Exponential optimization of adiabatic quantum-state preparation

TL;DR

This paper introduces an exponential optimization method for adiabatic quantum-state preparation, significantly reducing the required time and improving efficiency for quantum simulations on near-term quantum processors.

Contribution

The authors derive an explicit formula for the adiabatic evolution time and develop a preconditioning technique that exponentially accelerates quantum state preparation.

Findings

Reduced adiabatic preparation time by exponential factor

Validated method through numerical experiments on spin models

Potential for efficient quantum simulations on near-term devices

Abstract

The preparation of a given quantum state on a quantum computing register is a typically demanding operation, requiring a number of elementary gates that scales exponentially with the size of the problem. Using the adiabatic theorem for state preparation, whose error decreases exponentially as a function of the preparation time, we derive an explicit analytic expression for the dependence of the characteristic time on the Hamiltonian used in the adiabatic evolution. Exploiting this knowledge, we then design a preconditioning term that modifies the adiabatic preparation, thus reducing its characteristic time and hence giving an exponential advantage in state preparation. We prove the efficiency of our method with extensive numerical experiments on prototypical spin-models, which gives a promising strategy to perform quantum simulations of manybody models via Trotter evolution on near-term quantum processors.