Quantum State Preparation Using an Exact CNOT Synthesis Formulation

TL;DR

This paper introduces an exact CNOT synthesis algorithm for quantum state preparation that significantly reduces CNOT gate counts, surpassing manual designs and improving efficiency for states up to 20 qubits.

Contribution

It presents the first automated design method for CNOT optimization that outperforms manual approaches and existing algorithms in preparing complex quantum states.

Findings

Reduces CNOT gates for Dicke states by 2x.

Achieves 9% and 32% average reduction for dense and sparse states.

Surpasses previous algorithms in CNOT optimization for up to 20 qubits.

Abstract

Minimizing the use of CNOT gates in quantum state preparation is a crucial step in quantum compilation, as they introduce coupling constraints and more noise than single-qubit gates. Reducing the number of CNOT gates can lead to more efficient and accurate quantum computations. However, the lack of compatibility to model superposition and entanglement challenges the scalability and optimality of CNOT optimization algorithms on classical computers. In this paper, we propose an effective state preparation algorithm using an exact CNOT synthesis formulation. Our method represents a milestone as the first design automation algorithm to surpass manual design, reducing the best CNOT numbers to prepare a Dicke state by 2x. For general states with up to 20 qubits, our method reduces the CNOT number by 9% and 32% for dense and sparse states, on average, compared to the latest algorithms.