Pancharatnam\u2013Berry phase in condensate of indirect excitons

J R Leonard,L V Butov,K L Campman,A A High,A C Gossard,A T Hammack,M M Fogler

doi:10.1038/s41467-018-04667-x

Abstract

The Pancharatnam–Berry phase is a geometric phase acquired over a cycle of parameters in the Hamiltonian governing the evolution of the system. Here, we report on the observation of the Pancharatnam–Berry phase in a condensate of indirect excitons (IXs) in a GaAs-coupled quantum well structure. The Pancharatnam–Berry phase is directly measured by detecting phase shifts of interference fringes in IX interference patterns. Correlations are found between the phase shifts, polarization pattern of IX emission, and onset of IX spontaneous coherence. The evolving Pancharatnam–Berry phase is acquired due to coherent spin precession in IX condensate and is observed with no decay over lengths exceeding 10 μm indicating long-range coherent spin transport.

Highlights

The Pancharatnam–Berry phase is a geometric phase acquired over a cycle of parameters in the Hamiltonian governing the evolution of the system
Emission measured by shift-interferometry: The emission images produced by each of the two arms of the Mach–Zehnder interferometer are shifted with respect to each other to measure the interference between the emission of indirect excitons (IXs) separated by δr in the coupled quantum well (CQW) plane (Supplementary Note 3)
The experiment shows that the phase shifts correlate with the polarization pattern of IX emission and onset of IX spontaneous coherence

Summary

Introduction

The Pancharatnam–Berry phase is a geometric phase acquired over a cycle of parameters in the Hamiltonian governing the evolution of the system. We explore LBS to uncover the Pancharatnam–Berry phase in a condensate of IXs. Experiment.

Results

Conclusion