Multiple-time Quantum Imaginary Time Evolution

arXiv (Cornell University)

Abstract

Quantum Imaginary-Time Evolution (QITE) is a powerful method for preparing ground states on quantum hardware. However, executing QITE has costly measurement budgets for general Hamiltonians. Both fidelity and computational cost are strongly dependent on the definition of suitable local domains and Hamiltonian partitions. In this work, we introduce the Multiple-Time QITE algorithm (MT-QITE). We show how using more than one imaginary time substantially improves the fidelity of the resulting ground state as well as the measurement overhead with respect to the previously published QITE algorithm, while preserving its deterministic character and its independence from ad hoc ansatze. Moreover, unlike QITE and other QITE-based algorithms, MT-QITE is parallelizable, and we show that even in Hamiltonians with non-local interactions, partitioning may entail a computational advantage.

Authors 3

1. Julio Del Castillo
2. Mats Granath

   University of Gothenburg

   Affiliation as printed

   Department of Physics , University of Gothenburg , Sweden

3. Evert van Nieuwenburg Aachen Leiden Institute of Advanced Computer Science at Leiden Institute of Physics and

   Leiden University

   Affiliation as printed

   Leiden Institute of Advanced Computer Science , Leiden University , The Netherlands

   at Leiden Institute of Physics and the