Superconducting qubit, coupling regulation method and superconducting quantum chip

Abstract

The application discloses a superconducting quantum bit, a coupling regulation method and a superconducting quantum chip. First and second electrode regions of the superconducting quantum bit extend along spiral tracks in the same direction around the same center to form a coupling ring layer. On the one hand, the coupling ring layer can effectively constrain stray components of electromagnetic fields in unintended directions, thereby reducing undesired crosstalk between adjacent circuit elements. On the other hand, the spiral winding of the electrode regions can increase the effective coupling path between the two electrode regions, improve the proportion of the coupling capacitance in the equivalent total capacitance, reduce the area occupied by the electrode regions, and realize miniaturization of the superconducting quantum bit. Meanwhile, the boundary of the coupling ring layer is designed in a smooth arc shape, instead of the insertion finger or sharp edge structure in the related art, so that the electric field energy distribution is more uniform, the possibility of charge accumulation at local sharp ends or corners is reduced, and the superconducting quantum bit can maintain target anharmonicity while reducing the parasitic coupling of the electrode regions to the package and adjacent devices.

Description

Technical Field

[0001] This application relates to the field of superconducting quantum computing technology, and in particular to superconducting qubits, coupling and control methods, and superconducting quantum chips. Background Technology

[0002] Existing superconducting qubits typically employ floating-ground designs, meaning they generally consist of two facing capacitor plates and a Josephson junction connecting them. The capacitor plates are typically rectangular, semi-circular, cross-shaped, or other large-area planar capacitor plates. For floating-ground qubits, without considering coupling capacitance introduced by external readout lines, control lines, adjacent bits, or bus resonators, the equivalent total capacitance C... Σ This mainly includes the coupling capacitance C between the two capacitor plates. 12 Josephson junction capacitance C J The differential mode equivalent capacitance C of the two plates g,eff In related designs, if the equivalent total capacitance C can be... Σ Increasing the coupling capacitance C while keeping it constant 12 The proportion of this can reduce the differential mode equivalent capacitance C. g,eff This reduces the layout area required for the ground capacitance of the two large-area power boards, thereby enabling the miniaturization of floating ground bits.

[0003] In related designs, floating qubits typically employ techniques such as interdigitated edges, wavy edges, localized narrow slits, or extended relative boundaries to increase capacitance density per unit area and improve coupling capacitance C. 12 However, this structure easily introduces sharp points, long and thin edges, and local strong electric fields, thereby increasing the electric field energy participation rate of metal edges, dielectric surfaces, and substrate interfaces, which can easily lead to the accumulation of charge at the sharp points, thus affecting the performance of superconducting qubits. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides superconducting qubits, coupling control methods, and superconducting quantum chips.

[0005] In a first aspect, this application provides a superconducting quantum bit, including a first electrode region, a second electrode region, and a Josephson junction element. The second electrode region and the first electrode region are spaced apart in a preset plane. The first electrode region and the second electrode region extend in the same direction along a spiral trajectory around the same center to form a coupling layer. Capacitive coupling is formed between the first electrode region and the second electrode region. The Josephson junction element is disposed in the coupling layer and is electrically connected between a first end of the first electrode region and a first end of the second electrode region.

[0006] In some embodiments, the first end of the first electrode region is located in the central region of the coupling ring, and the first electrode region extends outward from its first end along a first spiral trajectory to its second end; the first end of the second electrode region is located in the central region of the coupling ring, and the second electrode region extends outward from its first end along a second spiral trajectory to its second end; the first spiral trajectory and the second spiral trajectory together form the coupling ring, and the first electrode region and the second electrode region are arranged alternately in the radial direction of the coupling ring.

[0007] In some embodiments, the superconducting quantum bit further includes a coupling transition member disposed at the second end of the first electrode region or the second end of the second electrode region.

[0008] In some embodiments, the coupling adapter includes a readout coupling electrode, a modulation coupling electrode, a resonant coupling electrode, and a wiring adapter electrode.

[0009] In some embodiments, both the first spiral trajectory and the second spiral trajectory are equidistant spirals.

[0010] In some embodiments, both the first spiral trajectory and the second spiral trajectory are non-equidistant spirals.

[0011] In some embodiments, the outline shape of the coupling layer is one of a circle, an ellipse, or a rounded rectangle.

[0012] In some embodiments, the width of the first electrode region is the same as the width of the second electrode region, and / or the number of surrounding layers of the first electrode region is the same as the number of surrounding layers of the second electrode region.

[0013] In some embodiments, the Josephson junction element is a superconducting quantum interference device or a single Josephson junction.

[0014] Secondly, this application provides a coupling control method applied to superconducting qubits. The superconducting qubit includes a first electrode region, a second electrode region, and a Josephson junction element. The first electrode region and the second electrode region extend in the same direction along a spiral trajectory around the same center to form a coupling layer. Capacitive coupling is formed between the first electrode region and the second electrode region. The Josephson junction element is electrically connected between a first end of the first electrode region and a first end of the second electrode region. The coupling control method includes: determining the target frequency band, target anharmonicity range, and coupling capacitance percentage threshold of the superconducting qubit; constructing the superconducting qubit... A simulation model of the superconducting quantum bit is constructed, and the structural parameters of the first and second electrode regions are adjusted. A capacitance matrix simulation is performed on the superconducting quantum bit to obtain the coupling capacitance between the first and second electrode regions and the total capacitance of the superconducting quantum bit. The above adjustment and simulation steps are repeated until the proportion of the coupling capacitance in the total capacitance reaches the coupling capacitance proportion threshold, and the anharmonicity calculated based on the total capacitance falls into the target anharmonicity range. The total capacitance at this time is obtained as the target total capacitance. The Josephson energy of the Josephson junction element is determined according to the target frequency band and the target total capacitance.

[0015] In some embodiments, adjusting the structural parameters of the first electrode region and the second electrode region includes: adjusting at least one of the following: the linewidth of the first electrode region and the linewidth of the second electrode region, the gap between the first electrode region and the second electrode region, the number of spiral turns of the coupling ring, the inner radius of the coupling ring, and the outer radius of the coupling ring.

[0016] In some embodiments, determining the Josephson energy of the Josephson junction element based on the target frequency band and the target total capacitance includes: calculating the charging energy of the superconducting quantum bit based on the target total capacitance; and calculating a target value of the Josephson energy based on the center frequency of the target frequency band and the charging energy.

[0017] In some embodiments, when the Josephson junction element is a single Josephson junction, the coupling control method further includes: calculating a critical current based on the target value of the Josephson energy; obtaining the critical current density corresponding to a preset process and a preset material; and calculating the junction area of ​​the single Josephson junction based on the critical current and the critical current density.

[0018] In some embodiments, when the Josephson junction element is a superconducting quantum interference device, the coupling control method further includes: determining the critical current of each Josephson junction in the superconducting quantum interference device based on the target value of the Josephson energy and the target magnetic flux bias point; obtaining the critical current density corresponding to a preset process and preset material; and calculating the junction area of ​​each Josephson junction based on the critical current and the critical current density.

[0019] Thirdly, this application provides a superconducting quantum chip, including a plurality of superconducting qubits and a coupler; the coupler is coupled to at least two of the superconducting qubits respectively to realize signal transmission between the coupled superconducting qubits.

[0020] This application provides a superconducting quantum bit, a coupling control method, and a superconducting quantum chip. The superconducting quantum bit includes a first electrode region, a second electrode region, and a Josephson junction element. The second electrode region and the first electrode region are spaced apart in a preset plane. The first and second electrode regions extend in the same direction along a spiral trajectory around the same center to form a coupling layer, and capacitive coupling is formed between the first and second electrode regions. The Josephson junction element is disposed in the coupling layer and electrically connected between the first end of the first electrode region and the first end of the second electrode region. The first and second electrode regions extending in the same direction along a spiral trajectory around the same center to form the coupling layer provides a deterministic spatial transmission path for coupled energy, effectively constraining stray electromagnetic field components in unintended directions and reducing unwanted crosstalk between adjacent circuit components. Furthermore, the spiral encirclement of the first and second electrode regions increases the effective relative edge length between the two electrode regions, thereby increasing the effective coupling capacitance value between the two electrode regions without significantly increasing the projected area. This increases the proportion of the coupling capacitance in the equivalent total capacitance, which is beneficial for reducing the area occupied by the electrode regions and realizing the miniaturization of the superconducting quantum bit. The two electrode regions form a coupling ring along a spiral trajectory, resulting in a continuous and smooth arc-shaped boundary design for the coupling ring. This replaces the interdigitated or sharp edge structures in related technologies, making the electric field energy distribution more uniform and reducing the possibility of charge accumulation at local tips or corners. This reduces nonlinear effects or additional losses caused by local high field strength. At the same time, the smooth boundary reduces the sensitivity of the electrode region to the external packaging environment and parasitic capacitance and inductive coupling between adjacent devices, which helps to improve the process tolerance and performance consistency of superconducting qubits while maintaining the stability of the target anharmonic parameters. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the structure of the first embodiment of the superconducting quantum bit provided in this application; Figure 2 This is a schematic diagram of the structure of the second embodiment of the superconducting quantum bit provided in this application; Figure 3 This is a schematic diagram of the structure of the third embodiment of the superconducting quantum bit provided in this application; Figure 4 This is a flowchart illustrating an embodiment of the coupling control method provided in this application; Figure 5 This is a schematic diagram of an embodiment of the superconducting quantum chip provided in this application.

[0022] In the figure, 10 is a superconducting quantum bit; 11 is the first electrode region; 111 is the first helical trajectory; 12 is the second electrode region; 121 is the second helical trajectory; 13 is a Josephson junction element; 14 is a coupling transition component; and 20 is a coupler. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0025] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0026] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of the first embodiment of the superconducting quantum bit provided in this application. Figure 1 As shown, this application embodiment first provides a superconducting quantum bit 10, which includes a first electrode region 11, a second electrode region 12, and a Josephson junction element 13.

[0027] The second electrode region 12 and the first electrode region 11 are spaced apart in a preset plane. The first electrode region 11 and the second electrode region 12 extend in the same direction along a spiral trajectory around the same center to form a coupling layer, and capacitive coupling is formed between the first electrode region 11 and the second electrode region 12. A Josephson junction element 13 is disposed in the coupling layer, and the Josephson junction element 13 is electrically connected between the first end of the first electrode region 11 and the first end of the second electrode region 12.

[0028] The first electrode region 11 and the second electrode region 12 constitute the capacitor body of the superconducting quantum bit 10. The first electrode region 11 and the second electrode region 12 can be, but are not limited to, a helical conductor formed from a superconducting metallic conductor. The first electrode region 11 and the second electrode region 12 are spaced apart within a predetermined plane, and the first ends of the first electrode region 11 and the first ends of the second electrode region 12 extend outward in the same direction around the same center. The helical trajectories of the first electrode region 11 and the second electrode region 12 intersect and surround to form a region with a specific number of turns or surrounding layers, which is the coupling layer. The main coupling capacitance is formed between the first electrode region 11 and the second electrode region 12.

[0029] Josephson junction element 13 is disposed in the coupling loop and is electrically connected to the first end of the first electrode region 11 and the first end of the second electrode region 12, respectively. Josephson junction element 13 is a component used to provide nonlinear inductance. In one embodiment, Josephson junction element 13 can be disposed in the central region of the coupling loop to make the coupling loop generated by the spiral highly symmetrical in distribution, thereby ensuring that the contributions of the two electrode regions to the coupling capacitance are essentially the same. This facilitates standard reciprocal coupling and improves the symmetry of the superconducting quantum bit 10, providing balanced coupling conditions for subsequent quantum logic gate operations. In another embodiment, Josephson junction element 13 can also be disposed off-center from the coupling loop to make the contribution ratio of the two electrode regions to the coupling capacitance no longer equivalent, thereby introducing a defined coupling strength gradient or phase difference distribution between the two electrode regions. This allows for fine adjustment of the strength and direction of non-reciprocal coupling, thereby achieving directional signal routing or specific quantum logic gate operations. Specifically, the Josephson junction element 13 has a predetermined displacement relative to the geometric center of the coupling layer, thereby breaking the original spatial symmetry layout of the coupling layer. Due to the asymmetric change in the relative positional relationship between the Josephson junction element 13 and the electrode region, the participation ratio and distributed capacitance parameters of the two electrode regions in the equivalent capacitance network exhibit controllable differences. As a result, the two coupling ports of the superconducting quantum bit 10 will each exhibit asymmetrical effective coupling rates relative to the external transmission line or neighboring quantum bits. This asymmetric coupling distribution is beneficial for achieving differentiated and independent configuration of the coupling strength between the two coupling ports, enabling the superconducting quantum bit 10 to flexibly adapt to different quantum logic gate operation requirements or signal routing preferences.

[0030] It should be noted that this asymmetric coupling distribution introduced by the displacement of junction elements provides the superconducting qubit 10 with valuable degrees of freedom for asymmetric coupling adjustment, enabling it to flexibly adapt to different operating modes according to practical application scenarios: at the signal routing level, it can be used to construct microwave channels with directional transmission characteristics; at the quantum manipulation level, it can serve as the hardware structure basis for executing non-reciprocal quantum logic gates (such as directional controlled rotation gates). Compared with qubits with traditional fixed symmetry structures, this implementation significantly enhances the functional flexibility and hardware reuse efficiency of the superconducting qubit 10 in multi-task quantum processing, and reduces the dependence on external tuning circuits.

[0031] Therefore, in this embodiment, the first electrode region 11 and the second electrode region 12 extend in the same direction along a spiral trajectory around the same center to form a coupling ring. On the one hand, the coupling ring provides a deterministic spatial transmission path for the coupled energy, effectively constrains stray electromagnetic field components in unexpected directions, and reduces unwanted crosstalk between adjacent circuit elements. On the other hand, the spiral encirclement of the first electrode region 11 and the second electrode region 12 can increase the effective relative edge length between the two electrode regions, thereby increasing the effective coupling capacitance value between the two electrode regions without significantly increasing the projected area, and thus increasing the proportion of the coupling capacitance in the equivalent total capacitance, which is beneficial to reducing the area occupied by the electrode regions and realizing the miniaturization of the superconducting quantum bit 10. The two electrode regions form a coupling ring along a spiral trajectory, resulting in a smooth arc-shaped boundary design for the coupling ring. This replaces the interdigitated or sharp edge structures used in related technologies, making the electric field energy distribution more uniform and reducing the possibility of charge accumulation at local tips or corners. This reduces nonlinear effects or additional losses caused by local high field strength. At the same time, the smooth boundary reduces the sensitivity of the electrode region to the external packaging environment and parasitic capacitance and inductive coupling between adjacent devices. This helps to improve the process tolerance and performance consistency of superconducting qubits while maintaining the stability of the target anharmonic parameters.

[0032] In some embodiments, the first end of the first electrode region 11 is located in the central region of the coupling layer, and the first electrode region 11 extends outward from its first end along a first helical trajectory 111 to its second end. The first end of the second electrode region 12 is located in the central region of the coupling layer, and the second electrode region 12 extends outward from its first end along a second helical trajectory 112 to its second end. The first helical trajectory 111 and the second helical trajectory 112 together form the coupling layer, and the first electrode region and the second electrode region are arranged alternately in the radial direction of the coupling layer.

[0033] The first end of the first electrode region 11 and the first end of the second electrode region 12 extend outward from the central region with a predetermined gap. It can be understood that the central region is formed within a predetermined range around the same center point around which the first electrode region 11 and the second electrode region 12 unfold; or, the central region specifically refers to a predetermined area extending from the geometric center of a spiral trajectory. The first ends of the first electrode region 11 and the second electrode region 12 are disposed within this central region.

[0034] The first end of the first electrode region 11 extends outward from the center region of the coupling layer along the first helical trajectory 111 until it reaches the second end of the first electrode region 11. The first end of the second electrode region 12 extends outward from the center region of the coupling layer along the second helical trajectory 112 until it reaches the second end of the second electrode region 12. The first helical trajectory 111 and the second helical trajectory 112 alternately surround and form a coupling layer with a specific number of turns. Along the radial direction of the coupling layer, the first electrode region 11 and the second electrode region 12 are arranged alternately.

[0035] The radial direction of the coupling ring is any direction from the center point of the first electrode region 11 and the second electrode region 12 surrounding the outermost ring. From the center region of the coupling ring along any radial direction, the first electrode region 11, the second electrode region 12, and so on are arranged alternately. In a possible scheme, the helical trajectory refers to the curved motion trajectory formed by the conductor of the electrode region continuously rotating around the center point in a plane or three-dimensional space and gradually moving away from the center point. The first helical trajectory 111 and the second helical trajectory 112 alternately surround the first electrode region 11, ensuring that the first electrode region 11 is adjacent to the second electrode region 12. A predetermined gap is maintained as the first electrode region 11 and the second electrode region 12 extend outwards to ensure effective coupling between them.

[0036] Therefore, the first electrode region 11 extends along the first helical trajectory 111, and the second electrode region 12 extends along the second helical trajectory 112, resulting in a smooth arc-shaped boundary design for the formed coupling layer. This effectively reduces the possibility of charge accumulation at local tips or corners, and reduces or avoids the possibility of strong local edge fields, thereby reducing nonlinear effects or additional losses caused by local high field strength. Simultaneously, the smooth boundary reduces the sensitivity of the electrode region to the external packaging environment and parasitic capacitance and inductive coupling between adjacent devices, helping to improve the process tolerance and performance consistency of superconducting qubits while maintaining the stability of the target anharmonic parameters.

[0037] In some embodiments, see Figure 2 , Figure 2 This is a schematic diagram of the structure of a second embodiment of the superconducting quantum bit provided in this application. Figure 2 As shown, the superconducting quantum bit 10 also includes a coupling transition member 14, which is disposed at the second end of the first electrode region 11 and / or the second end of the second electrode region 12.

[0038] The second end of the first electrode region 11 is a terminal region extending outward along the first helical trajectory 111; the second end of the second electrode region 12 is a terminal region extending outward along the second helical trajectory 112. A coupling adapter 14 is disposed at the second end of the first electrode region 11 and / or the second end of the second electrode region 12, enabling external circuits to establish an effective coupling channel with the electrode regions of the superconducting quantum bit 10 through the coupling adapter 14, thereby performing at least one function such as quantum state readout, flux / charge control, and bus bit interconnection. Simultaneously, since the coupling adapter 14 is disposed at the outer end of the electrode region, the geometric position of the outer end allows for convenient signal extraction or connection to the outside, reducing interference with the electric field distribution of the internal coupling layer, improving the electric field uniformity of the internal coupling layer, and maintaining a high capacitance density.

[0039] In possible solutions, but not limited to, adjusting the distance, overlap area, or coupling length between the coupling adapter 14 and the outer end of the electrode region, the coupling strength between the external circuit and the superconducting quantum bit 10 can be precisely controlled.

[0040] In some embodiments, the coupling adapter 14 includes a readout coupling electrode, a modulation coupling electrode, a resonant coupling electrode, and a wiring adapter electrode.

[0041] In a first embodiment, a readout coupling electrode may be provided at the second end of the first electrode region 11 and / or the second end of the second electrode region 12. The readout coupling electrode is used for capacitive or inductive coupling with the coupling coil to achieve signal readout. Exemplarily, the readout coupling electrode may be a readout coupling plate (e.g., a rectangular or arc-shaped metal plate) spaced apart from the outer end of the electrode region within a predetermined plane. This readout coupling plate establishes a coupling channel through the edge electric field or mutual inductance effect between itself and the outer end of the electrode region, transmitting the microwave signal in the coupling coil to an external readout resonator or transmission line.

[0042] In one embodiment, a readout coupling electrode is provided only at the second end of the first electrode region 11 to form a single-ended readout architecture, which reduces the area occupied by the electrode region leads and facilitates further compression of the qubit unit size. In another embodiment, readout coupling electrodes are provided simultaneously at the second ends of the first electrode region 11 and the second ends of the second electrode region 12 to form a differential readout architecture. This differential approach is beneficial for common-mode noise suppression and improves the readout signal-to-noise ratio.

[0043] In the second embodiment, a control coupling electrode may be provided at the second end of the first electrode region 11 and / or the second end of the second electrode region 12. The control coupling electrode is used to apply microwave pulses to the coupling loop, exciting charge level transitions through capacitive coupling (charge control) or modulating loop magnetic flux through inductive coupling (magnetic flux control), thereby achieving active manipulation of the quantum state of the superconducting quantum bit 10 (e.g., performing single-qubit rotation gate operation or frequency tuning). Exemplarily, the control coupling electrode may be a control line coupling piece spaced apart from the outer end of the electrode region in a preset plane. The control coupling electrode is typically connected to an external XY control line, serving as an intermediate coupling node for feeding microwave signals into the coupling loop via a transmission line.

[0044] In one embodiment, a control coupling electrode is provided only at the second end of the first electrode region 11 to form a single-ended driving architecture, which simplifies chip wiring and saves winding space. In another embodiment, control coupling electrodes are provided simultaneously at the second ends of the first electrode region 11 and the second ends of the second electrode region 12 to form a differential driving architecture. This differential method can achieve push-pull excitation, improve the coupling efficiency of microwave power, and effectively suppress the interference of common-mode noise on the quantum state.

[0045] In the third embodiment, a resonant coupling electrode may be provided at the second end of the first electrode region 11 and / or the second end of the second electrode region 12. The resonant coupling electrode is used to couple with an external bus resonator or other auxiliary resonant circuit to achieve coherent quantum state transfer between multiple qubits, frequency multiplexing of shared readout channels, or selective coupling / filtering of microwave signals in a specific frequency band. For example, the resonant coupling electrode may be a bus resonator coupling plate spaced apart from the outer end of the electrode region within a predetermined plane. The coupling plate establishes an energy exchange channel with the external bus resonator through an edge electric field or mutual inductance effect, thereby mapping the quantum state information of the superconducting quantum bit 10 to the microwave mode of the bus resonator, realizing the transfer or shared readout of quantum information between qubits.

[0046] In one embodiment, a resonant coupling electrode is provided only at the second end of the first electrode region 11 to form a single-ended coupling architecture, which simplifies the connection layout between bits and the bus and is suitable for small-scale quantum processors. In another embodiment, resonant coupling electrodes are provided simultaneously at the second ends of the first electrode region 11 and the second ends of the second electrode region 12 to form a differential coupling architecture. This differential method is beneficial for realizing push-pull energy transfer, improving the coupling efficiency between bits and the bus, and suppressing common-mode parasitic coupling.

[0047] In the fourth embodiment, a wiring transition electrode may be provided at the second end of the first electrode region 11 and / or the second end of the second electrode region 12. The wiring transition electrode is used to connect signal lines of different layers (such as M1 and M2 layers in a superconducting chip) or as a transition node in the signal transmission path (such as a vertical via pad or a lateral bridging pad) to achieve signal transition and interconnection between different wiring layers within the chip. For example, the wiring transition electrode may be constructed as a via pad or bridging lead terminal electrically connected to the outer end of the electrode region. It achieves low-impedance transition between signal lines of different layers through a metal-insulator-metal (MIM) structure or direct ohmic contact, thereby providing a flexible three-dimensional interconnection scheme for the lead-out wiring of superconducting qubits.

[0048] In the fifth embodiment, the second end of the first electrode region 11 and the second end of the second electrode region 12 can be respectively provided with any two or more of the following: readout coupling electrode, control coupling electrode, resonant coupling electrode, and wiring transition electrode. Through differentiated configurations of different ports on the same superconducting quantum bit 10, the superconducting quantum bit 10 can independently integrate and realize multiple functions such as quantum state readout, quantum state manipulation, bit-bus resonant coupling, and multilayer signal interconnection, achieving different external interactions and coupling functions. No specific limitations are made here. It should be noted that the specific combination of the above electrodes and their placement position (same side or opposite side) at the outer end of the coupling layer can be flexibly adjusted according to the layout plan of the target chip. This application does not exhaustively limit this.

[0049] In some implementation schemes, such as Figure 1 and Figure 2 As shown, both the first spiral trajectory 111 and the second spiral trajectory 112 are equidistant spirals.

[0050] Wherein, when both the first spiral trajectory 111 and the second spiral trajectory 112 are equidistant spirals, the radial distance between two adjacent turns of the first spiral trajectory 111 in the coupling layer remains constant, and the radial distance between two adjacent turns of the second spiral trajectory 112 in the coupling layer remains constant. Exemplarily, the first spiral trajectory 111 and the second spiral trajectory 112 may, but are not limited to, Archimedean spirals.

[0051] Therefore, both the first spiral trajectory 111 and the second spiral trajectory 112 are equidistant spirals. The spacing between the first electrode region 11 and the second electrode region 12 remains constant or changes only slightly during their spiral rotation. This effectively reduces capacitance parameter fluctuations caused by spacing variations, resulting in a good uniformity of electric field energy distribution along the spiral path between the two electrode regions. This avoids local high-field regions or electric field distortions introduced by non-uniform spacing changes. Furthermore, in the equidistant spiral configuration, the geometry of the coupling layers can be accurately described by simple polar coordinate equations (i.e., the radial coordinates and angular coordinates are linearly related). This allows the coupling capacitance value between the first electrode region 11 and the second electrode region 12 to be accurately calculated analytically or predicted through simulation using a few geometric parameters (such as the initial radius, radial spacing, and total number of turns). This facilitates rapid iteration and precise control of the coupling capacitance during the design phase using simple geometric parameters, simplifying coupling design and improving the consistency and repeatability of qubit parameters in mass production.

[0052] In other implementations, please refer to Figure 3 , Figure 3 This is a schematic diagram of the structure of the third embodiment of the superconducting quantum bit provided in this application. The first helical trajectory 111 and the second helical trajectory 112 are non-equidistant helices.

[0053] Wherein, the first helical trajectory 111 and the second helical trajectory 112 are non-equidistant helices, that is, the radial distance between two adjacent turns in the first helical trajectory 111 formed by the outward extension of the first electrode region 11 is not equal, and the radial distance between two adjacent turns in the second helical trajectory 112 is not equal. For example, as Figure 3 As shown, in the radial direction of the coupling layer, adjacent turns of the first helical trajectory 111 and the second helical trajectory 112 have different radial distances, such that the spacing between adjacent first helical trajectories 111 and second helical trajectories 112 in different layers of the coupling layer is different, such as d1, d2, d3, d4, and d5. Furthermore, by way of example, the first helical trajectory 111 and the second helical trajectory 112 can be, but are not limited to, Fibonacci spirals, logarithmic spirals, and Fermat spirals.

[0054] Therefore, by adjusting the helical spacing of the first helical trajectory 111 and the second helical trajectory 112, the coupling capacitance between electrodes in a specific region can be locally enhanced or weakened. This allows for fine-tuning of the capacitance ratio between the two electrode regions without changing the overall envelope area and total number of turns of the coupling loop, thus optimizing the local capacitance density distribution and better matching the target operating frequency and anharmonic parameters.

[0055] In some other embodiments, the first spiral trajectory 111 and the second spiral trajectory 112 are composed of discontinuous multi-segment curves.

[0056] The discontinuous multi-segment curves refer to the fact that the first helical trajectory 111 and the second helical trajectory 112 are not continuous single curves, but rather composed of multiple independent curve segments arranged sequentially along the same helical trend, spaced apart in space. For example, local breaks can be introduced into the originally continuously extending helical conductor, dividing the originally continuous helical trajectory into multiple electrically isolated or partially isolated curve segments to form discontinuous multi-segment curves. Each independent curve segment can have the same or different curve shapes; for example, the first helical trajectory 111 is composed of multiple circular or elliptical arcs. Therefore, the first electrode region 11 and the second electrode region 12 form local breaks at specific locations in the coupling layer, reserving wiring space or adjusting local geometry within the coupling layer, which is beneficial for improving the integration flexibility and design freedom of the superconducting quantum bit 10.

[0057] It is important to emphasize that these disconnected areas can be used for the following purposes: reserving wiring channels within the coupling layer for other signal lines to pass vertically or horizontally, which helps alleviate chip layout congestion and improve overall wiring efficiency; adaptively cutting off and adjusting the local geometry in areas where large-area continuous electrodes are not needed to avoid the space occupied by vias, contact holes, or other active / passive devices; and further optimizing the local capacitance density and inductance distribution of the coupling layer by changing the spacing between multiple curve segments or the arc length ratio of each curve segment, thereby obtaining more precise electromagnetic parameter control capabilities without changing the overall spiral envelope.

[0058] In some embodiments, the outline shape of the coupling layer is one of a circle, an ellipse, or a rounded rectangle.

[0059] In the first approach, the outline of the coupling ring is circular, and the radial distance of each trajectory within the coupling ring varies relatively uniformly. The first electrode region 11 and the second electrode region 12 extend outward from the central region, and the two spiral trajectories rotate around the central region at a constant interval, making the coupling ring form a structure similar to concentric circles but composed of alternating different electrode regions, which helps to improve the symmetry of the coupling ring.

[0060] In the second approach, the coupling ring has an elliptical outline, with different radii of curvature along its major and minor axes to accommodate specific packaging layouts. The first electrode region 11 and the second electrode region 12 extend outwards from the central region. The curvature of the two spiral trajectories along the major axis is less than that along the minor axis, allowing the coupling ring to extend a longer coupling length along the major axis. This enables higher capacitance density within a limited space along the minor axis, facilitating adaptation to narrow spatial layouts.

[0061] In the third approach, the outline of the coupling layer is a rounded rectangle. The four corners of the coupling layer are rounded to avoid electric field concentration caused by sharp corners. The first electrode region 11 and the second electrode region 12 extend outwards from the central region, with two spiral trajectories encircling the boundary of the rectangle. At abrupt changes in direction, a gradual transition is used to smooth the transition, resulting in a coupling layer that resembles a rounded rectangle but is composed of alternating different electrode regions, thus improving the utilization of the chip area.

[0062] In some embodiments, the capacitance width, electrode gap, and coupling length of the coupling layer can independently affect the coupling strength. Therefore, by adjusting at least one of the parameters of capacitance width, electrode gap, and coupling length, decoupling of coupling parameter variations can be achieved, which simplifies the coupling design process of superconducting qubit 10, improves design efficiency, and enhances the stability and repeatability of design results.

[0063] The capacitance width can be, but is not limited to, the width of the first electrode region 11 and / or the second electrode region 12. Variations in the width of the first electrode region 11 and / or the second electrode region 12 directly affect the effective coupling area between the first electrode region 11 and the second electrode region 12, thereby adjusting the coupling strength. The electrode gap can be, but is not limited to, the minimum distance between the first electrode region 11 and the second electrode region 12, i.e., the gap between the first electrode region 11 and the second electrode region 12. Variations in the gap between the first electrode region 11 and the second electrode region 12 can change the edge electric field distribution between the first electrode region 11 and the second electrode region 12, thus affecting the coupling capacitance. The coupling length can be, but is not limited to, the total length of the coupling loop formed by the spiral encirclement of the first electrode region 11 and the second electrode region 12. Variations in the coupling length directly affect the effective coupling area between the first electrode region 11 and the second electrode region 12, thus affecting the coupling capacitance.

[0064] In possible implementations, the aforementioned capacitor width, electrode gap, and coupling length can be finely adjusted, but are not limited to, through micrometer-level precision control. For example, the electrode gap can be changed by micrometer-level helical sliding of the first electrode region 11 and / or the second electrode region 12; alternatively, the capacitor width can be changed by adjusting the insulating layer or gap size of the first electrode region 11 and / or the second electrode region 12. Furthermore, the coupling length can be changed, but is not limited to, by adjusting at least one of the following: the winding pattern of the first electrode region 11 and the second electrode region 12, the radius of a single layer of winding, or the number of spiral layers.

[0065] In some embodiments, the width of the first electrode region 11 is the same as the width of the second electrode region 12; and / or, the number of surrounding layers of the first electrode region 11 is the same as the number of surrounding layers of the second electrode region 12.

[0066] Wherein, the width of the first electrode region 11 and the second electrode region 12 is the cross-sectional dimension of the electrode in the radial or normal direction. The number of surrounding layers is the number of rotations or angular range of the first helical trajectory 111 and the second helical trajectory around the central region. Therefore, having the same width and / or number of surrounding layers for the first electrode region 11 and the second electrode region 12 can improve the symmetry or consistency of the first electrode region 11 and the second electrode region 12 in terms of geometric structure, thereby keeping the equivalent electrical length and local capacitance contribution of the two in the coupling layer balanced, reducing the risk of capacitance mismatch or coupling asymmetry caused by parameter deviation, and helping to ensure the performance consistency and repeatability of the superconducting quantum bit 10 during the manufacturing process.

[0067] In one implementation, such as Figure 1 and Figure 2 As shown, the width of the first electrode region 11 is the same as the width of the second electrode region 12, and the number of spiral layers in the first electrode region 11 is the same as the number of spiral layers in the second electrode region 12. Therefore, the geometric symmetry of the superconducting quantum bit 10 in forming the coupling capacitance can be guaranteed, which is conducive to forming a balanced capacitance participation ratio in the coupling layers of the two electrode regions, thereby improving the uniformity of the electric field distribution and the stability of the coupling parameters of the superconducting quantum bit 10.

[0068] In another embodiment, the first electrode region 11 and the second electrode region 12 have the same width to further improve the symmetry of the coupling capacitance along the coupling path. For example, as... Figure 3 As shown, the first electrode region 11 and the second electrode region 12 have the same width, and the first electrode region 11 has fewer spiral layers than the second electrode region 12. In this type of asymmetric spiral layer layout, keeping the widths of the first electrode region 11 and the second electrode region 12 consistent ensures that in the overlapping area of ​​the coupling layers, the two electrodes have the same cross-sectional dimensions perpendicular to the spiral extension direction. This keeps the coupling capacitance density per unit length of electrodes relatively consistent within the coupling region, avoiding additional local capacitance fluctuations introduced by differences in electrode width.

[0069] In another embodiment, the number of spiral layers in the first electrode region 11 is the same as the number of spiral layers in the second electrode region 12, meaning they have the same total angular range. This ensures that the two spiral trajectories maintain consistency in both radial extension (i.e., the span from the starting radius to the ending radius) and angular extension (i.e., the total rotation angle), resulting in the two electrodes having the same equivalent electrical length across the entire coupling layer. This helps reduce the mismatch in equivalent capacitance caused by path length differences, improving the predictability of the superconducting quantum bit 10's parameters and manufacturing consistency.

[0070] In some embodiments, such as Figure 1 and Figure 2As shown, the maximum outer diameter of the first electrode region 11 is the same as the maximum outer diameter of the second electrode region 12.

[0071] The maximum outer diameter is the diameter or radius of the circumference of the outermost boundary of the corresponding helical trajectory. When the radius is used, the maximum outer diameter is the radial distance from the central region to the terminal end of the helical trajectory. The maximum outer diameters of the first electrode region 11 and the second electrode region 12 are the same, so that the outermost boundaries of the spirally encircling first electrode region 11 and second electrode region 12 are almost on the same circumference, and the coupling layer as a whole presents a compact and clearly defined circular or approximately circular outline. On the one hand, under the same maximum outer diameter constraint, the circular outline is conducive to maximizing the effective capacitive coupling area between electrodes per unit chip area, avoiding the waste of radial redundant space introduced by irregular outlines, thereby improving the chip area utilization efficiency. On the other hand, the clearly defined circular outline is conducive to forming a symmetrical far-field electromagnetic radiation distribution, reducing the undesirable far-field parasitic coupling introduced by asymmetrical outlines, effectively suppressing long-range crosstalk between the superconducting quantum bit 10 and neighboring circuit elements, which is of positive significance for large-scale quantum chip integration.

[0072] In some embodiments, the superconducting quantum bit 10 further includes a substrate (not shown), on which a first electrode region 11 and a second electrode region 12 are disposed.

[0073] The substrate supports and carries the circuit elements, providing mechanical support and electrical isolation for the first electrode region 11 and the second electrode region 12. This helps ensure the stability of the geometry and the consistency of the capacitance parameters of the superconducting quantum bit 10. The first electrode region 11 and the second electrode region 12 can be, but are not limited to, fabricated on the surface or in the inner layer of the substrate using processes such as photolithography, evaporation, or sputtering.

[0074] In some embodiments, the Josephson junction element 13 is a superconducting quantum interference device or a single Josephson junction.

[0075] In one embodiment, the Josephson junction element 13 includes a single Josephson junction. The single Josephson junction is connected to the first electrode region 11 and the second electrode region 12, respectively. The critical current of the single Josephson junction is a fixed value, and its equivalent Josephson inductance is a fixed parameter. Therefore, the superconducting quantum bit 10 using a single Josephson junction is a fixed-frequency quantum bit, and its operating frequency is determined by the capacitive coupling parameter between the first electrode region 11 and the second electrode region 12 and the equivalent inductance of the single junction. It has the advantages of simple structure and insensitivity to magnetic flux noise, and is suitable for applications with high requirements for decoherence time.

[0076] In another embodiment, the Josephson junction element 13 is a superconducting quantum interference device (QFID) consisting of two Josephson junctions and a superconducting loop. The two Josephson junctions are connected in parallel and then connected to the superconducting loop, which receives an external magnetic flux bias. By changing the magnetic flux passing through the loop, the equivalent critical current of the QFID is adjusted, thereby changing its equivalent Josephson inductance and achieving continuous tunability of the operating frequency of the superconducting quantum bit 10. Compared to the aforementioned single-junction fixed-frequency scheme, the superconducting quantum interference device-type Josephson junction element 13 in this embodiment enables the superconducting quantum bit 10 to have frequency tunability. During operation, its operating frequency can be dynamically adjusted by the magnetic flux bias to avoid noise frequencies, optimize gate operation timing, or achieve resonant coupling with neighboring bits of different frequencies. This application also proposes a coupling control method. This coupling control method is applied to the superconducting quantum bit 10 in any of the above embodiments. The superconducting quantum bit 10 includes a first electrode region 11, a second electrode region 12, and a Josephson junction element 13. The first electrode region 11 and the second electrode region 12 extend in the same direction along a spiral trajectory around the same center to form a coupling layer. Capacitive coupling is formed between the first electrode region 11 and the second electrode region 12. The Josephson junction element 13 is electrically connected between the first end of the first electrode region 11 and the first end of the second electrode region 12.

[0077] Please see Figure 4 , Figure 4 This is a flowchart illustrating an embodiment of the coupling control method provided in this application. Figure 4 As shown, in this embodiment, the coupling control method includes the following steps: Step S11: Determine the target frequency band, target anharmonicity range, and coupling capacitance percentage threshold of the superconducting quantum bit 10.

[0078] When initially coupling and controlling the superconducting quantum bit 10, it is first necessary to determine the target frequency band, target anharmonicity range, and coupling capacitance percentage threshold of the superconducting quantum bit 10. The target frequency band of the superconducting quantum bit 10 is the resonant frequency range required for normal operation, used to constrain the coupling structure from causing a significant shift in the bit's resonant frequency. The target anharmonicity range of the superconducting quantum bit 10 is used to limit the allowable fluctuation range of its anharmonicity, preventing additional parasitic capacitance and stray inductance from the coupling structure from causing the anharmonicity to exceed the usable range. The coupling capacitance percentage threshold of the superconducting quantum bit 10 is used to limit the maximum allowable percentage of the coupling capacitance contributed by the coupling structure, thereby controlling the weight of the coupling capacitance. By determining the target frequency band, target anharmonicity range, and coupling capacitance percentage threshold of the superconducting quantum bit 10, it can be ensured that the combination of structural parameters of the superconducting quantum bit 10 obtained by the coupling and control method of this embodiment satisfies the constraints of the target frequency band, target anharmonicity range, and coupling capacitance percentage threshold, thereby improving the reliability of the superconducting quantum bit.

[0079] Step S12: Construct a simulation model of the superconducting quantum bit 10 and adjust the structural parameters of the first electrode region 11 and the second electrode region 12.

[0080] After determining the target frequency band, target anharmonicity range, and coupling capacitance percentage threshold of the superconducting quantum bit 10, a simulation model of the superconducting quantum bit 10 is constructed. Understandably, this simulation model is a piecewise electromagnetic simulation model of the superconducting quantum bit 10, used to reproduce the electromagnetic field distribution of the superconducting quantum bit 10 at low temperatures, in order to establish a quantitative mapping relationship between structural parameters and coupling strength.

[0081] After constructing a simulation model of the superconducting quantum bit 10, the structural parameters of the first electrode region 11 and the second electrode region 12 are adjusted. Understandably, the structural parameters are parameters used to directly change the effective coupling area and / or effective coupling length of the first electrode region 11 and the second electrode region 12. Exemplarily, the aforementioned structural parameters include, but are not limited to, at least one of the following: the capacitance width of the first electrode region 11 and the second electrode region 12; the gap between the capacitor plates of the first electrode region 11 and the second electrode region 12; and the coupling length of the first electrode region 11 and the second electrode region 12.

[0082] Step S13: Perform capacitance matrix simulation on the superconducting quantum bit 10 to obtain the coupling capacitance between the first electrode region 11 and the second electrode region 12 and the total capacitance of the superconducting quantum bit 10.

[0083] After adjusting the structural parameters of the first electrode region 11 and the second electrode region 12, the capacitance matrix of the superconducting quantum bit 10 can be simulated using electromagnetic field simulation software to construct the simulated capacitance matrix of the superconducting quantum bit 10 after structural adjustment. Based on this simulated capacitance matrix, the coupling capacitance C between the first electrode region 11 and the second electrode region 12 can be obtained. 12 And obtain the total capacitance of 10 superconducting qubits.

[0084] In one possible approach, the coupling capacitance C between the first electrode region 11 and the second electrode region 12 can be determined by simulating a capacitance matrix. 12 The indirect capacitance C formed by the first electrode region 11 and the second electrode region 12 with respect to the reference potential. g,eff Based on indirect capacitance C g,eff and coupling capacitor C 12 The sum of these values ​​yields the total capacitance of 10 superconducting qubits. The reference potentials mentioned above include, but are not limited to, the potentials relative to the ground plane, the encapsulation wall, and the surrounding metal; the indirect capacitances can be, but are not limited to, the differential mode equivalent capacitances or parasitic capacitances to ground.

[0085] Step S14: Repeat the above adjustment and simulation steps until the proportion of coupling capacitor in the total capacitance reaches the coupling capacitor proportion threshold, and the anharmonicity calculated based on the total capacitance falls into the target anharmonicity range, and obtain the total capacitance at this time as the target total capacitance.

[0086] After adjusting the structural parameters of the first electrode region 11 and the second electrode region 12 and obtaining the adjusted coupling capacitance between the first electrode region 11 and the second electrode region 12, as well as the total capacitance of the superconducting quantum bit 10, the proportion of the coupling capacitance of the current superconducting quantum bit 10 in the total capacitance is calculated. When the proportion of the coupling capacitance in the total capacitance is still less than the target coupling capacitance proportion threshold, the structural parameters of the first electrode region 11 and the second electrode region 12 are adjusted again, and the simulation operation of step S13 is repeated until the proportion of the coupling capacitance in the total capacitance reaches the coupling capacitance proportion threshold. When the proportion of the coupling capacitance in the total capacitance is close to or reaches the target coupling capacitance proportion threshold, the anharmonicity of the current superconducting quantum bit 10 is calculated based on the total capacitance. When the anharmonicity falls into the target anharmonicity range, it is determined that the current structural parameters are adjusted in place. At this time, the total capacitance obtained from the simulation is taken as the target total capacitance of the superconducting quantum bit 10.

[0087] Understandably, after the above structural adjustments and simulation steps, when the proportion of the coupling capacitance of the current superconducting quantum bit 10 in the total capacitance is close to or reaches the target coupling capacitance proportion threshold, and the anharmonicity falls within the target anharmonicity range, the target total capacitance of the current superconducting quantum bit 10 can be determined, and subsequent control operations can be performed.

[0088] Step S15: Determine the Josephson energy of Josephson junction element 13 based on the target frequency band and the target total capacitance.

[0089] After determining the target total capacitance of the superconducting quantum bit 10, the Josephson energy required for the Josephson junction element 13 is calculated based on the target frequency band and the target total capacitance, thereby determining the specific parameters of the Josephson junction element 13.

[0090] In this embodiment, the first electrode region 11 and the second electrode region 12 of the superconducting quantum bit 10 extend in the same direction along a spiral trajectory around the same center to form a coupling loop, which significantly increases the effective coupling path of the superconducting quantum bit 10 and increases the proportion of coupling capacitance in the total capacitance within a limited layout area. At the same time, by constructing a simulation model of the superconducting quantum bit 10 and adjusting the structural parameters of the first electrode region 11 and the second electrode region 12 to change the coupling strength of the coupling loop, the target total capacitance of the superconducting quantum bit 10 can be determined based on parameters such as the proportion of coupling capacitance in the total capacitance and anharmonicity. Then, the Josephson energy of the Josephson junction element 13 can be determined based on the target total capacitance and the target frequency band of the superconducting quantum bit 10, so as to obtain a superconducting quantum bit 10 that meets the target parameters such as the target frequency band, the target anharmonic range, and the coupling capacitance proportion threshold.

[0091] In some embodiments, adjusting the structural parameters of the first electrode region 11 and the second electrode region 12 in step S12 further includes the following steps: adjusting at least one of the following: the line width of the first electrode region 11 and the line width of the second electrode region 12, the gap between the first electrode region 11 and the second electrode region 12, the number of spiral turns of the coupling layer, the inner radius of the coupling layer, and the outer radius of the coupling layer.

[0092] The linewidths of the first electrode region 11 and the second electrode region 12 refer to the conductor widths of the spiral-shaped electrode plates. The linewidths of the first electrode region 11 and the second electrode region 12 directly affect the surface area of ​​the capacitor plates and the total length of the metal edges, thereby altering the coupling capacitance of the superconducting quantum bit 10. By adjusting the linewidths of the first electrode region 11 and the second electrode region 12, the length and area of ​​the capacitor plates can be controlled. This helps to ensure sufficient capacitance density while avoiding the sensitivity to processing errors caused by excessively narrow linewidths and the area waste caused by excessively wide linewidths.

[0093] The gap between the first electrode region 11 and the second electrode region 12 refers to the minimum distance between two adjacent spiral plates. This gap affects the local electric field strength and capacitance density between the two capacitor plates, thus altering the coupling capacitance of the superconducting quantum bit 10. By adjusting the gap between the first electrode region 11 and the second electrode region 12, the local electric field strength between the two capacitor plates can be optimized. This helps to increase the proportion of coupling capacitance while avoiding localized strong electric field hotspots caused by an excessively small gap, thereby reducing the risk of surface dielectric loss.

[0094] The number of spiral turns in the coupling layer refers to the number of spiral layers that encircle the first electrode region 11 and the second electrode region 12. The number of spiral turns in the coupling layer affects the total length of the effective coupling path, thereby changing the coupling capacitance of the superconducting quantum bit 10. By adjusting the number of spiral turns in the coupling layer, it is beneficial to maximize the effective coupling path within a limited area, thereby increasing the proportion of coupling capacitance in a compact layout space.

[0095] The inner radius of the coupling ring refers to the radial distance from the starting end of the first electrode region 11 and / or the second electrode region 12 to the center point of the ring, and the outer radius of the coupling ring refers to the radial distance from the ending end of the first electrode region 11 and / or the second electrode region 12 to the center point of the ring. The inner and outer radii of the coupling ring affect the overall occupied area and shape of the coupling ring, thereby changing the proportion of the coupling capacitance of the superconducting quantum bit 10 in the total capacitance. By adjusting the inner and / or outer radii of the coupling ring, the shape and space occupied by the double helix structure can be adjusted, which is beneficial for adjusting the size according to the layout requirements of the superconducting quantum bit 10 and reducing parasitic coupling with adjacent devices or packaging structures.

[0096] It should be noted that this application effectively increases the effective relative edge length between the two electrode regions by forming coupling layers using a smooth, arc-shaped double-helix trajectory, thereby increasing the proportion of the coupling capacitance between them in the equivalent total capacitance. Simultaneously, compared to traditional interdigitated structures, this scheme avoids a large number of sharp points, acute angles, and thin finger-like structures, which can constrain stray electromagnetic field components in unexpected directions, making the electric field energy distribution more uniform. Therefore, this application can significantly reduce the area occupied by the electrode regions and reduce far-field parasitic coupling and adjacent crosstalk while maintaining the target anharmonicity and the preset frequency design window, thus greatly improving the layout integration density and performance consistency of the superconducting quantum chip.

[0097] In the first embodiment, at least one structural parameter of the first electrode region 11 and the second electrode region 12 can be iteratively adjusted based on the deviation between the proportion of the coupling capacitor in the total capacitance and the coupling capacitor proportion threshold, until the proportion of the coupling capacitor in the total capacitance reaches the coupling capacitor proportion threshold. In the second embodiment, a set value for at least one structural parameter corresponding to the coupling capacitor can be determined according to a preset mapping relationship, and the corresponding structural parameter can be set to the set value, thereby changing the proportion of the coupling capacitor to the total capacitance of the superconducting quantum bit 10. This mapping relationship can be determined using a lookup table, fitting function, analytical model, empirical curve, or trained machine learning model; the mapping relationship can be an independent mapping between the coupling capacitor and a single structural parameter, or a joint mapping between the coupling capacitor and multiple structural parameters. In other embodiments, linear control of the coupling capacitor can also be achieved by adjusting one structural parameter while keeping the other structural parameters at their initial values.

[0098] Therefore, by adjusting at least one of the above parameters, the geometric dimensions of the superconducting quantum bit 10 and / or the coupling layer can be changed, thereby altering the ratio of the coupling capacitance of the superconducting quantum bit 10 to the total capacitance.

[0099] In some embodiments, in the coupling control method of this embodiment, step S15 includes the following steps: calculating the charging energy of the superconducting quantum bit 10 based on the target total capacitance; and calculating the target value of the Josephson energy based on the center frequency of the target frequency band and the charging energy.

[0100] The aforementioned charging energy is a physical quantity characterizing the Coulomb blocking effect in superconducting quantum bit 10, and its magnitude depends on the total capacitance of the superconducting quantum bit. The aforementioned Josephson energy is an energy parameter characterizing the nonlinear characteristics of the Josephson junction element 13. The Josephson energy may, but is not limited to, be related to the oscillation frequency and charging energy of superconducting quantum bit 10. In a possible scheme, the charging energy of superconducting quantum bit 10 can be calculated using the following formula: (1) In formula (1), e is the natural constant; This represents the actual total capacitance. To charge the battery.

[0101] When determining the Josephson energy of Josephson junction element 13, the corresponding charging energy is first calculated using the determined target total capacitance and the above formula (1). Then, combining the center frequency corresponding to the target frequency band, the target value of the Josephson energy of Josephson junction element 13 can be further calculated using the energy level transition frequency formula of superconducting quantum bit 10, the determined center frequency, and the charging energy. For example, for floating-type quantum bits, the constraint relationship between the target value of the Josephson energy, the charging energy, and the center frequency can be reflected by the following formula: (2) in, The center frequency; To charge energy; For Josephson; is Planck's constant.

[0102] Therefore, by calculating the target value of the Josephson energy based on the center frequency and charging energy of the target frequency band, the target value of the Josephson junction element 13 can be strictly matched with the charging energy and target operating frequency determined by the double helix structure. This ensures that the energy level structure of the superconducting quantum bit 10 falls precisely within the target frequency band while realizing the miniaturization of the superconducting quantum bit 10. This is beneficial to improving the accuracy of the operating frequency and the controllability of the anharmonicity of the superconducting quantum bit 10.

[0103] In one possible implementation, the Josephson junction element 13 is a single Josephson junction. After determining the target value of the Josephson energy, the coupling control method of this embodiment further includes the following steps: calculating the critical current according to the target value of the Josephson energy; obtaining the critical current density corresponding to the preset process and preset material; and calculating the junction area of ​​the single Josephson junction according to the critical current and critical current density.

[0104] Since the electrical characteristics of a single Josephson junction are primarily determined by the critical current, which in turn directly depends on the junction's geometric area and the critical current density of the superconducting material used to fabricate it, the specific steps involve first deriving the critical current value required to achieve the target Josephson energy based on the target value and the physical model formula for a single Josephson junction. Then, a predetermined semiconductor or superconducting integrated circuit manufacturing process, a predetermined superconducting thin film material, and the corresponding operating temperature and conditions are obtained to determine the critical current density corresponding to that process and material. Finally, based on the ratio of the critical current to the critical current density, the required junction area for a single Josephson junction can be calculated.

[0105] Therefore, the geometry of the Josephson junction element 13 is made to correspond to the target total capacitance of the double helix structure, so as to complete the configuration of the Josephson junction element 13 in the superconducting quantum bit 10, and further improve the process robustness of the overall performance of the superconducting quantum bit 10.

[0106] In another possible implementation, when the Josephson junction element 13 is a superconducting quantum interference device (QFID), the Josephson junction element 13 includes a superconducting loop and at least two Josephson junctions disposed in the superconducting loop. In this case, after determining the target value of the Josephson energy, the coupling control method of this embodiment further includes the following steps: determining the critical current of each Josephson junction in the superconducting quantum interference device based on the target value of the Josephson energy and the target magnetic flux bias point; obtaining the critical current density corresponding to a preset process and preset material; and calculating the junction area of ​​each Josephson junction based on the critical current and critical current density.

[0107] The superconducting quantum interference device (SQFID) consists of two Josephson junctions connected in parallel. The effective Josephson energy of the SQFID is modulated by the magnetic flux bias caused by an external magnetic field. Therefore, the critical current of each Josephson junction in the SQFID must first be calculated based on the target value of the Josephson energy and a preset target magnetic flux bias point, using the functional relationship between the effective Josephson energy of the SQFID and the critical current and magnetic flux of a single junction. The effective Josephson energy of the SQFID is related to the critical current of each Josephson junction; therefore, when determining the target value of the Josephson energy, it can be set as the target value to calculate the critical current of each Josephson junction that satisfies this condition. After obtaining the critical current, the junction area of ​​each Josephson junction can be further calculated based on the critical current density and critical current corresponding to a preset process and preset materials. The specific method is similar to that in the above embodiment and will not be repeated here.

[0108] Therefore, by determining the critical current of each Josephson junction based on the target Josephson energy and the target magnetic flux bias point, the nonlinear characteristics of the superconducting quantum interference device (SQUID) can be precisely and dynamically controlled according to the external magnetic flux bias. This allows for flexible adjustment of the operating frequency while maintaining the overall parameter stability of the superconducting quantum bit 10. By obtaining the critical current density corresponding to the preset process and materials and calculating the junction area of ​​each Josephson junction accordingly, the physical dimensions of the Josephson junction strictly correspond to the electrical parameters. This improves the accuracy and consistency of Josephson junction fabrication, further enhancing the reliability and performance stability of the SQUID as a frequency-tunable element.

[0109] This application also proposes an electronic device, which can be a software module, a hardware module, or a combination of both as part of a computer device. Specifically, the electronic device includes an interconnected setting module and an adjustment module. Specifically: a determining module is used to determine the target frequency band, target anharmonicity range, and coupling capacitance percentage threshold of the superconducting quantum bit 10; a construction module is used to construct a simulation model of the superconducting quantum bit 10 and adjust the structural parameters of the first electrode region 11 and the second electrode region 12; a simulation module is used to perform capacitance matrix simulation on the superconducting quantum bit 10 to obtain the coupling capacitance between the first electrode region 11 and the second electrode region 12 and the total capacitance of the superconducting quantum bit 10; an adjustment module is used to repeat the above adjustment and simulation steps until the proportion of the coupling capacitance in the total capacitance reaches the coupling capacitance percentage threshold, and the anharmonicity calculated based on the total capacitance falls into the target anharmonicity range, and the total capacitance at this point is obtained as the target total capacitance; a coordination module is used to determine the Josephson energy of the Josephson junction element 13 according to the target frequency band and the target total capacitance.

[0110] The electronic device is also used to implement the above-described coupling control method. Exemplarily, the aforementioned determining module, construction module, simulation module, adjustment module, and coordination module can be implemented entirely or partially through software, hardware, or a combination thereof. Each of these modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each of the above modules.

[0111] In some embodiments, the determining module is used to receive at least one of the target frequency band, target anharmonicity range, and coupling capacitance percentage threshold input by the user through a calculation program or simulation control interface.

[0112] In some embodiments, the building module is used to construct a simulation model of the superconducting quantum bit 10 using relevant circuit simulation software.

[0113] In some embodiments, the simulation module is used to perform capacitance matrix simulation on the superconducting quantum bit 10 using relevant circuit simulation software.

[0114] This application also proposes an electronic device including a processor and a memory coupled to the processor. The memory stores program data, and the processor executes program instructions to implement the above-described coupling control method.

[0115] In this embodiment, the processor can also be referred to as a CPU (Central Processing Unit). The processor can be an integrated circuit chip with signal processing capabilities. The processor can also be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. A general-purpose processor can be a microprocessor or any conventional processor.

[0116] The electronic device in this embodiment can be a computer, mobile phone, tablet computer, smartwatch, or other smart device. By building simulation control software or a simulation control interface in the electronic device, the above-described coupling control method can be implemented by executing program instructions.

[0117] Please see Figure 5 , Figure 5 This is a schematic diagram of the structure of one embodiment of the superconducting quantum chip provided in this application. Figure 5As shown in the embodiments, this application also proposes a superconducting quantum chip, including at least two superconducting qubits 10 according to any of the above embodiments and a coupler 20. The coupler 20 is coupled to at least two superconducting qubits 10 respectively to realize signal transmission between the coupled superconducting qubits 10. Exemplarily, the coupler 20 may be provided with at least two external coupling segments, and the coupler 20 can be capacitively or inductively coupled to the superconducting qubits 10 through the external coupling segments.

[0118] In some embodiments, the coupler 20 includes a plurality of conductive elements spaced apart in a preset plane. The first ends of the plurality of conductive elements extend in the same direction along a spiral trajectory around the same center to form a coupling loop. The second ends of the plurality of conductive elements extend radially outward along the coupling loop to form a connection port. The connection port is used to form electromagnetic coupling with the first electrode region 11 and / or the second electrode region 12 of the superconducting quantum bit 10.

[0119] The multiple conductive elements in the coupler 20 described above are used to form the core capacitor matrix of the coupler through a multi-helix structure. For example, when the coupler 20 includes two conductive elements, the two conductive elements of the coupler 20 form a double helix structure, which is similar to the helix structure of the first electrode region 11 and the second electrode region 12 described above, and will not be described again here.

[0120] The number of conductive elements can be, but is not limited to, 2, 3, 4, 5, 6, 8, 10, or more; the specific number of conductive elements depends on the number of connection ports required to form the qubit nodes in the array, and is not specifically limited here. The first ends of multiple conductive elements spiral around each other to form a coupling layer, allowing electromagnetic energy to be transferred between the multiple conductive elements, and then the signal is transmitted to the corresponding qubit through the connection port.

[0121] In some embodiments, the coupler 20 further includes coupling control elements that are respectively connected to a plurality of conductive elements. The coupling control elements are used to dynamically change the coupling strength between at least two conductive elements by adjusting the magnetic flux bias, thereby controlling the coupling between at least two superconducting qubits 10, thereby enabling multi-qubit quantum gate operations or simulating interactions.

[0122] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A superconducting quantum bit, characterized in that, include: First electrode region; The second electrode region is spaced apart from the first electrode region in a preset plane, and the first electrode region and the second electrode region extend in the same direction along a spiral trajectory around the same center to form a coupling ring, and a capacitive coupling is formed between the first electrode region and the second electrode region. A Josephson junction element, wherein the Josephson junction element is electrically connected between a first end of the first electrode region and a first end of the second electrode region.

2. The superconducting quantum bit according to claim 1, characterized in that, The first end of the first electrode region is located in the central region of the coupling layer, and the first electrode region extends outward from its first end along a first spiral trajectory to its second end; The first end of the second electrode region is located in the central region of the coupling layer, and the second electrode region extends outward from its first end along a second spiral trajectory to its second end; The first helical trajectory and the second helical trajectory together form the coupling ring layer, and the first electrode region and the second electrode region are alternately arranged in the radial direction of the coupling ring layer.

3. The superconducting quantum bit according to claim 2, characterized in that, The superconducting quantum bit also includes a coupling transition component, which is disposed at the second end of the first electrode region or the second end of the second electrode region.

4. The superconducting quantum bit according to claim 3, characterized in that, The coupling adapter includes a readout coupling electrode, a control coupling electrode, a resonant coupling electrode, and a wiring adapter electrode.

5. The superconducting quantum bit according to claim 2, characterized in that, Both the first spiral trajectory and the second spiral trajectory are equidistant spirals.

6. The superconducting quantum bit according to claim 2, characterized in that, Both the first spiral trajectory and the second spiral trajectory are non-equidistant spirals.

7. The superconducting quantum bit according to claim 2, characterized in that, The outline shape of the coupling layer is one of a circle, an ellipse, or a rounded rectangle.

8. The superconducting quantum bit according to claim 2, characterized in that, The width of the first electrode region is the same as the width of the second electrode region, and / or the number of surrounding layers of the first electrode region is the same as the number of surrounding layers of the second electrode region.

9. The superconducting quantum bit according to claim 1, characterized in that, The Josephson junction element is a superconducting quantum interference device or a single Josephson junction.

10. A coupling control method, characterized in that, The superconducting quantum bit includes a first electrode region, a second electrode region, and a Josephson junction element. The first electrode region and the second electrode region extend in the same direction along a spiral trajectory around the same center to form a coupling layer. Capacitive coupling is formed between the first electrode region and the second electrode region. The Josephson junction element is electrically connected between the first end of the first electrode region and the first end of the second electrode region. The coupling control method includes: Determine the target frequency band, target anharmonic range, and coupling capacitance percentage threshold of the superconducting quantum bit; A simulation model of the superconducting quantum bit is constructed, and the structural parameters of the first electrode region and the second electrode region are adjusted. Capacitance matrix simulation is performed on the superconducting quantum bit to obtain the coupling capacitance between the first electrode region and the second electrode region and the total capacitance of the superconducting quantum bit. Repeat the above adjustment and simulation steps until the proportion of the coupling capacitor in the total capacitance reaches the coupling capacitor proportion threshold, and the anharmonicity calculated based on the total capacitance falls into the target anharmonicity range, and obtain the total capacitance at this time as the target total capacitance. The Josephson energy of the Josephson junction element is determined based on the target frequency band and the target total capacitance.

11. The coupling control method according to claim 10, characterized in that, The adjustment of the structural parameters of the first electrode region and the second electrode region includes: Adjust at least one of the following: the linewidth of the first electrode region and the linewidth of the second electrode region, the gap between the first electrode region and the second electrode region, the number of spiral turns of the coupling layer, the inner radius of the coupling layer, and the outer radius of the coupling layer.

12. The coupling control method according to claim 10, characterized in that, Determining the Josephson energy of the Josephson junction element based on the target frequency band and the target total capacitance includes: Calculate the charging energy of the superconducting quantum bit based on the target total capacitance; The target value of the Josephson energy is calculated based on the center frequency of the target frequency band and the charging energy.

13. The coupling control method according to claim 12, characterized in that, When the Josephson junction element is a single Josephson junction, the coupling control method further includes: Calculate the critical current based on the target value of the Josephson energy; Obtain the critical current density corresponding to the preset process and preset materials, and calculate the junction area of ​​the single Josephson junction based on the critical current and the critical current density.

14. The coupling control method according to claim 12, characterized in that, When the Josephson junction element is a superconducting quantum interference device, the coupling control method further includes: Based on the target value of the Josephson energy and the target magnetic flux bias point, determine the critical current of each Josephson junction in the superconducting quantum interference device; Obtain the critical current density corresponding to the preset process and preset materials, and calculate the junction area of ​​each Josephson junction based on the critical current and the critical current density.

15. A superconducting quantum chip, characterized in that, include: Multiple superconducting qubits as described in any one of claims 1-9; A coupler is used to couple to at least two of the superconducting qubits to enable signal transmission between the coupled superconducting qubits.

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