Protection of Logical Qubits via Optimal State Transfers

TL;DR

This paper presents an efficient dynamical decoupling method to create decoherence-free subspaces for logical qubits by optimally transferring states among qubits, enabling protection against collective noise with minimal steps.

Contribution

It introduces a novel optimal state transfer scheme to generate effective collective noise, facilitating the creation of decoherence-free subspaces with only N steps for N qubits.

Findings

Efficient creation of DFSs using N steps for N qubits.

Requires only nearest-neighbor state transfers.

Provides a feasible approach for protecting logical qubits.

Abstract

Dynamical decoupling can enforce a symmetry on the dynamics of an open quantum system. Here we develop an efficient dynamical-decoupling-based strategy to create the decoherence-free subspaces (DFSs) for a set of qubits by optimally transferring the states of these qubits. We design to transfer the state of each qubit to all of the other qubits in an optimal and efficient manner, so as to produce an effective collective-type noise for all qubits. This collective pseudo-noise is essentially derived from arbitrarily independent real baths and needs only nearest-neighbor state transfers for its implementation. Moreover, our scheme requires only N steps to produce the effective collective-type noise for a system of N qubits. It provides an experimentally feasible and efficient approach to achieving the DFSs for encoding the protected logical qubits.