Variational Quantum Measurement for Precision and Dynamic Range
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing measurement techniques for physical quantities in quantum systems face limitations in precision and dynamic range, particularly in applications like atomic clocks, where the optimization of Quantum Fisher information may reduce the dynamic range of entangled quantum sensors compared to uncorrelated spins.
Innovation Solution
A Bayesian approach is adopted in a hybrid classical-quantum system, utilizing a parametrized quantum circuit with controllable quantum systems and classical computation, where preparation and decoding gates are optimized to minimize estimation error over a defined prior distribution, enabling improved information gain and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Quantum Fisher information is used to optimize the measurement scheme, then the estimation error is reduced, but the dynamic range of the entangled quantum sensor is reduced
Solution Approach 1:
The patent applies dynamics by making the quantum measurement scheme adaptable through variational optimization of the measurement basis. Instead of using a fixed measurement scheme optimized for a specific phase value, the system dynamically adjusts the measurement parameters to optimize performance across different phases, thereby extending the dynamic range while maintaining precision.
Solution Approach 2:
The patent changes the parameters of the measurement scheme by introducing variational parameters that can be optimized to minimize the cost function. This allows the measurement scheme to adapt to different physical quantity ranges and optimize the balance between precision and dynamic range by adjusting measurement parameters rather than using a fixed configuration.
2Measurement precision
If entangled states are prepared before interaction, then the precision of phase measurement is improved, but the measurement stage becomes less effective
Solution Approach 1:
The patent applies preliminary action by preparing entangled states before the measurement interaction. This pre-preparation of quantum states enables the system to achieve high precision in phase measurement while the subsequent measurement stage remains effective through variational optimization of the measurement basis, resolving the apparent contradiction between preparation benefits and measurement effectiveness.
3Device complexity
If a fixed probe state is used, then the measurement scheme is simple, but the estimation error cannot be minimized across all phase values
Solution Approach 1:
The patent transitions from a static fixed probe state to a dynamic variational measurement scheme. The measurement basis is optimized through variational methods to minimize the cost function across different phase values, achieving superior precision without excessive complexity by finding the optimal balance point in the parameter space.
Data Source
AI summary
A method of measuring a physical quantity implemented in a hybrid classical-quantum system, the method comprising initializing the plurality of controllable quantum systems in an initial state, applying a set of preparation gates to the plurality of controllable quantum systems for preparing the plurality of controllable quantum systems in a non-classical state, evolving the non-classical state over a time period for obtaining an evolved state of the plurality of controllable quantum systems, applying a set of decoding gates to the plurality of controllable quantum systems in the evolved state, performing a measurement of the plurality of controllable quantum systems, and determining a derived value of the physical quantity based on a mapping function between an outcome of the measurement and the physical quantity on the classical computation system.