Decoupling using random diagonal-unitary matrices

Decoupling using random diagonal-unitary matrices

Seminar author:Yoshifumi Nakata

Event date and time:12/09/2014 03:00:pm

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Decoupling a system from environment is one of the most important tasks in quantum information theory and is achievable using Haar random unitary matrices, a unitary 2-design, or random quantum circuits. In this talk, we show that decoupling is also achievable using two diagonal-unitary matrices, where their bases should be complementary each other such as the Pauli-Z and Pauli-X basis, although there is a penalty of using diagonal-unitaries instead of Haar random unitaries. We also present a criteria for the existence of diagonal-unitary matrices that lead to decoupling. Since experimental implementations of diagonal-unitary matrices are simpler and more robust than non-diagonal ones, this possibly provides a practical way of implementing the decoupling by current technology.