Quantum computing device and quantum computer

Abstract

A quantum computing device (1) is proposed, comprising a permanent magnet device (2) and a substrate (50). The quantum computing device is configured to implement a planar Porro trap (100) for capturing at least one ionic crystal (6a, 6b) having a number of ions (6) arranged along a predefined line (7). Components of the quantum computing device, which form electrodes (20, 30, 40a, 40b) of a planar Porro trap for establishing an electrically trapping potential, are arranged on a top side (51) of a substrate (50). The predefined line is located above the top side (51). The permanent magnet arrangement establishes a magnetic field, wherein the magnitude of the magnetic field varies along a predefined line. Furthermore, a quantum computer (8) comprising the quantum computing device (1) is proposed.

Description

[0001] The present disclosure relates to quantum computing devices and quantum computers.

[0002] In many quantum computing processes using quantum computing devices, the device is configured to trap quantum particles, such as ions. During operation, the trapped quantum particles form quantum bits, or qubits for short. In order to perform calculations, the trapped quantum particles must be controlled and manipulated. For trapped quantum particles, interactions such as, for example, Coulomb repulsion can produce coupling to adjacent trapped quantum particles, and thus entanglement can be achieved. In order to perform quantum computing processes using trapped quantum particles, the trapped quantum particles must be controllable and individually addressable to each other.

[0003] It is desirable to individually address multiple trapped quantum particles (e.g., qubit registers) with negligible crosstalk. However, in quantum computer processing, crosstalk between adjacent trapped quantum particles is often a difficult-to-control source of error and hinders valuable applications of quantum error correction protocols and, therefore, scalability.

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

[0005] These objects are solved in particular by the subject matter of claim 1 and claim 16. Advantageous embodiments and further developments are subject matter of the dependent claims and can also be taken from the following description and the drawings.

[0006] First, a quantum computing device is described.

[0007] According to at least one embodiment, the quantum computing device includes a permanent magnet device. For example, the permanent magnet device is symmetrical with respect to a symmetry plane, in particular geometrically symmetrical. This means that the geometric shape or shape of the permanent magnet device is symmetrical with respect to the symmetry plane. The geometric shape of the permanent magnet device can also have rotational symmetry, for example, n-fold rotational symmetry with n being at least 3 or at least 4 or at least 6 or at least 8.

[0008] According to at least one embodiment, a quantum computing device includes a substrate. The substrate may be an electrically isolated substrate. The substrate may include or consist of sapphire or diamond or ceramic (such as AlN).

[0009] According to at least one embodiment, the quantum computing device is configured to implement a planar Paul trap for trapping at least one ion crystal having a number of ions arranged along a predefined line. In other words, during operation, the quantum computing device, i.e. at least a portion thereof, constitutes a planar Paul trap. A Paul trap is also known as a quadrupole ion trap or a radio frequency (RF) trap. It is an ion trap that uses a dynamic electric field to capture charged particles.

[0010] The planar Paul trap is configured to trap at least one ion crystal having two or more ions arranged along a predefined line, for example at least 8 or at least 20 or at least 100 and / or at most 1000 ions.

[0011] According to at least one embodiment, the components of the quantum computing device that constitute the electrodes for generating electric trapping potential of the planar Paul well (hereinafter simply referred to as the electrodes of the planar Paul well) are arranged on the top side of the substrate. In particular, all electrodes of the planar Paul well using which the electric trapping potential is generated are arranged on the top side of the substrate.

[0012] For example, the top side of the substrate is a planar top side. The substrate may be part of a planar Paul well. The electrode may be applied to the substrate by means of a deposition method such as sputtering or evaporation. The thickness of the electrode may be increased by using a galvanic process. The substrate may mechanically stabilize the electrode. Between the electrode and the top side, there may be an adhesion layer for improving the adhesion of the electrode to the top side.

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

[0014] The electrodes of the planar Paul trap may be different from the permanent magnet device. Therefore, the planar Paul trap may be a separate device of the quantum computing device different from the permanent magnet device. Alternatively, one or more components of the permanent magnet device also form the electrodes of the planar Paul trap, so that the planar Paul trap is at least partially formed by the permanent magnet device.

[0015] During operation, the electrodes of the planar Paul trap create an oscillating potential configured to capture at least one ion crystal having a plurality of ions arranged in a direction parallel to a predefined line and in a direction perpendicular to the predefined line (also referred to herein as radial). In practice, at least one potential well is created in which ions are captured in all spatial directions and formed such that the ions are arranged one after another along the predefined line, for example in a linear arrangement. Multiple ions captured in the same potential well are referred to herein as an ion crystal.

[0016] The predefined line, also referred to as the trap line, is defined by the potential generated by the planar Paul trap, so the predefined line depends on the geometry of the planar Paul trap. The trapped ions are arranged along the predefined line. For example, each of the ions of at least one ion crystal intersects with the predefined line and / or oscillates around the predefined line. In other words, in the Paul trap, the ions of at least one ion trap are arranged in an ion chain extending along the predefined line. The predefined line can be parallel to the top side of the substrate.

[0017] Each electrode may be formed as a plate or sheet or a film.For example, the main extension plane of the electrode is parallel to the top side.

[0018] The electrodes can each be formed by a metal. For example, they are formed by Au or another material such as Cu. In this case, the electrodes can be coated with Au. Each electrode is (in particular) a continuous metal element without interruption. For example, the extension of the electrode along its respective main extension plane is at most 300 mm or at most 50 mm or at most 10 mm or at most 1 mm. The thickness of the electrode measured perpendicular to the main extension plane is, for example, at most 100 μm or at most 50 μm.

[0019] In addition to electrodes for the Paul trap, the quantum computing device may further include components for powering the electrodes, such as a power supply and / or a control unit.

[0020] According to at least one embodiment, the quantum computing device is configured so that the predefined line is located above the top side, i.e., has an offset relative to the top side and has an offset relative to the substrate. In particular, the predefined line can be arranged above the electrodes of the planar Paul trap. This means that during operation, the ions float above the electrodes of the planar Paul trap or above the top side, respectively. For example, in a direction perpendicular to the top side, all electrodes of the Paul trap are arranged in front of the predefined line or arranged behind the predefined line, i.e., in front of or behind the ions.

[0021] By way of example, the average distance between the top side and the predefined line measured in a direction perpendicular to the top side 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 arrangement creates a magnetic field, the magnitude of which thus varies along a predefined line.

[0023] The magnetic field is understood in this article as the magnetic flux density. Therefore, the magnitude of the magnetic field is the absolute value of the magnetic flux density.

[0024] The magnetic field created by the permanent magnet device is, for example, a quadrupole magnetic field or includes a quadrupole magnetic field. Higher multipole moments may also exist. At the center of the magnetic field, the absolute value of the magnetic field may be zero. The center of the magnetic field may coincide with the geometric center of the permanent magnet device and / or the planar Paul trap. For example, the center of the magnetic field is located in the symmetry plane of the permanent magnet device and / or on a predefined line. The magnetic field may be point-symmetric relative to its center.

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

[0026] The change in the magnitude of the magnetic field may be monotonic, for example strictly monotonic at least in sections. For example, starting from the center of the magnetic field, the change in the magnetic field may be monotonic or strictly monotonic in both directions along a predefined line. The direction of the magnetic field may change along the predefined line, or may remain constant along the predefined line.

[0027] In at least one embodiment, a quantum computing device includes a permanent magnet device and a substrate. The quantum computing device is configured to implement a planar Paul trap for trapping at least one ion crystal having ions arranged along a predefined line. Components of the quantum computing device that constitute electrodes of the planar Paul trap for establishing an electrical trapping potential are arranged on the top side of the substrate. The predefined line is located above the top side. The permanent magnet device establishes a magnetic field, wherein the magnitude of the magnetic field varies along the predefined line.

[0028] Trapped ions provide excellent quantum systems for quantum control and quantum metrology. In the present invention, trapped ions are stored in a planar Paul trap and form at least one ion crystal oriented along a predefined line. For quantum computing of trapped ions, and for certain tasks in metrology, it is desirable to individually control individual ions. When ions are manipulated by RF radiation, this single ion control cannot be achieved by focused radiation because the wavelength typically exceeds the ion separation in the ion crystal by several orders of magnitude. In addition, the coupling of internal and external quantum states quantified by the Lamb-Dicke parameters cannot be achieved by RF radiation.

[0029] The invention is based in particular on the idea of ​​using an inhomogeneous magnetic field provided by a permanent magnet arrangement. This provides the possibility of individually addressing ions in frequency space by means of RF radiation. On the other hand, the superposition of the potential induced by the planar Paul trap and the magnetic field of the permanent magnet arrangement makes the equilibrium position of the ions depend on their respective quantum states. Thus, effective spin-spin coupling is achieved by the Coulomb interaction between the trapped ions. This enables the quantum states of the ions to be entangled.

[0030] Furthermore, several quantum registers or ion crystals (respectively) may be advantageous for further scaling. This can be achieved by using planar Paul traps, which allow scaling beyond hundreds of ions and thus reach total numbers of trapped ions that significantly exceed quantum supremacy, enabling computational problems that are currently inaccessible to classical supercomputers.

[0031] In conclusion, the use of the described quantum computing device for quantum information processing enables advanced addressing in frequency space and therefore individual single qubit rotations with low crosstalk, as well as the introduction of efficient coupling between ions, enabling multi-qubit gates. This can also be used in combination with RF frequencies, for which addressing by focused radiation is not an option due to the long wavelength, but the use of RF fields for qubit control allows the application of established economic miniaturization and integration techniques that are common even in consumer electronics and simplifies the scaling of quantum computers based on ion traps.

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

[0033] The permanent magnet arrangement may comprise at least four or at least eight or at least 16 or at least 32 segments. Each segment comprises or consists of a permanent magnetic material. For example, the permanent magnetic material is a ferromagnetic material. The segments may each comprise or consist of the same material. For example, each segment is integrally formed. Alternatively, each segment is formed of at least two sub-segments, wherein at least two sub-segments 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 corresponding permanent magnetic material. That is, the corresponding permanent magnetic material exhibits a dipole moment. The vector field, in particular the vector field of the dipole moment of the permanent magnetic material, defines the respective magnetization direction. The dipole moment mainly points in 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 differ from each other such that the permanent magnet arrangement creates a magnetic field wherein the magnitude of the magnetic field varies along a predefined 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 at least 5° or at least 10° and / or at most 90° or at most 45°. By way of example, if there are m segments, where m is an even natural number of at least 4, the magnetization directions of two directly adjacent segments are rotated relative to each other by 360°·3 / m.

[0037] The vector field defined by the magnetization directions of the segments and the positions of the segments in space may be symmetrical with respect to the above-mentioned symmetry plane. In particular, the vector field may have the same symmetry as the geometry of the permanent magnet arrangement. Alternatively, the vector field may be asymmetrical with respect to the symmetry plane and / or may have a different symmetry than the geometry of the permanent magnet arrangement, or may even be asymmetrical.

[0038] According to at least one embodiment of the quantum computing device, the permanent magnet arrangement comprises NdFeB. In particular, the permanent magnet arrangement comprises NdFeB N52. Exemplarily, each segment comprises or consists of NdFeB, in particular consists of 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 the magnetic field on the other side to near zero. In particular, this is achieved by having a spatially rotated pattern of the magnetization direction of the segments.

[0040] With such a Halbach arrangement, particularly high magnetic fields and magnetic field gradients can be achieved. Since the effective spin-spin coupling and the difference in the resonance of adjacent ions depend on the inhomogeneity and size of the magnetic field, the Halbach arrangement is particularly useful. In fact, even in the case where the distance between any surface (including the surface of the trap electrode and the magnet) and the trapped ion should be large, the Halbach arrangement allows large gradients, which is desirable for high-fidelity gates using trapped ions. This, combined with, for example, a segmented trap, allows flexible capture configurations to capture several registers for splitting and merging quantum registers, adjusting the coupling constants between qubits, and generally for scaling the power of ion-trap-based quantum computers.

[0041] According to at least one embodiment, the permanent magnet device surrounds the planar Paul trap and / or its electrodes. That is, the planar Paul trap is a device separated from the permanent magnet device. In particular, the segments of the permanent magnet device are different from the electrodes of the planar Paul trap. For example, the permanent magnet device has a ring shape or a polygonal outline shape or a polygonal periphery shape, respectively. Therefore, the planar Paul trap can be surrounded by a permanent magnet device in the shape of a ring or polygonal outline. The permanent magnet device can then enhance the magnetic field inside the ring or outline and offset the magnetic field outside the other side of the ring or outline to near zero.

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

[0043] According to at least one embodiment, at least some electrodes of the planar Paul trap, i.e. some electrodes or all electrodes in the planar Paul trap, are arranged in a common electrode plane. For example, all electrodes of the planar Paul trap with which the electric trapping potential is generated are arranged in the electrode plane. The top side may coincide with the electrode plane or be parallel to the electrode plane.

[0044] The electrodes arranged in the electrode plane intersect the electrode plane in particular. The main extension plane of the electrodes is, for example, parallel to or coincident with the electrode plane.

[0045] Some electrodes of the planar Paul trap may also be arranged at different heights relative to the top side. For example, a stack of electrodes is arranged on the top side, wherein an isolation layer separates every two electrodes in a direction perpendicular to the top side.

[0046] According to at least one embodiment, the lateral extension of the planar Paul well and / or substrate is at most 5 cm or at most 2 cm or at most 1 cm. The lateral extension is for example measured along the electrode plane. The thickness of the planar Paul well or substrate measured perpendicular to the electrode plane 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 arranged in the substrate, for example embedded in the substrate. For example, one or more segments of the permanent magnet device or all segments are arranged in the substrate. Whether the permanent magnet device is arranged around a planar Paul trap or in the substrate or elsewhere, the permanent magnet device can be annular or polygonal in outline. Therefore, the segments can be arranged in an annular or polygonal outline.

[0048] According to at least one embodiment, the planar Paul trap is a linear planar Paul trap of at least one ion crystal for capturing ions arranged along a predefined straight line or axis, respectively. Thus, the predefined lines are predefined straight lines or predefined axes, respectively. Alternatively, the planar Paul trap can be a circular planar Paul trap.

[0049] According to at least one embodiment, the permanent magnet arrangement establishes a substantially two-dimensional magnetic field that is mainly concentrated in the magnetic field plane. The center of the magnetic field can be located in the magnetic field plane. The above-mentioned symmetry plane of the permanent magnet arrangement is, for example, perpendicular to the magnetic field plane. For example, all segments of the permanent magnet arrangement are arranged in 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 decays, for example the average magnitude of the magnetic field decays to almost zero. The decay length depends on the dimensions of the permanent magnet arrangement, for example the inner radius and / or outer radius of the segment and / or the thickness measured perpendicular to the magnetic field plane. In particular, the decay length is proportional to the inner radius and / or outer radius and the thickness of the segment.

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

[0052] For example, when the segments of the permanent magnet arrangement are arranged in the form of a ring and the main extension plane of the ring defines the xy plane, the magnetic flux density corresponding to the magnetic field for:

[0053]

[0054] B R is the remanence of the segment, R i is the inner radius of the ring, R o is the outer radius of the ring, and x and y are the coordinates within the permanent magnet arrangement. In this case, the magnetic field plane is the xy plane or the main extension plane of the ring, respectively.

[0055] The magnetic field plane may extend parallel to the top side of the substrate and / or the electrode plane. As the segments are arranged or embedded in the substrate, respectively, the magnetic field plane may pass through the substrate. The electrodes and / or the predefined lines may then have an offset relative to the magnetic field plane. However, due to the small distance of the predefined line from the top side and according to this, due to the small distance of the predefined line to the magnetic field plane, e.g. at most 100 μm, the magnitude of the magnetic field along the predefined line is still sufficient to perform quantum computing.

[0056] According to at least one embodiment, the quantum computing device also includes a yoke structure for increasing the change in the magnetic field and / or the magnitude of the magnetic field along a predefined line established by the permanent magnet device. The yoke structure is particularly arranged so that it increases the magnetic field or magnetic field gradient in the trapped ion region, that is, the magnetic field or magnetic field gradient along the predefined line. For example, the yoke structure includes or consists of a soft magnetic material. It may have a coercive force of at most 1000A / m or at most 100A / 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 relative magnetic permeability of at least 300 or at least 1000 or at least 10000. Exemplarily, the soft magnetic material has a relative magnetic permeability of about 12000. The saturation magnetic flux density of the soft magnetic material may be at least 0.5T or at least 2T. For example, the soft magnetic material includes at least one of the following: iron, cobalt, vanadium, manganese, niobium, silicon, carbon.

[0057] The yoke structure may extend along or parallel to the predefined line. For example, the yoke structure comprises two portions spaced apart from each other in a direction parallel to the predefined line. Each of the two portions may be elongated (long) and may, for example, extend along or parallel to the predefined line, i.e. the elongated portion may be oriented parallel to the predefined line.

[0058] The steepness of the magnetic gradient can be further enhanced by using a yoke structure to concentrate the magnetic flux. For example, the yoke structure is placed in a region where the magnetic field of the permanent magnet device is already small, and the magnetic field of the permanent magnet device is concentrated to a small cross-section of the yoke structure without exceeding the saturation magnetization of the yoke structure, thereby greatly increasing the magnitude of the achievable gradient, achieving lower crosstalk, stronger coupling, and faster quantum gates.

[0059] According to at least one embodiment, the yoke structure is arranged or embedded in the substrate, respectively. In particular, at least two elongated portions of the yoke structure can be arranged in the substrate. For example, the yoke structure is embedded in the substrate.

[0060] Alternatively, the yoke structure may be arranged on the top side of the substrate. Likewise, the permanent magnet arrangement, eg at least some segments thereof, may be arranged on the top side of the substrate.

[0061] According to at least one embodiment, the yoke structure is at least partially formed by electrodes of the planar Paul trap. For example, at least some of the electrodes of the planar Paul trap constitute part of the yoke structure. In other words, at least some of the electrodes of the Paul trap may include or consist of a soft magnetic material to increase the magnetic field or magnetic field gradient established by the permanent magnet arrangement.

[0062] According to at least one embodiment, the yoke structure comprises or consists of an iron-cobalt alloy.The iron-cobalt alloy may comprise vanadium, for example with a concentration of at least 1.5% and at most 3%.

[0063] According to at least one embodiment, the variation of the magnetic field along the predefined line at the magnetic field center is at least 0.5 T / m or at least 50 T / m or at least 100 T / m and / or at most 500 T / m.

[0064] According to at least one embodiment, the planar Paul trap is a segmented planar Paul trap. For example, the planar Paul trap is configured to generate several potential wells. Each potential well is, for example, configured to accommodate or capture the following ion crystals, respectively: each ion crystal has several ions arranged along a predefined line. An electrical potential wall separating two adjacent ion crystals can be arranged between the potential wells.

[0065] All features disclosed herein for one ionic crystal also disclose features for all other ionic crystals.

[0066] The predefined lines assigned to different ionic crystals may all be straight lines. For example, they all coincide with the same straight line. Alternatively, the predefined lines assigned to the ionic crystals may be different from each other, for example, the predefined lines may be offset relative to each other and / or may be located at different heights relative to the top side of the substrate. The lines may also be parallel to each other.

[0067] For example, the potential wells and / or the ion crystals are arranged behind each other in a direction parallel to the predefined line or parallel to one of the predefined lines.

[0068] According to at least one embodiment, the quantum computing device is configured to enable interaction between ion crystals through ion transport and / or photon links. By way of example, photons emitted by ions of one ion crystal can interact with ions of an adjacent ion crystal. Alternatively, by changing the potential barrier between two adjacent potential wells, one or more ions can be transferred from one ion crystal to an adjacent ion crystal. For example, the potential barrier can be made shallow and / or narrow so that ions jump from one ion crystal to an adjacent ion crystal.

[0069] The planar segmented well allows for a large number of registers that can be independently controlled by RF but can also interact through ion transport or photonic links.

[0070] According to at least one embodiment, the piecewise planar Paul well is configured to merge two adjacent potential wells into a larger potential well. For example, the potential barrier between two adjacent potential wells can be decomposed to create a larger potential well from two smaller potential wells.

[0071] According to at least one embodiment, the segmented planar Paul well is configured to divide one potential well into two adjacent smaller potential wells. For example, a potential barrier may be generated within the potential well so that the two smaller potential wells are separated by the potential barrier.

[0072] The terms "smaller" and "larger" used in connection with a potential well particularly mean a smaller or larger extent of the potential well in a direction parallel to a predefined line.

[0073] According to at least one embodiment, the planar Paul trap comprises an inner electrode structure, two outer electrode structures and two intermediate electrode structures. Each of these electrode structures may comprise or consist of a plurality of electrodes spaced apart from one another, or may consist of a single continuous electrode.

[0074] According to at least one embodiment, the inner electrode structures are arranged between the intermediate electrode structures and the intermediate electrode structures are arranged between the outer electrode structures, for example in a lateral direction parallel to the top side or the electrode plane and perpendicular to the predefined line, respectively, the inner electrode structures are arranged between the intermediate electrode structures and the intermediate electrode structures are arranged between the outer electrode structures.

[0075] According to at least one embodiment, each electrode structure extends parallel to the predefined line. For example, each electrode structure is an elongated structure, wherein a main extension direction of the electrode structure is parallel to the predefined line.

[0076] According to at least one embodiment, the outer electrode structures each include at least three electrodes, namely two end electrodes and at least one central electrode. The at least one central electrode is arranged between the two end electrodes in a direction parallel to the predefined line. The inner electrode structure and the intermediate electrode structure may each consist of only one electrode elongated in a direction parallel to the predefined line.

[0077] According to at least one embodiment, the inner electrode structure comprises at least one electrode. The intermediate electrode structures each comprise at least one electrode. The electrodes of the inner electrode structure and the intermediate electrode structure extend, for example, in a direction parallel to the predefined line. Thus, they may extend on at least three electrodes of the outer electrode structure in a direction parallel to the predefined line.

[0078] According to at least one embodiment, the intermediate electrode structure is an RF electrode structure. During operation, the RF electrode structure is provided with an alternating voltage. By means of the RF electrode structure, an oscillating potential is generated for confining ions in a direction perpendicular to the predefined line, i.e. in a radial direction.

[0079] According to at least one embodiment, the inner electrode structure is a DC electrode structure. For example, during operation of the planar Paul trap, the inner electrode structure is grounded.

[0080] 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 or set to a different potential than the end electrodes. For this reason, a potential can be generated for trapping ions in a direction parallel to the predefined line. Thus, in general, a potential well for accommodating an ion crystal having a number of ions arranged along a predefined line is generated.

[0081] The end electrodes constitute, for example, end cap electrodes of a planar Paul trap. The at least one central electrode constitutes, for example, a DC electrode of a planar Paul trap. For example, when the central electrode is at a lower potential than the end electrodes, a potential well for accommodating an ion crystal is formed.

[0082] According to at least one embodiment, each outer electrode structure comprises at least five electrodes.

[0083] According to at least one embodiment, in each external electrode structure, at least the first central electrode and the second central electrode are controllable independently of the third central electrode. That is, the third central electrode can be set to a different potential than the first central electrode and the second central electrode. For example, the potential of the third central electrode can be changed.

[0084] The third central electrode is arranged between the first central electrode and the second central electrode in a direction parallel to the predefined line, for example, the third central electrode is adjacent to the first and second central electrodes. The central electrode is arranged between the end electrodes in a direction parallel to the predefined line. In this way, at least two potential wells arranged one behind the other in a direction parallel to the predefined line can be generated, and each potential well is configured to accommodate an ion crystal, i.e., to confine a plurality of ions arranged along the predefined line.

[0085] For example, each of the first and second center electrodes is assigned a potential well so that the assigned potential well (e.g., its minimum) is aligned with the corresponding center electrode in a direction parallel to the predefined line. The third center electrode can be assigned a potential barrier between the potential wells. The potential barrier can be aligned with the third center electrode in a direction parallel to the predefined line. For example, the third center electrode generates a potential barrier.

[0086] 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 corresponding outer electrode structure. For example, the potential of the third central electrode may vary between the potential of the end electrodes and the potential of the first and second central electrodes. The potential of the third central electrode may be controllable independently of the potential of the end electrodes to decompose or establish a potential barrier between potential wells. For example, the first and second central electrodes may be grounded during operation.

[0087] The electrodes of the two outer electrode structures corresponding to each other may be electrically connected such that they are at the same potential.

[0088] The planar Paul well can also be formed by multiple electrodes arranged on the top side of the substrate in a pixel arrangement. For example, each electrode is rectangular or square, and the electrodes are arranged in a rectangular pattern on the top side. The electrodes can each be individually and independently controlled with RF and / or DC voltages.

[0089] According to at least one embodiment, the quantum computing device includes at least two permanent magnet devices. Each of the two permanent magnet devices may include several segments, each of which has a magnetization direction. All features disclosed in conjunction with one permanent magnet device are also disclosed for the other permanent magnet devices. In particular, each permanent magnet device can be a Halbach arrangement and / or can be integrated in a substrate.

[0090] According to at least one embodiment, the permanent magnet devices are configured so that each permanent magnet device generates a magnetic field. For example, for each permanent magnet device, the size of the corresponding magnetic field varies along a predefined line. By using two such permanent magnet devices, an area of ​​high control and / or steep field variation can be combined with an area of ​​low control and / or nearly constant magnetic field for uncritical ion transport. For example, the permanent magnet devices are arranged one after another in a direction parallel to the predefined line.

[0091] According to at least one embodiment, each potential well or ion crystal is respectively assigned a respective permanent magnet arrangement.

[0092] According to at least one embodiment, each permanent magnet device is configured so that the magnitude of its magnetic field varies along a predefined line of the assigned ion crystal. For example, the center of each permanent magnet device or the center of the magnetic field established by the permanent magnet device is aligned with the assigned potential well (e.g., its minimum) in a direction parallel to the corresponding predefined line and / or in a lateral direction.

[0093] For example, the center of each permanent magnet arrangement or the center of the magnetic field established by the permanent magnet arrangement is aligned with the center electrode of the outer electrode structure in a direction parallel to the predefined line. The center of the first permanent magnet arrangement can be aligned with the first center electrode, and the center of the second permanent magnet arrangement can be aligned with the second center electrode. In a top plan view, the centers of the permanent magnet arrangements can overlap with the inner electrode structure.

[0094] According to at least one embodiment, the quantum computing device includes a vacuum chamber. During operation, ions are trapped in the vacuum chamber. The planar Paul trap or its electrodes may also be arranged in the vacuum chamber. The vacuum chamber may be an ultra-high vacuum chamber, an extremely high vacuum chamber and / or a cryostat.

[0095] According to at least one embodiment, the permanent magnet device is arranged outside the vacuum chamber. This can be advantageous because the creation of an ultra-high vacuum (UHV for short) may involve steps such as baking, which may be incompatible with many magnetic materials, especially those with a low Curie temperature. Even when the permanent magnet device is located outside the vacuum chamber, the permanent magnet device still generates a sufficiently high magnetic field or magnetic field gradient in the region of the ions. Alternatively, the permanent magnet device can also be located inside the vacuum chamber. An optional yoke structure can be arranged inside or outside the vacuum chamber and can increase the magnetic field (gradient).

[0096] Next, a quantum computer is described. The quantum computer includes a quantum computing device as described herein. Therefore, all features disclosed for the quantum computing device are also disclosed for the quantum computer, and vice versa.

[0097] The quantum computer is configured to perform a quantum computing process by using a quantum computing device. The trapped ions of the quantum computing device can be particularly well controlled and manipulated by the permanent magnet device described herein above to perform a predetermined quantum computing.

[0098] According to at least one embodiment, the quantum computer further comprises a cooling and / or readout system. The cooling and / or readout system is, for example, laser-based. The cooling system is configured to cool the ions so as to prepare the ions in a low-motion state and trap them in their respective ground states. The readout system is configured to determine the state of each ion. For example, the ions are cooled and / or readout by irradiating a laser beam onto the ions or by scattering photons of the laser beam, respectively.

[0099] In the following, a quantum computing device and a quantum computer will be described in more detail with reference to the accompanying drawings based on exemplary embodiments. The accompanying drawings are included to provide further understanding. In the accompanying drawings, elements of the same structure and / or function may be referenced by the same reference numerals. It will be understood that the embodiments shown in the accompanying drawings are illustrative representations and are not necessarily drawn to scale. As long as elements or components correspond to each other according to their functions in different figures, their description will not be repeated for each of the following figures. For the sake of clarity, elements may not appear in all figures with corresponding reference numerals.

[0100] Figure 1 A first exemplary embodiment of a quantum computing device is shown,

[0101] Figure 2 and Figure 3 An exemplary embodiment of a planar Paul trap is shown in different views,

[0102] Figure 4 and Figure 5 A second exemplary embodiment of a quantum computing device is shown in different views,

[0103] Figure 6 Another exemplary embodiment of a planar Paul trap is shown,

[0104] Figure 7 and Figure 8 Another exemplary embodiment of a quantum computing device is shown,

[0105] Fig. 9 An exemplary implementation of a quantum computer is shown.

[0106] Figure 1 A first exemplary embodiment of a quantum computing device 1 is shown. The quantum computing device 1 comprises a permanent magnet device 2. The permanent magnet device 2 comprises 16 permanently magnetized segments 3. The segments 3 surround a planar Paul trap 100. The planar Paul trap 100 is configured to trap an ion crystal 6a having a plurality of ions 6 arranged along a predefined line 7 or trap line 7, respectively. In this exemplary embodiment, the planar Paul trap 100 is a linear planar Paul trap for trapping ions 6 along a straight line 7. The straight line 7 defines an x-axis.

[0107] The permanent magnet device 2 has the shape of a ring, wherein a planar Paul trap 100 is arranged in the center of the ring. The thickness of each segment 3 is, for example, 100 μm. The ring spans 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. In addition, the extension of each segment 3 along the corresponding minimum distance is approximately 0.2 mm. Therefore, the outer diameter 2Ro of the permanent magnet device 2 is approximately 0.6 mm. For example, the edges of directly adjacent segments 3 facing each other have a distance of approximately 10 μm from each other.

[0108] In addition, each segment 3 has a Figure 1 The magnetization directions 4 of the arrows in the middle segments 3. For example, the segments each consist of NdFeB N52. The magnetization directions 4 of the segments 3 arranged in opposite regions relative to the center of the permanent magnet arrangement 2 point in opposite directions. The predefined line 7 passes through the center of the permanent magnet arrangement 2 and intersects two opposite segments 3, wherein the magnetization directions 4 of the two segments 3 are parallel to the predefined line 7.

[0109] Each magnetization direction 4 encloses an angle with the predefined line 7. All of these angles are formed differently from one another. For example, the angles of each two directly adjacent segments 3 differ from one another by 67.5°. The magnetization directions 4 are all in the xy plane.

[0110] Figure 1The permanent magnet arrangement is a Halbach arrangement which establishes a magnetic quadrupole field, wherein the magnitude of the magnetic field varies along the predefined line 7. In other words, the magnetic field has a magnetic field gradient along the predefined line 7. For example, each of the trapped ions arranged along the predefined line thus sees a different magnetic field.

[0111] pass Figure 1 The permanent magnet arrangement produces the following idealized magnetic flux density

[0112]

[0113] The residual magnetism B of each segment 3 R is, for example, 1 T. As can be derived from this idealized magnetic flux density, the magnetic field is mainly a two-dimensional magnetic field concentrated in the xy plane constituting the magnetic field plane.

[0114] Figure 2 and Figure 3 Two different views are shown Figure 1 The planar Paul trap 100 comprises a plurality of electrodes 20, 30, 40a, 40b configured to generate an electric potential to capture ions 6 along a predefined line 7. The electrodes 20, 30, 40a, 40b are all arranged on the top side 51 of the substrate 50 and are all located in a common electrode plane EP. Figure 2 is a plan view of the top side 51, wherein Figure 3 is a cross-sectional view perpendicular to the top side 51 .

[0115] The electrodes 20, 30, 40a, 40b are formed of, for example, Au. The substrate 50 may be a sapphire substrate.

[0116] The electrodes 20, 30, 40a, 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 a continuous elongated electrode 30 extending parallel to the predefined line 7. The intermediate electrode structures 22 are each formed by a continuous elongated electrode 20 also extending parallel to the predefined line 7. Thus, the inner electrode structure 32 is arranged between the intermediate electrode structures 22 in a transverse direction perpendicular to the direction of the predefined line 7. The intermediate electrodes 20 are RF electrodes which are provided with an alternating voltage during operation. The inner electrode 30 is a DC electrode which is, for example, grounded during operation. Alternatively, the inner electrode 30 can be an RF electrode. By means of the inner electrode 30 and the intermediate electrodes 20, an oscillating potential is generated which confines the ions in particular in the radial direction, i.e. in the direction perpendicular to the predefined line 7.

[0117] The outer electrode structures 42 each comprise three electrodes 40a, 40b. The inner electrode structures 32 and the intermediate electrode structures 22 are arranged between the outer electrode structures 42 in a transverse direction. The electrodes 40a, 40b of the outer electrode structures 42 are arranged one after the other in a row, wherein the row is parallel to the predefined line 7. The end electrodes 40a of each outer electrode structure 42 constitute end cap electrodes, which are at the same potential, for example, during operation. The center electrode 40b arranged between the end electrodes 40a is, for example, grounded during operation.

[0118] Figure 2 The graph of shows the potential V(x,0,0) generated by the electrodes 20, 30, 40a, 40b along the x-axis (predefined line 7). Overall, a potential well W is formed to trap the ions 6. The ions 6 in the potential well W form a linear ionic crystal 6a.

[0119] exist Figure 2 The figure also shows that Figure 1 The magnitude of the magnetic field generated by the permanent magnet device 2 on the x-axis, that is, the magnitude of the magnetic flux density |B(x,0,0)|.

[0120] like Figure 3 As best shown in FIG. 5 , a 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 the predefined line 7. Each part of the yoke structure 60 is an elongated element and is composed of a soft magnetic material. The yoke structure 60 increases the magnetic field and its gradient along the predefined line 7.

[0121] Figures 1 to 3 The ion 6 shown in is for example 171 Yb + 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 arrangement 2. The energy of the π transition from the ground state quantum state to the excited m=0 quantum state is weakly dependent on the magnetic field seen by the ion. Similarly, the σ transition from the ground state quantum state to the excited m=±1 quantum state is ± - The energy of the transition depends on the magnetic field seen by the ions. Since the magnitude of the magnetic field depends on the position of the ions 6 along the predefined line 7, the energy of the transition depends on the position along the predefined line 7. For example, for every two adjacent ions 6, σ ± The frequency difference of the transitions is at least 1 MHz and at most 100 MHz. In addition, for every two adjacent ions 6, the frequency difference of the π transitions is at least 0.001 MHz and at most 10 MHz.

[0122] Furthermore, due to the formation of the potential well W along the predefined line 7 and the magnetic field provided by the permanent magnet arrangement 2, the equilibrium position of the ions 6 depends on their respective quantum states. Thus, due to the Coulomb interaction, an effective spin-spin coupling between the ions 6 is achieved. This allows the quantum states of the ions 6 to be entangled.

[0123] In particular, the coupling strength between two directly adjacent trapped ions 6 depends on the square of the magnetic field gradient. In addition, relaxation times, in particular the spin relaxation time T2, are inversely proportional to the decoherence rate. Therefore, in order to provide multi-qubit gates, the magnetic field gradient must be relatively high to provide a large number of gates in a given time. This can be achieved using the permanent magnet arrangement described herein.

[0124] Figure 4 and Figure 5 Another exemplary embodiment of a quantum computing device 1 is shown. Figure 1 Compared with the quantum computing device of FIG. 5 , the permanent magnet device 2 including a plurality of permanent magnetized segments 3 is arranged or embedded in the substrate 50. The permanent magnet device 2 is Figure 4 Indicated by dotted line.

[0125] The magnetic field plane BP of the magnetic field established by the permanent magnet device 2 is mainly located in the substrate 50. Therefore, the predefined line 7 has an offset relative to the magnetic field plane BP. However, since the distance of the predefined line 7 or the ion 6 to the magnetic field plane BP is small, for example less than 150 μm, the ion 6 still feels enough magnetic field to allow appropriate quantum computing operations.

[0126] Figure 6 Another exemplary embodiment of a planar Paul trap 100 is shown, which can be used, for example, with Figure 4 and Figure 5 The integrated permanent magnet device shown in Figure 1 Used with the surrounding permanent magnet device shown in Figures 2 to 5 Compared with the planar Paul well 100, Figure 6 The planar Paul trap 100 comprises outer electrode structures 42 each having five electrodes 40a, 40b, 40c arranged one after another in a direction parallel to the predefined line 7. Each outer electrode structure 42 comprises two end electrodes 40a and three central electrodes 40b, 40c.

[0127] The third center electrode 40c is thus arranged between the first and second center electrodes 40b. The third center electrode 40c can be controlled independently of the other center electrodes 40b. For example, during operation, the third center electrode 40c can be set to the same potential as the end electrode 40a, wherein the first and second center electrodes 40b can be grounded.

[0128] The result is the electric potential V(x,0,0) in the x direction, as Figure 6 As shown. Two adjacent potential wells W are generated, which are arranged one behind the other in a direction parallel to the predefined line 7. Each potential well W confines and accommodates an ion crystal 6a, 6b including a plurality of ions 6 arranged along the predefined line 7. The two potential wells W are separated from each other by a potential barrier mainly due to the third central electrode 40c.

[0129] Figure 6 The ion crystals 6a, 6b can interact with each other, for example, via a photonic link. Alternatively, the ion crystals 6a, 6b can interact with each other via ion transport. For example, by changing the potentials of the electrodes 40a, 40b, 40c of the external electrode structure 42, the form 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 an example, when the third central electrode 40c is set at the same potential as the first and second central electrodes 40b, Figure 6 The two potential wells W shown in can be merged into one larger potential well, and the two separate ion crystals 6a, 6b are then merged into one large ion crystal 6a.

[0130] Figure 7 An exemplary embodiment of a quantum computing device 1 is shown, in which two permanent magnet devices 2, each in the form of a Halbach arrangement, are embedded in a substrate 50 of a planar Paul trap 100. The permanent magnet devices 2 are thereby arranged one behind the other in a direction parallel to a predefined line 7, wherein the centers of the permanent magnet devices 2 overlap the predefined line 7 in a plan view of the top side 51. The two permanent magnet devices 2 are arranged such that each of them is uniquely assigned to a potential well W and a corresponding ion crystal 6a, 6b.

[0131] exist Figure 8 In the exemplary embodiment of , the permanent magnet arrangement 2 is in the form of a polygonal outline surrounding the planar Paul trap 100. Each segment 3 has a square shape. Adjacent segments 3 are rotated relative to each other.

[0132] like Figure 8 As can further be seen in FIG. 1 , the Paul trap 100 is arranged in the chamber 10, and the chamber 10 is surrounded by the permanent magnet arrangement 2. The chamber 10 is, for example, an ultra-high vacuum chamber.

[0133] Fig. 9 1 shows an exemplary embodiment of a quantum computer 8. The quantum computer 8 comprises a quantum computing device 1 according to one of the exemplary embodiments described herein. A planar Paul trap 100 is connected to external components of the quantum computer 8 via a chamber 10 by a plurality of connections 11. For example, the connections 11 connect the planar Paul trap 100 to external control electronics 12 and a classical computer 13.

[0134] The quantum computing device 1 is configured to capture, manipulate and measure the captured ions. To this end, in addition to the permanent magnet device 2 and any components of the planar Paul trap 100, the quantum computing device 1 may also include an optical guide and / or internal electronic devices including electronic devices. The electronic devices may include circuit systems, integrated electronic devices, power supplies and / or detectors (such as photon detectors and / or charge detectors), controllers, etc. Exemplarily, internal electronic devices are provided for preprocessing. For example, these components allow the corresponding states of the ions to be measured and allow the ions to be gated. Therefore, the quantum computing device 1 is configured to capture ions and perform operations and measurements on the captured ions.

[0135] The Paul trap 100 is installed in a chamber 10, wherein the chamber 10 may be an ultra-high vacuum chamber, an extremely high vacuum chamber and / or a cryostat. The permanent magnet device 2 may be arranged outside the chamber 10. In this case, the permanent magnet device 2 surrounds the chamber 10. Alternatively, the permanent magnet device 2 may be arranged inside the chamber 10 (not shown here).

[0136] The quantum computing device 1, in particular the Paul 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.

[0137] The external electronic device 12 includes, for example, an analog-to-digital converter and a signal generator, such as a radio frequency generator, a microwave signal generator, a low frequency signal generator and / or a direct current signal generator. In addition, the external electronic device 12 may include a transistor-transistor logic circuit TTL.

[0138] Furthermore, the external electronic device 12 may also 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.

[0139] The classical computer 13 is configured, for example, to provide and receive digital signals. The digital signals correspond to control signals for operating the qubits / ions, and measurement signals corresponding to the states of the qubits.

[0140] The external electronic device 12 is configured in particular to convert digital signals into 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 provide the measured analog signals from the quantum computing device 1 to the classical computer 13, or to process such signals to directly initiate some response signals generated by the control electronics 12.

[0141] The classical computer 13 is exemplarily configured to be provided with a specific algorithm, i.e. a predetermined quantum calculation to solve a specific problem. The classical computer 13 is then configured to convert the compiled code corresponding to the algorithm into commands for the quantum computing device 1. The commands are then forwarded to the quantum computing device 1 via the external control electronics 12. In addition, the classical computer 13 is configured to receive the measurement results of the specific algorithm.

[0142] For example, all components of the quantum computer 8 , in particular all electronic components of the quantum computer 8 , are synchronized, for example, via an atomic clock reference.

[0143] The invention is not limited to the exemplary embodiments described by it. On the contrary, the invention comprises any novel feature and any combination of features, which in particular includes any combination of features in the claims, even if this feature or combination itself is not explicitly indicated in the claims or exemplary embodiments.

[0144] List of reference numerals:

[0145] 1 Quantum computing device

[0146] 2 Permanent magnet device

[0147] 3 segments

[0148] 4 Magnetization direction

[0149] 6 Ions

[0150] 6a, 6b Ionic crystals

[0151] 7 Predefined lines

[0152] 8 Quantum Computers

[0153] Room 10

[0154] 11 Connectors

[0155] 12 Control electronics

[0156] 13 Classical Computers

[0157] 20 Electrodes

[0158] 22 Internal electrode structure

[0159] 30 electrodes

[0160] 32 Intermediate electrode structure

[0161] 40a, b, c electrodes

[0162] 42 External electrode structure

[0163] 50 base

[0164] 51 Top side

[0165] 60 Yoke structure

[0166] 100 Paul Trap

[0167] R i inner radius

[0168] R o Outer Radius

[0169] BP magnetic field plane

[0170] EP Electrode Plane

[0171] W potential well

[0172] V(x,y,z) electric potential

[0173] B(x,y,z) magnetic flux density

Claims

1. A quantum computing device (1), comprising: - a permanent magnet device (2), - a substrate (50), wherein - the quantum computing device (1) is configured to implement a planar Paul trap (100) for trapping at least one ion crystal (6a, 6b) having a number of ions (6) arranged along a predefined line (7), wherein - components of the quantum computing device (1) constituting electrodes (20, 30, 40a, 40b) for generating an electrical trapping potential of the planar Paul trap (100) are arranged on the top side (51) of the substrate (50), - said predefined line (7) is located above said top side (51), - the permanent magnet arrangement (2) creates a magnetic field, wherein the magnitude of the magnetic field varies along the predefined line (7).

2. The quantum computing device (1) according to claim 1, wherein - the permanent magnet device (2) comprises a plurality of permanently magnetized segments (3), - each segment (3) has a magnetization direction (4), - The segments (3) are arranged in a Halbach arrangement.

3. The quantum computing device (1) according to claim 1 or 2, - wherein the permanent magnet arrangement (2) surrounds the planar Paul trap (100) in the form of a ring or in the form of a polygonal outline.

4. A quantum computing device (1) according to claim 1 or 2, wherein - All electrodes (20, 30, 40a, 40b) of the planar Paul trap (100) are arranged in a common electrode plane (EP).

5. A quantum computing device (1) according to any one of the preceding claims, wherein - At least a part of the permanent magnet arrangement (2) is arranged in the substrate (50).

6. The quantum computing device (1) according to any one of the preceding claims, further comprising: A yoke structure (60) for increasing the magnetic field established by the permanent magnet arrangement (2) along the predefined line (7) and / or the variation of the magnitude of the magnetic field.

7. A quantum computing device (1) according to any one of the preceding claims, wherein - The yoke structure (60) is arranged in the substrate (50).

8. A quantum computing device (1) according to claim 6 or 7, wherein - The yoke structure (60) comprises a soft magnetic material.

9. A quantum computing device (1) according to any one of the preceding claims, wherein The planar Paul trap (100) is a segmented planar Paul trap (100) configured to generate a plurality of potential wells (W), and each potential well (W) is configured to accommodate an ion crystal (6a, 6b) having a plurality of ions (6) arranged along a predefined line (7).

10. The quantum computing device (1) according to claim 9, wherein - The quantum computing device (1) is configured to enable interaction between the ionic crystals (6a, 6b) via ionic transmission and / or photonic links.

11. A quantum computing device (1) according to claim 9 or 10, wherein: The piecewise planar Paul trap (100) is configured as follows: - merge two adjacent potential wells (W) into a larger potential well (W), and / or - Split a potential well (W) into two adjacent smaller potential wells (W).

12. A quantum computing device (1) according to any one of the preceding claims, wherein - the planar Paul trap (100) comprises an inner electrode structure (32), two outer electrode structures (42) and two intermediate electrode structures (22), - the inner electrode structure (32) is arranged between the intermediate electrode structures (22), and the intermediate electrode structures (22) are arranged between the outer electrode structures (42), - the electrode structures (22, 32, 42) extend parallel to the predefined line (7), - the outer electrode structures (42) each comprise at least three electrodes (40a, 40b), namely two end electrodes (40a) and at least one central electrode (40b) arranged between the end electrodes (40a) in a direction parallel to the predefined line (7), - the internal electrode structure (32) comprises at least one electrode (30), and the intermediate electrode structures (22) each comprise at least one electrode (20), - the intermediate electrode structure (22) is an RF electrode structure supplied with an alternating voltage, - In each outer electrode structure (42), the at least one central electrode (40b) is controllable independently of the end electrodes (40a) so as to generate at least one potential well (W) for accommodating an ionic crystal (6a) having a number of ions (6) arranged along the predefined line (7).

13. A quantum computing device (1) according to claim 12 in combination with claim 10 or 11, wherein - each outer electrode structure (42) comprises at least five electrodes (40a, 40b, 40c), - In each external electrode structure (42), at least a first central electrode (40b) and a second central electrode (40b) are controllable independently of a third central electrode (40c) arranged between the first central electrode (40b) and the second central electrode (40b) so as to generate at least two potential wells (W) arranged one behind the other in a direction parallel to the predefined line (7), and each potential well (W) is configured to accommodate an ionic crystal (6a, 6b).

14. A quantum computing device (1) according to any one of the preceding claims, comprising: - at least two permanent magnet arrangements (2), wherein - the permanent magnet arrangements (2) are configured such that each permanent magnet arrangement generates a magnetic field.

15. A quantum computing device (1) according to claim 14 as appended to claim 9, wherein - Each ionic crystal (6a, 6b) is assigned a separate permanent magnet arrangement (2), - Each permanent magnet device (2) is configured so that the magnitude of its magnetic field varies along said predefined line (7) of the assigned ionic crystal (6a, 6b).

16. A quantum computer (8), comprising a quantum computing device (1) according to any one of claims 1 to 15, wherein the quantum computer (8) is configured to perform quantum computing.

17. A quantum computer (8) according to claim 16, further comprising a laser-based cooling system and / or readout system.

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