Quantum computing devices and quantum computers

Abstract

A quantum computing device is provided that includes a permanent magnet device and a substrate. [Solution] The quantum computing device is configured to implement a planar Paul trap for trapping at least one ion crystal having a plurality of ions aligned along a predetermined line. Components of the quantum computing device comprising electrodes of the planar Paul trap for establishing an electrical trapping potential are disposed on a top surface of a substrate. The predetermined line is disposed above the top surface. A permanent magnet device establishes a magnetic field, the magnitude of which varies along the predetermined line. Further, a quantum computer comprising the quantum computing device is specified.

Description

Technical Field

[0001] The present disclosure relates to a quantum computing device and a quantum computer.

Background Art

[0002] In many quantum computing processes that use a quantum computing device (arrangement), the device is configured to trap quantum particles, such as ions. During operation, the trapped quantum particles form quantum bits, abbreviated as qubits. In order to perform calculations, the trapped quantum particles need to be controlled and manipulated. For the trapped quantum particles, interactions, such as Coulomb repulsion for example, can generate the coupling of adjacent trapped quantum particles and thus enable entanglement. In order to perform a quantum computing process using the trapped quantum particles, the trapped quantum particles need to be controllable and addressable individually and mutually.

[0003] It is desirable for the individual addressing of a plurality of trapped quantum particles, for example, a quantum bit register, to have negligible crosstalk. However, crosstalk between adjacent trapped quantum particles is typically a source of errors that are difficult to control in a quantum computer process and can prevent the meaningful application of quantum error correction protocols and thus scalability.

[0004] Therefore, one objective to be achieved is to provide an improved quantum computing device, for example, one that is compact in design and / or alternatively easy to manufacture and / or alternatively allows for improved controllability. A further objective to be achieved is to provide a quantum computer using such a quantum computing device.

[0005] These objectives are addressed, in particular, by the subject matter of claims 1 and 16. Advantageous embodiments and further developments are the subject matter of the dependent claims and can also be derived from the following description and drawings. [Overview of the project]

[0006] First, the quantum computing device will be described in detail.

[0007] According to at least one embodiment, the quantum computing device comprises a permanent magnet device. For example, the permanent magnet device is symmetric with respect to a plane of symmetry, and in particular, geometrically symmetric. This means that the geometry or shape of each permanent magnet device is symmetric with respect to a plane of symmetry. The shape of the permanent magnet device may also have rotational symmetry, for example, n-fold rotational symmetry, where n is at least 3, at least 4, at least 6, or at least 8.

[0008] According to at least one embodiment, the quantum computing device comprises a substrate. The substrate may be an electrically insulating substrate. The substrate may contain or consist of sapphire, or diamond, or a ceramic such as AlN.

[0009] According to at least one embodiment, a quantum computing device is configured to realize a planar pole trap to trap at least one ion crystal having several ions aligned along a predetermined line. In other words, during operation, the quantum computing device, or at least a part thereof, constitutes a planar pole trap. A pole trap is also known as a quadrupole ion trap or radio frequency (RF) trap. This is a type of ion trap that uses a dynamic electric field to trap charged particles.

[0010] A planar pole trap is configured to trap two or more ion crystals arranged along a predetermined line, for example, at least 8, or at least 20, or at least 100, and / or at least 1000 ions.

[0011] According to at least one embodiment, the components of the quantum computing device that constitute the electrodes of a planar pole trap for generating an electrical trapping potential are hereafter simply referred to as planar pole trap electrodes and are located on the top surface of the substrate. In particular, all electrodes of the planar pole trap that generate the electrical trapping potential are located on the top surface of the substrate.

[0012] For example, the top surface of the substrate is a flat top surface (top side). The substrate may be part of a planar pole trap. Electrodes may be applied to the substrate by a deposition method, such as sputtering or vapor deposition. The thickness of the electrodes may be increased by using a galvanic process. The substrate may mechanically stabilize the electrodes. Between the electrodes and the top surface, there may be an adhesive layer to improve the adhesion of the electrodes to the top surface.

[0013] For example, a planar pole trap comprises at least two RF electrodes, at least two DC electrodes, and at least two end cap electrodes. All of these electrodes may be arranged on a common electrode plane.

[0014] The electrodes of a planar pole trap may be different from those of a permanent magnet device. Therefore, a planar pole trap can be a separate device in a quantum computing apparatus that is distinct from a permanent magnet device. Alternatively, one or more components of a permanent magnet device may also form the electrodes of a planar pole trap, and as a result, the planar pole trap may be at least partially formed by the permanent magnet device.

[0015] During operation, the electrodes of the planar pole trap generate an oscillating electrical potential configured to trap at least one ion crystal, and several ions are aligned in directions parallel to a predetermined line and in directions perpendicular to a predetermined line, also referred to herein as the radial direction. Effectively, at least one electrical potential well is generated, in which ions are trapped in all spatial directions and formed so that the ions are arranged back and forth along a predetermined line, for example, in a linear configuration. Multiple ions trapped in the same electrical potential well are referred to herein as an ion crystal.

[0016] The default line, also called the trap line, is defined by the potential generated by the planar pole trap and, therefore, depends on the shape of the planar pole trap. Trapped ions are positioned along the default line. For example, each ion in at least one ion crystal intersects the default line and / or oscillates around it. In other words, in a pole trap, the ions in at least one ion trap are positioned in an ion chain extending along the default line. The default line may be parallel to the upper surface of the substrate.

[0017] Each electrode may be formed as a plate, sheet, or film. The main extending surface of the electrode extends, for example, parallel to the upper surface.

[0018] The electrodes may be made of metal. For example, they may be made of Au, or other materials such as Cu. In this case, the electrodes may be coated with Au. Each electrode is, in particular, a continuous, uninterrupted metallic element. For example, the extension of the electrode along each main extension plane of the electrode is a maximum of 300 mm, or a maximum of 50 mm, or a maximum of 10 mm, or a maximum of 1 mm. The thickness of the electrode, measured perpendicular to the main extension plane, is, for example, a maximum of 100 μm, or a maximum of 50 μm.

[0019] In addition to electrodes for pole traps, the quantum computing device may include components for supplying power to the electrodes, such as a power supply and / or control unit.

[0020] According to at least one embodiment, the quantum computing device is configured such that a default line is positioned above the top surface, i.e., offset from the top surface and offset from the substrate. In particular, the default line may be positioned above the electrodes of a planar pole trap. This means that during operation, ions float, respectively, above the top surface or electrodes of the planar pole trap. For example, in a direction perpendicular to the top, all electrodes of the pole trap are positioned either in front of or behind the default line, i.e., in front of or behind the ions.

[0021] For example, the average distance between the top surface and a predetermined line measured perpendicular to the top surface is at least 20 μm, or at least 100 μm. Additionally or alternatively, the minimum distance is at most 500 μm, or at most 200 μm.

[0022] According to at least one embodiment, the permanent magnet device forms a magnetic field. The magnitude of the magnetic field thereby varies along a given line.

[0023] The magnetic field is understood herein to be the magnetic flux density. Thus, the magnitude of the magnetic field is the absolute value of the magnetic flux density.

[0024] The magnetic field generated by the permanent magnet device is, for example, a magnetic quadrupole field or includes it. Higher multipole moments may also exist. At the center of the magnetic field, the absolute value of the magnetic field can be zero. The center of the magnetic field can coincide with the geometric center of the permanent magnet device and / or the planar pole trap. For example, the center of the magnetic field is within the symmetry plane of the permanent magnet device and / or on a given line. The magnetic field can be point-symmetric with respect to its center.

[0025] The magnitude of the magnetic field varies along a given line. This means that the magnitudes of the magnetic field at different positions on the given line are different from each other. The variation of the magnitude of the magnetic field along the given line is also referred to herein as the gradient of the magnetic field along the given line.

[0026] The variation of the magnitude of the magnetic field can be monotone. For example, at least in part, it is strictly monotone. For example, starting from the center of the magnetic field, the variation of the magnetic field can be monotone or strictly monotone in both directions along the given line. The direction of the magnetic field may vary along the given line or remain constant along the given line.

[0027] In at least one embodiment, the quantum computing device comprises a permanent magnet device and a substrate. The quantum computing device is configured to realize a planar pole trap to trap at least one ion crystal having ions aligned along a predetermined line. Components of the quantum computing device that constitute the electrodes of the planar pole trap to establish an electrical trap potential are located on the upper surface of the substrate. The predetermined line is located above the upper surface. The permanent magnet device establishes a magnetic field, the magnitude of which is varied along the predetermined line.

[0028] Trapped ions provide an excellent quantum system for quantum control and metrology. In this invention, they are stored in a planar pole trap and form at least one ion crystal oriented along a predetermined line. For quantum computations using trapped ions, as well as for specific tasks in measurement, individual control of single ions is desirable. When ions are manipulated by RF radiation, this single-ion control cannot be achieved by focusing the radiation because the wavelength typically exceeds the ion separation within the ion crystal by several orders of magnitude. Furthermore, the coupling between internal and external quantum states, quantified by the Lamb-Dicke parameter, cannot be achieved by RF radiation.

[0029] This invention is based, in particular, on the idea of ​​using the non-uniform magnetic field provided by a permanent magnet device. This provides the possibility of individually addressing ions in frequency space by RF radiation. On the other hand, the superposition of the potential caused by the planar pole trap and the magnetic field of the permanent magnet device causes the equilibrium position of the ions to depend on their respective quantum states. As a result, effective spin-spin coupling is achieved through Coulomb interaction between the trapped ions. This makes entanglement of the quantum states of the ions possible.

[0030] Furthermore, some quantum registers or ion crystals may each be advantageous for further scaling. This can be achieved using planar Paul traps that enable scaling of over hundreds of ions and thus reach the total number of trapped ions clearly beyond quantum supremacy, thus enabling the solution of computational problems that have hitherto been inaccessible to classical supercomputers.

[0031] In summary, using a quantum computing device described for quantum information processing enables advanced addressing in frequency space and thus individual single qubit rotations with low crosstalk, and introduces effective coupling between ions, thus enabling multi qubit gates. This can also be used in relation to RF frequencies, although addressing by focusing radiation due to long wavelengths is not an option, and the use of RF fields for qubit control enables the application of established, economical miniaturization and integration techniques already common even in household appliances, and simplifies the scaling of ion trap based quantum computers.

[0032] According to at least one embodiment, the permanent magnet device comprises a plurality of permanently magnetized segments. The segments can all be formed identically within the limits of manufacturing tolerances.

[0033] A permanent magnet device may include at least four, or at least eight, or at least sixteen, or at least thirty-two segments. Each segment contains or consists of a permanent magnet material. For example, the permanent magnet material is a ferromagnetic material. Each segment may contain or consist of the same material. Each segment is formed, for example, as a single unit. Alternatively, each segment may be formed from at least two subsegments, where at least two subsegments have the same material and / or magnetization properties.

[0034] According to at least one embodiment, each segment has a magnetization direction. The magnetization of each segment is defined by a vector field representing the dipole moment of the respective permanent magnetic material. That is, each permanent magnetic material exhibits a dipole moment. The vector field, in particular the dipole moment of the permanent magnetic material, defines the respective magnetization direction. The dipole moment primarily indicates the magnetization direction.

[0035] According to at least one embodiment, the segments are arranged such that the magnetization directions of at least some of the segments are different from each other, and as a result, the permanent magnet device establishes a magnetic field having a magnetic field magnitude that varies along a predetermined line.

[0036] For example, the magnetization directions of each pair of directly adjacent segments are different from each other. The magnetization directions may differ from each other by an angle of at least 5°, or at least 10°, and / or at most 90°, or at most 45°. For example, if there are m segments and m is an even natural number at least 4, then the magnetization directions of two directly adjacent segments are rotated by 360°·3 / m relative to each other.

[0037] The vector field, defined by the magnetization direction of the segment and the position of the segment in space, may be symmetric with respect to the aforementioned plane of symmetry. In particular, this vector field may have the same symmetry as the geometry of the permanent magnet device. Alternatively, the vector field may be asymmetric with respect to the plane of symmetry and / or may have different symmetries from the geometry of the permanent magnet device, or may even be asymmetric.

[0038] According to at least one embodiment of the quantum computing device, the permanent magnet device includes NdFeB. In particular, the permanent magnet device includes NdFeB N52. Exemplarily, each segment includes or consists of NdFeB, in particular NdFeB N52.

[0039] According to at least one embodiment, the segments are arranged in a Halbach arrangement. A Halbach arrangement is a special arrangement of permanent magnets that increases the magnetic field on one side of the arrangement and cancels it out to near zero on the other side. In particular, this is achieved by having a spatially rotating pattern of the magnetization direction of the segments.

[0040] Using such Halbach arrays, particularly high magnetic fields and magnetic field gradients can be achieved. Halbach arrays are especially useful because effective spin-spin coupling, as well as differences in resonance between adjacent ions, depend on the non-uniformity and magnitude of the magnetic field. Indeed, Halbach arrays enable large gradients even when the distance between any surface (including trap electrodes and magnet surfaces) and the trapped ions should be large, which is desirable for high-fidelity gates with trapped ions. This, for example, when combined with segmented traps, allows for flexible trapping configurations, trapping several registers to adjust coupling constants between qubits for partitioning and merging quantum registers, and generally scaling the power of ion-trap-based quantum computers.

[0041] According to at least one embodiment, the permanent magnet device surrounds a planar pole trap and / or its electrodes. That is, the planar pole trap is a separate device from the permanent magnet device. In particular, segments of the permanent magnet device are different from the electrodes of the planar pole trap. For example, the permanent magnet device has a ring shape, or a polygonal contour or perimeter shape, respectively. Thus, the planar pole trap can be surrounded by a permanent magnet device of ring shape or polygonal contour shape. The permanent magnet device can then increase the magnetic field inside the ring or contour and cancel out the magnetic field outside the ring or contour to near zero.

[0042] According to at least one embodiment, at least some electrodes of a planar pole trap are formed by segments of a permanent magnet device.

[0043] According to at least one embodiment, at least some electrodes of a planar pole trap, i.e., some or all electrodes of a planar pole trap, are arranged in a common electrode plane. For example, all electrodes of a planar pole trap that generate an electrical trapping potential are arranged in the electrode plane. The top surface may coincide with the electrode plane or be parallel to the electrode plane.

[0044] The electrodes positioned on the electrode surface are, in particular, intersecting with the electrode surface. The main extending surface of the electrode extends, for example, parallel to the electrode surface or coincides with the electrode surface.

[0045] Some electrodes in a planar pole trap may also be positioned at different heights relative to the top surface. For example, an electrode stack may be positioned on the top surface, with an insulating layer separating each pair of electrodes perpendicular to the top surface.

[0046] According to at least one embodiment, the lateral spread of the planar pole trap and / or substrate is at most 5 cm, or at most 2 cm, or at most 1 cm. The lateral spread is measured, for example, along the electrode surface. The thickness of the planar pole trap or substrate, measured perpendicular to the electrode surface, may be at most 1 cm, or at most 0.5 cm, or at most 0.2 cm.

[0047] According to at least one embodiment, at least a portion of the permanent magnet device is placed within a substrate, for example, embedded within the substrate. For example, one or more segments or all segments of the permanent magnet device are placed on a substrate. Regardless of whether the permanent magnet device surrounds a planar pole trap, is placed within a substrate, or is placed elsewhere, the permanent magnet device can have a ring shape or a polygonal contour shape. Thus, the segments can be arranged in a ring shape or a polygonal contour.

[0048] According to at least one embodiment, a planar pole trap is a linear planar pole trap for trapping at least one ion crystal, each having ions aligned along a predetermined straight line or axis. Thus, the predetermined line is a predetermined straight line or axis, respectively. Alternatively, the planar pole trap may be a circular planar pole trap.

[0049] According to at least one embodiment, the permanent magnet device establishes a substantially two-dimensional magnetic field that is primarily concentrated in the magnetic field plane. The center of the magnetic field may lie within the magnetic field plane. The aforementioned plane of symmetry of the permanent magnet device is, for example, perpendicular to the magnetic field plane. For example, all segments of the permanent magnet device are positioned within the magnetic field plane.

[0050] When starting from the magnetic field plane and moving in a direction perpendicular to the magnetic field plane, the magnetic field attenuates, for example, until the average magnitude of the magnetic field decreases to approximately zero. The decay length depends on the dimensions of the permanent magnet device, such as the inner and / or outer diameters and / or thickness of the segment measured perpendicular to the magnetic field plane. In particular, the decay length is proportional to the inner and / or outer diameters and thickness of the segment.

[0051] For example, the average magnitude of a magnetic field has a full width at half maximum (FWHM) of at least 1 μm, or at least 10 μm, and / or up to 10 mm, or up to 500 μm, in the direction perpendicular to the magnetic field surface. For example, in this case, the average magnitude of the magnetic field outside the magnetic field surface, for example, at a distance of 1 mm from the magnetic field surface, is at least an order of magnitude smaller than the average magnitude of the magnetic field at the magnetic field surface. In other words, the magnetic field surface is the main extension plane of the magnetic field magnitude.

[0052] For example, in a segment of a permanent magnet device arranged in the form of a ring whose main extending surface defines the xy plane, the magnetic flux density corresponding to the magnetic field

number

number

[0053] B R is the remanence of the segment, and R i is the inner diameter of the ring, R o x is the outer diameter of the ring, and x and y are the coordinates within the permanent magnet device. In this case, the magnetic field plane is the xy-plane or the main extending plane of the ring, respectively.

[0054] The magnetic field plane may extend parallel to the top surface of the substrate and / or the electrode surface. The segments are either positioned within the substrate or embedded within it, respectively. The magnetic field plane may extend through the substrate. The electrodes and / or default lines may be offset from the magnetic field plane. However, due to the small distance of the default lines from the top surface, and together with this, due to the small distance of the default lines to the magnetic field plane, e.g., up to 100 μm, the magnitude of the magnetic field along the default lines is still sufficient to perform quantum computations.

[0055] According to at least one embodiment, the quantum computing device further comprises a yoke structure for increasing the magnetic field and / or the change in the magnitude of the magnetic field along a predetermined line established by a permanent magnet device. The yoke structure is positioned to increase the magnetic field or magnetic field gradient, in particular, in the region of trapped ions, i.e., along the predetermined line. For example, the yoke structure includes or consists of a soft magnetic material. It may have a coercivity of up to 1000 A / m, or up to 100 A / m. The soft magnetic material may be a ferromagnetic material configured to be magnetized by the magnetic field established by the permanent magnet device. The soft magnetic material may have a magnetic permeability of at least 300, or at least 1000, or at least 10000. Exemplarily, the soft magnetic material has a magnetic permeability of about 12000. The saturation magnetic flux density of the soft magnetic material may be at least 0.5 T, or at least 2 T. For example, soft magnetic materials contain at least one of the following: iron-cobalt, vanadium, manganese, niobium, silicon, and carbon.

[0056] A yoke structure may extend along or parallel to a predetermined line. For example, a yoke structure may include two parts spaced apart from each other in a direction parallel to a predetermined line. Each of the two parts may be elongated and may extend, for example, along or parallel to a predetermined line. That is, the elongated parts may be oriented parallel to a predetermined line.

[0057] The steepness of the magnetic gradient can be further enhanced by using a yoke structure to concentrate the magnetic flux. The yoke structure is placed in a region where, for example, the magnitude of the magnetic field in the permanent magnet device is already small, and the magnetic field is concentrated in a small cross-section of the yoke structure without exceeding the saturation magnetization of the yoke structure, thus substantially boosting the magnitude of the achievable gradient, enabling lower crosstalk, stronger coupling, and faster quantum gates.

[0058] According to at least one embodiment, the yoke structure is either placed within the substrate or embedded within it. In particular, at least two elongated portions of the yoke structure may be placed within the substrate. For example, the yoke structure is embedded within the substrate.

[0059] Alternatively, the yoke structure may be placed on the upper surface of the substrate. Similarly, a permanent magnet device, for example, at least some of its segments, may be placed on the upper surface of the substrate.

[0060] According to at least one embodiment, the yoke structure is formed at least partially by electrodes of a planar pole trap. For example, at least some electrodes of the planar pole trap constitute part of the yoke structure. In other words, at least some electrodes of the pole trap include or may consist of a soft magnetic material to increase the magnetic field or magnetic field gradient established by the permanent magnet device.

[0061] According to at least one embodiment, the yoke structure comprises or consists of an iron-cobalt alloy. The iron-cobalt alloy may contain vanadium in a concentration of, for example, at least 1.5% and up to 3%.

[0062] According to at least one embodiment, the change in the magnetic field along a predetermined line at the center of the magnetic field is at least 0.5 T / m, or at least 50 T / m, or at least 100 T / m, and / or up to 500 T / m.

[0063] According to at least one embodiment, the planar pole trap is a segmented planar pole trap. The planar pole trap is configured, for example, to generate several electric potential wells. Each potential well is configured, for example, to host or trap an ion crystal, each ion crystal having several ions arranged along a predetermined line. An electrical potential wall separating two adjacent ion crystals may be placed between the electric potential wells.

[0064] All features disclosed herein for one ionic crystal are also disclosed for all further ionic crystals.

[0065] The individual default lines assigned to different ion crystals can all be straight lines. For example, they can all coincide with the same straight line. Alternatively, the individual default lines assigned to individual ion crystals can be different from each other, for example, they can be offset from each other and / or at different heights relative to the top surface of the substrate. The individual lines can still be parallel to each other.

[0066] The potential wells and / or ion crystals are arranged behind each other, for example, in a direction parallel to a predetermined line, or in a direction parallel to one of the individual predetermined lines.

[0067] According to at least one embodiment, a quantum computing device is configured to enable interactions between ion crystals by ion transport and / or photonic links. For example, a photon emitted by an ion in one ion crystal may interact with an ion in an adjacent ion crystal. Alternatively, one or more ions may be moved from one ion crystal to an adjacent ion crystal by changing the potential wall between two adjacent potential wells. For example, the potential wall may be made shallow and / or narrow so that ions hop from one ion crystal to an adjacent ion crystal.

[0068] Planar segmentation traps allow for a number of registers that can be controlled independently by RF, but can also interact with each other via ion transport or photonic links.

[0069] According to at least one embodiment, a segmented planar pole trap is configured to merge two adjacent potential wells into a larger potential well. For example, the potential wall between two adjacent potential wells may be resolved to create one larger potential well from two smaller potential wells.

[0070] According to at least one embodiment, a segmented planar pole trap is configured to divide one potential well into two adjacent, smaller potential wells. For example, a potential wall may be generated within the potential well such that the two smaller potential wells are separated by the potential wall.

[0071] The terms “smaller” and “larger” used in conjunction with potential wells specifically refer to the smaller or larger range of potential wells in a direction parallel to a predetermined line.

[0072] According to at least one embodiment, the planar pole trap comprises an inner electrode structure, two outer electrode structures, and two intermediate electrode structures. Each of these electrode structures may include or consist of multiple electrodes spaced apart from each other, or it may consist of a single, continuous electrode.

[0073] According to at least one embodiment, an inner electrode structure is positioned between intermediate electrode structures, and an intermediate electrode structure is positioned between outer electrode structures. For example, in a transverse direction parallel to the top surface or electrode surface and perpendicular to a predetermined line, the inner electrode structure is positioned between intermediate electrode structures, and an intermediate electrode structure is positioned between outer electrode structures.

[0074] According to at least one embodiment, the electrode structures each extend parallel to a predetermined line. For example, each electrode structure is an elongated structure whose main direction of extension is parallel to a predetermined line.

[0075] According to at least one embodiment, the outer electrode structure each comprises at least three electrodes, namely two end electrodes and at least one central electrode. The at least one central electrode is positioned between the two end electrodes in a direction parallel to a predetermined line. The inner electrode structure and the intermediate electrode structure may each consist of only one elongated electrode in a direction parallel to a predetermined line.

[0076] According to at least one embodiment, the inner electrode structure comprises at least one electrode. Each intermediate electrode structure includes at least one electrode. The electrodes of the inner and intermediate electrode structures extend, for example, in a direction parallel to a predetermined line. Thus, these electrodes may extend across at least three electrodes of the outer electrode structure in a direction parallel to the predetermined line.

[0077] According to at least one embodiment, the intermediate electrode structure is an RF electrode structure. During operation, an AC voltage is supplied to the RF electrode structure. With the help of the RF electrode structure, an oscillating potential is generated to confine ions in a direction perpendicular to a predetermined line, i.e., radially.

[0078] According to at least one embodiment, the inner electrode structure is a DC electrode structure. For example, the inner electrode structure is grounded during the operation of a planar pole trap.

[0079] According to at least one embodiment, in each outer electrode structure, at least one central electrode is controllable independently of the end electrodes. That is, at least one central electrode can be set to a different potential from the end electrodes. As a result, a potential that traps ions in a direction parallel to a predetermined line can be generated. Thus, as a whole, a potential well is generated for hosting an ion crystal having several ions aligned along a predetermined line.

[0080] The end electrodes constitute, for example, the end cap electrodes of a planar pole trap. At least one central electrode constitutes, for example, the DC electrode of a planar pole trap. For example, when the central electrode is at a lower potential than the end electrodes, a potential well for hosting an ion crystal is formed.

[0081] According to at least one embodiment, each outer electrode structure comprises at least five electrodes.

[0082] According to at least one embodiment, in each outer electrode structure, at least the first and second central electrodes are controllable independently of the third central electrode. That is, the third central electrode can be set to a different potential than the first and second central electrodes. For example, the potential of the third central electrode can be changed.

[0083] The third central electrode is positioned between the first and second central electrodes in a direction parallel to a predetermined line, for example, adjacent to the first and second central electrodes. The central electrodes are positioned between the end electrodes in a direction parallel to a predetermined line. In this way, at least two potential wells can be generated, positioned one behind the other in a direction parallel to a predetermined line. Each potential well is configured to host an ion crystal, that is, to confine a plurality of ions aligned along a predetermined line.

[0084] For example, the first and second central electrodes are each assigned potential wells such that their assigned potential wells, for example, their minimum value, align with the respective central electrodes in a direction parallel to a predetermined line. The third central electrode may be assigned a potential wall between potential wells. The potential wall may be aligned with the third central electrode in a direction parallel to a predetermined line. For example, the third central electrode generates a potential wall.

[0085] During operation, the third central electrode may be at the same potential as the end electrodes, or at the same potential as the first and second central electrodes of the respective outer electrode structures. For example, the potential of the third central electrode may be variable between the potentials of the end electrodes and the potentials of the first and second central electrodes. The potential of the third central electrode may be controllable independently of the potentials of the end electrodes in order to decompose or establish potential walls between potential wells. The first and second central electrodes may be grounded during operation, for example.

[0086] The electrodes of two corresponding external electrode structures can be electrically connected such that they are at the same potential.

[0087] A planar pole trap can also be formed by multiple electrodes arranged on the upper side of a substrate in a pixel arrangement. For example, each electrode may be rectangular or square, and the electrodes may be arranged in a rectangular pattern on the upper surface. All electrodes may be individually and independently controllable using radio frequency (RF) or DC voltage.

[0088] According to at least one embodiment, the quantum computing device comprises at least two permanent magnet devices. Each of the two permanent magnet devices may comprise several segments, each having a magnetization direction. All features disclosed in relation to one permanent magnet device are also disclosed for the other permanent magnet device. In particular, each permanent magnet device may be a Halbach array and / or be incorporated into a substrate.

[0089] According to at least one embodiment, the permanent magnet devices are configured such that each generates a magnetic field. For example, for each permanent magnet device, the magnitude of its respective magnetic field varies along a predetermined line. By using two such permanent magnet devices, a zone of high control and / or steep magnetic field changes can be combined with a zone of low and / or nearly constant magnetic field for noncritical ion transport. For example, the permanent magnet devices are arranged one behind the other in a direction parallel to the predetermined line.

[0090] According to at least one embodiment, each potential well or ion crystal is assigned an individual permanent magnet device.

[0091] According to at least one embodiment, each permanent magnet device is configured such that the magnitude of its magnetic field varies along a predetermined line of the assigned ion crystal. For example, the center of each permanent magnet device, or the center of the magnetic field established by that permanent magnet device, is aligned with the assigned potential well (e.g., its minimum value) in a direction parallel to and / or transverse to the respective predetermined line.

[0092] For example, the center of each permanent magnet device, or the center of the magnetic field established by that permanent magnet device, is aligned with the central electrode of the outer electrode structure in a direction parallel to a predetermined line. The center of the first permanent magnet device may be aligned with the first central electrode, and the center of the second permanent magnet device may be aligned with the second central electrode. In the top plan view, the centers of the permanent magnet devices may overlap with the inner electrode structure.

[0093] According to at least one embodiment, the quantum computing device comprises a vacuum chamber. During operation, ions are trapped within the vacuum chamber. Planar pole traps, or their electrodes, may also be located within the vacuum chamber. The vacuum chamber may be an ultra-high vacuum chamber, an extremely high vacuum chamber, and / or a cryostat.

[0094] According to at least one embodiment, the permanent magnet device is located outside the vacuum chamber. This can be advantageous because generating an ultra-high vacuum, abbreviated as UHV, may involve steps such as baking, which can be incompatible with many magnetic materials, especially those with low Curie temperatures. Even when the permanent magnet device is located outside the vacuum chamber, it still generates a sufficiently high magnetic field or magnetic field gradient in the ionic region. Alternatively, the permanent magnet device may also be located inside the vacuum chamber. An optional yoke structure may be located inside or outside the vacuum chamber and may increase the magnetic field (gradient).

[0095] Next, a quantum computer is identified. A quantum computer includes the quantum computing device described herein. Therefore, all the features disclosed for a quantum computing device are also disclosed for a quantum computer, and vice versa.

[0096] A quantum computer is configured to perform quantum computing processes by using a quantum computing device. The trapped ions in the quantum computing device can be controlled and manipulated particularly well using the permanent magnet device described herein to perform a predetermined quantum computation.

[0097] According to at least one embodiment, the quantum computer further comprises a cooling and / or read-out system. The cooling and / or read-out system is, for example, laser-based. The cooling system is configured to cool the ions in order to prepare them to a low-motional state and to trap them in their respective ground state. The read-out system is configured to determine the state of each ion. For example, the ions are cooled and / or read out by colliding with a laser beam or by scattering photons from a laser beam. [Brief explanation of the drawing]

[0098] Hereafter, quantum computing devices and quantum computers will be described in more detail with reference to the drawings, based on exemplary embodiments. The accompanying drawings are included for further understanding. In the drawings, elements relating to the same structure and / or function may be referred to by the same reference numeral. It should be understood that the embodiments shown in the figures are exemplary representations and are not necessarily drawn to scale. To the extent that elements or components correspond to each other in terms of their function in different figures, the description will not be repeated for each of the following figures. For clarity, elements may not appear with corresponding reference numerals in all figures. [Figure 1] Figure 1 shows an exemplary first embodiment relating to a quantum computing device. [Figure 2]Figure 2 shows an exemplary embodiment of a planar pole trap in a different diagram. [Figure 3] Figure 3 shows an exemplary embodiment relating to a planar pole trap in a different figure. [Figure 4] Figure 4 shows an exemplary second embodiment relating to a quantum computing device from a different perspective. [Figure 5] Figure 5 shows an exemplary second embodiment relating to a quantum computing device from a different perspective. [Figure 6] Figure 6 shows a further exemplary embodiment relating to a planar pole trap. [Figure 7] Figure 7 shows a further exemplary embodiment relating to a quantum computing device. [Figure 8] Figure 8 shows a further exemplary embodiment relating to a quantum computing device. [Figure 9] Figure 9 shows an exemplary embodiment relating to a quantum computer. [Modes for carrying out the invention]

[0099] Figure 1 shows an exemplary first embodiment relating to a quantum computing device 1. The quantum computing device 1 comprises a permanent magnet arrangement 2. The permanent magnet arrangement 2 comprises 16 permanently magnetized segments 3. The segments 3 surround a planar pole trap 100. Each planar pole trap 100 is configured to trap an ion crystal 6a having a plurality of ions 6 aligned along a predetermined line 7, i.e., a trap line 7. In this exemplary embodiment, the planar pole trap 100 is a linear planar pole trap for trapping ions 6 along a straight line 7. The straight line 7 defines the x-axis.

[0100] The permanent magnet device 2 has a ring shape, and a planar pole trap 100 is positioned at the center of the ring. The thickness of each segment 3 is, for example, 100 μm. The ring extends in the xy plane. Each segment 3 has the shape of a ring segment. The minimum distance between two opposing segments 3, i.e., the inner ring diameter 2Ri, is approximately 0.2 mm. Furthermore, each segment 3 has a range of approximately 0.2 mm along its corresponding minimum distance. The outer diameter 2Ro of the permanent magnet device 2 is therefore approximately 0.6 mm. The edges of mutually opposing and directly adjacent segments 3 have a distance of approximately 10 μm from each other.

[0101] Furthermore, each segment 3 has a magnetization direction 4, which is depicted as an arrow within the segment 3 in Figure 1. Each segment is formed of, for example, NdFeB N52. The magnetization directions 4 of segments 3 located in regions opposite the center of the permanent magnet device 2 are oriented in opposite directions. A predetermined line 7 extends through the center of the permanent magnet device 2 and intersects with two opposing segments 3. Here, the magnetization directions 4 of these two segments 3 are parallel to the predetermined line 7.

[0102] Each magnetization direction 4 forms an angle with a predetermined line 7. All of these angles are formed to be different from each other. For example, the angles of two directly adjacent segments 3 differ from each other by 67.5°. All magnetization directions 4 lie in the xy-plane.

[0103] The permanent magnet device in Figure 1 is a Halbach arrangement that establishes a quadrupole field with a magnetic field magnitude that varies along a predetermined line 7. In other words, the magnetic field has a magnetic field gradient along the predetermined line 7. For example, each of the trapped ions arranged along the predetermined line therefore experiences a different magnetic field.

[0104] Using the permanent magnet device in Figure 1, the following ideal magnetic flux density

number

number

[0105] The remanent magnetic flux density (remanence) of each segment 3 is B. R For example, this is 1T. As can be extracted from this ideal magnetic flux density, the magnetic field is primarily a two-dimensional magnetic field, concentrated in the xy-plane that constitutes the magnetic field plane.

[0106] Figures 2 and 3 show the planar pole trap 100 of Figure 1 from two different viewpoints. The planar pole trap 100 comprises several electrodes 20, 30, 40a, and 40b configured to generate a potential to trap ions 6 along a predetermined 7. The electrodes 20, 30, 40a, and 40b are all located on the top side 51 of the substrate 50 and are all on a common electrode surface EP. Figure 2 is a plan view of the top side 51, where Figure 3 is a cross-sectional view perpendicular to the top side 51.

[0107] The electrodes 20, 30, 40a, and 40b are made of, for example, Au. The substrate 50 may be a sapphire substrate.

[0108] Electrodes 20, 30, 40a, and 40b are part of an inner electrode structure 32, two intermediate electrode structures 22, and two outer electrode structures 42. The inner electrode structure 32 is formed by one continuous elongated electrode 30 extending parallel to the predetermined line 7. Each intermediate electrode structure 22 is also formed by one continuous elongated electrode 20 extending parallel to the predetermined line 7. The inner electrode structure 32 is thus positioned between the intermediate electrode structures 22 in a transverse direction perpendicular to the direction of the predetermined line 7. The intermediate electrodes 20 are RF electrodes to which an AC voltage is supplied during operation. The inner electrodes 30 are DC electrodes, for example, which are grounded during operation. Alternatively, the inner electrodes 30 may be RF electrodes. With the help of the inner electrodes 30 and the intermediate electrodes 20, an oscillating electrical potential is generated, which, in particular, confines ions radially, i.e., perpendicular to the predetermined line 7.

[0109] Each outer electrode structure 42 comprises three electrodes 40a, 40b. The inner electrode structure 32 and the intermediate electrode structure 22 are positioned between the outer electrode structures 42 in the lateral direction. The electrodes 40a, 40b of the outer electrode structures 42 are arranged in a line behind the other, where this line is parallel to the predetermined line 7. The end electrodes 40a of each outer electrode structure 42 constitute an end cap electrode, which is at the same potential, for example, during operation. The central electrode 40b, positioned between the end electrodes 40a, is grounded, for example, during operation.

[0110] The potential V(x,0,0) along the x-axis (default line 7) generated by electrodes 20, 30, 40a, and 40b is shown in the graph of Figure 2. Overall, a potential well W is formed that traps ions 6. The ions 6 in the potential well W form a linear ion crystal 6a.

[0111] The diagram in Figure 2 also shows the magnitude of the magnetic field on the x-axis generated by the permanent magnet device 2 in Figure 1, i.e., the magnitude of the magnetic flux density |B(x,0,0)|.

[0112] As best illustrated in Figure 3, the yoke structure 60 is embedded in the substrate 50. The yoke structure 60 comprises two parts spaced apart from each other in a direction parallel to a predetermined line 7. Each part of the yoke structure 60 is an elongated element and is made of a soft magnetic material. The yoke structure 60 increases the magnetic field along the predetermined line 7 and its gradient.

[0113] The ions 6 shown in Figures 1 to 3 are, for example, 171Yb+ ions. The distance d between directly adjacent trapped ions is, for example, approximately 3 μm. The degeneracy of the excited quantum state is resolved by the magnetic field generated by the permanent magnet device 2. The energy of the π-transition from the ground quantum state to the excited m=0 quantum state is weakly dependent on the magnetic field acting on the ion. Similarly, the energy of the σ± transition from the ground quantum state to the excited m=±1 quantum state depends on the magnetic field acting on the ion. Since the magnitude of the magnetic field depends on the position of ion 6 along a predetermined line 7, the energy of the transitions depends on the position along the predetermined line 7. For example, for each of two adjacent ions 6, the frequency difference of the σ+ / - transition is at least 1 MHz and at most 100 MHz. Furthermore, for each of two adjacent ions 6, the frequency difference of the π-transition is at least 0.001 MHz and at most 10 MHz.

[0114] Furthermore, due to the shape of the potential well W along the predetermined line 7 and the magnetic field provided by the permanent magnet device 2, the equilibrium position of the ions 6 depends on their respective quantum states. Thus, an effective spin-spin coupling between the ions 6 is realized through Coulomb interaction. This allows the quantum states of the ions 6 to be entangled.

[0115] In particular, the coupling strength between two directly adjacent trapped ions 6 depends on the square of the magnetic field gradient. Furthermore, the relaxation time, especially the spin relaxation time T2, is inversely proportional to the decoherence rate. Therefore, in order to provide multi-qubit gates, the magnetic field gradient must be relatively high so as to provide a large number of gates within a given time. This can be achieved by the permanent magnet apparatus described herein.

[0116] Figures 4 and 5 show further exemplary embodiments relating to the quantum computing device 1. In contrast to the quantum computing device of Figure 1, a permanent magnet device 2, each containing a plurality of permanent magnetization segments 3, is disposed within or embedded in the substrate 50. The permanent magnet device 2 is shown by dashed lines in Figure 4.

[0117] The magnetic field plane BP, where the magnetic field established by the permanent magnet device 2 primarily resides, is located within the substrate 50. The default line 7 is therefore offset from the magnetic field plane BP. However, since the distances of the default line 7 or ion 6 to the magnetic field plane BP are small, for example less than 150 μm, ion 6 still feels a magnetic field sufficient to enable proper quantum computing operation.

[0118] Figure 6 shows a further exemplary embodiment of the planar pole trap 100, which can be used, for example, in conjunction with an integrated permanent magnet configuration as shown in Figures 4 and 5, or with a surrounding permanent magnet configuration as shown in Figure 1. In contrast to the planar pole traps 100 of Figures 2 to 5, the planar pole trap 100 of Figure 6 comprises an outer electrode structure 42, with five electrodes 40a, 40b, and 40c, each positioned front to back in a direction parallel to a predetermined line 7. Each outer electrode structure 42 comprises two end electrodes 40a and three central electrodes 40b, and 40c.

[0119] The third central electrode 40c is positioned between the first central electrode 40b and the second central electrode 40b. The third central electrode 40c can be controlled independently of the other central electrodes 40b. For example, during operation, the third central electrode 40c can be set to the same potential as the end electrodes 40a, where the first and second central electrodes 40b can be grounded.

[0120] The result is the potential V(x,0,0) in the x-direction, as shown in Figure 6. Two adjacent potential wells W are generated, positioned one behind the other in a direction parallel to the predetermined line 7. Each potential well W confines and hosts ion crystals 6a, 6b containing multiple ions 6 aligned along the predetermined line 7. The two potential wells W are separated from each other by a potential wall mainly attributable to the third central electrode 40c.

[0121] The ion crystals 6a and 6b in Figure 6 can interact with each other, for example, by photonic links. Alternatively, the ion crystals 6a and 6b can interact with each other by ion transport. For example, by changing the potentials of electrodes 40a, 40b, and 40c of the outer electrode structure 42, the shape of the potential V(x, 0, 0) in the x-direction can be changed, and ions 6 can be transported from one ion crystal 6a to an adjacent ion crystal 6b. As one example, if the third central electrode 40c is set to the same potential as the first and second central electrodes 40b, the two potential wells W shown in Figure 6 can be merged into one larger potential well, and the two separate ion crystals 6a and 6b can then be merged into one larger ion crystal 6a.

[0122] Figure 7 shows an exemplary embodiment of the quantum computing device 1. Here, two permanent magnet devices 2 are embedded in the substrate 50 of the planar pole trap 100, each in the form of a Halbach array. The permanent magnet devices 2 are thereby positioned behind each other in a direction parallel to the predetermined line 7, and the centers of the permanent magnet devices 2 coincide with the predetermined line 7 in the plan view of the top surface 51. The two permanent magnet devices 2 are arranged so that each of them is uniquely assigned to the potential well W and the respective ion crystals 6a and 6b.

[0123] In the exemplary embodiment shown in Figure 8, the permanent magnet device 2 surrounds the planar pole trap 100 in the form of a polygonal contour. Each segment 3 has a square shape. Adjacent segments 3 are rotated relative to each other.

[0124] As can be seen further in Figure 8, the pole trap 100 is located inside the chamber 10, and the chamber 10 is surrounded by the permanent magnet device 2. The chamber 10 is, for example, an ultra-high vacuum chamber.

[0125] Figure 9 shows one exemplary embodiment relating to a quantum computer 8. The quantum computer 8 comprises a quantum computing device 1 according to one of the exemplary embodiments described herein. The planar pole trap 100 is connected to the external components of the quantum computer 8 via a chamber 10 by a plurality of connectors 11. For example, the connectors 11 connect the planar pole trap 100 to externally controlled electronics 12 and a classical computer 13.

[0126] The quantum computing device 1 is configured to trap ions, manipulate the trapped ions, and perform measurements. For this purpose, the quantum computing device 1 may include an optical guide and / or internal electronics, including electronic devices, in addition to the permanent magnet device 2 and any components of the planar pole trap 100. The electronic devices may include detectors, controllers, etc., such as circuits, integrated electronics, power supplies, and / or photon detectors and / or charge detectors. Exemplarily, the internal electronics are provided for pre-processing. For example, these components enable measurement of each state of the ions and enable gate operations on the ions. Thus, the quantum computing device 1 is configured to trap ions and perform calculations and measurements on the trapped ions.

[0127] The pole trap 100 is installed inside the chamber 10, which may be an ultra-high vacuum chamber, an extremely high vacuum chamber, and / or a cryostat. The permanent magnet device 2 can be located outside the chamber 10. In this case, the permanent magnet device 2 surrounds the chamber 10. Alternatively, the permanent magnet device 2 can be located inside the chamber 10 (not shown here).

[0128] The quantum computing device 1, in particular the pole trap 100, is connected to an external electronic device 12 via a connection 11. The external electronic device 12 may be located at least partially inside the chamber 10 and partially outside the chamber 10. Furthermore, the external electronic device 12 is connected to a classical computer 13.

[0129] The external electronic equipment 12 includes, for example, an analog-to-digital converter, and signal generators such as a radio frequency generator, a microwave signal generator, a low-frequency signal generator, and / or a DC signal generator. Furthermore, the external electronic equipment 12 may include transistor-to-transistor logic (TTL).

[0130] Additionally, the external electronic equipment 12 may further include at least one laser-based system configured to cool the trapped ions. Furthermore, the laser-based system may be configured to excite a specific state of the trapped ions and / or to read out a specific state of the ions.

[0131] A classical computer 13 is configured, for example, to provide and receive digital signals. These digital signals correspond to control signals used for operations on qubits / ions, as well as measurement signals corresponding to the state of the qubits.

[0132] The external electronic device 12 is configured, among other things, to convert digital signals to analog signals and vice versa. Thus, the external electronic device 12 is configured to provide the converted analog signals for manipulating ions (qubits) to the quantum computing device 1. Furthermore, the external electronic device 12 is configured to process such signals to provide the measured analog signals from the quantum computing device 1 to the classical computer 13, or to directly initiate any response signals generated by the control electronic device 12.

[0133] The classical computer 13 is exemplary configured to have a specific algorithm, i.e., a default quantum computation for solving a specific problem. The classical computer 13 is then configured to translate the compiled code corresponding to the algorithm into commands for the quantum computing device 1. The commands are then transferred to the quantum computing device 1 via the external control electronic equipment 12. Furthermore, the classical computer 13 is configured to receive the measured results of the specific algorithm.

[0134] For example, all elements of quantum computer 8, especially all electronic elements of quantum computer 8, are synchronized by, for example, an atomic clock reference.

[0135] The present invention is not limited to the exemplary embodiments described herein. Rather, the present invention encompasses any new features and any combination of features. This includes, in particular, any combination of features in the claims, even if the feature or combination itself is not expressly shown in the claims or exemplary embodiments. [Explanation of Symbols]

[0136] Reference code list: 1. Quantum computing device 2. Permanent magnet device 3 segments 4 Magnetization direction 6 Ions 6a, 6b Ion Crystal 7 Default lines 8. Quantum Computers 10 Chambers 11 connections 12 Control Electronic Equipment 13 Classical Computers 20 electrodes 22 Intermediate electrode structure 30 electrodes 32 Inner electrode structure 40a, b, c electrodes 42 Outer electrode structure 50 circuit boards 51 Top side 60 Yoke Structure 100 Pole Traps Ri inner radius Ro outer radius BP magnetic field EP electrode surface W potential well V(x,y,z) potential B(x,y,z) Magnetic flux density

Claims

1. A quantum computing device, Permanent magnet device, Including a substrate, The quantum computing device is configured to implement a planar pole trap to trap at least one ion crystal having multiple ions arranged along a predetermined line, The components of the quantum computing device that constitute the electrodes of the planar pole trap to generate an electrical trapping potential are arranged on the upper surface of the substrate. The aforementioned predetermined line is positioned above the upper surface, The permanent magnet device establishes a magnetic field, and the magnitude of the magnetic field changes along the predetermined line. The aforementioned permanent magnet device comprises a plurality of permanent magnetization segments, Each segment has a magnetization direction, and The aforementioned segments are arranged in a Halbach arrangement. Quantum computing device.

2. The permanent magnet device surrounds the planar pole trap in the form of a ring or a polygonal outline. The quantum computing device according to claim 1.

3. All electrodes of the aforementioned planar pole trap are arranged on a common electrode surface (EP). The quantum computing device according to claim 1.

4. At least a portion of the permanent magnet device is arranged on the substrate. The quantum computing device according to claim 1.

5. The aforementioned quantum computing device, further, A yoke structure for increasing the change in the magnetic field and / or the magnitude of the magnetic field along the predetermined line established by the permanent magnet device, A quantum computing device according to claim 1, including the above.

6. The yoke structure is disposed on the substrate, The quantum computing device according to claim 5.

7. The yoke structure includes a soft magnetic material, The quantum computing device according to claim 5.

8. The aforementioned planar pole trap is a segmented planar pole trap configured to generate multiple potential wells, Each potential well is configured to host an ion crystal having multiple ions arranged along a predetermined line. The quantum computing device according to claim 1.

9. The quantum computing device is configured to enable interaction between the ion crystals by ion transport and / or photonic linking. The quantum computing device according to claim 8.

10. The segmented planar pole trap is Merging two adjacent potential wells into a larger potential well, and / or, Dividing one potential well into two adjacent, smaller potential wells. It is structured in such a way. The quantum computing device according to claim 8.

11. The planar pole trap comprises an inner electrode structure, two outer electrode structures, and two intermediate electrode structures. The inner electrode structure is positioned between the intermediate electrode structures, and the intermediate electrode structure is positioned between the outer electrode structures. The electrode structure extends parallel to the predetermined line, Each of the outer electrode structures comprises two end electrodes, each having at least three electrodes, and at least one central electrode positioned between the end electrodes in a direction parallel to the predetermined line. The inner electrode structure comprises at least one electrode, and each of the intermediate electrode structures comprises at least one electrode. The aforementioned intermediate electrode structure is an RF electrode structure to which an AC voltage is supplied, In each outer electrode structure, the at least one central electrode is controllable independently of the end electrodes to generate at least one potential well for hosting an ion crystal having a plurality of ions arranged along the predetermined line. The quantum computing device according to claim 1.

12. Each outer electrode structure is equipped with at least five electrodes. In each outer electrode structure, at least the first and second central electrodes are controllable independently of the third central electrode positioned between the first and second central electrodes to generate at least two potential wells positioned behind each other in a direction parallel to a predetermined line, and each potential well is configured to host an ion crystal. The quantum computing device according to claim 11.

13. The aforementioned quantum computing device, Includes at least two permanent magnet devices, Each of the aforementioned permanent magnet devices is configured to generate a magnetic field. The quantum computing device according to claim 1.

14. Each ion crystal is assigned an individual permanent magnet device. Each permanent magnet device is configured such that the magnitude of the magnetic field changes along the predetermined line relating to the assigned ion crystal. The quantum computing device according to claim 13.

15. A quantum computer configured to perform quantum computations, A quantum computing device comprising the one described in any one of claims 1 to 14, Quantum computer.

16. The aforementioned quantum computer further, Equipped with a laser-based cooling and / or readout system, The quantum computer according to claim 15.

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