Quantum computing device, quantum computing apparatus, quantum computer, and method for operating 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 implement a planar Porro trap for capturing at least one ion (6). Components of the quantum computing device forming electrodes (20 to 25) of a planar Porro trap for generating an electrically trapping potential are arranged on the top side (10) of the substrate. The resonator electrode has a plurality of coils and is configured as a resonator for electromagnetic waves having a resonant frequency. When provided with an alternating electrical signal having a resonant frequency, the resonator electrode generates an oscillating magnetic field at the location of at least one trapped ion to induce a transition in the trapped ion.

Description

Technical Field

[0001] The present disclosure relates to a quantum computing device, a quantum computing apparatus, a quantum computer, and a method of operating a quantum computing device. Background Art

[0002] Many research groups and companies around the world are researching the use of hyperfine energy levels of atomic ions as qubits (quantum bits) to build quantum computers. The energy gap between hyperfine energy levels typically corresponds to the microwave (MW) range, i.e., the wavelength of electromagnetic radiation is on the order of millimeters or centimeters, and the corresponding transition frequency is on the order of a few GHz to several hundred GHz. To drive the transitions between hyperfine energy levels, a magnetic field oscillating at the transition frequency can be used.

[0003] One objective to be achieved is to provide an improved quantum computing device, such as a quantum computing device capable of maximizing the amplitude of the oscillating magnetic field at the ion position to accelerate single qubit gate operations. Another objective 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. Yet another objective to be achieved is to provide a method of operating such a quantum computing device. Summary of the Invention

[0004] First, a quantum computing device will be described.

[0005] According to at least one embodiment, the quantum computing device includes a substrate. The substrate may be an electrically isolated substrate. The substrate may include one or more of the following or be composed of one or more of the following: glass, sapphire, diamond, ceramic, such as AlN.

[0006] According to at least one embodiment, the quantum computing device includes resonator electrodes fixed to the substrate. The resonator electrodes may be arranged on the outer surface of the substrate or may be integrated into the substrate. The resonator electrodes are particularly conductor lines.

[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, i.e., at least a part of it, constitutes a planar Paul trap. The Paul trap is also referred to as a quadrupole ion trap or a radio frequency (RF) trap. It is an 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, such as at least eight or at least 20 or at least 100 and / or at most 1000 ions. The ions of the ion crystal may be arranged along a predetermined line, such as along a predetermined straight line.

[0009] According to at least one embodiment, components of a quantum computing device that form the electrodes of a planar Paul trap for generating an electrocaptive potential (hereinafter simply referred to as trap electrodes) are arranged on the top side of a substrate. For example, all trap electrodes of the planar Paul trap for generating an electrocaptive potential are arranged on the top side of the substrate. The top side of the substrate is, for example, the out-of-plane surface of the substrate. The substrate can mechanically stabilize the trap electrodes. For example, the planar Paul trap includes at least two RF electrodes and at least two DC electrodes.

[0010] During operation, the trap electrodes of the planar Paul trap generate an oscillating potential that is configured to trap at least one ion or a plurality of ions in at least one ion crystal arranged along a direction parallel to a predetermined line and a direction perpendicular to the predetermined line (also referred to herein as the radial direction). In fact, at least one potential well is created in which one or more ions are trapped in all spatial directions and, for example, formed such that the ions are arranged one after another along the predetermined line, for example, in a linear arrangement. A plurality of ions trapped in the same potential well are hereinafter referred to as an ion crystal. The predetermined line of the ion crystal can be parallel to the top side of the substrate.

[0011] In the planar Paul trap, the trapped ion or ions float above the top side of the substrate and, for example, at a height (measured relative to the top side) that exceeds the height of each trap electrode. Thus, the trapped one or more ions can float above all the trap electrodes.

[0012] The trap electrodes of the planar Paul trap can be different from the resonator electrodes. Alternatively, the resonator electrodes can form the trap electrodes of the planar Paul trap such that the resonator electrodes are part of the planar Paul trap. Here and hereinafter, when describing the characteristics of the electrodes without specifying whether the electrodes are trap electrodes or resonator electrodes, the characteristics are disclosed specifically for the resonator electrodes and / or the trap electrodes.

[0013] The electrodes can be applied to the substrate by means of a deposition method (such as sputtering or evaporation). The electrodes can be formed by means of lithography. The thickness of the trap electrodes can be increased by using an electroplating process. An adhesion layer can be present between the electrodes and the substrate to improve the adhesion of the electrodes to the substrate. Each electrode can be formed as a plate or a sheet or a film. For example, the main extension plane of the electrode is parallel to the top side. Each electrode can be formed of metal. For example, they are formed of gold or other materials (such as copper). In this case, the electrodes can be coated with gold. In particular, each electrode is a continuous metal element without interruption. For example, the extension of the electrode along its corresponding main extension plane is at most 10 mm or at most 5 mm or at most 1 mm. The thickness of the electrode measured perpendicular to the top side of the substrate is, for example, at most 100 μm or at most 50 μm. The area of the top side of the substrate can be at most 300 mm 2 、at most 100 mm 2 or at most 50 2mm.

[0016] Due to the small size of the quantum computing device and the method for manufacturing the quantum computing device, the quantum computing device can also be referred to as a "quantum computing chip".

[0017] According to at least one embodiment, the resonator electrode has a plurality of coils. Specifically, the resonator electrode is a conductor wire wound around itself. For example, each coil can surround the geometric center of the resonator electrode. The coils of the resonator electrode can each be rectangular or elliptical or circular or hexagonal. The different coils of the resonator electrode are electrically connected to each other, for example, formed integrally. For example, the resonator electrode is spiral. The resonator electrode has at least two coils or at least three coils or at least four coils or at least five coils. Additionally or alternatively, the resonator electrode can have at most 20 coils or at most 15 coils or at most ten coils or at most eight coils or at most seven coils.

[0018] For example, the width of the resonator electrode in the coil portion is constant within the manufacturing tolerance. The width is, for example, at least 5 μm and at most 50 μm, for example, between 10 μm and 13 μm (including 10 μm and 13 μm). The gap between every two adjacent coils can be at least 1 μm and at most 10 μm, for example, between 4 μm and 6 μm (including 4 μm and 6 μm).

[0019] According to at least one embodiment, the resonator electrode is configured to be a resonator for an electromagnetic wave or an alternating electric signal having a resonant frequency. That is, the resonator electrode is configured such that the electromagnetic wave / alternating electric signal having the resonant frequency fed into the reflector electrode is reflected back and forth in the resonator electrode by internal reflection, and the resulting wave / signal propagating in the resonator electrode is overall superimposed into a standing wave. Therefore, for a specific frequency, that is, the resonant frequency, the phases of the electromagnetic wave / signal reflected back and forth in the resonator electrode match, thereby amplifying the corresponding current in the resonator electrode and making it a resonator.

[0020] According to at least one embodiment, the quantum computing device is configured such that when the resonator electrode is provided with an alternating electric signal having the resonant frequency, the resonator electrode generates an oscillating magnetic field at the position of at least one trapped ion. This oscillating magnetic field is particularly intended to cause a transition in the ion, such as a hyperfine transition.

[0021] For example, a quantum computing device is configured such that when provided with an alternating electrical signal having a resonant frequency, the position of at least one trapped ion lies in the near field of the resonator electrode. For example, the quantum computing device is configured such that the distance of at least one trapped ion from 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 is 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.

[0022] In at least one embodiment, the quantum computing device includes a substrate and a resonator electrode fixed to the substrate. The quantum computing device is configured to implement a planar Paul trap for trapping at least one ion. The components of the quantum computing device form the electrodes of a planar Paul trap for generating an electrical trapping potential, and the components are arranged on the top side of the substrate. The resonator electrode has a plurality of coils and is configured as a resonator for electromagnetic waves having a resonant frequency. When provided with an alternating electrical signal having a resonant frequency, the resonator electrode generates an oscillating magnetic field at the position of at least one trapped ion so as to cause a transition in the trapped ion.

[0023] The present invention is in particular based on the recognition that it is beneficial to maximize the amplitude of the oscillating magnetic field for a given applied electrical power, as this can maximize the single qubit gate speed. Furthermore, the electrical power that can be applied to the quantum computing device may be limited, especially in cryogenic settings, and thus this limited power should be used to its maximum extent.

[0024] The inventors have come up with the idea of combining a wire-wound resonator electrode with a planar Paul trap. Due to the resonant characteristics of the resonator electrode, the amplitude of the generated oscillating magnetic field is maximized. Furthermore, due to the design of the resonator electrode having a plurality of coils, the generated oscillating magnetic field, especially its maximum amplitude, is spatially focused and can thus be precisely applied to the position where at least one ion is to be trapped.

[0025] It has proven to be particularly advantageous to combine such a resonator electrode with a planar Paul trap because in a planar Paul trap, the ions can be trapped very close to the substrate, for example, only a few tens or hundreds of micrometers above the top side of the substrate. This enables the resonator electrode to be positioned very close to the trapped ions such that the trapped ions sense the near field of the resonator electrode. The amplitude of the generated oscillating magnetic field sensed by the trapped ions is particularly high. The planar Paul trap can be produced using microfabrication techniques (such as lithography), and thus has high precision and can implement trap electrodes with complex 2D shapes. Furthermore, the planar Paul trap is easily scalable to multiple quantum processor regions.

[0026] The design of the resonator electrode proposed in this paper has another advantage, that is, the generated oscillating magnetic field has a large gradient in the magnetic field amplitude. For example, the resonator electrode is arranged such that the gradient of the magnetic field amplitude is along a predetermined line of ion arrangement. Thus, two adjacent ions will experience different amplitudes of the oscillating magnetic field. This is necessary for specific multi-qubit coupling mechanisms and single-ion addressing mechanisms.

[0027] According to at least one embodiment, the resonator electrode is arranged on the top side of the substrate, that is, on the same side as the trap electrode of the planar Paul trap. In this way, at least one trapped ion can be particularly close to the resonator electrode.

[0028] According to at least one embodiment, the resonator electrode has an open end, and each coil extends around the open end.

[0029] The open end of the resonator electrode is especially the longitudinal end of the resonator electrode. The open end is the end of the resonator electrode that reflects electromagnetic waves or electrical signals respectively. That is, the electrical signal transmitted along the resonator electrode towards the open end cannot travel beyond the open end.

[0030] Each coil of the resonator electrode can extend completely around the open end. For example, in a top view of the top side of the substrate, each coil completely surrounds the open end. For example, the open end coincides with the geometric center of the coil.

[0031] According to at least one embodiment, the resonator electrode has an innermost coil. The innermost coil terminates at the open end. In other words, the innermost coil includes the open end. The innermost coil is the coil in the resonator electrode with the smallest average distance from the open end.

[0032] According to at least one embodiment, the distance to the open end increases monotonically when moving from the innermost coil along the resonator electrode to the outermost coil of the resonator electrode. The outermost coil extends around the innermost coil or around every other coil of the resonator electrode. The outermost coil is the coil in the resonator electrode with the largest average distance from the open end.

[0033] According to at least one embodiment, the coils of the resonator electrode form a rectangular helix. For example, each coil includes four parts, and each part follows a straight line within the manufacturing tolerance. The distances of every two straight parts of the coil from the open end are different.

[0034] According to at least one embodiment, the resonator electrode has a transition from a part of the resonator electrode to a feeder, and there is a characteristic impedance mismatch (i.e., a mismatch between characteristic impedances) between the feeder and the said part at the transition, such that an electromagnetic wave or an alternating electrical signal with a resonant frequency is reflected back and forth between the open end and the transition. The said part can be the outermost coil of the resonator electrode, and the transition can be located at the end of the outermost coil, for example, at one end of the helix opposite to the open end.

[0035] The feeder can be part of the resonator electrode. The feeder is used to supply an electrical signal to the coil of the resonator electrode. The characteristic impedance mismatch particularly depends on the geometries of the feeder and the resonator electrode, such as the thickness and the width.

[0036] For example, the resonator electrode is 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.

[0037] The feeder is, for example, straight. The width of the resonator electrode in the section can be less than the width of the feeder, for example, at most 75% of the width of the feeder.

[0038] 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 relative to the top side. For example, in a top view of the top side, at least one trapped ion is located within a circle around the open end, and the radius of the circle is at most the average distance from the innermost coil to the open end. The radius is, for example, at most 50 μm or at most 30 μm or at most 10 μm. In other words, in the lateral direction parallel to the top side, at least one ion is aligned with or overlaps the open end respectively. For example, the vertical distance between the position of the trapped ion measured in the direction perpendicular to the top side and the open end is at least 50 μm and at most 90 μm.

[0039] According to at least one embodiment, the planar Paul trap is configured to trap ions having internal transitions, and the internal transitions have transition energies corresponding to the transition frequency f_t. For example, the transition frequency f_t corresponds to the microwave range. For example, the transition frequency f is at least 1 GHz and at most 100 GHz.

[0040] According to at least one embodiment, the resonance frequency of the resonator is f_t±10% or f_t±1%. That is, the resonance frequency of the resonator matches the transition frequency f_t of the internal transition of the ion.

[0041] By way of example, the trapped ion is one having a hyperfine transition 171 Yb + ion, and its transition frequency is f_t = 12.64 GHz. This corresponds to a wavelength of 24 mm in vacuum. The resonance frequency of the resonator is, for example, between 11 GHz and 14 GHz (including 11 GHz and 14 GHz).

[0042] 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 ≥1, c is the speed of light in the resonator electrode, and f_res is the resonance frequency. For example, n is equal to 1.

[0043] According to at least one embodiment, the coils of the resonator electrodes are all arranged in a first plane. This means that the first plane intersects each coil. The first plane can be a virtual plane. For example, the first plane is parallel to the main extension plane of each coil. The first plane can be parallel to the top side of the substrate but offset from the top side.

[0044] 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, such as RF electrodes or DC electrodes, are arranged in the second plane. Similarly, here, the fact that the trap electrodes are located in the second plane means that the second plane intersects the trap electrodes. The second plane can be a virtual plane. For example, the second plane is parallel to the main extension plane of the electrodes it intersects. The second plane can be parallel to the top side of the substrate but offset from the top side.

[0045] According to at least one embodiment, the second plane and the first plane are at different heights above the top side. Specifically, the coils of the resonator electrodes do not intersect the second plane, and the electrodes of the planar Paul trap arranged in the second plane do not intersect the first plane. Specifically, the first plane and the second plane can be parallel to each other but can be spaced apart from each other, for example, spaced apart from each other by at least 5 μm and / or at most 50 μm.

[0046] For example, in the vertical direction perpendicular to the top side, the coils of the resonator electrodes do not overlap with the trap electrodes arranged in the second plane.

[0047] According to at least one embodiment, the first plane is arranged between the top side of the substrate and the second plane.

[0048] According to at least one embodiment, the RF electrodes of the planar Paul trap to which an alternating voltage is to be provided are arranged in the second plane. During operation, for example, an alternating voltage in the frequency range between 1 MHz and 50 MHz is provided to the RF electrodes. With the aid of the RF electrodes, an oscillating electric potential is generated to confine one or more ions in the radial direction. Placing the coils in a plane different from the RF electrodes enables the geometries of the RF electrodes and the resonator electrodes to be optimized independently of each other, so that ions can be trapped at a low height in a high magnetic field and high magnetic field gradient region.

[0049] According to at least one embodiment, the DC electrodes of the planar Paul trap, such as all the DC electrodes of the planar Paul trap, are arranged in the first plane. For example, during operation, a constant voltage is provided to the DC electrodes. The DC electrodes are particularly used to confine at least one ion in a longitudinal direction, for example, parallel to a predetermined line.

[0050] According to at least one embodiment, the open end is arranged between two RF electrodes of a planar Paul trap in a first transverse direction. The first transverse direction is, for example, a direction parallel to the top side of the substrate. The two RF electrodes can be adjacent RF electrodes in the first transverse direction.

[0051] For example, at least one coil or at least two coils of the resonator electrode are arranged between two RF electrodes in the first transverse direction. At least one coil or at least two coils of the resonator electrode can be aligned with the two RF electrodes in the first transverse direction. For example, in a top view of the top side, at least one or at least two coils of the resonator electrode are partially covered by the two RF electrodes.

[0052] According to at least one embodiment, the open end is arranged between two DC electrodes of a planar Paul trap in a second transverse direction. The second transverse direction is perpendicular to the first transverse direction. Specifically, the second transverse direction is a direction parallel to the top side of the substrate. The two DC electrodes can be adjacent DC electrodes in the second transverse direction.

[0053] For example, at least one coil or at least two coils (e.g., all coils) of the resonator electrode can be arranged between two DC electrodes in the second transverse direction.

[0054] The above-mentioned predetermined line (along which multiple ions can be arranged) can be parallel to the second transverse direction. For example, each RF electrode is an elongated electrode whose main extension direction is parallel to the second transverse direction. Every two adjacent RF electrodes can be spaced apart from each other in the first transverse direction.

[0055] For example, in a top view of the top side, the open end of the resonator electrode and optionally at least one or at least two coils of the resonator electrode can be exposed such that they are neither covered by the RC electrodes of the planar Paul trap nor covered by the DC electrodes of the planar Paul trap. In this way, the oscillating magnetic field generated by the resonator electrode can reach one or more trapped ions particularly effectively.

[0056] According to at least one embodiment, there is no conductive material in the space between the open end and the position where at least one ion will be trapped in the quantum computing device. Therefore, the oscillating magnetic field can reach the trapped ions without being shielded. For example, there is no solid material in the space between the open end of the resonator electrode and the position where the ion will be trapped.

[0057] Next, the quantum computer device will be specifically described. The quantum computer device particularly includes the quantum computing device specifically described herein. In addition, the quantum computing device includes a signal generator configured to provide an alternating electrical signal to the resonator electrode. That is, the signal generator is configured to provide an alternating current to the resonator electrode or induce an alternating current in the resonator electrode. The signal generator can be electrically connected to the resonator electrode.

[0058] According to at least one embodiment, the signal generator is configured to supply an alternating electrical signal having a resonant frequency or an approximate resonant frequency with a maximum deviation from the resonant frequency of, for example, 10% or 1% to the resonator electrode.

[0059] According to at least one embodiment, the quantum computing device includes a vacuum chamber. During operation, ions are trapped in the vacuum chamber. A planar Paul trap may 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.

[0060] Next, the quantum computer will be specifically described. The quantum computer includes the quantum computing device or the quantum computing equipment specifically described herein. The quantum computer is configured to perform quantum computing.

[0061] With the resonator electrode described herein, one or more trapped ions of the quantum computing device can be particularly well controlled and manipulated to perform a predetermined quantum computing.

[0062] According to at least one embodiment, the quantum computer further includes a cooling and / or reading system. The cooling and / or reading system is based on, for example, a laser. The cooling system is configured to cool at least one ion so as to prepare it in a low motion state and trap it in its respective ground state. The reading system is configured to determine the state of each ion. For example, the ions are cooled and / or read by irradiating laser beams on the ions or scattering photons of the laser beams respectively.

[0063] Next, a method for operating a quantum computing device will be specifically described. Specifically, the method is configured to operate a quantum computing device according to any one of the embodiments described herein. Therefore, all the disclosed features of the quantum computing device are also disclosed for this method, and vice versa.

[0064] According to at least one embodiment, the method includes the step of supplying an alternating electrical signal having a resonant frequency or an approximate resonant frequency with a maximum deviation from the resonant frequency of, for example, 10% or 1% to the resonator electrode.

[0065] Hereinafter, based on exemplary embodiments, the quantum computer device, the quantum computer equipment, and the quantum computer will be explained in more detail with reference to the accompanying drawings. The accompanying drawings are used to provide further understanding. In the accompanying drawings, elements having the same structure and / or function may be represented by the same reference numerals. It should be understood that the embodiments shown in the accompanying drawings are illustrative representations and not necessarily drawn to scale. In cases where the functions of elements or components correspond to each other in different accompanying drawings, the description thereof will not be repeated for each of the following accompanying drawings. For the sake of clarity, elements may not appear with corresponding reference numerals in all the accompanying drawings. Description of the Drawings

[0066] Figure 1 The first exemplary embodiment of the quantum computing device is shown in a top view.

[0067] Figure 2 A part of the first exemplary embodiment of the quantum computing device is shown in a perspective view.

[0068] Figure 3 The first exemplary embodiment of the quantum computing device is shown in a sectional view.

[0069] Figure 4 The first exemplary embodiment of the quantum computing device is shown in a top view, with some elements omitted.

[0070] Figure 5 A photograph of the second exemplary embodiment of the quantum computing device is shown in a top view.

[0071] Figure 6 Exemplary embodiments of a quantum computer and a quantum computing device are shown. Detailed Description

[0072] In Figure 1 , the first exemplary embodiment of the quantum computing device 100 is shown in a top view on the top side 10 of the substrate 1 of the quantum computing device 100. The substrate 1 is made of, for example, glass, sapphire, diamond, or AlN.

[0073] The resonator electrode 2 is arranged on the top side 10 of the substrate 1. The resonator electrode 2 is partially covered by some electrodes 4, 30. To better see the details of the resonator electrode 2, Figure 4 the same view as Figure 1 is shown, but the electrodes 4, 30 are omitted.

[0074] The resonator electrode 2 is a conductor line of, for example, gold on the top side 10. A part of the resonator electrode 2 has a rectangular spiral geometry with a plurality of coils 20 to 25. In this example, the resonator electrode 2 includes six coils 20 to 25, all of which surround the open end 2a of the resonator electrode 2. The open end 2a is assigned to the innermost coil 20 of the resonator electrode 2. The outermost coil 25 of the resonator electrode 2 is electrically connected to the feeder 26 of the resonator electrode 2. A characteristic impedance mismatch occurs at the transition 2b between the feeder 26 and the outermost coil 25.

[0075] During operation, an alternating current signal is supplied to coils 20 to 25 of resonator electrode 2 through feeder 26. Then, the signal is reflected back and forth between open end 2a and transition 2b (due to characteristic impedance mismatch). If the frequency of the signal has a specific frequency (referred to as the resonant frequency), the back-and-forth signals will constructively superimpose, resulting in a standing electromagnetic wave between open end 2a and transition 2b. Therefore, resonator electrode 2 is a resonator for electromagnetic waves / signals having the resonant frequency.

[0076] In this example, the length of resonator electrode 2 measured between open end 2a and transition 2b is, for example, c / (4*f_res) ± 10%, where c is the speed of light in resonator electrode 2 and f_res is the resonant frequency. The width of coils 20 to 25 is, for example, 11.8 μm, and the gap between every two adjacent coils is, for example, 5 μm.

[0077] When an alternating electric signal having the resonant frequency is supplied to resonator electrode 2, a rather strong oscillating magnetic field is generated at least in the near-field region above open end 2a. Due to the helical shape of resonator electrode 2, the amplitude of the oscillating magnetic field is spatially concentrated and is particularly high in the region directly above open end 2a. The amplitude also has a gradient in the direction parallel to the top side 10 of substrate 1. The maximum gradient can be lateral, i.e., in the direction parallel to the top side, deviating from open end 2a by, for example, about 100 μm.

[0078] To utilize this oscillating magnetic field for quantum computing, Figure 1 the quantum computing device 100 in Figure 1 constitutes a planar Paul trap. The planar Paul trap includes an RF electrode 30 and a DC electrode 31. For example, the RF electrode 30 is supplied with an alternating voltage during operation, and the DC electrode 31 is supplied with a constant voltage. In addition, there is a ground electrode 4 on the top side 10 of substrate 1. Another electrode 32 is located below the RF electrode and is electrically connected to the RF electrode through a via hole. Electrodes 4, 30, 31, 32 can be made of Au. The electric field generated by electrodes 30, 31 is used to trap ions 6, and these ions 6 are also shown in Here, several ions 6 are trapped and arranged along a predetermined straight line. The trapped ions 6 are located above the top side 10 of the near-field of resonator electrode 2.

[0079] As Figure 1 shown, the open end 2a of resonator electrode 2 is located between two RF electrodes 30 in the first lateral direction L1 and between two DC electrodes 31 in the second lateral direction L2. The lateral directions L1, L2 are directions parallel to the top side 10 of substrate 1. The predetermined line along which the ions 6 are arranged is parallel to the second lateral direction L2.

[0080] Different from that shown in the drawings, the ion 6 can be trapped in the region of the maximum magnetic field gradient, rather than directly above the open end 2a. That is, the line along which the ion 6 is arranged can be offset relative to the open end 2a in the first transverse direction L1.

[0081] It can be seen in Figure 2 and Figure 3 that the RF electrode 30 is actually arranged in a different plane relative to the top side 10 of the substrate 1 compared to the DC electrode 31 and the resonator electrode 2. Specifically, all the coils 20 to 25 of the resonator electrode 2 and the DC electrode 31 intersect the first plane P_1. The RF electrode 31 intersects the second plane P_2, which is above the first plane P_1 relative to the top side 10. The RF electrode 31 does not intersect the first plane P_1, and the resonator electrode 2 and the DC electrode 31 do not intersect the second plane P_2.

[0082] Figure 2 and Figure 3 It is also shown that in order to place the ground electrode 4 and the RF electrode 30 at a higher level than the DC electrode 31 and the resonator electrode 2, they are arranged on the dielectric layer 5, which is made of, for example, polyimide. The dielectric layer 5 also electrically isolates the RF electrode 30 from the resonator electrode 2.

[0083] For example, the thickness of the electrodes 2, 4, 30, 31, 32 is 10 μm in each case. The thickness of the dielectric layer 5 can also be 10 μm.

[0084] In the Figure 3 cross-sectional view, the position where the ion 6 is trapped is indicated again. It can be seen that the trapped ion 6 floats above the open end 2a of the resonator electrode 2 and is at a height exceeding that of the RF electrode 30 and the ground electrode 4. For example, the ion 6 floats 72 μm above the open end 2a of the resonator electrode 2.

[0085] The ion 6 can be a 171 Yb + ion with a hyperfine transition corresponding to a transition frequency of 12.64 GHz. The resonance frequency of the resonator electrode 2 can be selected to be approximately 12.64 GHz. It has been experimentally measured that when an electrical signal is provided to the resonator electrode 2 with this frequency and an estimated power of 8.4 mW, the magnetic field amplitude of the oscillating magnetic field generated at the position of the ion 6 directly above the open end 2a (at a height of 72 μm) is approximately 176 μT. Starting from 1 W applied to the resonator electrode 2, the maximum magnetic field amplitude gradient is expected to be 13 T / m.

[0086] It should be noted that in Figures 1 to 3In a first exemplary embodiment, there are actually three RF electrodes 30 arranged parallel to each other. The open end 2a of the resonator electrode 2 is arranged between the first RF electrode and the second RF electrode 30 in a first lateral direction L1. For example, the third RF electrode arranged on the Figure 1 right hand side 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, when three RF electrodes are used, two ions or two ion crystals can be trapped at different heights relative to the top side 10.

[0087] Figure 5 A photograph of a second exemplary embodiment of the quantum computing device 100 is shown. The photograph shows the quantum computing device 100 as actually implemented. The quantum computing device 100 is a chip of 5×5 mm 2 .

[0088] Figure 6 An exemplary embodiment of a quantum computer 1000 is shown. The quantum computer 1000 includes a quantum computing device having a quantum computing device 100 according to one of the exemplary embodiments described herein and an external control electronics 200, the external control electronics 200 including a signal generator for supplying an alternating electrical signal having a resonance frequency to the resonator electrode 2. The quantum computing device further includes a chamber 300 in which the quantum computing device 100 is located. The chamber 300 can be an ultra-high vacuum chamber, an extremely high vacuum chamber, and / or a cryostat.

[0089] The quantum computing device 100 is connected to the external control electronics 200 through the chamber 300 by a plurality of connections 11. The connection 11 further connects the quantum computing device 100 to a classical computer 400.

[0090] The quantum computing device is configured to trap, manipulate, and measure the trapped ions. To this end, in addition to the quantum computing device 100, the quantum computing device may further include an optical waveguide and / or internal electronics including electronics. The electronics may include circuits, integrated electronics, power supplies, and / or detectors, such as photon detectors and / or charge detectors, controllers, etc. Exemplarily, internal electronics are provided for preprocessing. For example, these components enable the measurement of the respective states of the ions and enable gate operations on the ions. Therefore, the quantum computing device is configured to trap ions and to operate on and measure the trapped ions.

[0091] A quantum computing device, particularly quantum computing apparatus 100, is connected to an external electronic device 200 via connection 11. The external electronic device 200 can be at least partially located inside the chamber 300 and partially outside the chamber 300. In addition, the external electronic device 200 is connected to a classical computer 400.

[0092] In addition to a signal generator for providing signals to resonator electrodes, the external electronic device 200 can also include an analog-to-digital converter, a low-frequency signal generator, and / or a direct-current signal generator. In addition, the external electronic device 200 can include transistor-transistor logic TTL.

[0093] In addition, the external electronic device 200 can also include at least one laser-based system configured to cool trapped ions. In addition, the laser-based system can be configured to excite a specific state of the trapped ions and / or read a specific state of the ions.

[0094] The classical computer 400 is configured to, for example, provide and receive digital signals. The digital signals correspond to control signals for operations performed on qubits / ions and measurement signals corresponding to the states of the qubits.

[0095] The external electronic device 200 is particularly configured to convert digital signals to analog signals and vice versa. Thus, the external electronic device 200 is configured to provide the converted analog signals for manipulating ions (qubits) to the quantum computing device. In addition, the external electronic device 412 is configured to provide measurement analog signals from the quantum computing device to the classical computer 400.

[0096] The classical computer 400 is exemplarily configured to be equipped with a specific algorithm, namely a predetermined quantum computation for solving a specific problem. Then, the classical computer 400 is configured to convert the compiled code corresponding to the algorithm into commands for the quantum computing device. Subsequently, the commands are forwarded to the quantum computing device via the external control electronic device 200. In addition, the classical computer 400 is configured to receive the measurement results of the specific algorithm.

[0097] For example, all elements of the quantum computer 1000, particularly all electronic elements of the quantum computer 1000, are synchronized, for example, by an atomic clock reference.

[0098] The present invention is not limited to the description of the exemplary embodiments. On the contrary, the present invention encompasses any new feature and any combination of features, which particularly includes any combination of features in the claims, even if the feature or combination itself is not explicitly stated in the claims or the exemplary embodiments.

[0099] List of reference signs

[0100] 1 Substrate

[0101] 2 Resonator electrodes

[0102] 2a Open end

[0103] 2b Transition

[0104] 4 Ground electrode

[0105] 5 Dielectric layer

[0106] 6 Ion

[0107] 10 Top side

[0108] 11 Connection

[0109] 20 Innermost coil

[0110] 21 to 24 Coils

[0111] 25 Outermost coil

[0112] 26 Feeder

[0113] 30 RF electrode

[0114] 31 DC electrode

[0115] 32 Another electrode

[0116] 100 Quantum computing device

[0117] 200 External control electronics / signal generator

[0118] 300 Chamber

[0119] 400 Classical computer

[0120] 1000 Quantum computer

[0121] L1 First transverse direction

[0122] L2 Second transverse direction

[0123] P_1 First plane

[0124] P_2 Second plane

Claims

1. A quantum computing device (100), comprising: - a substrate (1), - a resonator electrode (2) fixed to the substrate (1), wherein: - 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) that constitute the electrodes (30, 31) of the planar Paul trap for generating an electric trapping potential are arranged on the top side (10) of the substrate (1), - the resonator electrode (2) has a plurality of coils (20 to 25), - the resonator electrode (2) is configured as a resonator for electromagnetic waves having a resonance frequency, - when the resonator electrode (2) is provided with an alternating electrical signal having the resonance frequency, an oscillating magnetic field is generated at the position of the at least one trapped ion (6) to cause a transition in the ion (6).

2. The quantum computing device (100) according to claim 1, wherein - the resonator electrode (2) is arranged on the top side (10) of the substrate (1).

3. The quantum computing device (100) according to claim 1 or 2, wherein - the resonator electrode (2) has an open end (2a), wherein, each coil (20 to 25) extends around the open end (2a).

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

5. The quantum computing device (100) according to claim 4, wherein - the coils (20 to 25) of the resonator electrode (2) form a rectangular helix.

6. The quantum computing device (100) according to any one of claims 3 to 5, wherein - the resonator electrode (2) has a transition (2b) from a part (25) of the resonator electrode (2) to a feeder (26), wherein, at the transition (2b), there is a characteristic impedance mismatch between the feeder (26) and the part (25), such that electromagnetic waves having the resonance frequency are reflected back and forth between the open end (2a) and the transition (2b).

7. The quantum computing device (100) according to any one of claims 3 to 6, wherein - 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).

8. The quantum computing device (100) according to any of the preceding claims, wherein - the planar Paul trap is configured to trap an ion (6) having an internal transition, and the transition energy of the internal transition corresponds to a transition frequency f_t, - the resonance frequency is f_t ± 10%.

9. The quantum computing device (100) according to claim 6 or according to any one of claims 7 and 8 when referring to claim 6, wherein - the length of the resonator electrode (2) between the open end (2a) and the transition (2b) is n*c / (4*f_res) ± 10%, wherein n is an integer ≥ 1, c is the speed of light in the resonator electrode, and f_res is the resonant frequency.

10. The quantum computing device (100) according to any one of the preceding claims, wherein - the coils (20 to 25) of the resonator electrode (2) are all arranged in 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 top side (10) such that the coils (20 to 25) of the resonator electrode (2) do not intersect the second plane (P_2), and such that the electrodes (30) of the planar Paul trap arranged in the second plane (P_2) do not intersect the first plane (P_1), - the first plane (P_1) is arranged between the top side (10) of the substrate (1) and the second plane (P_2).

11. The quantum computing device (100) according to claim 10, wherein - the RF electrode (30) of the planar Paul trap to which an alternating voltage is to be supplied is arranged in the second plane (P_2).

12. The quantum computing device (100) according to claim 3 or according to any one of claims 4 to 11 when referring to claim 3, wherein - the open end (2a) is arranged between two RF electrodes (30) of the planar Paul trap (3) in a first transverse direction (L1), - the open end (2a) is arranged between two DC electrodes (31) of the planar Paul trap (3) in a second transverse direction (L2) perpendicular to the first transverse direction.

13. The quantum computing device (100) according to any one of the preceding claims, wherein - there is no conductive material in the space between the open end (2a) of the quantum computing device (100) and the position where the at least one ion (6) is to be trapped, such that the oscillating magnetic field can reach the trapped ion (6) without being shielded.

14. A quantum computer device, comprising - the quantum computing device (100) according to any one of the preceding claims, - a signal generator (200) configured to supply an alternating electrical signal having the resonant frequency to the resonator electrode (2).

15. A quantum computer (1000) comprising the quantum computing device (100) according to any one of claims 1 to 13 or the quantum computer device according to claim 14, and the quantum computer (1000) is configured to perform quantum computing.

16. A quantum computer (1000), further comprising a laser-based cooling and / or reading system.

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

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