Experimental Observation of a Generalized Thouless Pump with a Single Spin

TL;DR

This paper reports the experimental realization of a generalized Thouless pump using a single spin in diamond, demonstrating continuous control and highlighting the role of interband coherence in topological charge transport.

Contribution

It introduces the first experimental observation of a generalized Thouless pump enabled by interband coherence, extending the classical topological pump concept.

Findings

Demonstrated a controllable generalized Thouless pump in a single spin system

Showed the pump's sensitivity to band-touching points for detecting phase transitions

Validated the role of quantum superposition in topological charge transport

Abstract

Adiabatic cyclic modulation of a one-dimensional periodic potential will result in quantized charge transport, which is termed the Thouless pump. In contrast to the original Thouless pump restricted by the topology of the energy band, here we experimentally observe a generalized Thouless pump that can be extensively and continuously controlled. The extraordinary features of the new pump originate from interband coherence in nonequilibrium initial states, and this fact indicates that a quantum superposition of different eigenstates individually undergoing quantum adiabatic following can also be an important ingredient unavailable in classical physics. The quantum simulation of this generalized Thouless pump in a two-band insulator is achieved by applying delicate control fields to a single spin in diamond. The experimental results demonstrate all principal characteristics of the generalized Thouless pump. Because the pumping in our system is most pronounced around a band-touching point, this work also suggests an alternative means to detect quantum or topological phase transitions.