Optical manipulation of Berry phase in a solid-state spin qubit

TL;DR

This paper demonstrates an all-optical method to control and measure Berry phases in a single solid-state spin qubit, specifically an NV center in diamond, using laser light to enhance spatial resolution and robustness.

Contribution

It introduces a novel optical approach for geometric phase control in solid-state qubits, enabling precise manipulation and characterization with potential for scalable quantum networks.

Findings

Successfully accumulated Berry phases using laser-driven loops on the Bloch sphere

Demonstrated robustness of geometric phase control against noise and decoherence

Identified limits due to adiabaticity loss and decoherence effects

Abstract

The phase relation between quantum states represents an essential resource for the storage and processing of quantum information. While quantum phases are commonly controlled dynamically by tuning energetic interactions, utilizing geometric phases that accumulate during cyclic evolution may offer superior robustness to noise. To date, demonstrations of geometric phase control in solid-state systems rely on microwave fields that have limited spatial resolution. Here, we demonstrate an all-optical method based on stimulated Raman adiabatic passage to accumulate a geometric phase, the Berry phase, in an individual nitrogen-vacancy (NV) center in diamond. Using diffraction-limited laser light, we guide the NV center's spin along loops on the Bloch sphere to enclose arbitrary Berry phase and characterize these trajectories through time-resolved state tomography. We investigate the limits of this control due to loss of adiabiaticity and decoherence, as well as its robustness to noise intentionally introduced into the experimental control parameters, finding its resilience to be independent of the amount of Berry phase enclosed. These techniques set the foundation for optical geometric manipulation in future implementations of photonic networks of solid state qubits linked and controlled by light.