Quantum computing device, quantum computing apparatus, quantum computer, and method of operating a quantum computing device

Abstract

In at least one embodiment, a quantum computing device (100) includes a substrate (1) and a resonator electrode (2) fixed to the substrate. The quantum computing device is configured to realize a planar Paul trap for trapping at least one ion (6). The quantum computing device components, comprising planar Paul trap electrodes (20-25) for generating an electrical trapping potential, are disposed on the top surface (10) of the substrate. The resonator electrode has multiple windings and is configured as an electromagnetic wave resonator having a resonant frequency. When an alternating current electrical signal having the resonant frequency is applied, the resonator electrode generates an oscillating magnetic field at the location of at least one trapped ion to induce transitions in the trapped ion.

Description

[Technical Field]

[0001] The present disclosure relates to quantum computing devices, quantum computing apparatus, quantum computers, and methods for operating quantum computing devices. [Background technology]

[0002] The use of hyperfine levels of atomic ions as quantum bits (qubits) to build quantum computers is being investigated by many research groups and companies around the world. The energy separation between hyperfine levels often corresponds to the microwave (MW) range, i.e., the wavelength of the electromagnetic radiation is on the order of millimeters or centimeters, and the corresponding transition frequencies are on the order of a few GHz to hundreds of GHz. To drive the transitions between hyperfine levels, a magnetic field oscillating at the transition frequency can be used. Summary of the Invention [Problem to be solved by the invention]

[0003] One object to be achieved is to provide an improved quantum computing device, for example, a quantum computing device that allows the amplitude of an oscillating magnetic field to be maximized at the position of an ion to speed up single-qubit gate operations. A further object to be achieved is to provide a quantum computing apparatus having such a quantum computing device, and a quantum computer having such a quantum computing device. A further object to be achieved is to provide a method for operating such a quantum computing device. [Means for solving the problem]

[0004] First, identify the quantum computing device.

[0005] According to at least one embodiment, the quantum computing device comprises a substrate, which may be an electrically insulating substrate, which may include or consist of one or more of glass, sapphire, diamond, or ceramic, such as AlN.

[0006] According to at least one embodiment, the quantum computing device comprises a resonator electrode fixed to a substrate, the resonator electrode being disposed on an outer surface of the substrate or being integrated into the substrate, the resonator electrode being in particular a conductor track.

[0007] According to at least one embodiment, the quantum computing device is configured to implement a planar Paul trap for trapping at least one ion. In other words, during operation, the quantum computing device, or 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 a type of ion trap that uses a dynamic electric field to trap charged particles.

[0008] The planar Paul trap is configured to trap at least one ion, i.e., one or more ions. For example, the planar Paul trap is configured to trap at least one ion crystal having two or more ions, e.g., at least 8, or at least 20, or at least 100, and / or up to 1000 ions. The ions in the ion crystal may be aligned along a predetermined line, e.g., along a predetermined straight line.

[0009] According to at least one embodiment, components of a quantum computing device, comprising electrodes of a planar Paul trap for generating an electrical trapping potential, hereinafter simply referred to as trapping electrodes, are disposed on a top surface of a substrate. For example, all trapping electrodes of a planar Paul trap through which an electrical trapping potential is generated are disposed on a top surface of a substrate. The top surface of the substrate may be, for example, a planar outer surface of the substrate. The substrate may mechanically stabilize the trapping electrodes. For example, a planar Paul trap may include at least two RF electrodes and at least two DC electrodes.

[0010] During operation, the trapping electrodes of the planar Paul trap generate an oscillating electric potential configured to trap at least one ion or at least one ion crystal having several ions aligned in directions parallel to and perpendicular to the predetermined line, also referred to herein as radial directions. Effectively, at least one electric potential well is generated in which ions are trapped in all spatial directions, e.g., shaped such that ions are arranged sequentially, e.g., in a linear arrangement, along the predetermined line. Multiple ions trapped in the same electric potential well are referred to herein as an ion crystal. The predetermined line of the ion crystal may be parallel to the top surface of the substrate.

[0011] In a planar Paul trap, trapped ions float above the top surface of the substrate, for example, at a height (measured relative to the top surface) that exceeds the height of each trapping electrode, so that trapped ions can float above all of the trapping electrodes.

[0012] The trapping electrodes of a planar Paul trap can each be distinct from the resonator electrodes. Alternatively, the resonator electrodes may constitute trapping electrodes of a planar Paul trap, whereby the resonator electrodes are part of the planar Paul trap. Here and below, when a feature of an electrode is described without specifying whether the electrode is a trapping electrode or a resonator electrode, the feature is specifically disclosed for the resonator electrode and / or the trapping electrode.

[0013] The electrodes may be applied to the substrate with the aid of a deposition method such as sputtering or evaporation. The electrodes may be formed with the aid of lithography. The thickness of the trapping electrode may be increased by using a galvanic process. An adhesive layer may be present between the electrode and the substrate to improve the adhesion of the electrode to the substrate. The electrodes may each be formed as a plate, sheet, or film. The main extension plane of the electrodes extends, for example, parallel to the upper surface. The electrodes may each be formed of a metal. For example, they may be formed of Au or another material such as Cu. In this case, the electrodes may be coated with Au. The electrodes are, in particular, each continuous metal element without interruptions. For example, the extension of the electrodes along their respective main extension planes is at most 10 mm, or at most 5 mm, or at most 1 mm. The thickness of the electrodes measured perpendicular to the upper surface of the substrate is, for example, at most 100 μm or at most 50 μm. The upper surface of the substrate may be at most 300 mm. 2 , max. 100mm 2 , or up to 50 mm 2 The area may be

[0014] Due to the small size of quantum computing devices and the methods used to fabricate them, quantum computing devices are sometimes referred to as "quantum computing chips."

[0015] According to at least one embodiment, the resonator electrode has multiple windings. In particular, the resonator electrode is an inwardly spiraling conductor path. For example, each winding may surround the geometric center of the resonator electrode. The windings of the resonator electrode may each have a rectangular, elliptical, circular, or hexagonal shape. The different windings of the resonator electrode are electrically connected to each other and, for example, are integrally formed. For example, the resonator electrode is spiral-shaped. The resonator electrode has at least two windings, or at least three windings, or at least four windings, or at least five windings. Additionally or alternatively, the resonator electrode may have up to 20 windings, or up to 15 windings, or up to 10 windings, or up to 8 windings, or up to 7 windings.

[0016] For example, the width of the resonator electrodes in the cross section of the windings is constant within manufacturing tolerances. The width may be, for example, at least 5 μm and at most 50 μm, such as 10 μm to 13 μm. The gap between each two adjacent windings may be at least 1 μm and at most 10 μm, such as 4 μm to 6 μm.

[0017] According to at least one embodiment, the resonator electrodes are configured as resonators for electromagnetic waves or AC electrical signals having a resonant frequency. That is, the resonator electrodes are configured such that an electromagnetic wave / AC electrical signal having a resonant frequency fed to the reflector electrodes is reflected back and forth within the resonator electrodes by internal reflection, and the resulting waves / signals traveling within the resonator electrodes add up to form standing waves. Thus, for a particular frequency, i.e., the resonant frequency, the electromagnetic waves / signals reflected back and forth within the resonator electrodes are in phase, which amplifies the corresponding current in the resonator electrode, making it a resonator.

[0018] According to at least one embodiment, the quantum computing device is configured such that, when the resonator electrodes are supplied with an alternating current electrical signal having a resonant frequency, the resonator electrodes generate an oscillating magnetic field at the location of at least one trapped ion, the oscillating magnetic field intended to induce transitions, such as hyperfine transitions, in the ions.

[0019] For example, the quantum computing device may be configured such that, when an alternating current electrical signal at the resonant frequency is applied, at least one trapped ion is positioned in the near field of the resonator electrode. In one example, the quantum computing device may be configured such that the distance of the at least one trapped ion to the resonator electrode is at most 300 μm, or at most 200 μm, and / or at least 10 μm. The resonant frequency may correspond to the microwave range. For example, the resonant frequency may be at least 300 MHz, or at least 1 GHz, or at least 10 GHz, and / or at most 300 GHz, or at most 100 GHz, or at most 50 GHz.

[0020] In at least one embodiment, a quantum computing device includes a substrate and a resonator electrode affixed to the substrate. The quantum computing device is configured to implement a planar Paul trap for trapping at least one ion. Components of the quantum computing device, comprising electrodes of the planar Paul trap for generating an electric trapping potential, are disposed on an upper side of the substrate. The resonator electrode has a plurality of windings and is configured as an electromagnetic wave resonator having a resonant frequency. When an alternating current electrical signal having the resonant frequency is applied, the resonator electrode generates an oscillating magnetic field at the location of the at least one trapped ion to induce a transition in the trapped ion.

[0021] The present invention recognizes that maximizing the amplitude of the oscillating magnetic field at a given applied power is beneficial, as it will, among other things, maximize the single-qubit gate speed. Furthermore, the power that can be applied to a quantum computing device may be limited, especially in cryogenic settings, and as a result, the maximum value of this limited power should be used.

[0022] The inventors had the idea of ​​combining a wound resonator electrode with a planar Paul trap. Due to the resonant nature of the resonator electrode, the amplitude of the generated oscillating magnetic field is maximized. Furthermore, due to the design of the resonator electrode with multiple windings, the generated oscillating magnetic field, especially its maximum amplitude, is spatially focused and can therefore be precisely applied to the location where at least one ion is trapped.

[0023] Combining such resonator electrodes with a planar Paul trap proved particularly advantageous, since ions can be trapped very close to the substrate, e.g., only tens or hundreds of micrometers above the substrate's top surface. This allows the resonator electrodes to be placed very close to the trapped ions, so that the trapped ions sense the near-field of the resonator electrodes. The amplitude of the generated oscillating magnetic field felt by the trapped ions is then particularly large. Planar Paul traps can be fabricated using microfabrication techniques such as lithography, thus allowing for high precision and complex 2D shapes of the trapping electrodes. Furthermore, planar Paul traps are easily scalable to multiple quantum processor zones.

[0024] The resonator electrode design presented herein has an additional advantage: the generated oscillating magnetic field has a large gradient in field amplitude. For example, the resonator electrodes are positioned so that the gradient in magnetic field amplitude is along a predetermined line along which ions are aligned. Thus, two nearby ions experience different amplitudes of the oscillating magnetic field. This is necessary for certain multi-qubit coupling and individual ion addressing mechanisms.

[0025] According to at least one embodiment, the resonator electrode is located on the top surface of the substrate, i.e., on the same side as the trapping electrode of the planar Paul trap, so that at least one trapped ion can be particularly close to the resonator electrode.

[0026] According to at least one embodiment, the resonator electrodes have open ends and each winding passes around the open end.

[0027] The open end of a resonator electrode is in particular the longitudinal end of the resonator electrode, which is the end of the resonator electrode at which an electromagnetic wave or an electric signal, respectively, is reflected, i.e. an electric signal transported along the resonator electrode towards the open end cannot travel beyond the open end.

[0028] Each winding of the resonator electrode may pass completely around the open end, e.g., when viewed from above on the top surface of the substrate, each winding completely surrounds the open end, e.g., the open end coincides with the geometric center of the winding.

[0029] According to at least one embodiment, the resonator electrode has an innermost winding. The innermost winding terminates in an open end. In other words, the innermost winding includes an open end. The innermost winding is the winding of the resonator electrode that has the smallest average distance to the open end.

[0030] According to at least one embodiment, the distance to the open end increases monotonically when moving along the resonator electrode from the innermost turn of the resonator electrode to the outermost turn of the resonator electrode, where the outermost turn passes around the innermost turn of the resonator electrode or around every other turn of the resonator electrode, and the outermost turn is the turn of the resonator electrode with the greatest average distance to the open end.

[0031] According to at least one embodiment, the windings of the resonator electrodes form a rectangular spiral. For example, each winding includes four sections, each of which follows a straight line within manufacturing tolerances. Each of the two straight sections of the winding has a different distance to the open end.

[0032] According to at least one embodiment, the resonator electrode has a transition from a section of the resonator electrode to a feed line, where there is a characteristic impedance mismatch (i.e., a mismatch between the characteristic impedances) between the feed line and the section, such that an electromagnetic wave or an AC electrical signal having a resonant frequency is reflected back and forth between the open end and the transition, respectively. The section may be an outermost winding of the resonator electrode, and the transition may be at an end of the outermost winding, e.g., the end of the spiral opposite the open end.

[0033] The feed line may be part of the resonator electrode. The feed line is used to supply an electrical signal to the winding of the resonator electrode. The mismatch in characteristic impedance depends, among other things, on the geometry of the feed line and the resonator electrode, e.g., thickness and width.

[0034] For example, the resonator electrodes are configured such that the Q factor of the resonator is at least 5, or at least 10, or at least 20, or at least 30.

[0035] The feed line is, for example, linear. The width of the resonator electrode in said section may be smaller than the width of the feed line, for example by up to 75%.

[0036] According to at least one embodiment, the quantum computing device is configured such that at least one ion is trapped above the open end of the resonator electrode. "Above" herein means with respect to the top surface. For example, in a plan view of the top surface, the at least one trapped ion is located within a circle around the open end having a radius that is at most the average distance from the innermost winding to the open end. The radius may be, for example, at most 50 μm, at most 30 μm, or at most 10 μm. In other words, in a lateral direction parallel to the top surface, the at least one ion is aligned with or overlaps the open end, respectively. For example, the vertical distance from the position of the trapped ion to the open end, measured in a direction perpendicular to the top surface, is at least 50 μm and at most 90 μm.

[0037] According to at least one embodiment, the planar Paul trap is configured to trap ions having internal transitions with transition energies corresponding to a transition frequency f_t, for example, the transition frequency f_t corresponds to the microwave range, for example, the transition frequency f is greater than or equal to 1 GHz and less than or equal to 100 GHz.

[0038] According to at least one embodiment, the resonant frequency of the resonator is f_t±10% or f_t±1%, i.e. the resonant frequency of the resonator is matched to the transition frequency f_t of the internal transition of the ion.

[0039] As an example, the trapped ion has a hyperfine transition with a transition frequency f_t=12.64 GHz. 171 Yb + This corresponds to a wavelength of 24 mm in a vacuum. In this case, the resonant frequency of the resonator is, for example, between 11 GHz and 14 GHz.

[0040] According to at least one embodiment, the length of the resonator electrode between the open end and the transition is n*c / (4*f_res)±10% or n*c / (4*f_res)±1%, where n is an integer greater than or equal to 1, c is the speed of light in the resonator electrode, and f_res is the resonant frequency. For example, n is equal to 1.

[0041] According to at least one embodiment, the windings of the resonator electrodes are all arranged in a first plane. This means that the first plane intersects each of the windings. The first plane may be an imaginary plane. For example, the first plane may be parallel to the main extension plane of each winding. The first plane may be parallel to but offset from the top surface of the substrate.

[0042] According to at least one embodiment, at least some of the electrodes of the planar Paul trap are arranged in a second plane. For example, electrodes of the same type, e.g., RF or DC electrodes, are arranged in the second plane. Again, the trap electrodes being in the second plane means that the second plane intersects the trap electrodes. The second plane may be a virtual plane. For example, the second plane is parallel to the main extension plane of the electrodes it intersects. The second plane may be parallel to the top surface of the substrate but offset from the top surface.

[0043] According to at least one embodiment, the second plane and the first plane are located at different heights above the top surface. In particular, the windings of the resonator electrodes do not intersect with the second plane, and the electrodes of the planar Paul trap arranged in the second plane do not intersect with the first plane. In particular, the first plane and the second plane may be parallel to each other but may be spaced apart from each other by, for example, at least 5 μm and / or at most 50 μm.

[0044] For example, in the vertical direction perpendicular to the top surface, the windings of the resonator electrode do not overlap with the trapping electrode disposed in the second plane.

[0045] According to at least one embodiment, the first plane is disposed between the top surface of the substrate and the second plane.

[0046] According to at least one embodiment, the RF electrodes of a planar Paul trap, which are supplied with an AC voltage, are located in a second plane. During operation, the RF electrodes are supplied with an AC voltage, for example, in the frequency range of 1 MHz to 50 MHz. With the help of the RF electrodes, an oscillating electric potential is generated to radially confine ions. By placing the windings in a different plane from the RF electrodes, it is possible to optimize the geometries of the RF electrodes and the resonator electrodes independently of each other, thereby enabling ions to be trapped at low heights in regions of high magnetic fields and high magnetic field gradients.

[0047] According to at least one embodiment, the DC electrodes of a planar Paul trap, e.g., all DC electrodes of the planar Paul trap, are arranged in a first plane. The DC electrodes are, for example, supplied with a constant voltage during operation. The DC electrodes are used, inter alia, to confine at least one ion longitudinally, e.g., parallel to a predetermined line.

[0048] According to at least one embodiment, the open end is disposed between two RF electrodes of the planar Paul trap in a first transverse direction, for example, parallel to the top surface of the substrate, and the two RF electrodes may be adjacent RF electrodes in the first transverse direction.

[0049] For example, at least one winding or at least two windings of the resonator electrode may be disposed between the two RF electrodes in the first lateral direction. At least one winding or at least two windings of the resonator electrode may be aligned with the two RF electrodes in the first lateral direction. For example, in a top plan view, at least one or at least two windings of the resonator electrode are partially covered by the two RF electrodes.

[0050] According to at least one embodiment, the open end is disposed between two DC electrodes of the planar Paul trap in a second transverse direction, the second transverse direction being perpendicular to the first transverse direction. In particular, the second transverse direction is parallel to the top surface of the substrate. The two DC electrodes may be adjacent DC electrodes in the second transverse direction.

[0051] For example, at least one winding or at least two windings, eg all windings, of the resonator electrode may be arranged between the two DC electrodes in the second lateral direction.

[0052] The predetermined line, along which the ions may be aligned, defined above may be parallel to the second transverse direction. Each of the RF electrodes may be, for example, an elongated electrode having a main extension direction parallel to the second transverse direction. Each two adjacent RF electrodes may be spaced apart from each other in the first transverse direction.

[0053] For example, when viewed from above, the open ends of the resonator electrodes and, optionally, at least one or at least two windings of the resonator electrodes may be exposed so that they are not covered by either the RC or DC electrodes of the planar Paul trap, allowing the oscillating magnetic field generated by the resonator electrodes to reach the trapped ions particularly efficiently.

[0054] According to at least one embodiment, the quantum computing device does not include conductive material in the space between the open end and the location where at least one ion is trapped, allowing the oscillating magnetic field to reach the trapped ion without being blocked. For example, there is no solid material in the space between the open end of the resonator electrode and the location where the ion is trapped.

[0055] Next, a quantum computing apparatus is specified. The quantum computing apparatus particularly comprises a quantum computing device as described herein. Furthermore, the quantum computing apparatus comprises a signal generator configured to supply an alternating current electrical signal to the resonator electrodes. That is, the signal generator is configured to supply an alternating current to the resonator electrodes or to induce an alternating current in the resonator electrodes. The signal generator may be electrically connected to the resonator electrodes.

[0056] According to at least one embodiment, the signal generator is configured to supply the resonator electrodes with an alternating electrical signal having a resonant frequency or at least approximately the resonant frequency, e.g., a maximum deviation of 10% or 1% from the resonant frequency.

[0057] According to at least one embodiment, the quantum computing device includes a vacuum chamber. During operation, ions are trapped within the vacuum chamber. A planar Paul trap may be disposed within the vacuum chamber. The vacuum chamber may be an ultra-high vacuum chamber, an extremely high vacuum chamber, and / or a cryostat.

[0058] Next, a quantum computer is specified. The quantum computer comprises a quantum computing device or quantum computing apparatus as specified herein. The quantum computer is configured to perform quantum computations.

[0059] Trapped ions in quantum computing devices can be particularly well controlled and manipulated with the aid of the resonator electrodes described herein to perform predetermined quantum computations.

[0060] According to at least one embodiment, the quantum computer further comprises a cooling and / or readout system, e.g., laser-based. The cooling system is configured to cool at least one ion to prepare it in a low-motion state and trap it in its respective ground state. The readout system is configured to determine the state of each ion. For example, the ions are cooled and / or readout by impinging a laser beam on the ions or scattering photons of the laser beam, respectively.

[0061] Next, a method of operating a quantum computing device is specified. In particular, the method is configured to operate a quantum computing device according to any of the embodiments described herein. Accordingly, all features disclosed in relation to the quantum computing device are also disclosed in relation to the method, and vice versa.

[0062] According to at least one embodiment, the method includes supplying an alternating current electrical signal to the resonator electrodes that has a resonant frequency or at least approximately the resonant frequency, for example, with a maximum deviation of 10% or 1% from the resonant frequency. [Brief explanation of the drawings]

[0063] Hereinafter, quantum computer devices, quantum computer apparatuses, and quantum computers will be described in more detail based on exemplary embodiments with reference to the drawings. The accompanying drawings are included to provide a further understanding. In the drawings, elements of the same structure and / or function may be referred to by the same reference numerals. It should be understood that the embodiments shown in the drawings are illustrative representations and are not necessarily drawn to scale. To the extent that elements or components correspond to each other in terms of their functions in different drawings, the description will not be repeated for each of the following drawings. For clarity, elements may not be accompanied by corresponding reference numerals in all drawings.

[0064] [Figure 1] 1 illustrates a first exemplary embodiment of a quantum computing device in a top view.

[0065] [Figure 2] 1 illustrates a perspective view of a portion of a first exemplary embodiment of a quantum computing device.

[0066] [Figure 3] 1 illustrates a first exemplary embodiment of a quantum computing device in cross section.

[0067] [Figure 4] A first exemplary embodiment of a quantum computing device is shown in a top view with some elements omitted.

[0068] [Figure 5] 1 shows a top view of a second exemplary embodiment of a quantum computing device.

[0069] [Figure 6] 1 illustrates an exemplary embodiment of a quantum computer and a quantum computing device. DETAILED DESCRIPTION OF THE INVENTION

[0070] 1, a first exemplary embodiment of a quantum computing device 100 is shown in top view of a top surface 10 of a substrate 1 of the quantum computing device 100. The substrate 1 may be, for example, glass, sapphire, diamond, AlN, or the like.

[0071] On the top surface 10 of the substrate 1 there is disposed a resonator electrode 2. The resonator electrode 2 is partially covered by several electrodes 4, 30. To better see the details of the resonator electrode 2, Figure 4 shows the same view as Figure 1, but with the electrodes 4, 30 omitted.

[0072] The resonator electrode 2 is a conductor track, for example of Au, on the top surface 10. A section of the resonator electrode 2 has the geometric shape of a rectangular spiral with several windings 20-25. In this case, the resonator electrode 2 comprises six windings 20-25, all of which surround an open end 2a of the resonator electrode 2. The open end 2a is assigned to the innermost winding 20 of the resonator electrode 2. The outermost winding 25 of the resonator electrode 2 is electrically connected to the feed line 26 of the resonator electrode 2. A mismatch in the characteristic impedance appears at the transition 2b between the feed line 26 and the outermost winding 25.

[0073] In operation, an AC electrical signal is fed to the windings 20-25 of the resonator electrode 2 via the feed line 26. This signal is then reflected back and forth between the open end 2a and the transition 2b (due to characteristic impedance mismatch). When the signal has a certain frequency, called the resonant frequency, the back and forth signals constructively superimpose, resulting in a standing electromagnetic wave between the open end 2a and the transition 2b. Thus, the resonator electrode 2 is a resonator for electromagnetic waves / signals having the resonant frequency.

[0074] In the present case, the length of the resonator electrode 2 measured between the open end 2a and the transition portion 2b is, for example, c / (4*f_res)±10%, where c is the speed of light in the resonator electrode 2 and f_res is the resonant frequency. The width of the windings 20-25 is, for example, 11.8 μm, and the spacing between each two adjacent windings is, for example, 5 μm.

[0075] When an AC electrical signal having a resonant frequency is supplied to the resonator electrode 2, a relatively strong oscillating magnetic field is generated in at least the near-field region above the open end 2a. Due to the spiral shape of the resonator electrode 2, the amplitude of the oscillating magnetic field is spatially concentrated and is particularly high in the region directly above the open end 2a. The amplitude also has a gradient in a direction parallel to the top surface 10 of the substrate 1. The maximum gradient may be offset laterally, i.e., in a direction parallel to the top surface, relative to the open end 2a by, for example, about 100 μm.

[0076] To use this oscillating magnetic field for quantum computing, the quantum computing device 100 of FIG. 1 constitutes a planar Paul trap. This planar Paul trap includes an RF electrode 30 and a DC electrode 31. The RF electrode 30 is supplied with an AC voltage during operation, while the DC electrode 31 is supplied with, for example, a constant voltage. Furthermore, a ground electrode 4 is located on the top surface 10 of the substrate 1. An electrode 32 is disposed below the RF electrode and electrically connected to it by a via. The electrodes 4, 30, 31, and 32 may be made of Au. The electric field generated by the electrodes 30 and 31 is used to trap ions 6, also shown in FIG. 1. Here, several ions 6 are trapped and aligned along a predetermined straight line. The trapped ions 6 are located above the top surface 10 in the near field of the resonator electrode 2.

[0077] 1, the open end 2a of the resonator electrode 2 is located between two RF electrodes 30 in a first transverse direction L1, and between two DC electrodes 31 in a second transverse direction L2. The transverse directions L1 and L2 are parallel to the upper surface 10 of the substrate 1. The predetermined line along which the ions 6 align is parallel to the second transverse direction L2.

[0078] Contrary to what is shown in the figure, ions 6 may be trapped in a region of maximum magnetic field gradient rather than directly above open end 2a, i.e. the line along which ions 6 align may be offset in the first transverse direction L1 relative to open end 2a.

[0079] 2 and 3, it can be seen that the RF electrode 30 is actually disposed on a different plane from the DC electrode 31 and the resonator electrode 2 with respect to the top surface 10 of the substrate 1. In particular, all windings 20 to 25 of the resonator electrode 2, as well as the DC electrode 31, intersect with a first plane P_1. The RF electrode 31 intersects with a second plane P_2 located above the first plane P_1 with respect to the top surface 10. The RF electrode 31 does not intersect with the first plane P_1, and the resonator electrode 2 and the DC electrode 31 do not intersect with the second plane P_2.

[0080] 2 and 3 also show that the ground electrode 4 and the RF electrode 30 are disposed on a dielectric layer 5, made for example from polyimide, to place them at a higher level than the DC electrode 31 and the resonator electrode 2. The dielectric layer 5 also electrically insulates the RF electrode 30 from the resonator electrode 2.

[0081] As an example, the thickness of each of the electrodes 2, 4, 30, 31, and 32 is 10 μm. The thickness of the dielectric layer 5 may also be 10 μm.

[0082] 3, the position of the trapped ion 6 is again shown. As can be seen, the trapped ion 6 is suspended above the open end 2a of the resonator electrode 2, and is located at a height above the RF electrode 30 and the ground electrode 4. In one example, the ion 6 is suspended 72 μm above the open end 2a of the resonator electrode 2.

[0083] Ion 6 has a hyperfine transition corresponding to a transition frequency of 12.64 GHz 171 Yb +The resonator electrode 2 may be an ion. The resonant frequency of the resonator electrode 2 may be selected to be approximately 12.64 GHz. When an electrical signal having such a frequency and an estimated power of 8.4 mW is supplied to the resonator electrode 2, the magnetic field amplitude of the oscillating magnetic field generated at the position of the ion 6 directly above the open end 2a (height 72 μm) has been experimentally measured to be approximately 176 μT. The maximum magnetic field amplitude gradient is expected to be 13 T / m from 1 W applied to the resonator electrode 2.

[0084] Note that in the first exemplary embodiment of FIGS. 1-3, there are actually three RF electrodes 30 arranged parallel to one another. The open end 2a of the resonator electrode 2 is disposed between the first and second RF electrodes 30 in the first transverse direction L1. For example, the third RF electrode disposed on the right side of FIG. 1 may be omitted. However, this third RF electrode 30 can be used to trap ions at a different height than when only the first and second RF electrodes are used. In this way, for example, when three RF electrodes are used, two ions or two ion crystals can be trapped at different heights relative to the upper surface 10.

[0085] 5 shows a photograph of a second exemplary embodiment of quantum computing device 100. The photograph shows a practical implementation of quantum computing device 100. Quantum computing device 100 is 5×5 mm 2 It is a chip.

[0086] 6 illustrates an exemplary embodiment of a quantum computer 1000. The quantum computer 1000 comprises a quantum computing apparatus having a quantum computing device 100 according to one of the exemplary embodiments described herein, and external control electronics 200 comprising a signal generator for supplying an alternating current electrical signal having a resonant frequency to the resonator electrode 2. The quantum computing apparatus further comprises a chamber 300 in which the quantum computing device 100 is located. The chamber 300 may be an ultra-high vacuum chamber, an extremely high vacuum chamber, and / or a cryostat.

[0087] Quantum computing device 100 is connected to external control electronics 200 through chamber 300 by a number of connections 11. Connections 11 further connect quantum computing device 100 to classical computer 400.

[0088] The quantum computing device is configured to trap, manipulate, and measure the trapped ions. To this end, the quantum computing device may include internal electronics, including a light guide and / or an electronic device, in addition to quantum computing device 100. The electronic device may include circuitry, integrated electronics, a power supply, and / or a detector, such as a photon detector and / or a charge detector, a controller, etc. Illustratively, the internal electronics are provided for pre-processing. For example, these components enable measurement of the respective states of the ions and enable gate operations on the ions. Thus, the quantum computing device is configured to trap ions and perform operations and measurements on the trapped ions.

[0089] Quantum computing apparatus, particularly quantum computing device 100, is connected to external electronics 200 via connection 11. External electronics 200 can be located at least partially inside chamber 300 and partially outside chamber 110. Furthermore, external electronics 200 is connected to classical computer 400.

[0090] The external electronics 200 may include an analog-to-digital converter, a low frequency signal generator, and / or a DC signal generator, in addition to a signal generator for supplying the resonator electrodes. Additionally, the external electronics 200 may include transistor-transistor logic (TTL) circuits.

[0091] Additionally, the external electronics 200 can further comprise at least one laser-based system configured to cool the trapped ions, and the laser-based system can be configured to excite and / or read out particular states of the trapped ions.

[0092] Classical computer 400 is configured, for example, to provide and receive digital signals that correspond to control signals used for operations on qubits / ions, as well as measurement signals that correspond to the state of the qubits.

[0093] External electronics 200 is configured, among other things, to convert digital signals to analog signals and vice versa. Thus, external electronics 200 is configured to provide converted analog signals to the quantum computing device for manipulating ions (qubits). Furthermore, external electronics 412 is configured to provide measured analog signals from the quantum computing device to classical computer 400.

[0094] Classical computer 400 is illustratively configured with a specific algorithm, i.e., a predetermined quantum computation that solves a specific problem. Classical computer 400 is then configured to translate compiled code corresponding to the algorithm into commands for the quantum computing device. The commands are then transmitted to the quantum computing device via external control electronics 200. Additionally, classical computer 400 is configured to receive measured results of the specific algorithm.

[0095] For example, all elements of quantum computer 1000, and in particular all electronic elements of quantum computer 1000, are synchronized, for example, by an atomic clock reference.

[0096] The present invention is not limited to the exemplary embodiments by the description thereof, but rather includes any novel feature and any combination of features, and in particular any combination of features in the claims, even if the feature or combination itself is not explicitly set forth in the claims or in the exemplary embodiments. [Explanation of symbols]

[0097] 1 board 2 resonator electrodes 2a open end 2b Transition 4 Ground electrode 5 Dielectric Layer 6. Ion 10 Top side 11 Connection 20 innermost winding 21~24 windings 25 outermost winding 26 Power line 30 RF electrodes 31 DC electrode 32 Further electrodes 100 Quantum Computing Devices 200 External control electronics / signal generators 300 Chamber 400 Classical Computers 1000 quantum computers L1 First lateral direction L2 Second direction P_1 First face P_2 Second face

Claims

1. A quantum computing device (100), comprising: A substrate (1), a resonator electrode (2) fixed to the substrate (1); It has the quantum computing device (100) is configured to implement a planar Paul trap for trapping at least one ion (6); components (30, 31) of the quantum computing device (100) constituting electrodes (30, 31) of the planar Paul trap for generating an electrical trapping potential are disposed on the upper surface (10) of the substrate (1); The resonator electrode (2) It has multiple windings (20-25), configured as a resonator for electromagnetic waves having a resonant frequency; generating an oscillating magnetic field at the location of the at least one trapped ion (6) to induce transitions of the ion (6) when an alternating current electrical signal having the resonant frequency is applied; Quantum computing devices (100).

2. The resonator electrode (2) is disposed on the upper surface (10) of the substrate (1). The quantum computing device (100) of claim 1.

3. The resonator electrode (2) has an open end (2a), and each winding (20-25) passes around the open end (2a). The quantum computing device (100) of claim 1.

4. The resonator electrode (2) has an innermost winding (20) that terminates at the open end (2a), the distance to the open end (2a) increases monotonically when proceeding along the resonator electrode (2) from the innermost winding (20) of the resonator electrode (2) to the outermost winding (25) of the resonator electrode (2); The quantum computing device (100) of claim 3.

5. The windings (20-25) of the resonator electrode (2) form a rectangular spiral. The quantum computing device (100) of claim 4.

6. The resonator electrode (2) has a transition portion (2b) from one section (25) of the resonator electrode (2) to a power supply line (26), and there is a characteristic impedance mismatch between the power supply line (26) and the section (25) at the transition portion (2b) such that an electromagnetic wave having the resonant frequency is reflected back and forth between the open end (2a) and the transition portion (2b). The quantum computing device (100) of claim 3.

7. The quantum computing device (100) is configured such that the at least one ion (6) is trapped above the open end (2a) of the resonator electrode (2). The quantum computing device (100) of claim 3.

8. the planar Paul trap is configured to trap ions (6) with an internal transition having a transition energy corresponding to a transition frequency f_t; The resonant frequency is f_t±10%. The quantum computing device (100) of claim 1.

9. the length of the resonator electrode (2) between the open end (2a) and the transition portion (2b) is n*c / (4*f_res)±10%, where n is an integer greater than or equal to 1, c is the speed of light in the resonator electrode, and f_res is the resonant frequency; The quantum computing device (100) of claim 6.

10. The windings (20 to 25) of the resonator electrode (2) are all arranged on a first plane (P_1); At least some of the electrodes (30) of the planar Paul trap are arranged in a second plane (P_2); the second plane (P_2) and the first plane (P_1) are at different heights above the upper surface (10) such that the windings (20-25) of the resonator electrode (2) do not intersect with the second plane (P_2) and such that the electrode (30) of the planar Paul trap arranged in the second plane (P_2) does not intersect with the first plane (P_1); The first plane (P_1) is disposed between the upper surface (10) of the substrate (1) and the second plane (P_2); The quantum computing device (100) of claim 1.

11. The RF electrode (30) of the planar Paul trap, to which an AC voltage is applied, is arranged in the second plane (P_2). The quantum computing device (100) of claim 10.

12. the open end (2a) is disposed between two RF electrodes (30) of the planar Paul trap (3) in a first transverse direction (L1); The open end (2a) is disposed between two DC electrodes (31) of the planar Paul trap (3) in a second transverse direction (L2) perpendicular to the first transverse direction; The quantum computing device (100) of claim 3.

13. the quantum computing device (100) has no electrically conductive material in the space between the open end (2 a) and the location where the at least one ion (6) is to be trapped, so that the oscillating magnetic field can reach the trapped ion (6) without being shielded; The quantum computing device (100) of claim 1.

14. A quantum computing device (100) according to any one of claims 1 to 13; a signal generator (200) configured to supply an AC electrical signal having the resonant frequency to the resonator electrode (2); A quantum computer device having:

15. A quantum computer (1000) configured to perform quantum computations, comprising a quantum computing device (100) according to any one of claims 1 to 13.

16. The quantum computer (1000) further comprises a laser-based cooling and / or readout system.

17. 14. A method for operating a quantum computing device (100) according to any one of claims 1 to 13, comprising: supplying an AC signal having a frequency that differs from the resonant frequency by at most 10% to the resonator electrode (2); method.

Images