A Comparison of Three Ways to Measure Time-Dependent Densities With Quantum Simulators

Frontiers in Physics

Jun Yang¹  James Brown¹  James Daniel Whitfield² 

[1] Department of Physics and Astronomy, Dartmouth College, Hanover, NH, United States;null;

关键词: quantum measurement;    TDDFT;    Bayesian inference;    harmonic inversion;    potential inversion;   

DOI  :  10.3389/fphy.2021.546538

来源: Frontiers

【 摘 要 】

Quantum algorithms are touted as a way around some classically intractable problems such as the simulation of quantum mechanics. At the end of all quantum algorithms is a quantum measurement whereby classical data is extracted and utilized. In fact, many of the modern hybrid-classical approaches are essentially quantum measurements of states with short quantum circuit descriptions. Here, we compare and examine three methods of extracting the time-dependent one-particle probability density from a quantum simulation: direct Z-measurement, Bayesian phase estimation, and harmonic inversion. We have tested these methods in the context of the potential inversion problem of time-dependent density functional theory. Our test results suggest that direct measurement is the preferable method. We also highlight areas where the other two methods may be useful and report on tests using Rigetti's quantum virtual device. This study provides a starting point for imminent applications of quantum computing.

【 授权许可】

CC BY