Topological Burning Glass Effect

TL;DR

This paper introduces the topological burning glass effect, where a central spin's response exhibits enhanced topological quantization due to environmental coupling, demonstrated through driven spin systems.

Contribution

It reveals a novel topological phenomenon in driven spin systems, showing how environmental coupling can amplify topological responses in a central spin model.

Findings

Central spin exhibits N-fold enhanced topological frequency conversion.

The effect is driven by non-unitary dynamics and collective motion of surrounding spins.

Results are supported by adiabatic perturbation theory and numerical simulations.

Abstract

We reveal a topological burning glass effect, where the local response of a system exhibits a topological quantization that is enhanced by an integer due to its environmental coupling. As a paradigmatic platform for this intriguing phenomenon, we study a central spin that is quasiperiodically driven by two incommensurate frequencies, and statically coupled to $N-1$ surrounding spins. In the strong coupling regime, the adiabatic dynamics of the total system is readily understood to imprint on the central spin an $N$-fold enhanced topological frequency conversion between the two driving frequencies. We argue that the topological burning glass effect is induced by the non-unitary dynamics of the central spin, which locally involves the collective motion of the surrounding spins. Our results are derived in the framework of adiabatic perturbation theory and fully corroborated by exact numerical simulations.