Quantum Catalysis of Magnetic Phase Transitions in a Quantum Simulator

TL;DR

This study demonstrates the use of quantum fluctuations to induce and observe magnetic phase transitions in a small quantum simulator, revealing complex fractal structures related to many-body problems.

Contribution

It introduces a method to control quantum fluctuations in a small ion spin system to explore magnetic phases and phase transitions, including the emergence of a fractal devil's staircase.

Findings

Observation of multiple first-order phase transitions

Mapping of the devil's staircase in a quantum simulator

Quantum catalyst enables exploration of complex phase structures

Abstract

We control quantum fluctuations to create the ground state magnetic phases of a classical Ising model with a tunable longitudinal magnetic field using a system of 6 to 10 atomic ion spins. Due to the long-range Ising interactions, the various ground state spin configurations are separated by multiple first-order phase transitions, which in our zero temperature system cannot be driven by thermal fluctuations. We instead use a transverse magnetic field as a quantum catalyst to observe the first steps of the complete fractal devil's staircase, which emerges in the thermodynamic limit and can be mapped to a large number of many-body and energy-optimization problems.