Many-body interferometry with semiconductor spins

TL;DR

This paper demonstrates spectroscopy of up to eight interacting spins in germanium quantum dots, revealing a transition from localization to chaos, advancing the study of many-body phenomena in semiconductor spin systems.

Contribution

It introduces a spectroscopy protocol for many-body eigenstates in quantum dot arrays, enabling energy spectrum reconstruction and observation of many-body phase crossover.

Findings

Spectroscopy of up to eight spins in germanium quantum dots achieved.

Observation of the crossover from localization to a chaotic phase.

Complete energy spectrum reconstruction of many-body eigenstates.

Abstract

Quantum simulators enable studies of many-body phenomena which are intractable with classical hardware. Spins in devices based on semiconductor quantum dots promise precise electrical control and scalability advantages, but accessing many-body phenomena has so far been restricted by challenges in nanofabrication and simultaneous control of multiple interactions. Here, we perform spectroscopy of up to eight interacting spins using a 2x4 array of gate-defined germanium quantum dots. The spectroscopy protocol is based on Ramsey interferometry and adiabatic mapping of many-body eigenstates to single-spin eigenstates, enabling a complete energy spectrum reconstruction. As the interaction strength exceeds magnetic disorder, we observe signatures of the crossover from localization to a chaotic phase marking a step towards the observation of many-body phenomena in quantum dot systems.