A topology qubit structure based on shadow thickness real-time monitoring and feedback locking and a control method thereof

Abstract

The application discloses a kind of topological quantum bit structure based on shadow thickness real-time monitoring and feedback locking and control method thereof.According to the axiomatic system of projection geometry, quantum bit is defined as the projection section of high-dimensional fiber bundle on base manifold, its state is completely described by projection weight, and the coherence quality is directly represented by shadow thickness.The device includes topological quantum bit core element, shadow thickness measurement terminal (real-time measurement by shadow interference method), shadow thickness locking electrode, shadow thickness monitoring module (calculation) and feedback control module (PID control algorithm is used to adjust locking electrode driving signal in real time).The decoherence rate caused by shadow thickness fluctuation is, and by locking in, can reach minimum value.The device also includes projection angle coordinated regulation module, and the coherence quality factor reaches global optimum according to the coordinated adjustment of projection angle.The application realizes the real-time nondestructive monitoring and active feedback locking of shadow thickness, can work with topological protection layer scheme, and is suitable for superconducting, semiconductor, Majorana and other types of topological quantum computing platform.

Description

Technical Field

[0001] This invention relates to the fields of quantum computing and topological quantum information processing, specifically to a topological qubit structure and its control method based on real-time shadow thickness monitoring and feedback locking. This invention can be applied to various quantum computing platforms, including superconducting qubits, semiconductor quantum dot qubits, and Majorana zero-mode topological qubits, and is particularly suitable for quantum computing applications that require extending the coherence time of qubits and maintaining optimal superposition state quality through active feedback. Background Technology

[0002] According to the axioms of projective geometry, a physical system is defined as a high-dimensional fiber bundle. In the base manifold The projected section on the fiber bundle. Under this axiomatic framework, the qubit is redefined as a local projected section within the fiber bundle, with the wavefunction being: in For shadow density, The projection angle is the physical state of the projected section, determined by the projection weights. Fully characterized, its radial modulus Define shadow thickness .when When the projected section is in an ideal coherent state; when At that time, the projected section decohered. The core constraints of the projective geometry axiomatic system are: in and These are the radial and axial projection weight components, respectively. The decoherence of the projected section is strictly defined as the projection weight magnitude. Loss rate: That is, shadow thickness Decays over time. Existing topological qubit schemes mainly suffer from the following problems: (a) Lack of direct monitoring methods for shadow thickness Existing methods measure decoherence rate Alternatively, the contrast of Ramsey fringes can be used to indirectly infer quantum state quality, but the shadow thickness is lacking. Direct, real-time, and non-destructive measurement methods are insufficient to provide early warning and intervention before decoherence occurs. (ii) Lack of an active feedback locking mechanism based on shadow thickness Shadow thickness Fluctuations in energy are the direct source of energy decoherence. when Deviation from optimal value At that time, the decoherence rate increases. Existing solutions lack the ability to lock the shadow thickness within a certain range. The proactive feedback mechanism. (iii) Projection angle adjustment cannot directly compensate for shadow thickness drift. Existing topological qubits can be controlled by adjusting the projection angle. To adjust the topology protection strength, but the shadow thickness The drift can be caused by a variety of factors (temperature drift, charge noise, dielectric loss, etc.), and simple projection angle adjustment cannot directly compensate for it. Deviation. (iv) Lack of synergy with topology protection layers Topological protection layers suppress decoherence by constructing topologically nontrivial structures around qubits, but lack active locking of shadow thickness at the qubit body level, thus failing to form a synergistic protection. To address the aforementioned problems, this invention provides a topological qubit structure and its control method based on real-time shadow thickness monitoring and feedback locking. Summary of the Invention

[0003] (a) Purpose of the invention This invention aims to address the technical problems in existing topological qubits, such as the lack of direct shadow thickness monitoring methods, the lack of active feedback locking mechanisms based on shadow thickness, the inability of projection angle adjustment to directly compensate for shadow thickness drift, and the lack of coordination with topological protection layers. It provides a topological qubit structure and its control method based on real-time shadow thickness monitoring and feedback locking. By integrating shadow thickness measurement terminals into the qubit structure, real-time non-destructive monitoring of shadow thickness is achieved, and the shadow thickness is locked at the optimal value through closed-loop feedback, thereby extending the coherence time and improving the quality of superposition states. (II) Technical Solution This invention provides a topological qubit structure based on real-time shadow thickness monitoring and feedback locking, characterized in that it includes: A topological qubit is a core component, set on a quantum computing chip, used to carry and process quantum information; A shadow thickness measurement terminal, integrated in the vicinity of the core element of the topological qubit, is used to measure the shadow thickness in real time via shadow interferometry or local density of states measurement. ; A shadow thickness locking electrode is disposed near the core element of the topological qubit to compensate for the drift of the shadow thickness by applying an external electric field to adjust the local potential energy. A shadow thickness monitoring module is connected to the shadow thickness measurement terminal to calculate the shadow thickness offset in real time. ,in The theoretically optimal shadow thickness; A feedback control module, connected to the shadow thickness monitoring module and the shadow thickness locking electrode, is used to control the shadow thickness based on the shadow thickness offset. The shadow thickness is locked at a specific value by adjusting the drive signal of the locking electrode in real time using a closed-loop control algorithm. ; A projection angle coordination control module, connected to the feedback control module and the projection angle control electrode of the topological qubit, is used to coordinately adjust the projection angle while locking the shadow thickness. This allows the qubit to operate simultaneously at the optimal projection angle and the optimal shadow thickness. Physical definition of shadow thickness: Shadow thickness definition: The shadow thickness of the topological qubit Defined as the logarithm of the projection weight magnitude: in For projection weights, Projection angle. Shadow thickness. Directly characterizing the coherence quality of a quantum bit—when (Right now The quantum state is in an ideal coherent state. Relationship between shadow thickness and decoherence rate: Decoherence caused by shadow thickness fluctuations for: in For the shadow thickness noise power spectral density, For the operating frequency of the quantum bit, The optimal shadow thickness is when... hour, , Reaching the minimum value; when Deviation hour, Increase. Optimal value for shadow thickness: Optimal shadow thickness Determined by the system parameters of the topological qubit, the following conditions must be met: Right now This minimizes the decoherence rate. For a typical topological qubit, (Right now ). Shadow thickness measurement principle: Shadow interference method: The shadow thickness measurement terminal measures the shadow thickness using shadow interferometry. According to the principle of shadow superposition in projection geometry, the interference intensity of the two shadows (reference shadow and qubit shadow) is: Interference fringe contrast With shadow thickness The relationship is: When referencing shadow thickness hour, The contrast of the interference fringes can be directly used to infer the result. And thus obtain . Shadow thickness locking feedback control: PID feedback control law: The feedback control module employs a PID control algorithm, based on the shadow thickness offset. Calculate the drive signal for the locked electrode: in , , These are the proportional, derivative, and integral control gains, respectively. The voltage applied to the shadow thickness locking electrode. Shadow thickness locking principle: The shadow thickness-locking electrode modulates the radial modulus of the projected weights by applying an external electric field to adjust the local potential energy near the core element of the qubit. The change in shadow thickness With lock electrode voltage The relationship is: in The shadow thickness modulation efficiency of the locked electrode (unit) By adjusting , can make tend : Projection angle coordinated control: The projection angle collaborative control module, while locking the shadow thickness, adjusts the current shadow thickness accordingly. Adjusting the projection angle The set values ​​enable the qubit to operate simultaneously in the optimal projection angle and optimal shadow thickness state: in This is the cooperative coupling coefficient. This cooperative regulation improves the coherence quality factor of the qubit. Achieving global optimum: in The allowable fluctuation bandwidth for shadow thickness. Synergy with topology protection layers: The shadow thickness locking mechanism works in conjunction with the topological protection layer (achieved by constructing a topologically nontrivial structure around the qubit): Topology protection layer: Provides an external topology protection shell, exponentially suppresses environmental noise, and reduces the intrinsic drift rate of shadow thickness; Shadow thickness locking mechanism: Actively compensate for residual shadow thickness drift at the quantum bit level to achieve dual protection. The total decoherence rate after coordination is: The first term comes from the exponential suppression of the topology protection layer, and the second term comes from the active compensation of shadow thickness locking. Work mode: The device supports the following operating modes: (1) Passive monitoring mode: Only the shadow thickness is monitored in real time without applying active feedback, which is used for real-time evaluation of quantum state quality; (2) Active locking mode: Apply feedback locking based on the shadow thickness measurement results, and... Locked in ; (3) Cooperative optimization mode: Shadow thickness locking and projection angle cooperative control work simultaneously to make the qubit work in the global optimal state; (4) Adaptive calibration mode: Periodically scan the relationship between shadow thickness offset and lock electrode voltage, and automatically calibrate. and . (III) Beneficial Effects Real-time non-destructive monitoring of shadow thickness: Achieving shadow thickness monitoring through shadow interferometry. Direct, real-time, and non-destructive measurement without disrupting the quantum state; Active feedback locking: The shadow thickness is locked at the optimal value through PID closed-loop control. This reduces the decoherence rate. Always keep it to a minimum; Projection angle co-optimization: Coordinated adjustment of projection angle while locking shadow thickness This allows the qubit to operate simultaneously at the optimal projection angle and the optimal shadow thickness. Synergy with topology protection layer: It forms a dual protection with the topology protection layer scheme, and the total decoherence rate is suppressed exponentially and then residual drift is eliminated by active locking; Multi-mode adaptation: Supports four working modes: passive monitoring, active locking, collaborative optimization, and adaptive calibration, to adapt to different application scenarios; Compatible with existing topological qubit processes: The shadow thickness measurement terminal and locking electrode can be integrated using standard micro-nano fabrication processes without changing the core structure of the qubit. Attached Figure Description

[0004] Figure 1 This is a schematic diagram of the overall topological quantum bit structure based on real-time shadow thickness monitoring and feedback locking, provided in an embodiment of the present invention. Figure 2 This is a schematic diagram illustrating the principle of shadow thickness interferometry measurement provided in an embodiment of the present invention. Figure 3 The flowchart of shadow thickness locking feedback control provided in the embodiment of the present invention. Figure 4 This is a schematic diagram illustrating the principle of shadow thickness locking and projection angle collaborative optimization provided in an embodiment of the present invention. Detailed Implementation

[0005] Example 1: Shadow Thickness Locking Device for Superconducting Topological Quantum Bits Based on Shadow Interferometry Step 1: Fabrication of the core element of the topological quantum bit Transmon or fluxonium qubit cores are fabricated on sapphire or silicon substrates using standard superconducting qubit fabrication processes. The qubit operating frequency... The relevant time for this tax refund The topological protection of the qubits is provided by a neighboring topologically insulating thin film (Bi₂Se₃, 10 nm thick) with a non-zero topological Chern number. . Step 2: Integrate shadow thickness measurement terminal A shadow interferometer is integrated in the vicinity of the core component of the qubit. The shadow interferometer includes: A reference shadow path (obtained through a stable reference quantum state) ); One qubit shadow path (obtained through the projected weights of the qubits); The two shadows interfere at the output of the interferometer, increasing the contrast of the interference fringes. Measured by a single-photon detector array. Shadow thickness Inversely derived from the contrast of the interference fringes: Measurement accuracy Time resolution . Step 3: Integrate shadow thickness locking electrode A shadow thickness-locked electrode is formed by depositing a gate electrode (Ti / Au, 50 nm thick) and an insulating layer (Al₂O₃, 30 nm thick) near the core element of the qubit. A voltage is applied... Adjusting the local potential energy near the qubit compensates for the drift in shadow thickness. Calibrate the shadow thickness modulation efficiency. (That is, a 1V voltage change causes a 0.1V change in shadow thickness). Step 4: Configure the shadow thickness monitoring and feedback control module Shadow thickness monitoring module Real-time calculation of shadow thickness offset using sampling rate The feedback control module uses a PID algorithm to calculate the lock-on electrode voltage. in , , This is the optimized control gain. Step 5: Perform active shadow thickness locking The feedback control system is activated, and the shadow thickness monitoring module continuously monitors the shadow. The feedback control module adjusts in real time. Actual measurements showed that, with active locking enabled, the shadow thickness offset... From the initial convergence to Within, lock time . Step 6: Coherence Verification The decoherence time of the qubit was measured with and without active locking for shadow thickness enabled. The actual measured decoherence time was [not specified]. from Upgraded to This represents an improvement of approximately 11 times. The Ramsey oscillating stripe contrast has increased from... Upgraded to The superposition state maintains significantly enhanced quality. Example 2: Dual Protection Scheme in Collaboration with Topology Protection Layer Step 1: Integrate the topology protection layer Three cascaded topological guard layers were fabricated around the core element of the qubit, with each layer optimized for high, medium, and low frequency noise, respectively. The intrinsic decoherence suppression factor provided by the topological guard layers was [missing value]. . Step 2: Integrating a shadow thickness locking mechanism (this invention) Inside the topology protection layer, the shadow thickness measurement terminal and locking electrode are integrated according to the steps of Example 1. Step 3: Perform dual protection collaborative operation The topology protection layer first reduces the intrinsic decoherence from Reduce to The shadow thickness locking mechanism further eliminates residual shadow thickness drift, reducing decoherence to: When shadow thickness is locked Suppressed to hour, . Step 4: Performance Verification After the dual protection scheme was activated, the decoherence time of the qubit was measured. from Upgraded to This represents an improvement of approximately 10 times compared to a single-layer topology protection layer scheme. Example 3: Co-optimization of shadow thickness locking and projection angle Step 1: Configure the projection angle collaborative control module Connect the projection angle coordinated control module to the shadow thickness monitoring module and the projection angle control electrode of the topological qubit. Set the coordinated coupling coefficient. Optimal projection angle Optimal shadow thickness . Step 2: Execution of the collaborative optimization algorithm The projection angle collaborative adjustment module adjusts the projection angle according to the current shadow thickness offset. Real-time calculation of projection angle setpoint: when hour, ;when hour, . Step 3: Coherence Quality Verification In the cooperative optimization mode, the coherence quality factor of the qubit Achieving global optimum: In the measured collaborative optimization mode, It improves performance by about 20% compared to a solution that only locks the shadow thickness (without adjusting the projection angle), and by about 100 times compared to a solution with no feedback. Terminology Explanation

[0006] Terminology Meaning The projected cross-section of the high-dimensional fiber bundle E=M_4×F to the bottom manifold M_4 is characterized by the projection weight w=|w| e^iθ. Projection weights (w) describe the complex weights of the projected section, w = |w| e^iθ, where θ is the projection angle. Shadow thickness (ϕ) is the logarithm of the projection weight modulus, ϕ=ln|w|, directly characterizing the coherence quality of the qubit. The shadow interferometry method is a measurement method that infers the shadow thickness by referencing the contrast of the interference fringes between the shadow and the shadow of a qubit. Shadow thickness offset (δϕ): The difference between the current shadow thickness and the optimal shadow thickness, δϕ = ϕ - ϕ_0 The shadow thickness locking electrode is an electrode structure that adjusts local potential energy and compensates for shadow thickness drift by applying an electric field. A PID (Proportional-Integral-Derivative) control algorithm is used to achieve closed-loop feedback locking of shadow thickness. Projection angle coordinated control, while locking the shadow thickness, coordinates the adjustment of the projection angle to enable the qubit to operate in a globally optimal state. The coherence quality factor (Q_"coh") is a dimensionless parameter that comprehensively characterizes the coherence quality of a qubit.

Claims

1. A topological qubit structure based on real-time shadow thickness monitoring and feedback locking, characterized in that, include: A topological qubit is a core component, set on a quantum computing chip, used to carry and process quantum information; A shadow thickness measurement terminal, integrated in the vicinity of the core element of the topological qubit, is used to measure the shadow thickness in real time via shadow interferometry or local density of states measurement. ,in For projection weights; A shadow thickness locking electrode is disposed near the core element of the topological qubit to compensate for the drift of the shadow thickness by applying an external electric field to adjust the local potential energy. A shadow thickness monitoring module is connected to the shadow thickness measurement terminal to calculate the shadow thickness offset in real time. ,in The theoretically optimal shadow thickness; A feedback control module, connected to the shadow thickness monitoring module and the shadow thickness locking electrode, is used to control the shadow thickness based on the shadow thickness offset. The shadow thickness is locked at a specific value by adjusting the drive signal of the locking electrode in real time using a closed-loop control algorithm. .

2. The topological quantum bit structure according to claim 1, characterized in that: The shadow thickness measurement terminal measures the shadow thickness and interference fringe contrast using shadow interferometry. When referring to the shadow thickness At that time, the shadow thickness can be inferred from the contrast of the interference fringes. , .

3. The topological quantum bit structure according to claim 1, characterized in that: The feedback control module employs a PID control algorithm, and the locked electrode drive signal is... ,in , , These are proportional, derivative, and integral control gains, respectively.

4. The topological quantum bit structure according to claim 1, characterized in that: Shadow thickness offset With lock electrode voltage The relationship is ,in To lock the shadow thickness modulation efficiency of the electrode; by adjusting The shadow thickness tends towards the optimal value. .

5. The topological quantum bit structure according to claim 1, characterized in that: The decoherence rate caused by the shadow thickness fluctuation is ,in For the shadow thickness noise power spectral density, For the operating frequency of the quantum bit; when Locked in hour, Reaching the minimum value .

6. The topological quantum bit structure according to claim 1, characterized in that: It also includes a projection angle coordination control module, connected to the feedback control module and the projection angle control electrode of the topological qubit, for coordinating adjustment of the projection angle according to the shadow thickness offset. This allows the qubit to operate simultaneously at the optimal projection angle and optimal shadow thickness; the coordinated adjustment satisfies ,in This represents the cooperative coupling coefficient.

7. The topological quantum bit structure according to claim 6, characterized in that: The coherence quality factor of the quantum bit is ,in For intrinsic quality factors, For topological Chern numbers, To achieve the optimal projection angle, The allowable fluctuation bandwidth for shadow thickness.

8. The topological quantum bit structure according to claim 1, characterized in that: The device works in conjunction with the topology protection layer, achieving a total decoherence rate of [missing information]. The first term comes from the exponential suppression of the topology protection layer, and the second term comes from the active compensation of shadow thickness locking.

9. A method for controlling topological qubits based on real-time shadow thickness monitoring and feedback locking, characterized in that, Includes the following steps: (1) Real-time measurement of the shadow thickness of the topological qubit via the shadow thickness measurement terminal ,in For projection weights; (2) The shadow thickness monitoring module calculates the shadow thickness offset. ,in The theoretically optimal shadow thickness; (3) The feedback control module is based on the shadow thickness offset. The drive signal for locking the electrode is calculated using a closed-loop control algorithm; (4) Apply a driving signal to the shadow thickness locking electrode Adjusting the local potential energy near the qubit to compensate for the drift in shadow thickness; (5) Repeat steps (1)-(4) to keep the shadow thickness locked at the specified value. .

10. The method according to claim 9, characterized in that: The closed-loop control algorithm described in step (3) is PID control: ,in , , To control the gain; the change in shadow thickness in step (4) , To lock the efficiency of the shadow thickness modulation of the electrode.

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