Many-body spin rotation by adiabatic passage in spin-1/2 XXZ chains of ultracold atoms

TL;DR

This paper demonstrates a protocol for adiabatically transforming a fully magnetized state into a correlated zero-magnetization state in ultracold atom systems, revealing insights into many-body quantum state preparation.

Contribution

It introduces a microwave sweep protocol to realize many-body spin rotation in ultracold atoms, showing partial magnetization restoration and highlighting challenges in adiabatic state preparation.

Findings

Restored up to 50% of original magnetization

Correlations formed during the adiabatic sweep

Limitations due to many-body gap and technical noise

Abstract

Quantum many-body phases offer unique properties and emergent phenomena, making them an active area of research. A promising approach for their experimental realization in model systems is to adiabatically follow the ground state of a quantum Hamiltonian from a product state of isolated particles to one that is strongly-correlated. Such protocols are relevant also more broadly in coherent quantum annealing and adiabatic quantum computing. Here we explore one such protocol in a system of ultracold atoms in an optical lattice. A fully magnetized state is connected to a correlated zero-magnetization state (an xy-ferromagnet) by a many-body spin rotation, realized by sweeping the detuning and power of a microwave field. The efficiency is characterized by applying a reverse sweep with a variable relative phase. We restore up to 50% of the original magnetization independent of the relative phase, evidence for the formation of correlations. The protocol is limited by the many-body gap of the final state, which is inversely proportional to system size, and technical noise. Our experimental and theoretical studies highlight the potential and challenges for adiabatic preparation protocols to prepare many-body eigenstates of spin Hamiltonians.