet. This means that the point is represented by the predetermined point described above.

[0020] According to at least one embodiment of the ion trap, a magnetization direction of the first permanent magnet and a magnetization direction of the second permanent magnet are identical to one another. The magnetization direction is characteristic of a predominant orientation of the magnetic moments of the material of the permanent magnets. For example, the material of the permanent magnets is identical to one another and the material is equally magnetized.

[0021] For example, the magnetization direction of the first permanent magnet and the magnetization direction of the second permanent magnet are oriented perpendicular to lateral directions, i.e., along the vertical direction. In particular, the magnetization directions of the first permanent magnet and the second permanent magnet point in the same direction, for example, in the direction of the capture axis. Due to manufacturing tolerances, the magnetization direction of the first permanent magnet and the magnetization direction of the second permanent magnet may form an angle of at most 5° or at most 1°.

[0022] According to at least one embodiment of the ion trap, the first permanent magnet and the second permanent magnet are mirror-symmetrical to each other with respect to a virtual first mirror plane. In particular, the virtual first mirror plane is exclusively virtual in nature and not present as a physical entity in the ion trap.

[0023] According to at least one embodiment of the ion trap, the virtual first mirror plane is arranged between the first permanent magnet and the second permanent magnet. In particular, the virtual first mirror plane is arranged at a center point of the distance between the first permanent magnet and the second permanent magnet, e.g., divides the distance.

[0024] According to at least one embodiment of the ion trap, the virtual first mirror plane extends perpendicular to the trapping axis. The point arranged vertically above the first permanent magnet and the second permanent magnet with the vanishing size lies, for example, within the virtual first mirror plane.

[0025] According to at least one embodiment of the ion trap, the trapping axis and the vertical direction are characteristic of a virtual second mirror plane for the first permanent magnet itself. In particular, the virtual second mirror plane is exclusively virtual in nature and is not present as a physical entity in the ion trap.

[0026] According to at least one embodiment of the ion trap, the trapping axis and the vertical direction are characteristic of the virtual second mirror plane of the second permanent magnet itself.

[0027] According to at least one embodiment of the ion trap, the first permanent magnet has a first side surface region facing away from the second permanent magnet. In particular, the second permanent magnet also has a corresponding first side surface region. For example, the first permanent magnet has a closed outer circumference in lateral directions, which is defined by the side surface. The closed outer circumference can be virtually segmented into different regions.

[0028] For example, the first side surface region overlaps with the capture axis and extends in lateral directions to at least 60% and / or at most 90% of the length of the first permanent magnet along the main extension direction.

[0029] According to at least one embodiment of the ion trap, the first side surface region has a first mean curvature. The first mean curvature is in particular characteristic of a total curvature of the closed outer circumference along the first side surface region in lateral directions. For example, the mean curvature is characteristic of an amount by which a curve deviates from a straight line. If the amount is comparatively large, the deviation of the shape of the side surface in lateral directions from the straight line is comparatively large. If the amount is comparatively small, the deviation of the shape of the side surface in lateral directions from the straight line is comparatively small.

[0030] According to at least one embodiment of the ion trap, the first permanent magnet has a second side surface region and a third side surface region facing the second permanent magnet. In particular, the second permanent magnet has a second side surface region and a third side surface region, respectively. The second side surface region and the third side surface region are arranged, in particular, directly opposite the first side surface region in the lateral direction along the trapping axis of the same permanent magnet.

[0031] According to at least one embodiment of the ion trap, the second side surface region has a second mean curvature, and the third side surface region has a third mean curvature. The second mean curvature is, for example, characteristic of an overall curvature of the closed outer circumference along the second side surface region. The third mean curvature is, for example, characteristic of an overall curvature of the closed outer circumference along the third side surface region.

[0032] For example, the second mean curvature and the third mean curvature are different from each other. For example, all mean curvatures are different from each other.

[0033] According to at least one embodiment of the ion trap, the second side surface region is arranged in a central region that overlaps with the trapping axis.

[0034] According to at least one embodiment of the ion trap, the third side surface region is arranged in a peripheral region that does not overlap with the trapping axis. In particular, the peripheral region surrounds the central region.

[0035] For example, the second side surface region overlaps the capture axis and extends in lateral directions to at least 5% and / or at most 20% of the length of the respective permanent magnet along the main extension direction. For example, the third side surface region does not overlap the capture axis and extends in lateral directions from the second side surface region to at least 60% and / or at most 90% of the length of the respective permanent magnet along the main extension direction.

[0036] According to at least one embodiment of the ion trap, the second mean curvature is greater than the third mean curvature. For example, the closed outer periphery over the second side surface region is more strongly curved than the closed outer periphery over the third side surface region.

[0037] According to at least one embodiment of the ion trap, the first mean curvature is greater than the third mean curvature. This means, for example, that the closed outer circumference above the first side surface region is more strongly curved than the closed outer circumference above the third side surface region.

[0038] According to at least one embodiment of the ion trap, the gradient is maximized in lateral directions with respect to a shape of the first permanent magnet and the second permanent magnet. For example, an analytical solution of the Euler-Lagrange equation with the included conditions using the method of Lagrange multipliers results in particular in an optimal shape of the first permanent magnet and the second permanent magnet that are mirror-symmetric, wherein the optimal shape of one of the permanent magnets is implicitly defined by the following equation: μ−15x2(1+x2+y2)72+3(1+x2+y2)52+λ(3(1+x2+y2)52−1(1+x2+y2)32)=0, where x and y are coordinates that define the closed outer perimeter in lateral directions. For example, the parameters µ and λ are numerically defined by the first and second conditions, respectively. Specifically, x and y in this equation are given in relative units, with the height of the given point set to 1. For example, if only the first condition is met, µ = 0.

[0039] According to at least one embodiment of the ion trap, an extension of the first permanent magnet and / or an extension of the second permanent magnet along the trapping axis is at most 0.4 mm. For example, the extension of the first permanent magnet and / or the extension of the second permanent magnet along the trapping axis is at most 0.38 mm and at least 0.35 mm.

[0040] According to at least one embodiment of the ion trap, an extension of the first permanent magnet and / or an extension of the second permanent magnet perpendicular to the capture axis is at most 0.6 mm. The extension perpendicular to the capture axis is in the respective main extension direction of the respective permanent magnet. For example, the extension of the first permanent magnet and / or an extension of the second permanent magnet perpendicular to the capture axis is at most 0.55 mm and at least 0.5 mm.

[0041] For example, each length of the first permanent magnet and the second permanent magnet is about 526 micrometers and each width of the first permanent magnet and the second permanent magnet is about 369 micrometers.

[0042] According to at least one embodiment, the ion trap comprises a substrate on which the first permanent magnet and the second permanent magnet are provided. For example, at least some of the electrodes are mounted on the substrate. The substrate is, for example, electrically insulating. For example, the substrate is formed with or consists of an electrically insulating material. The electrically insulating material comprises or consists of, for example, at least one of the following materials: sapphire, aluminum oxide, such as Al2O3, aluminum nitride, silicon, or diamond.

[0043] According to at least one embodiment, the first permanent magnet and the second permanent magnet are arranged on a main surface of the substrate.

[0044] According to at least one embodiment, the first permanent magnet and the second permanent magnet are embedded in the substrate. In particular, the first permanent magnet and / or the second permanent magnet are arranged within the substrate.

[0045] In particular, "embedded" here means that at least one outer surface of the first permanent magnet and the second permanent magnet is covered by the substrate. For example, all outer surfaces of the first permanent magnet and the second permanent magnet are covered by the substrate, or all outer surfaces of the first permanent magnet and the second permanent magnet are covered by the substrate, except for the top surface.

[0046] For example, the main surface of the substrate is planar. For example, the main surface can have depressions or elevations due to manufacturing tolerances. The permanent magnets are arranged on the main surface, for example. A cover body is then arranged on the permanent magnets and on the main surface not covered by the permanent magnets. For example, the permanent magnets are completely covered by the cover body, so that the permanent magnets are three-dimensionally encapsulated by the cover body and the substrate. The cover body is formed, for example, with polyimide. A main surface of the cover body facing away from the substrate is, for example, planar. The main surface of the cover body is, for example, planarized in order to prepare the main surface for further electrode application.

[0047] Furthermore, a quantum computer system configured to perform quantum computations is described. The quantum computer system specifically includes an ion trap described herein. Therefore, all features and embodiments disclosed in connection with the quantum computer system are also disclosed in connection with the ion trap, and vice versa.

[0048] In the following, the ion trap and the quantum computer system are explained in more detail with reference to embodiments and the associated figures. Fig. 1 shows the ion trap according to an embodiment. Fig. 2 shows a plan view of the permanent magnets according to an embodiment. Fig. 3 shows a side view of the permanent magnets according to an embodiment with the generated corresponding magnetic field. Fig. 4 shows a quantum computer system according to an embodiment.

[0049] Elements that are identical or similar, or have the same effect, are provided with the same reference numerals in the figures. The figures and the proportions of the elements depicted in the figures are not to be considered to scale. Rather, individual elements may be exaggerated for clarity and / or clarity.

[0050] The ion trap in connection with the embodiment of the Fig. 1 comprises a first permanent magnet 2 and a second permanent magnet 3. The first permanent magnet 2 and the second permanent magnet 3 are arranged on a substrate 10 of the ion trap. The first permanent magnet 2 and the second permanent magnet 3 each have a main extension direction in the lateral directions x, y. Both the first permanent magnet 2 and the second permanent magnet 3 have a top surface, a bottom surface opposite the top surface, and a side surface connecting the bottom surface to the top surface. The bottom surfaces are arranged on the substrate 10. A thickness 4 of the first permanent magnet 2 and a thickness 4 of the second permanent magnet 3 are the same.

[0051] The first permanent magnet 2 and the second permanent magnet 3 are spaced apart from each other in lateral directions x, y, in particular along one of the lateral directions x. The first permanent magnet 2 and the second permanent magnet 3 are configured to generate a gradient of magnetic field magnitudes along a capture axis 5, wherein the capture axis 5 is arranged in the vertical direction z above the first permanent magnet 2 and the second permanent magnet 3. The capture axis 5 is, for example, parallel to the lateral direction x.

[0052] In particular, the magnitude of the magnetic field changes continuously along the capture axis 5, i.e., for different positions on the capture axis 5, starting from a center point between the first permanent magnet 2 and the second permanent magnet 3. Thus, the magnetic field strengths for different positions on the capture axis 5 are characteristic of a magnetic field gradient along the capture axis 5.

[0053] For a point 6 located above the first permanent magnet 2 and the second permanent magnet 3 in the vertical direction z, the magnitude of the magnetic field is zero. In particular, point 6 is located in a central region between the first permanent magnet 2 and the second permanent magnet 3 in lateral directions.

[0054] In particular, the magnetization direction of the first permanent magnet 2 and the magnetization direction of the second permanent magnet 3 are equal to each other and aligned in the vertical direction, as shown in Fig. 1 indicated by arrows.

[0055] The first permanent magnet 2 and the second permanent magnet 3 in Fig. 2 each have a main extension direction in lateral directions perpendicular to the capture axis 5, along one of the lateral directions y.

[0056] The first permanent magnet 2 has a first side surface region 7 facing away from the second permanent magnet 3 and having a first central curvature. Since the first permanent magnet 2 and the second permanent magnet 3 are mirror-symmetrical to one another, the second permanent magnet 3 has a first side surface region 7 facing away from the first permanent magnet 2 and having the first central curvature. In addition, the first permanent magnet 2 has a second side surface region 8 facing the second permanent magnet 3 with a second central curvature, and the second permanent magnet 3 has a second side surface region 8 facing the first permanent magnet 2 and having the second central curvature.Furthermore, the first permanent magnet 2 has a third side surface region 9 which faces the second permanent magnet 3 with a third mean curvature, and the second permanent magnet 3 has a third side surface region 9 which faces the first permanent magnet 2 with the third mean curvature.

[0057] The first mean curvature, the second mean curvature, and the third mean curvature are different from each other. In particular, the first mean curvature is larger than the third mean curvature.

[0058] The first permanent magnet 2 and the second permanent magnet 3 are designed to generate a gradient of magnitudes of a magnetic field along the capture axis 5, as shown in Fig. 3. The magnetic field lines are in Fig.3 are shown as arrows. The magnitudes of the magnetic field for different positions on the capture axis 5 are characteristic of a magnetic field gradient along the capture axis 5.

[0059] The quantum computer system 11 comprises an ion trap 1 as the processor unit of the quantum computer system 11, which is arranged in a chamber 12. The ion trap 1 is connected to external components of the quantum computer system 11 via the chamber 12 through a plurality of connections 13. The connections 13 connect the ion trap 1, for example, to electronic devices 14 and a conventional computer 15.

[0060] The electronic devices 14 include, for example, a laser, a wave measuring device, an acousto-optic modulator, an electro-optic modulator, a detector, a signal generator, an amplifier, a power supply, a piezo controller, a motor, analog-to-digital converters, and signal generators such as high-frequency generators, microwave signal generators, low-frequency signal generators, and / or DC signal generators. The electronic devices 14 can also be partially arranged within the chamber 12. Reference symbol 1 ion trap 2 first permanent magnet 3 second permanent magnet 4 thickness 5 Capture axis 6 points 7 first side surface area 8 second side surface area 9 third side surface area 10 Substrat 11 Quantum computer system 12 chambers 13 Connection 14 electronic device 15 classic computers

Claims

[1] Ion trap (1), comprising - a first permanent magnet (2), and - a second permanent magnet (3) which is spaced apart in lateral directions from the first permanent magnet (2), wherein - a thickness (4) of the first permanent magnet (2) and a thickness (4) of the second permanent magnet (3) are equal to each other, - the first permanent magnet (2) and the second permanent magnet (3) are designed to generate a gradient of magnetic field sizes along a capture axis (5), - the capture axis (5) is arranged vertically above the first permanent magnet (2) and the second permanent magnet (3), and - the first permanent magnet (2) and the second permanent magnet (3) each have a main extension direction in lateral directions perpendicular to the capture axis (5). [2] Ion trap (1) according to claim 1, wherein - a magnitude of the magnetic field for a point (6) arranged in lateral directions between the first permanent magnet (2) and the second permanent magnet (3) and in vertical direction above the first permanent magnet (2) and the second permanent magnet (3) is zero. [3] Ion trap (1) according to one of claims 1 or 2, wherein - a magnetization direction of the first permanent magnet (2) and a magnetization direction of the second permanent magnet (3) are equal to each other. [4] Ion trap (1) according to one of claims 1 to 3, wherein - the first permanent magnet (2) and the second permanent magnet (3) are mirror-symmetrical to each other with respect to a virtual first mirror plane, - the virtual first mirror plane is arranged between the first permanent magnet (2) and the second permanent magnet (3), and - the virtual first mirror plane extends perpendicular to the capture axis (5). [5] Ion trap (1) according to one of claims 1 to 4, wherein - the capture axis (5) and the vertical direction are characteristic of a virtual second mirror plane for the first permanent magnet (2) itself, and - the capture axis (5) and the vertical direction are characteristic of the virtual second mirror plane for the second permanent magnet (3) itself. [6] Ion trap (1) according to one of claims 1 to 5, wherein - the first permanent magnet (2) has a first side surface region (7) which faces away from the second permanent magnet (3), and - the first side surface region (7) has a first mean curvature, and / or - the first permanent magnet (2) has a second side surface region (8) and a third side surface region (9) facing the second permanent magnet (3), and - the second side surface region (8) has a second mean curvature and the third side surface region (9) has a third mean curvature. [7] Ion trap (1) according to claim 6, wherein - the second side surface region (8) is arranged in a central region which overlaps with the capture axis (5), - the third side surface region (9) is arranged in a peripheral region which does not overlap with the capture axis (5), and - the second mean curvature is greater than the third mean curvature. [8] Ion trap (1) according to one of claims 6 or 7, wherein - the first mean curvature is greater than the third mean curvature. [9] Ion trap (1) according to one of claims 1 to 8, wherein - the gradient with respect to a shape of the first permanent magnet (2) and the second permanent magnet (3) is maximized in lateral directions. [10] Ion trap (1) according to one of claims 1 to 9, wherein - an extension of the first permanent magnet (2) and / or an extension of the second permanent magnet (3) along the capture axis (5) is at most 0.4 mm, and - an extension of the first permanent magnet (2) and / or an extension of the second permanent magnet (3) perpendicular to the capture axis (5) is at most 0.6 mm. [11] Ion trap (1) according to one of claims 1 to 10, further comprising - a substrate (10) on which the first permanent magnet (2) and the second permanent magnet (3) are provided. [12] Ion trap (1) according to claim 11, wherein - the first permanent magnet (2) and the second permanent magnet (3) are arranged on a main surface of the substrate (10). [13] Ion trap (1) according to claim 11, wherein - the first permanent magnet (2) and the second permanent magnet (3) are embedded in the substrate (10). [14] Quantum computer system (11) comprising the ion trap (1) according to one of claims 1 to 13, which is designed to perform quantum calculations.

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