Efficient compilation of quantum circuits using multi-qubit gates

TL;DR

This paper introduces a quantum circuit compilation method that replaces many two-qubit gates with fewer multi-qubit gates, improving implementation fidelity and quantum volume in systems with long-range connectivity.

Contribution

The authors propose a novel compilation scheme that efficiently decomposes quantum circuits into multi-qubit entangling gates, reducing gate count and enhancing fidelity compared to traditional methods.

Findings

Replaces $3N^2/2$ two-qubit gates with $2N+1$ multi-qubit gates.

Improves the logarithm of quantum volume by 20-25%.

Applicable to systems with connectivity beyond nearest neighbors.

Abstract

As quantum processors grow in scale and reliability, the need for efficient quantum gate decomposition of circuits to a set of specific available gates, becomes ever more critical. The decomposition of a particular algorithm into a sequence of these available gates is not unique. Thus, the fidelity of an algorithm's implementation can be increased by choosing an optimized decomposition. This is true both for noisy intermediate-scale quantum platforms as well as for implementation of quantum error correction schemes. Here we present a compilation scheme which implements a general-circuit decomposition to a sequence of Ising-type, long-range, multi-qubit entangling gates, that are separated by layers of single qubit rotations. We use trapped ions as an example in which multi-qubit gates naturally arise, yet any system that has connectivity beyond nearest-neighbors may gain from our approach. We evaluate our methods using the quantum volume test over $N$ qubits. In this context, our method replaces $3N^2/2$ two-qubit gates with $2N+1$ multi-qubit gates. Furthermore, our method minimizes the magnitude of the entanglement phases, which typically enables an improved implementation fidelity, by using weaker driving fields or faster realizations. We numerically test our compilation and show that, compared to conventional realizations with sequential two-qubit gates, our compilations improves the logarithm of quantum volume by $20\%$ to $25\%$.