Efficient quantum algorithm for computing n-time correlation functions

Phys Rev Lett. 2014 Jul 11;113(2):020505. doi: 10.1103/PhysRevLett.113.020505. Epub 2014 Jul 10.

Abstract

We propose a method for computing n-time correlation functions of arbitrary spinorial, fermionic, and bosonic operators, consisting of an efficient quantum algorithm that encodes these correlations in an initially added ancillary qubit for probe and control tasks. For spinorial and fermionic systems, the reconstruction of arbitrary n-time correlation functions requires the measurement of two ancilla observables, while for bosonic variables time derivatives of the same observables are needed. Finally, we provide examples applicable to different quantum platforms in the frame of the linear response theory.