Design method and device of quantum memory architecture, and storage medium

Abstract

The invention provides a design method and device of a quantum memory architecture and a storage medium. The method comprises the following steps: receiving a physical quantum bit specification and an environmental noise model constructed based on environmental noise; selecting a continuous symmetric group according to the interaction between the physical quantum bit specification and the environmental noise; synthesizing a quantum state code in the symmetrically protected subspace through a continuous symmetric group; a control pulse sequence for keeping symmetric protection is designed through a continuous symmetric group; and outputting a quantum memory architecture specification according to the quantum state code and the control pulse sequence, including: in an access stage of the quantum memory, actively and dynamically decoupling the quantum state of the quantum memory from the environmental noise based on the control pulse sequence. On the basis, the quantum memory architecture adopting the continuous symmetric groups to realize symmetric protection can reduce the number of physical quantum bits of the quantum memory and simplify the error correction overhead.

Description

Technical Field

[0001] This application relates to the field of quantum memory architecture design technology, specifically to a quantum memory architecture design method, device, and storage medium. Background Technology

[0002] Quantum memories differ from traditional memories in that they perform high-speed arithmetic and logical operations, as well as process and store quantum information, according to the principles of quantum mechanics. Coherence is fundamental to quantum mechanical operations, but in real-world environments, qubits are affected by external factors, particularly noise, leading to short coherence times in quantum states and disrupting quantum entanglement. Once the coherence of a quantum memory is disturbed by quantum entanglement, it decreases, a phenomenon known as decoherence. In practical quantum memories, completely preventing qubits from contacting the external environment is impossible, making it difficult to maintain quantum coherence. Currently, quantum decoherence is one of the most pressing problems to be solved in quantum memories, significantly impacting their future development.

[0003] Given that the coherence of quantum memories is fundamentally limited by environmental decoherence and material defects, current methods generally employ dynamic decoupling to extend the coherence time. Dynamic decoupling involves applying a periodic sequence of control pulses to suppress environmental noise. Specifically, this sequence periodically flips the state of a qubit during its evolution, averaging the impact of environmental noise, reducing its cumulative effect, and mitigating random phase drift, thereby extending the coherence time. However, this approach only externally perturbs the operation of the quantum memory, rather than embedding it into the quantum memory architecture design. To achieve fault tolerance, this means that the actual construction of a quantum memory architecture requires more physical qubits than theoretically required. For example, three physical qubits might be needed to encode one logical qubit to maintain system stability. Furthermore, traditional decoding methods may struggle to handle the noise effects of such a large number of real-world hardware components, leading to more frequent logic operations and decoding algorithms, ultimately resulting in additional physical qubits and complex error correction overhead. Summary of the Invention

[0004] In view of this, this application provides a design method, device, and storage medium for a quantum memory architecture, which can improve the problem that the design of traditional quantum memory architectures leads to additional physical qubits and complex error correction overhead while extending the coherence time.

[0005] This application provides a design method for a quantum memory architecture, including: Receive physical qubit specifications and an environmental noise model based on environmental noise; Based on the interaction between the physical qubit specifications and environmental noise, a continuous symmetry group is selected; Quantum state encoding located in a symmetry-protected subspace is synthesized through the continuous symmetry group; The control pulse sequence that maintains symmetry protection is achieved through the design of the continuous symmetry group; Based on the quantum state encoding and the control pulse sequence, a quantum memory architecture specification is output, including: during the access phase of the quantum memory, actively decoupling the quantum state of the quantum memory from the environmental noise based on the control pulse sequence.

[0006] Optionally, the continuous symmetry group is a Lie group, and the synthesis of quantum state encoding located in a symmetry-protected subspace through the continuous symmetry group includes: Perform Lie group analysis on the quantum states of the quantum memory; Based on the results of the Lie group analysis, a symmetry-protected decoherent free subspace is defined; Quantum states are encoded into the decoherent free subspace to achieve quantum state encoding.

[0007] Optionally, the manner in which the decoherent free subspace is defined includes: The physical characteristics of environmental noise are obtained based on the environmental noise model. Based on the aforementioned physical characteristics, the noise generator and its constituent Lie algebra are obtained; The subspace that commutes with the noise generator is determined based on the Lie algebra to serve as a decoherent free subspace, in which the quantum states remain coherent under the influence of environmental noise.

[0008] Optionally, the memory architecture specification also includes: Based on the control pulse sequence, the access phase of the quantum memory is executed sequentially according to the Lie group analysis, the quantum state encoding, and the dynamic decoupling.

[0009] Optionally, the continuous symmetry group is a Lie group, and the design of the control pulse sequence for symmetry protection using the continuous symmetry group includes: The access operations to the quantum memory are represented as Lie group elements of the unitary evolution matrix; The Lie group elements of the unitary evolution matrix are decomposed into a sequence of exponential operations of Lie algebras using a pre-defined decomposition technique. The shortest path of the exponential operation sequence of the Lie algebra is found by geometric method, and a symmetric control pulse sequence is formed according to the control parameters corresponding to the shortest path.

[0010] Optionally, the geometric method is a gradient descent algorithm or a genetic algorithm, and the preset decomposition technique is a Cartan decomposition technique or a Gaussian decomposition technique.

[0011] Optionally, the control parameters corresponding to the shortest path include the pulse amplitude, phase, and timing.

[0012] Optionally, the dynamic decoupling is performed in a continuous control field, which is a physical field through which the quantum memory is regulated by continuous parameters.

[0013] This application provides a design device for a quantum memory architecture, including a processor and a memory. The memory stores a design program, and when the design program is executed by the processor, it implements the steps of any of the above-described quantum memory architecture design methods.

[0014] This application provides a storage medium storing a computer program, which, when executed by a processor, implements the steps of any of the above-described quantum memory architecture design methods.

[0015] As described above, this application selects a continuous symmetry group based on the interaction between physical qubit specifications and environmental noise. Then, it synthesizes quantum state codes within a symmetry-protected subspace and designs control pulse sequences to maintain symmetry protection using these continuous symmetry groups. Subsequently, based on the quantum state codes and control pulse sequences, it outputs the quantum memory architecture specifications. In other words, this application uses a continuous symmetry group to implement a symmetry-protected quantum memory architecture. Since symmetry-protected quantum memories are inherently immune to specific types of errors, such as bit flips, through physical design, error correction resources can be concentrated on other types of errors, such as phase flips. This simplifies the error correction scheme and significantly reduces the number of physical qubits required. For example, only 5 cat qubits are needed to achieve error suppression, while traditional schemes require dozens of additional qubits. Therefore, this application can reduce the number of physical qubits and simplify error correction overhead. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating a design method for a quantum memory architecture according to an embodiment of this application; Figure 2 This is a schematic diagram of the process of synthesizing quantum state encoding using continuous symmetry groups in this application; Figure 3 This is a schematic diagram of the design device of a quantum memory architecture according to an embodiment of this application. Detailed Implementation

[0017] Traditional quantum memory architectures primarily extend coherence time through external perturbations, leading to additional physical qubits and complex error correction overhead. To address these issues in the prior art, this application provides a design method, device, and storage medium for a quantum memory architecture. These protected subjects are based on the same concept, and their solutions are fundamentally the same or similar. Implementation methods for each protected subject can be referenced interchangeably; duplicate details are omitted.

[0018] In this application, a continuous symmetry group is selected based on the interaction between the physical qubit specifications and environmental noise. Then, a quantum state encoding located in a symmetry-protected subspace is synthesized through the continuous symmetry group, and a control pulse sequence for maintaining symmetry protection is designed. Subsequently, based on the quantum state encoding and control pulse sequence, the quantum memory architecture specification is output. That is, this application uses a continuous symmetry group to realize a symmetry-protected quantum memory architecture. Since symmetry-protected quantum memories are naturally immune to specific types of errors, such as bit flips, through physical design, error correction resources can be concentrated on other types of errors, such as phase flips, making the error correction scheme simpler and significantly reducing the number of physical qubits required.

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly described below in conjunction with specific embodiments and corresponding drawings. Obviously, the embodiments described below are only a part of the embodiments of this application, and not all of them. Unless otherwise specified, the following embodiments and their technical features can be combined with each other, and also belong to the technical solutions of this application.

[0020] Figure 1 This is a flowchart illustrating a design method for a quantum memory architecture according to an embodiment of this application. The design method for the quantum memory architecture can also be referred to as a "method" or "design method," and the entity executing each step can be a design device adapted to the quantum memory architecture, a computer performing quantum memory design, or a storage medium, processor, controller, etc., with design functionality.

[0021] like Figure 1 As shown, the method includes at least the following steps S1 to S5.

[0022] S1, Specifications of the received physical qubits and an environmental noise model based on environmental noise.

[0023] A physical qubit, also known as a quantum bit, is the fundamental unit of information in a quantum memory. Quantum memories store information through the quantum states (i.e., superposition states) and entanglement properties of physical qubits. Unlike traditional bits, which can only be in one of two states (0 or 1), a qubit can simultaneously represent a superposition of 0 and 1, i.e., |ψ|. = α|0 + β|1 , where α and β are complex probability amplitudes, satisfying |α| 2 + |β| 2 = 1. This superposition property allows a single qubit to encode multiple information states in parallel, thus achieving a storage density far exceeding that of classical storage devices. A quantum memory can include multiple storage cells, each containing multiple qubits. Therefore, the physical qubit specification must at least include the storage capacity of the quantum memory to be designed, which determines the number of qubits it contains.

[0024] Furthermore, the physical qubit specifications may also include the coherence time of the quantum state, the error rate or fault tolerance rate, and the physical implementation platform. The coherence time of the quantum state refers to the duration for which the quantum state of the qubit is kept stable. The error rate refers to the minimum error rate operation allowed to maintain the integrity of quantum information; generally, the error rate can be less than 0.1%. The physical implementation platform refers to a hardware device built in a real physical system capable of storing quantum states (such as a superposition of 0 and 1). This hardware device needs to meet two core conditions: first, there must be two mutually orthogonal quantum states, i.e., |0|. and |1 Secondly, it can prepare and maintain any superposition state of these two quantum states. In practical scenarios, the physical realization platform can trap ions with electromagnetic fields, use their energy levels as qubits, and achieve storage through laser manipulation, or construct qubits based on solid-state devices such as Josephson junctions.

[0025] The environmental noise model refers to the noise that affects the quantum state that needs to be considered when designing the quantum memory architecture. In actual fields, the types of environmental noise include, but are not limited to, thermal noise, Gaussian white noise, 1 / f noise, Poisson impulse noise, and one or more of quantum noise.

[0026] S2. Based on the interaction between the physical qubit specifications and environmental noise, select a continuous symmetry group.

[0027] The continuous symmetry group was chosen to better describe and suppress environmental noise.

[0028] When selecting a continuous symmetry group based on the physical qubit specifications, parameters such as storage capacity, coherence time, and error rate are considered to choose a symmetry group that can effectively protect quantum information. For example, for quantum storage systems with high storage capacity, a group with higher symmetry needs to be selected to ensure stable storage of information.

[0029] When selecting a continuous symmetry group based on an environmental noise model, for specific noise types (such as thermal noise, Gaussian white noise, and 1 / f noise), a symmetry group that can suppress or cancel these noises should be chosen. For example, for 1 / f noise, it may be necessary to select a symmetry group that can effectively suppress low-frequency fluctuations.

[0030] Therefore, by combining physical qubit specifications with environmental noise models, a continuous symmetry group that can both protect quantum information and suppress environmental noise can be selected, thereby optimizing the performance of quantum memory.

[0031] In one example, the continuous symmetry group corresponding to the maximum summation value can be obtained by assigning weight coefficients to the terms of the physical qubit specifications and the environmental noise model, and then using this weighted summation as the continuous symmetry group selected in S2. For example, first, the three terms of the physical qubit specifications (storage capacity, coherence time, and error rate) and the three terms of the environmental noise model (thermal noise, Gaussian white noise, and 1 / f noise) are obtained. Then, according to the importance of each term, weight coefficients k1, k2, and k3 are assigned to storage capacity, coherence time, and error rate, respectively, and weight coefficients k4, k5, and k6 are assigned to thermal noise, Gaussian white noise, and 1 / f noise, respectively. The candidate continuous symmetry groups are Q1 and Q2. The influence values ​​of continuous symmetry groups Q1 and Q2 on the terms of the physical qubit specifications and the environmental noise model can be obtained through multiple experiments. For example, with other terms unchanged, the duration for which the two continuous symmetry groups maintain quantum state stability when a certain term (e.g., storage capacity) takes different values ​​is tested. For example, the influence values ​​of continuous symmetry group Q1 on storage capacity, coherence time, and error rate are S1, S2, and S3, respectively. 11 S 12 S 13 The effects on thermal noise, Gaussian white noise, and 1 / f noise are S, respectively. 14 S 15 S 16 The effects of the continuous symmetric group Q2 on storage capacity, coherence time, and error rate are S, respectively. 21 S 22 S 23 The effects on thermal noise, Gaussian white noise, and 1 / f noise are S, respectively. 24 S 25 S 26 Then, by summing the following relation, we obtain two values ​​S1 and S2. When S1 is greater than S2, we select the continuous symmetric group Q1. When S1 is less than S2, we select the continuous symmetric group Q2. When S1 is equal to S2, we can select either one.

[0032] S1 = k1*S 11 +k2*S 12 +k3*S 13+k4*S 14 +k5*S 15 +k6*S 16 S2 = k1*S 21 +k2*S 22 +k3*S 23 +k4*S 24 +k5*S 15 +k6*S 26 In a specific scenario, the continuous symmetric group can be a Lie group, such as at least one of the following: rotation group SO(3), translation group T(3), unitary group U(n), special unitary group SU(n), and Lorentz group.

[0033] S3. Quantum state encoding located in a symmetry-protected subspace is synthesized through continuous symmetry group synthesis.

[0034] In one example, when the continuous symmetric group is a Lie group, combined with Figure 2 As shown, the method of synthesizing the quantum state encoding by continuous symmetry group includes steps S31 to S33.

[0035] S31. Perform Lie group analysis on the quantum states of the quantum memory.

[0036] As a quantum system, a quantum memory contains all possible quantum states that constitute a complex geometric space, such as a Hilbert space. Lie group analysis first identifies the physical properties of the ambient noise in the quantum system, namely continuous symmetries, such as rotational symmetries or phase symmetries, to form a Lie group. Then, based on Lie group analysis, the noise generators and the Lie algebras they constitute are obtained.

[0037] S32. Based on the results of Lie group analysis, define a symmetry-protected decoherent free subspace.

[0038] The noise generator and its Lie algebra are obtained through Lie group analysis. Then, the subspace that commutes with the noise generator is determined based on the Lie algebra. This subspace is a symmetry-protected subspace. The quantum states in this symmetry-protected subspace maintain coherence under the influence of environmental noise, thus serving as a decoherent free subspace.

[0039] S33. Encode the quantum state into the decoherent free subspace to achieve quantum state encoding.

[0040] S4. A control pulse sequence that maintains symmetry protection through continuous symmetry group design.

[0041] In one example, the continuous symmetric group is a Lie group. The method for designing the control pulse sequence includes: first, representing the access operation to the quantum memory as Lie group elements of the unitary evolution matrix; then, using a preset decomposition technique to decompose the Lie group elements of the unitary evolution matrix into a sequence of exponential operations of Lie algebras; finally, solving for the shortest path of the exponential operation sequence of the Lie algebras using a geometric method; and forming a symmetric control pulse sequence based on the control parameters corresponding to the shortest path.

[0042] Optionally, the geometric method is a gradient descent algorithm or a genetic algorithm, and the preset decomposition technique is a Cartan decomposition technique or a Gaussian decomposition technique.

[0043] Optionally, the control parameters corresponding to the shortest path include the pulse amplitude, phase, and timing.

[0044] It should be noted that the principles and processes of performing the aforementioned Lie group analysis and designing control pulse sequences based on Lie group synthesis quantum state encoding can be found in common knowledge in the field, and will not be elaborated upon here.

[0045] S5. Based on the quantum state encoding and control pulse sequence, output the quantum memory architecture specification, including: during the access phase of the quantum memory, actively decouple the quantum state of the quantum memory from environmental noise based on the control pulse sequence.

[0046] Based on the aforementioned method of constructing a symmetry-protected decoherent free subspace through Lie group analysis, the memory architecture specification further includes: based on the control pulse sequence, executing the access phase of the quantum memory in the order of Lie group analysis, quantum state encoding, and dynamic decoupling.

[0047] In one example, the dynamic decoupling is performed in a continuous control field, which is a physical field through which the quantum memory is modulated by continuous parameters. That is, a continuous microwave field resonating or nearly resonating with the qubit is applied, which flips the quantum state of the qubit, causing the quantum state to rotate continuously and rapidly around a fixed axis. The quantum system is very weakly affected by rapid oscillations, thus greatly suppressing the influence of noise on the quantum system. The sequence of control pulses can be considered as the timing, amplitude, and phase of the quantum state flipping.

[0048] Based on steps S1 to S5 above, this application employs a continuous symmetry group to implement a symmetry-protected quantum memory architecture. Since symmetry-protected quantum memories are inherently immune to specific types of errors, such as bit flips, through physical design, error correction resources can be concentrated on other types of errors, such as phase flips. This simplifies the error correction scheme and significantly reduces the number of physical qubits required; for example, only 5 cat qubits are needed to achieve error suppression, while traditional schemes require dozens of additional qubits. Therefore, this application can reduce the number of physical qubits and simplify error correction overhead.

[0049] This application embodiment also provides a storage medium storing a design program for a quantum memory architecture. This design program is essentially a computer program, and when executed by a processor, it implements the steps of a quantum memory architecture design method as in any example.

[0050] The storage medium includes, but is not limited to, any one of read-only memory (ROM), random access memory (RAM), magnetic disk, and optical disk.

[0051] Since the program stored in the storage medium can execute the steps in the design method of the quantum memory architecture of any embodiment provided in this application, the beneficial effects that the design method of the quantum memory architecture of any of the foregoing embodiments can achieve can be realized, as detailed in the foregoing embodiments, which will not be repeated here.

[0052] This application also provides a quantum memory architecture design device or chip, including a memory and a processor. The memory stores a quantum memory architecture design program, which, when executed by the processor, implements the steps of the quantum memory architecture design method of any of the foregoing embodiments; and / or, the quantum memory architecture design device or chip is provided with a storage medium as shown in the above example, and the processor loads the storage medium to execute the steps of the quantum memory architecture design method, thereby achieving the beneficial effects that the quantum memory architecture design method of the corresponding embodiment can achieve.

[0053] Figure 3 This is a schematic diagram of the design device for a quantum memory architecture provided in an embodiment of this application. Figure 3 As shown, the design device 30 for the quantum memory architecture, also known as design device 30, or simply device 30, includes: Receiver module 31 is used to receive the physical quantum bit specifications and the environmental noise model constructed based on environmental noise; Module 32 is selected to select a continuous symmetry group based on the interaction between the physical quantum bit specifications and environmental noise. The first design module 33 is used to synthesize quantum state encodings located in symmetry-protected subspaces through continuous symmetry groups; The second design module 34 is used to maintain a control pulse sequence for symmetry protection through continuous symmetry group design; and... The output module 35 is used to output the quantum memory architecture specification based on the quantum state encoding and control pulse sequence, including: actively decoupling the quantum state of the quantum memory from the environmental noise dynamically based on the control pulse sequence during the access phase of the quantum memory.

[0054] It should be understood that the various modules of the device 30 described above can be represented as physical devices or virtual modules (i.e., modules in general) in a real-world scenario. A module can be implemented by a single physical device or by two or more physical devices working together. Similarly, the function performed by a module can be implemented by a single physical device or by two or more physical devices working together. Furthermore, the functions corresponding to each module can be implemented by the corresponding steps of the quantum memory architecture design method of any of the foregoing embodiments.

[0055] The above are only some embodiments of this application and do not limit the patent scope of this application. For those skilled in the art, any equivalent structural transformations made using the content of this specification and drawings are similarly included within the patent protection scope of this application.

[0056] The use of step designations such as S1 and S2 in this document is intended to more clearly and concisely describe the corresponding content and does not constitute a substantial restriction on the order. In specific implementation, those skilled in the art may execute S2 first and then S1, etc., but these should all be within the scope of protection of this application.

[0057] Although this document uses terms such as "first," "second," etc., to describe various types of information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. Furthermore, the singular forms "a," "an," and "the" are intended to also include the plural forms. The terms "or" and "and / or" are interpreted as inclusive, or meaning either one or any combination thereof. Exceptions to this definition only arise when combinations of elements, functions, steps, or operations are inherently mutually exclusive in some way.

Claims

1. A design method for a quantum memory architecture, characterized in that, include: Receive physical qubit specifications and an environmental noise model based on environmental noise; Based on the interaction between the physical qubit specifications and environmental noise, a continuous symmetry group is selected; Quantum state encoding located in a symmetry-protected subspace is synthesized through the continuous symmetry group; The control pulse sequence that maintains symmetry protection is achieved through the design of the continuous symmetry group; Based on the quantum state encoding and the control pulse sequence, a quantum memory architecture specification is output, including: during the access phase of the quantum memory, actively decoupling the quantum state of the quantum memory from the environmental noise based on the control pulse sequence.

2. The method according to claim 1, characterized in that, The continuous symmetry group is a Lie group, and the synthesis of quantum state encodings located in symmetry-protected subspaces through the continuous symmetry group includes: Perform Lie group analysis on the quantum states of the quantum memory; Based on the results of the Lie group analysis, a symmetry-protected decoherent free subspace is defined; Quantum states are encoded into the decoherent free subspace to achieve quantum state encoding.

3. The method according to claim 2, characterized in that, The methods for defining the decoherent free subspace include: The physical characteristics of environmental noise are obtained based on the environmental noise model. Based on the aforementioned physical characteristics, the noise generator and its constituent Lie algebra are obtained; The subspace that commutes with the noise generator is determined based on the Lie algebra to serve as a decoherent free subspace, in which the quantum states remain coherent under the influence of environmental noise.

4. The method according to claim 2, characterized in that, The memory architecture specification also includes: Based on the control pulse sequence, the access phase of the quantum memory is executed sequentially according to the Lie group analysis, the quantum state encoding, and the dynamic decoupling.

5. The method according to claim 1, characterized in that, The continuous symmetry group is a Lie group, and the control pulse sequence designed using the continuous symmetry group to maintain symmetry protection includes: The access operations to the quantum memory are represented as Lie group elements of the unitary evolution matrix; The Lie group elements of the unitary evolution matrix are decomposed into a sequence of exponential operations of Lie algebras using a pre-defined decomposition technique. The shortest path of the exponential operation sequence of the Lie algebra is found by geometric method, and a symmetric control pulse sequence is formed according to the control parameters corresponding to the shortest path.

6. The method according to claim 5, characterized in that, The geometric method is either gradient descent or genetic algorithm, and the preset decomposition technique is either Cartan decomposition or Gauss decomposition.

7. The method according to claim 5, characterized in that, The control parameters corresponding to the shortest path include the pulse amplitude, phase, and timing.

8. The method according to claim 1, characterized in that, The dynamic decoupling is performed in a continuous control field, which is a physical field through which the quantum memory is regulated by continuous parameters.

9. A design device for a quantum memory architecture, characterized in that, It includes a processor and a memory, the memory storing a design program, which, when executed by the processor, implements the steps of the design method for the quantum memory architecture as described in any one of claims 1 to 8.

10. A storage medium, characterized in that, The device contains a computer program that, when executed by a processor, implements the steps of the method as described in any one of claims 1 to 8.

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