Measurement of geometric dephasing using a superconducting qubit

TL;DR

This paper experimentally investigates geometric dephasing in a superconducting qubit, revealing its dual role in coherence loss or restoration depending on the qubit's path in Hilbert space.

Contribution

It demonstrates that geometric dephasing occurs even in the adiabatic limit and without acquiring a geometric phase, highlighting its fundamental role in quantum coherence.

Findings

Geometric dephasing exists even without geometric phase acquisition.

Path orientation in Hilbert space influences coherence restoration or reduction.

Dephasing has both dynamic and geometric components.

Abstract

A quantum system interacting with its environment is subject to dephasing which ultimately destroys the information it holds. Using a superconducting qubit, we experimentally show that this dephasing has both dynamic and geometric origins. It is found that geometric dephasing, which is present even in the adiabatic limit and when no geometric phase is acquired, can either reduce or restore coherence depending on the orientation of the path the qubit traces out in its projective Hilbert space. It accompanies the evolution of any system in Hilbert space subjected to noise.