Method and device for eliminating crosstalk between qubits in a superconducting quantum chip

Abstract

The present application provides a method and apparatus for eliminating crosstalk between qubits in a superconducting quantum chip, an electronic device, and a non-transitory computer-readable storage medium. The elimination method includes: in response to an instruction for eliminating crosstalk between qubits in a superconducting quantum chip, determining a topological structure corresponding to the superconducting quantum chip; mapping the topological structure into an undirected graph; classifying vertices in the undirected graph so that qubits corresponding to both ends of any edge in the undirected graph belong to different classifications; decomposing the undirected graph into multiple subgraphs according to the classification of vertices until the obtained subgraphs only include one classification; and applying control pulses to qubits corresponding to edges connecting different subgraphs to eliminate crosstalk between qubits. According to the embodiments of the present application, crosstalk caused by the interaction between qubits is eliminated.

Description

Technical Field

[0001] The present application relates to the field of quantum chips, and more particularly, to a method and apparatus for eliminating crosstalk between qubits in a superconducting quantum chip, an electronic device, and a non-transitory computer-readable storage medium. Background Art

[0002] Quantum computers have the ability to outperform classical computers in solving certain specific problems, but the realization of this ability requires the performance of quantum chips to reach a certain level. Superconducting quantum chips are currently the quantum computer hardware solutions with relatively mature technologies and the most attention. Using superconducting quantum computers to implement valuable quantum algorithms requires overcoming the noise on superconducting qubits and the crosstalk between qubits.

[0003] Most of the existing solutions to the crosstalk problem start from the perspective of hardware, and solve this problem by designing new qubit or chip structures. The advantage of this idea is that it can solve the crosstalk problem from the bottom layer without subsequent operations or resource consumption. However, the new hardware structure is usually much more complex than the existing design, which puts higher requirements on chip design and fabrication processes. It is still very difficult to meet such requirements with the current superconducting hardware processing level.

[0004] Currently, the dynamic decoupling method can be used to apply control pulses on qubits to equivalently cancel the interaction between qubits and the surrounding environment, thereby protecting qubits from environmental noise. However, this method is only applicable to the arrangement of qubits in a square grid. In fact, there are many other arrangements in existing superconducting quantum chips, such as hexagonal arrangement, star arrangement, or cross arrangement, etc. Currently, there is no technical solution to eliminate the crosstalk between qubits in these qubit arrangements. Summary of the Invention

[0005] The present application aims to propose a method and apparatus for eliminating crosstalk between qubits in a superconducting quantum chip, an electronic device, and a non-transitory computer-readable storage medium to solve the crosstalk between qubits in a superconducting quantum chip.

[0006] According to an aspect of the present application, a method for eliminating crosstalk between qubits in a superconducting quantum chip is proposed, including: in response to an instruction for eliminating crosstalk between qubits in a superconducting quantum chip, determining a topological structure corresponding to the superconducting quantum chip; mapping the topological structure to an undirected graph; classifying vertices in the undirected graph so that qubits corresponding to both ends of any edge in the undirected graph belong to different classifications; decomposing the undirected graph into multiple subgraphs according to the classification of vertices, so that each obtained subgraph only includes one classification; applying control pulses on qubits corresponding to edges connecting different subgraphs to eliminate crosstalk between qubits.

[0007] According to some embodiments, determining a topological structure corresponding to the superconducting quantum chip includes: determining the topological structure according to the arrangement of qubits and the interactions between qubits in the superconducting quantum chip.

[0008] According to some embodiments, mapping the topological structure to an undirected graph includes: mapping the qubits in the superconducting quantum chip to vertices in the undirected graph; mapping the interactions between qubits in the superconducting quantum chip to edges in the undirected graph.

[0009] According to some embodiments, classifying the vertices in the undirected graph so that the qubits corresponding to both ends of any edge in the undirected graph belong to different classifications includes: coloring the vertices in the undirected graph, where the qubits at both ends of any edge in the undirected graph are colored with different colors.

[0010] According to some embodiments, before decomposing the undirected graph into multiple subgraphs according to the classification of vertices so that each obtained subgraph includes only one classification, it further includes: determining the chromatic number according to the colored mapping graph.

[0011] According to some embodiments, decomposing the undirected graph into multiple subgraphs according to the classification of vertices so that each obtained subgraph includes only one classification includes: decomposing the undirected graph into two subgraphs, a first subgraph and a second subgraph, according to the classification colors of the qubits; using a preset decoupling rule to eliminate the connection between the first subgraph and the second subgraph; if the chromatic number of the first subgraph and / or the second subgraph is greater than 1, continue to decompose the first subgraph and / or the second subgraph, and use the decoupling rule to decouple the subgraphs obtained after decomposing the first subgraph and / or the second subgraph until the chromatic number of the subgraphs of the first subgraph and / or the second subgraph obtained is equal to 1.

[0012] According to some embodiments, using a preset decoupling rule to eliminate the connection between the first subgraph and the second subgraph includes: performing a first free evolution on the qubits belonging to the first subgraph or the second subgraph among the qubits connecting the first subgraph and the second subgraph; applying a Pauli-X operator to the qubits after the first free evolution; performing a second free evolution on the qubits after the application; applying a Pauli-X operator to the qubits after the second free evolution.

[0013] According to one aspect of the present application, a device for eliminating crosstalk between qubits in a superconducting quantum chip is proposed, including: a topology determination unit, configured to determine a topology corresponding to the superconducting quantum chip in response to an instruction for eliminating crosstalk between qubits in the superconducting quantum chip; a mapping graph generation unit, configured to map the topology into an undirected graph to obtain a corresponding mapping graph; a qubit classification unit, configured to classify vertices in the undirected graph such that qubits corresponding to both ends of any edge in the undirected graph belong to different classifications; a mapping graph decomposition unit, configured to decompose the undirected graph into multiple subgraphs according to the classification of vertices until the obtained subgraphs include only one classification; and a crosstalk elimination unit, configured to apply control pulses to qubits corresponding to edges connecting different subgraphs to eliminate crosstalk between qubits.

[0014] According to one aspect of the present application, an electronic device is proposed, including one or more processing units; a storage unit, configured to store one or more programs; when the one or more programs are executed by the one or more processing units, the one or more processing units are caused to implement the elimination method described in any of the previous embodiments.

[0015] According to one aspect of the present application, a non-transitory computer-readable storage medium is proposed, on which computer-readable instructions are stored, and when the instructions are executed by a processor, the processor is caused to execute the elimination method described in any of the previous embodiments.

[0016] According to an embodiment of the present application, first, the qubit arrangement in the superconducting quantum chip is mapped into an undirected graph, and then, the obtained undirected graph is decomposed until the obtained mapping subgraphs include only one classification, so as to decouple the interaction between qubits, thereby eliminating the crosstalk caused by the interaction between qubits.

[0017] It should be understood that the above general description and the following detailed description are only exemplary and do not limit the present application. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. By referring to the drawings and describing its exemplary embodiments in detail, the above and other objectives, features, and advantages of the present application will become more obvious.

[0019] Figure 1 Shows a flowchart of a method for eliminating crosstalk between qubits in a superconducting quantum chip according to an exemplary embodiment of the present application.

[0020] Figure 2a Shows a mapping graph of a superconducting quantum chip according to an exemplary embodiment of the present application.

[0021] Figure 2b Shows a mapping diagram of another superconducting quantum chip according to an exemplary embodiment of the present application.

[0022] Figure 3a Shows a flowchart of a method for eliminating crosstalk between qubits in another superconducting quantum chip according to an exemplary embodiment of the present application.

[0023] Figure 3b Shows a schematic diagram of the decoupling process of crosstalk between qubits in another superconducting quantum chip according to an exemplary embodiment of the present application.

[0024] Figure 4 Shows a schematic diagram of the decoupling process with a chromatic number of 5 according to an exemplary embodiment of the present application.

[0025] Figure 5a Shows a schematic diagram of the topological structure of a superconducting quantum chip.

[0026] Figure 5b Shows a mapping diagram of a superconducting quantum chip according to an exemplary embodiment of the present application.

[0027] Figure 6a Shows a schematic diagram of the topological structure of another superconducting quantum chip.

[0028] Figure 6b Shows a mapping diagram of another superconducting quantum chip according to an exemplary embodiment of the present application.

[0029] Figure 7 Shows a device for eliminating crosstalk between qubits in a superconducting quantum chip according to an exemplary embodiment of the present application.

[0030] Figure 8 Shows an electronic device according to an exemplary embodiment of the present application. Detailed implementation manners

[0031] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. Identical reference numerals in the figures denote identical or similar parts, and thus their repeated description will be omitted.

[0032] The described features, structures, or characteristics can be combined in one or more embodiments in any suitable manner. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of the present disclosure. However, those skilled in the art will realize that the technical solutions of the present disclosure can be practiced without one or more of these specific details, or other means, components, materials, devices, or operations, etc. can be adopted. In these cases, well-known structures, methods, devices, implementations, materials, or operations will not be shown or described in detail.

[0033] The flowcharts shown in the accompanying drawings are only illustrative and not necessarily include all the contents and operations / steps, nor are they necessarily executed in the described order. For example, some operations / steps can be decomposed, while some operations / steps can be combined or partially combined, so the actual execution order may change according to the actual situation.

[0034] The terms "first", "second", etc. in the specification, claims, and above-mentioned drawings of this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products, or devices.

[0035] The following will describe in detail the specific embodiments according to the present application with reference to the accompanying drawings.

[0036] Figure 1 A flowchart of a method for eliminating crosstalk between qubits in a superconducting quantum chip according to an exemplary embodiment of the present application is shown, as Figure 1 The shown elimination method includes steps S101, S103, S105, S107, and S109.

[0037] In step S101, in response to an instruction to eliminate crosstalk between qubits in the superconducting quantum chip, determine the topological structure corresponding to the superconducting quantum chip.

[0038] The topological structure of the superconducting quantum chip consists of two parts: the first part is the positions of the qubits in the superconducting quantum chip, and the second part is the interaction between the qubits. According to the embodiments of the present application, the topological structure is determined according to the qubit arrangement and the interaction between qubits in the superconducting quantum chip.

[0039] In step S103, map the topological structure to an undirected graph.

[0040] According to an embodiment of the present application, when mapping a superconducting quantum chip into an undirected graph according to the topological structure of the superconducting quantum chip, each qubit corresponds to a vertex on the graph, and the interaction between two qubits corresponds to an edge connecting the corresponding two vertices on the graph.

[0041] Since superconducting qubits interact pairwise, each edge will only connect two vertices and there will be no case of three vertices. Therefore, the topological structure of the chip can always be mapped into a graph. According to this mapping rule, if each qubit in the superconducting quantum chip interacts with other qubits, all vertices on the mapped undirected graph are connected to other vertices by edges, and there are no free vertices; if due to manufacturing process problems, there are isolated qubits in the superconducting quantum chip that do not interact with any other qubits, such isolated qubits are useless when implementing quantum algorithms and are also free vertices on the finally mapped undirected graph.

[0042] In step S105, the vertices in the undirected graph are classified so that the qubits corresponding to both ends of any edge in the undirected graph belong to different classifications.

[0043] According to an embodiment of the present application, in step S105, the vertices in the undirected graph are colored, where the qubits at both ends of any edge in the undirected graph are colored with different colors.

[0044] In a specific embodiment, after mapping the topological structure of the superconducting quantum chip into an undirected graph, the undirected graph is colored. In some embodiments, the coloring rule is to assign a color to each vertex, and it is required that the vertices at both ends of an edge are assigned different colors. It should be noted that vertices not on the same edge can be assigned the same color.

[0045] In step S107, the undirected graph is decomposed into multiple subgraphs according to the classification of the vertices, so that each obtained subgraph only includes one classification.

[0046] According to an embodiment of the present application, before step S107, it is also necessary to determine the chromatic number according to the colored undirected graph. For a given graph, the minimum number of colors required is usually called the chromatic number. For any graph, for example, a graph with qubits having cross interactions, the value of the chromatic number may be very large. However, for a superconducting quantum chip involved in planarization, since the qubits are all arranged on a two-dimensional plane and there are no cross interactions between the qubits, according to the four-color theorem, the chromatic number is at most 4.

[0047] As Figure 2a shown in the undirected graph of a superconducting quantum chip arranged in a square grid, there are only interactions between nearest-neighbor qubits. The two vertices of each edge in the undirected graph are assigned different colors and are represented by circles and squares respectively. Figure 2aThe chromatic number of the undirected graph shown is 2, represented by yellow and blue respectively.

[0048] As Figure 2b For the undirected graph of the superconducting quantum chip with cross interactions between qubits shown, there are two types of interactions between qubits, nearest neighbor and next-nearest neighbor. The chromatic number in this case is 4, represented by yellow, blue, green, and purple respectively, and are represented by a circle, a square, an ellipse, and a hexagon respectively.

[0049] In some embodiments, in step S107, according to the chromatic number, the undirected graph is decomposed into two subgraphs to obtain a first subgraph and a second subgraph; the two subgraphs are decoupled using a preset decoupling rule; if the chromatic number in the first subgraph and / or the second subgraph is greater than 1, continue to decompose the first subgraph and / or the second subgraph, and use the decoupling rule to decouple the subgraphs obtained after decomposing the first subgraph and / or the second subgraph until the chromatic number of the subgraphs of the first subgraph and / or the second subgraph obtained is equal to 1 to eliminate the connection between the subgraphs.

[0050] According to an embodiment of the present application, when using the preset decoupling rule to eliminate the connection between the first subgraph and the second subgraph, first, perform a first free evolution on the qubits belonging to the first or second subgraph among the qubits connecting the first subgraph and the second subgraph; then, apply the Pauli-X operator to the qubits after the first free evolution, and perform a second free evolution on the qubits after the application; finally, apply the Pauli-X operator to the qubits after the second free evolution.

[0051] In a specific embodiment, the interaction between qubits is usually turned on and off by a coupler. When the interaction between qubits is turned off by the coupler, due to the error of the system, there is usually still a relatively small interaction between the two qubits, where is the Pauli-Z operator acting on the k-th qubit, is the interaction strength between the two qubits. These residual interactions cause crosstalk between the qubits.

[0052] In an embodiment of the present application, it is assumed that the interaction causing crosstalk between two qubits is as shown in formula (1).

[0053] (1)

[0054] Wherein, the two relevant qubits are respectively assigned two different colors.

[0055] In step S109, apply a control pulse to the qubits corresponding to the edges connecting different subgraphs to eliminate the crosstalk between the qubits.

[0056] In some embodiments, to eliminate the interaction between qubits in two subgraphs, the decoupling sequence adopted is as shown in formula (2), that is, first let the two qubits freely evolve for a sufficiently short time (for example, dozens to hundreds of nanoseconds), and then, apply a Pauli-X operator to the -th qubit, and then let the two qubits freely evolve for a short time (for example, dozens to hundreds of nanoseconds), and finally apply a Pauli-X operator to the -th qubit.

[0057] (2)

[0058] The entire evolution process is as shown in formula (3).

[0059] (3)

[0060] According to formula (3), it can be seen that the crosstalk between the two qubits is eliminated during the decoupling process.

[0061] The method of eliminating qubit crosstalk shown in formula (3) is to eliminate the crosstalk between qubits that interact with each other. According to the embodiments of the present application, the decoupling sequence shown in formula (4) can eliminate the crosstalk between qubits representing multiple qubits of the same color between mapped subgraphs to eliminate the crosstalk between qubits in the mapped subgraphs. That is, the qubits between the mapped subgraphs with interactions are decoupled at one time. Figure 4 The decoupling sequence required for the decoupling process shown includes two decoupling pulses, as Figure 4 shown.

[0062] (4)

[0063] Among them, and are labels of two colors, is the Pauli-X operator acting on all qubits of the -th color.

[0064] Because there is no interaction between qubits of the same color, the Pauli-X operator only needs to act on the It is only necessary to perform operations on the qubits of the two colors. In a specific embodiment, after determining the qubits to which the decoupling pulse needs to be applied, according to the frequencies of the corresponding qubits, an arbitrary waveform amplifier is used to generate a control pulse in the X direction, and the pulse is maintained for a certain period of time according to its intensity (for example, twenty to forty nanoseconds). After this decoupling effect, the interaction between the qubits of these two colors between the mapped subgraphs is eliminated.

[0065] For example, decompose the mapped graph to obtain subgraphs A and B. Among them, there is an interaction between qubit a1 in subgraph A and b1 in subgraph B, and there is an interaction between qubit a2 in subgraph A and b2 in subgraph B. According to the embodiments of the present application, the method shown in formula (3) can be used to act on qubits a1 and a2 to eliminate the crosstalk between qubits between the mapped subgraphs.

[0066] According to Figure 1 the shown embodiment, first, map the qubit arrangement in the superconducting quantum chip into an undirected graph, and then decompose the obtained undirected graph based on the chromatic number to decouple the interaction between qubits, thereby eliminating the crosstalk caused by the interaction between qubits.

[0067] According to the embodiments of the present application, it can be used to solve the crosstalk between qubits in quantum chips with any topological structure, and the complexity of control only relates to the chromatic number of the graph and does not increase with the increase in the scale of the chip.

[0068] Figure 3a shows a flowchart of another method for eliminating crosstalk between qubits in a superconducting quantum chip according to an exemplary embodiment of the present application. Figure 3b shows a schematic diagram of the decoupling process of crosstalk between qubits in another superconducting quantum chip according to an exemplary embodiment of the present application.

[0069] As Figure 3a and 3b shown, in step S301, determine the topological structure T corresponding to the superconducting quantum chip according to the qubit arrangement and the interaction between qubits of the given superconducting quantum chip.

[0070] In step S303, map the topological structure of the superconducting quantum chip into a corresponding undirected graph.

[0071] For example, map the topological structure T of the superconducting quantum chip into a corresponding undirected graph G(V, E).

[0072] In this mapping, the qubits in the topological structure correspond to the vertices V in the graph, and the interaction between qubits corresponds to the edges E in the graph.

[0073] In step S305, the vertices in the undirected graph (representing qubits) are colored, and the chromatic number of the graph is determined.

[0074] It should be noted here that since the vertices in the undirected graph correspond to the qubits in the superconducting quantum chip, in this application, for the convenience of understanding, the vertices in the undirected graph are replaced by qubits.

[0075] For example, the vertices in the undirected graph G(V, E) (representing qubits) are colored, and the chromatic number C of the graph is determined.

[0076] According to the embodiments of the present application, when coloring, it is required that the vertices (representing qubits) at both ends of an edge cannot be colored with the same color.

[0077] In step S307, the undirected graph is divided into two subgraphs according to the chromatic number.

[0078] For example, the graph G is divided into two subgraphs G1 and G2 according to the chromatic number C, where G1 has qubits of C / 2 (rounded down if not an integer) colors.

[0079] If C is even, then each of G1 and G2 contains the qubits corresponding to C / 2 colors; if C is odd, then G2 contains one more color than G1 or G1 contains one more color than G2. Either way can be chosen and is not limited here.

[0080] In step S309, the interaction between the subgraphs is eliminated using a preset decoupling rule.

[0081] For example, the qubits connecting the two subgraphs G1 and G2 are determined, and a decoupling sequence is applied to the relevant qubits on the subgraph G1 , to eliminate the interaction between the subgraphs G1 and G2. According to some embodiments, a decoupling sequence can also be applied to the relevant qubits on the subgraph G2 , and is not limited here.

[0082] According to the embodiments of the present application, the decoupling sequence is determined according to formula (4) .

[0083] In step S311, the subgraph is further decomposed, and the interaction between the decomposed subgraphs is eliminated until the decomposed subgraphs only contain qubits of one color.

[0084] Taking G1 as an example, first, G1 is further divided into two subgraphs G 1,1 and G 1,2 , then, the qubits connecting the two subgraphs G 1,1 and G 1,2 are determined, and on the subgraph G 1,1Apply a decoupling sequence to the relevant physical bits , and eliminate the interaction between subgraphs G 1,1 and G 1,2 .

[0085] According to some embodiments, a decoupling sequence can also be applied to the relevant qubits on subgraph G 1,2 , which is not limited herein.

[0086] When decomposing G1, if the number of colors contained in G1 is even, then G 1,1 and G 1,2 each contain half of the bits corresponding to the colors; if the number of colors contained in G1 is odd, then choose G 1,2 that contains one more color than G 1,1 or choose G 1,1 that contains one more color than G 1,2 , which is not limited herein.

[0087] Similarly, first, further divide G2 into two subgraphs G 2,1 and G 2,2 , then, determine the qubits connecting the two subgraphs G 2,1 and G 2,2 , and apply a decoupling sequence to the relevant physical bits on subgraph G 2,1 2,2 , and eliminate the interaction between subgraphs G 2,2 .

[0088] According to some embodiments, a decoupling sequence can also be applied to the relevant qubits on subgraph G 2,2 , which is not limited herein.

[0089] When decomposing G2, if the number of colors contained in G2 is even, then G 2,1 and G 2,2 each contain half of the bits corresponding to the colors; if the number of colors contained in G2 is odd, then G 2,2 contains one more color than G 2,1 , or G 2,1 contains one more color than G 2,2 , which is not limited herein.

[0090] According to the embodiments of the present application, if the obtained subgraphs , , , ​​If the number of colors is greater than 1, it is necessary to continue the decomposition according to the method shown in step S311, and use the decoupling sequence shown in formula (4) to eliminate the interaction between subgraphs until the decomposed subgraphs contain only qubits of one color.

[0091] Figure 4 FIG. shows a decoupling process diagram with a coloring number of 5 according to an exemplary embodiment of the present application. As Figure 4 shown, first, the mapping graph is decomposed into subgraphs and , where represents sub- Figure 1 , including 2 qubits; represents subgraph 2, including 3 qubits, and according to the decoupling sequence D 1 shown in formula (4), the interaction between the qubits in and is eliminated. Then, subgraph is further decomposed to obtain and . Subgraph is further decomposed to obtain and , and according to the decoupling sequence D 2 shown in formula (4), the interaction between the qubits in and , as well as the interaction between the qubits in and , are eliminated respectively. Then, continue to decompose until the decomposed subgraphs contain only qubits of one color.

[0092] Figure 5a FIG. shows a schematic diagram of the topological structure of a superconducting quantum chip. As Figure 5a shown, each multiplication sign represents a qubit, and the square between two multiplication signs represents a coupler for the interaction between control bits. Figure 5a There are a total of 54 bits in the superconducting quantum chip shown.

[0093] Figure 5b FIG. shows an undirected graph corresponding to the superconducting quantum chip. As Figure 5b shown, the coloring number of this undirected graph is 2, and the hollow circle and the solid circle correspond to two colors respectively. According to the embodiment of the present application, when decoupling the undirected graph , only need to split into two subgraphs and , where the first subgraph contains the bits corresponding to the solid circles, and the second subgraph Contains the bits corresponding to the circles. Therefore, as long as a decoupling pulse is applied to the bits corresponding to the solid circles, the interaction between all bits can be eliminated, and the required decoupling sequence is as shown in formula (5).

[0094] (5)

[0095] Figure 6a Shows a schematic diagram of the topological structure of another superconducting quantum chip, as Figure 6a shown, where each circle represents a qubit, the number inside the circle represents the serial number of the qubit, and the rhombus between the circles represents the coupler that controls the interaction between the qubits. There are a total of 130 qubits in this superconducting quantum chip.

[0096] Figure 6b Shows an undirected graph corresponding to this superconducting quantum chip ,as Figure 6b shown, and this undirected graph is a 2-color graph containing 130 vertices. Therefore, according to the embodiments of the present application, when decoupling the undirected graph only need to be split into two subgraphs and , where the first subgraph contains the bits corresponding to the solid circles, while the second subgraph contains the bits corresponding to the circles. Therefore, as long as a decoupling pulse is applied to the bits corresponding to the solid circles according to the decoupling sequence shown in formula (5), the interaction between all bits can be eliminated.

[0097] The above mainly introduced the embodiments of the present application from the perspective of methods. Those skilled in the art should easily realize that, combined with the operations or steps of each example described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Those skilled in the art can use different methods to implement the described functions for each specific operation or method, and such implementation should not be considered to exceed the scope of the present application.

[0098] Next, the device embodiments of the present application are described. For details not described in the device embodiments of the present application, reference can be made to the method embodiments of the present application.

[0099] Figure 7 Shows a device for eliminating crosstalk between qubits in a superconducting quantum chip according to an exemplary embodiment of the present application, as Figure 7The shown cancellation device includes a topology determination unit 701, an undirected graph generation unit 703, a qubit classification unit 705, an undirected graph decomposition unit 707, and a crosstalk cancellation unit 709. Among them, the topology determination unit 701 is configured to determine a topology corresponding to the superconducting quantum chip in response to a crosstalk cancellation instruction between qubits in the superconducting quantum chip; the undirected graph generation unit 703 is configured to map the topology into an undirected graph; the qubit classification unit 705 is configured to classify vertices in the undirected graph so that qubits corresponding to both ends of any edge in the undirected graph belong to different classifications; the undirected graph decomposition unit 707 is configured to decompose the undirected graph into multiple subgraphs according to the classification of vertices until the obtained subgraphs only include one classification. The crosstalk cancellation unit 709 is configured to apply control pulses to qubits corresponding to edges connecting different subgraphs to eliminate crosstalk between subgraphs.

[0100] Figure 8 FIG. shows an electronic device according to an exemplary embodiment of the present application. The following will be described with reference to Figure 8 the electronic device 200 according to this embodiment of the present application. Figure 8 The shown electronic device 200 is only an example and should not impose any limitation on the functions and usage scope of the embodiments of the present application.

[0101] As Figure 8 shown, the electronic device 200 is presented in the form of a general computing device. The components of the electronic device 200 may include but are not limited to: at least one processing unit 210, at least one storage unit 220, a bus 230 connecting different system components (including the storage unit 220 and the processing unit 210), a display unit 240, etc.

[0102] Among them, the storage unit stores program codes, and the program codes can be executed by the processing unit 210, so that the processing unit 210 executes the methods according to various exemplary embodiments of the present application described in this specification. For example, the processing unit 210 can execute the method as Figure 1 shown in.

[0103] The storage unit 220 may include a readable medium in the form of a volatile storage unit, such as a random access storage unit (RAM) 2201 and / or a cache storage unit 2202, and may further include a read-only storage unit (ROM) 2203.

[0104] The storage unit 220 may further include a program / utility 2204 having a set (at least one) of program modules 2205. Such program modules 2205 include but are not limited to: an operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include an implementation of a network environment.

[0105] The bus 230 may represent one or more of several types of bus structures, including a memory bus or a memory controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local bus using any of the various bus structures.

[0106] The electronic device 200 may also communicate with one or more external devices 300 (such as a keyboard, a pointing device, a Bluetooth device, etc.), and may also communicate with one or more devices that enable a user to interact with the electronic device 200, and / or communicate with any device that enables the electronic device 200 to communicate with one or more other computing devices (such as a router, a modem, etc.). Such communication may be carried out through the input / output (I / O) interface 250. In addition, the electronic device 200 may also communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) through the network adapter 260. The network adapter 260 may communicate with other modules of the electronic device 200 through the bus 230. It should be understood that, although not shown in the figure, other hardware and / or software modules may be used in conjunction with the electronic device 200, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, etc.

[0107] Through the description of the above embodiments, those skilled in the art can easily understand that the example embodiments described herein can be implemented by software, or can be implemented by a combination of software and necessary hardware. The technical solutions according to the embodiments of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.) or on a network, including several instructions to enable a computing device (which can be a personal computer, a server, or a network device, etc.) to execute the above methods according to the embodiments of the present application.

[0108] The software product may adopt any combination of one or more readable media. The readable media may be a readable signal medium or a readable storage medium. The readable storage medium may, for example, but not be limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (a non-exhaustive list) of the readable storage medium include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0109] A computer-readable storage medium may include a data signal propagated in a baseband or as part of a carrier wave, in which a readable program code is carried. Such a propagated data signal may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the foregoing. The readable storage medium may also be any readable medium other than the readable storage medium, which can send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device. The program code contained on the readable storage medium may be transmitted using any appropriate medium, including but not limited to wireless, wired, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

[0110] The program code for performing the operations of this application may be written in any combination of one or more programming languages. The programming languages include object-oriented programming languages such as Java, C++, etc., and also include conventional procedural programming languages such as the "C" language or similar programming languages. The program code may be executed entirely on the user's computing device, partially on the user's device, executed as a stand-alone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user's computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computing device (e.g., by using an Internet service provider to connect through the Internet).

[0111] The above computer-readable medium carries one or more programs, and when the one or more programs are executed by a device, the computer-readable medium implements the foregoing functions.

[0112] Those skilled in the art can understand that the above modules may be distributed in the device according to the description of the embodiments, or may be correspondingly changed and distributed in one or more devices that are uniquely different from the embodiments. The modules of the above embodiments may be combined into one module, or may be further split into multiple sub-modules.

[0113] According to an embodiment of the present application, a computer program is provided, including a computer program or instruction, and when the computer program or instruction is executed by a processor, the method described above can be executed.

[0114] According to an embodiment of the present application, a given superconducting quantum chip is mapped into an undirected graph, which is a basic element studied in graph theory. After finding the chromatic number of the graph, the qubits are classified according to different colors, and the decoupling operation is performed on the qubits of different colors to decouple the interaction between the qubits, thereby eliminating the crosstalk caused by these interactions. The embodiment of the present application can be applied to quantum chips with any topological structure, and the complexity of control is only related to the chromatic number of the graph and does not increase with the increase of the chip scale.

[0115] The above has introduced the embodiments of the present application in detail. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application. At the same time, any changes or deformations made by those skilled in the art based on the idea of the present application, within the specific implementation manner and application scope of the present application, fall within the protection scope of the present application. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A method for eliminating crosstalk between qubits in a superconducting quantum chip, characterized in that Including: In response to an instruction for eliminating crosstalk between qubits in a superconducting quantum chip, determining a topological structure corresponding to the superconducting quantum chip; Mapping the topological structure into an undirected graph to obtain a corresponding mapping graph; Classifying vertices in the undirected graph so that qubits corresponding to both ends of any edge in the undirected graph belong to different classifications; Decomposing the undirected graph into multiple subgraphs according to the classification of vertices, so that each obtained subgraph includes only one classification; Applying a control pulse to qubits corresponding to edges connecting different subgraphs to eliminate crosstalk between qubits; Among them, classifying vertices in the undirected graph so that qubits corresponding to both ends of any edge in the undirected graph belong to different classifications includes: Coloring vertices in the undirected graph, where qubits at both ends of any edge in the undirected graph are colored with different colors.

2. The elimination method according to claim 1, wherein Determining a topological structure corresponding to the superconducting quantum chip includes: Determining the topological structure according to the qubit arrangement and the interaction between qubits in the superconducting quantum chip.

3. The elimination method according to claim 2, characterized in that, Mapping the topological structure into an undirected graph includes: Mapping qubits in the superconducting quantum chip into vertices in the undirected graph; Mapping the interaction between qubits in the superconducting quantum chip into edges in the undirected graph.

4. The elimination method according to claim 1, wherein Before decomposing the undirected graph into multiple subgraphs according to the classification of vertices so that each obtained subgraph includes only one classification, it further includes: Determining the chromatic number according to the colored mapping graph.

5. The elimination method according to claim 4, characterized in that, Decomposing the undirected graph into multiple subgraphs according to the classification of vertices so that each obtained subgraph includes only one classification includes: Decomposing the undirected graph into two subgraphs, namely a first subgraph and a second subgraph, according to the classification colors of qubits; Using a preset decoupling rule to eliminate the connection between the first subgraph and the second subgraph; If the chromatic number of the first subgraph and / or the second subgraph is greater than 1, continue to decompose the first subgraph and / or the second subgraph, and use the decoupling rule to decouple the subgraphs obtained after decomposing the first subgraph and / or the second subgraph until the chromatic number of the subgraphs of the first subgraph and / or the second subgraph obtained is equal to 1.

6. The elimination method according to claim 5, characterized in that, Using a preset decoupling rule to eliminate the connection between the first subgraph and the second subgraph includes: Performing a first free evolution on qubits belonging to the first subgraph or the second subgraph among the qubits connecting the first subgraph and the second subgraph; Acting on the qubits after the first free evolution with a Pauli-X operator; Performing a second free evolution on the qubits after the action; Acting on the qubits after the second free evolution with a Pauli-X operator.

7. An apparatus for eliminating crosstalk between qubits in a superconducting quantum chip, characterized in that, For executing the elimination method according to any one of claims 1-6, the elimination device includes: A topological structure determination unit, configured to determine a topological structure corresponding to the superconducting quantum chip in response to an instruction for eliminating crosstalk between qubits in the superconducting quantum chip; An undirected graph generation unit, configured to map the topological structure into an undirected graph to obtain a corresponding mapping graph; A quantum bit classification unit for classifying vertices in the undirected graph so that the quantum bits corresponding to both ends of any edge in the undirected graph belong to different classifications; A mapping graph decomposition unit for decomposing the undirected graph into multiple subgraphs according to the classification of vertices until the obtained subgraphs only include one classification; A crosstalk elimination unit for applying control pulses to the quantum bits corresponding to the edges connecting different subgraphs to eliminate crosstalk between quantum bits.

8. An electronic device, comprising: A processor; And A memory storing a computer program, which when executed by the processor causes the processor to execute the elimination method according to any one of claims 1-6.

9. A non-transitory computer-readable storage medium storing computer-readable instructions, which when executed by a processor cause the processor to execute the elimination method according to any one of claims 1-6.

Images