10 papers
A Lower Bound Framework for Quantum Functional Estimation
Qisheng Wang
We develop a unified framework for proving lower bounds for estimating functionals of -dimensional quantum states: \[ \mathcal L_ϕ(ρ)=\frac1d\sum_{i=1}^dϕ(dλ_i(ρ)). \] The frame…
Sample-Optimal Quantum Estimators for Pure-State Trace Distance and Fidelity via Samplizer
Qisheng Wang, Zhicheng Zhang
We settle the problem of estimating the trace distance and (square root) fidelity between -qubit pure quantum states to within additive error , given their independ…
Estimating Fidelity to a Reference Quantum State
Qisheng Wang
We consider the problem of estimating the fidelity of an unknown quantum state to a known reference state to within additive error . We show that the sample complexity…
Strict Hierarchy for Quantum Channel Certification to Unitary
Kean Chen, Qisheng Wang, Zhicheng Zhang
We consider the problem of quantum channel certification to unitary, where one is given access to an unknown -dimensional channel , and wants to test whether $\math…
Trace Estimation of Quantum State Powers: Sample Complexity and Computational Hardness
Kean Chen, Yupan Liu, Qisheng Wang
As often emerges in various basic quantum properties such as Rényi and Tsallis entropies, the trace of quantum state powers has attracted a lot of attention. The…
A List of Complexity Bounds for Property Testing by Quantum Sample-to-Query Lifting
Kean Chen, Qisheng Wang, Zhicheng Zhang
Quantum sample-to-query lifting, a relation between quantum sample complexity and quantum query complexity presented in Wang and Zhang (SIAM J. Comput. 2025), was significantly str…