Practical Subarchitectures for Optimal Quantum Layout Synthesis

TL;DR

This paper presents a method to efficiently identify relevant subarchitectures for optimal quantum layout synthesis, reducing computational complexity while guaranteeing optimality within a fixed ancilla qubit limit.

Contribution

It introduces a novel enumeration technique for subarchitectures that enhances optimal quantum layout synthesis by reducing the search space and computational effort.

Findings

Significant reduction in subarchitecture enumeration time.

Improved performance over state-of-the-art tools.

Guarantees optimal layouts within ancilla qubit constraints.

Abstract

Quantum Layout Synthesis (QLS) maps a logical quantum circuit to a physical quantum platform. Optimal QLS minimizes circuit size and depth, which is essential to reduce the noise on current quantum platforms. Optimal QLS is an NP-hard problem, so in practice, one maps a quantum circuit to a subset of the complete quantum platform. However, to guarantee optimality, one still has to consider exponentially many subarchitectures. We introduce an effective method to enumerate relevant subarchitectures. This reduces the number of considered subarchitectures, as well as the number of expensive subgraph isomorphism checks, thus boosting Optimal QLS with subarchitectures. To do so, we assume a fixed number of ancilla qubits that can be used in the mapping. We guarantee optimality of the quantum layout, for the selected ancilla bound. We evaluate our technique on a number of benchmarks and compare it with state-of-the-art Optimal QLS tools with and without using subarchitectures.