Linear-Optical Generation of Eigenstates of the Two-SiteXYModel

Stefanie Barz,James D Whitfield,Borivoje Dakić,Frank Verstraete,Yannick Ole Lipp,Philip Walther

doi:10.1103/physrevx.5.021010

Abstract

Much of the anticipation accompanying the development of a quantum computer relates to its application to simulating dynamics of another quantum system of interest. Here we study the building blocks for simulating quantum spin systems with linear optics. We experimentally generate the eigenstates of the XY Hamiltonian under an external magnetic field. The implemented quantum circuit consists of two CNOT gates, which are realized experimentally by harnessing entanglement from a photon source and by applying a CPhase gate. We tune the ratio of coupling constants and magnetic field by changing local parameters. This implementation of the XY model using linear quantum optics might open the door to the future studies of quenching dynamics using linear optics.

Highlights

In 1982, Feynman proposed the idea for the efficient simulation of quantum systems [1]
Bell states can naturally be obtained by exploiting the entanglement of a spontaneous parametric downconversion (SPDC) source
We demonstrate the preparation of the eigenstates for the XY Hamiltonian under an external magnetic field

Summary

Introduction

In 1982, Feynman proposed the idea for the efficient simulation of quantum systems [1]. Complex systems, whose properties cannot be computed with classical computers, can be simulated by other well-controllable quantum systems In this way, an accessible system can be used for reproducing the dynamics and the quantum state of another system of study. The effect of the unitary evolution of a quantum system may be regarded as that of a quantum circuit acting on some initial state. This inspires the approach of a digital quantum simulator where the state of the system is encoded into qubits and processed via quantum logic gates [4,5,6,7]. Basic quantum simulations of both types have been demonstrated as proof-of-concept

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Conclusion