Suppressing decoherence in quantum state transfer with unitary operations

TL;DR

This paper explores a method using unitary operations to protect quantum states from decoherence during transfer, demonstrating increased fidelity in both simulated and real quantum experiments.

Contribution

It applies quantum state-dependent pre- and post-processing unitaries to suppress decoherence, extending previous theoretical proposals to practical quantum state transfer scenarios.

Findings

Fidelity of quantum states increased in emulation and real experiments.

Protection method effective even when unitaries are affected by noise.

Applicable to distributing multi-qubit states over remote quantum processors.

Abstract

Decoherence is the fundamental obstacle limiting the performance of quantum information processing devices. The problem of transmitting a quantum state (known or unknown) from one place to another is of great interest in this context. In this work, by following the recent theoretical proposal [Opt. Eng. {\bf 59}, 061625 (2020)] we study an application of quantum state-dependent pre- and post-processing unitary operations for protecting the given (multi-qubit) quantum state against the effect of decoherence acting on all qubits. We observe the increase in the fidelity of the output quantum state both in a quantum emulation experiment, where all protecting unitaries are perfect, and in a real experiment with a cloud-accessible quantum processor, where protecting unitaries themselves are affected by the noise. We expect the considered approach can be useful for analyzing capabilities of quantum information processing devices in transmitting known quantum states. We also demonstrate an applicability of the developed approach for suppressing decoherence in the process of distributing a two-qubit state over remote physical qubits of a quantum processor.