Measurement of a Vacuum-Induced Geometric Phase

TL;DR

This paper demonstrates the experimental observation of a vacuum-induced Berry phase in a superconducting transmon coupled to a microwave cavity, revealing new ways to manipulate quantum systems for information processing.

Contribution

It reports the first measurement of a vacuum-induced geometric phase in an artificial atom-cavity system, expanding understanding of geometric phases in quantum mechanics.

Findings

Observation of vacuum-induced Berry phase in a superconducting transmon.

Control of the geometric phase via interaction phase variation.

Implications for quantum information processing applications.

Abstract

Berry's geometric phase naturally appears when a quantum system is driven by an external field whose parameters are slowly and cyclically changed. A variation in the coupling between the system and the external field can also give rise to a geometric phase, even when the field is in the vacuum state or any other Fock state. Here we demonstrate the appearance of a vacuum-induced Berry phase in an artificial atom, a superconducting transmon, interacting with a single mode of a microwave cavity. As we vary the phase of the interaction, the artificial atom acquires a geometric phase determined by the path traced out in the combined Hilbert space of the atom and the quantum field. Our ability to control this phase opens new possibilities for the geometric manipulation of atom-cavity systems also in the context of quantum information processing.