Quantum Control Sequences for Nonlinear Distortion Compensation

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Solution Overview

Problem

Existing quantum control systems face challenges in generating robust and high-fidelity control sequences for quantum devices, particularly due to nonlinear distortions and uncertainties in classical control hardware, which affect the performance and scalability of quantum systems.

Innovation Solution

A control framework that incorporates a distortion model representing nonlinear relationships between control signals and input signals, using optimal control theory to iteratively modify control sequences, and accounts for uncertainties in classical control hardware, enabling robust quantum gate design and operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If optimal control theory is used to generate control sequences, then control precision is improved, but device complexity increases due to the need for distortion models and iterative optimization

Engineering Contradiction:
Improvecontrol precisionVSAvoiddevice complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

A distortion model is constructed beforehand to represent the nonlinear relationship between control signals and input signals. This preliminary model allows the optimization process to account for hardware distortions without requiring real-time complex computations, thus improving control precision while managing device complexity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The optimization process uses feedback from the distortion model to iteratively modify control sequences. By incorporating the distortion model into the optimization loop, the system can compensate for nonlinearities and uncertainties in classical control hardware, achieving high-fidelity control while keeping the complexity manageable through structured feedback mechanisms.

Inventive Principle:
Principle #23Feedback

2Productivity

If high-power control signals are used to increase operation speed, then productivity is improved, but reliability deteriorates due to nonlinear distortions in control hardware

Engineering Contradiction:
Improveoperation speedVSAvoidcontrol fidelity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The distortion model is used to predict and compensate for nonlinear distortions before they affect the control sequence. By pre-characterizing the hardware's nonlinear behavior and incorporating this information into the optimization process, the system can generate control sequences that are resilient to distortions even when using high-power signals, thus maintaining both productivity and reliability.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The optimization process adjusts control signal parameters (amplitude, phase, duration) to account for nonlinear distortions. By modifying these parameters based on the distortion model, the system can achieve high operation speeds with high-power signals while compensating for reliability-deteriorating effects through parameter optimization.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If distortion models are incorporated into the control framework, then control fidelity is improved, but computational cost increases

Engineering Contradiction:
Improvecontrol fidelityVSAvoidcomputational time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The distortion model is constructed and characterized in advance, allowing the optimization process to use pre-computed distortion information rather than performing complex real-time simulations. This preliminary action reduces computational time while maintaining high control fidelity by leveraging pre-analyzed hardware characteristics.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The distortion model creates a simplified representation (copy) of the complex nonlinear hardware behavior. This copy can be used efficiently in the optimization process without requiring full-scale simulations of the actual hardware, thus reducing computational time while preserving control fidelity through the accurate distortion characterization.

Inventive Principle:
Principle #26Copying

Data Source

PatentEP3660601B1Generating a control sequence for quantum control
Publication Date: 2021.05.19 QUANTUM VALLEY INVESTMENT FUND
  • EP3660601B1 patent drawingFigure 1
  • EP3660601B1 patent drawingFigure 2
  • EP3660601B1 patent drawingFigure 3A

AI summary

In some aspects, a control system interacts with a quantum system. In some instances, the quantum system includes qubits that respond to a control signal generated by the control system, and the control system is configured to generate the control signal in response to an input signal. A control sequence (which may include, for example, a sequence of values for the input signal) can be generated by a computing system based on a target operation to be applied to the qubits. The control sequence can be generated based on the target operation, a quantum system model, a distortion model and possibly other information. The quantum system model represents the quantum system and includes a control parameter representing the control signal. The distortion model represents a nonlinear relationship between the control signal and the input signal. The control sequence is applied to the quantum system by operation of the control system.