Suppressing Decoherence in Quantum State Transfer with Unitary Operations

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, 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 to be useful for analyzing capabilities of quantum information processing devices in transmitting known quantum states. We also demonstrate the 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.

Automated summary

Decoherence is a fundamental obstacle in quantum information processing devices. This study focuses on the problem of transmitting quantum states from one place to another and proposes a method using unitary operations to protect quantum states against decoherence. The approach is shown to be effective in both theoretical and real experiments, suggesting its usefulness in analyzing the capabilities of quantum information processing devices. The study also demonstrates how the approach can be applied to suppress decoherence in distributing quantum states over remote physical qubits.