Theoretical analysis demonstrates criteria for unbiased multiparameter estimation across quantum states and channels, highlighting noise-resilient sensing protocols.
Key Points
Establish the necessary and sufficient conditions for local unbiased multi-parameter estimation in quantum states and quantum channels.
Formulated mathematical conditions for local unbiased state estimation based on the derivatives of encoded quantum states.
Extended the theoretical framework to quantum channel estimation incorporating arbitrary completely positive trace-preserving controls, noiseless ancillae, and sequential channel queries.
Applied the criteria to phase estimation subject to unknown Pauli noise and noise parameter estimation in non-Clifford gates using cycle benchmarking under state preparation and measurement errors.
Demonstrated that standard probe schemes fail to achieve local unbiased phase estimation under unknown Pauli noise, whereas an entangled probe with a noiseless ancilla makes it feasible.
Derived exact necessary and sufficient criteria for local unbiased estimation of quantum channel parameters under general operational controls.
Confirmed the viability of unbiased noise parameter characterization for non-Clifford gates in the presence of state preparation and measurement errors.