Quantum simulation of a system with competing two- and three-body interactions

TL;DR

This paper experimentally simulates a quantum system with competing one-, two-, and three-body interactions, observing quantum phase transitions and entanglement changes using an NMR quantum simulator.

Contribution

It demonstrates the first experimental simulation of a system with multiple competing interactions and observes quantum phase transitions between different ground states.

Findings

Different ground states identified via correlations and entanglement witnesses.

Quantum phase transitions observed by adiabatically tuning interaction strengths.

Genuine tripartite entanglement detected in the system.

Abstract

Quantum phase transitions occur at zero temperature, when the ground state of a Hamiltonian undergoes a qualitative change as a function of a control parameter. We consider a particularly interesting system with competing one-, two- and three-body interactions. Depending on the relative strength of these interactions, the ground state of the system can be a product state, or it can exhibit genuine tripartite entanglement. We experimentally simulate such a system in an NMR quantum simulator and observe the different ground states. By adiabatically changing the strength of one coupling constant, we push the system from one ground state to a qualitatively different ground state. We show that these ground states can be distinguished and the transitions between them observed by measuring correlations between the spins or the expectation values of suitable entanglement witnesses.