Non-local synchronization of continuous time crystals in a semiconductor

TL;DR

This paper demonstrates long-range synchronization of auto-oscillating spin systems in a semiconductor, revealing spin transport as the coupling mechanism and enabling stable, collective auto-oscillations over mesoscopic distances.

Contribution

It presents the first observation of non-local synchronization in solid-state spin systems, linking spin transport to phase coherence over mesoscopic scales.

Findings

Synchronization occurs over distances up to 40 μm.

Spin transport mediates the coupling between oscillators.

Synchronization enhances stability of auto-oscillations.

Abstract

Synchronization resulting in unified collective behavior of the individual elements of a system that are weakly coupled to each other has long fascinated scientists. Examples range from the periodic oscillation of coupled pendulum clocks to the rhythmic behavior in biological systems. Here we demonstrate this effect in a solid-state platform: spatially remote, auto-oscillating electron-nuclear spin systems in a semiconductor. When two such oscillators separated by up to 40 ${\mu}$m are optically pumped, their individually different frequencies lock to a common value, revealing long-range coherent coupling. For larger separations, the synchronization breaks. The interaction distance matches the electron spin diffusion length, identifying spin transport as the coupling-mediating mechanism and establishing phase coherence over mesoscopic distances. As a consequence, a wide-area optical pump drives all oscillators within the illuminated spot into a single synchronized state, despite their inhomogeneity. This synchronization accounts for the exceptional stability of the resulting auto-oscillations, enabling collective motion in distributed spin systems and paving the way toward coherent spin networks in spintronics.