Variational Quantum Circuit Decoupling

TL;DR

This paper introduces a variational decoupling algorithm for quantum systems that decomposes complex unitary dynamics into independent parts, improving quantum circuit synthesis for multi-qubit gates.

Contribution

It presents a novel variational decoupling method for unitary quantum dynamics, enhancing the synthesis of multi-qubit quantum circuits beyond conventional approaches.

Findings

Enables decomposition of $n$-qubit unitaries into independent components.

Achieves higher fidelity in synthesizing 2- and 4-qubit gates.

Demonstrates advantages over traditional variational circuits.

Abstract

Decoupling systems into independently evolving components has a long history of simplifying seemingly complex systems. They enable a better understanding of the underlying dynamics and causal structures while providing more efficient means to simulate such processes on a computer. Here we outline a variational decoupling algorithm for decoupling unitary quantum dynamics -- allowing us to decompose a given $n$-qubit unitary gate into multiple independently evolving sub-components. We apply this approach to quantum circuit synthesis - the task of discovering quantum circuit implementations of target unitary dynamics. Our numerical studies illustrate significant benefits, showing that variational decoupling enables us to synthesize general $2$ and $4$-qubit gates to fidelity that conventional variational circuits cannot reach.