Dynamical Decoupling in Common Environment

TL;DR

This paper demonstrates that applying independent Uhrig Dynamical Decoupling sequences with different parity on each qubit effectively suppresses both qubit-environment and indirect qubit-qubit interactions, enhancing quantum state preservation.

Contribution

It provides a simplified solution for decoupling indirect qubit interactions via common environment using UDD sequences with different parity, extending dynamical decoupling techniques.

Findings

UDD sequences with different parity suppress interactions to the same order as single qubit case.

Applying UDD(n) and UDD(m) with odd n + m achieves min(n,m)th order suppression.

Results can reduce pulse numbers in experiments and manipulate indirect interactions in quantum gates.

Abstract

Dynamical decoupling (DD) sequences were invented to eliminate the direct coupling between qubit and its environment. We further investigate the possibility of decoupling the indirect qubit-qubit interaction induced by a common environment, and sucessfully find simplified solutions that preserve the bipartite quantum states to arbitrary order. Through analyzing the exact dynamics of the controlled two-qubit density matrix, we have proven that applying independent Uhrig Dynamical Decoupling (UDD) on each qubit will effectively eliminate both the qubit- environment and indirect qubit-qubit coupling to the same order as in single qubit case, only if orders of the two UDD sequences have different parity. More specifically, UDD(n) on one qubit with UDD(m) on another are able to produce min(n,m)th order suppression while n + m is odd. Our results can be used to reduce the pulse number in relevant experiments for protecting bipartite quantum states, or dynamically manipulate the indirect interaction within certain quantum gate and quantum bus.