6 papers · 1 filter
Optimal lower bound for quantum channel tomography in away-from-boundary regime
Kean Chen, Zhicheng Zhang, Nengkun Yu
Consider quantum channels with input dimension , output dimension and Kraus rank at most . Any such channel must satisfy the constraint , and the parame…
Quantum channel tomography and estimation by local test
Kean Chen, Nengkun Yu, Zhicheng Zhang
We study the estimation of an unknown quantum channel with input dimension , output dimension and Kraus rank at most . We establish a connection between…
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…
Inverse-free quantum state estimation with Heisenberg scaling
Kean Chen
In this paper, we present an inverse-free pure quantum state estimation protocol that achieves Heisenberg scaling. Specifically, let be a -dimens…
Simultaneous Estimation of Nonlinear Functionals of a Quantum State
Kean Chen, Qisheng Wang, Zhan Yu +1
We consider a fundamental task in quantum information theory, estimating the values of , , ..., for an obs…
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 r…