4 papers
Quantum channel tomography: optimal bounds and a Heisenberg-to-classical phase transition
Kean Chen, Filippo Girardi, Aadil Oufkir +2
How many black-box queries to a quantum channel are needed to learn its full classical description? This question lies at the heart of quantum channel tomography (also known as qua…
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…
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…
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…