# Spatial spin-wave modulator for quantum memory assisted adaptive measurements

## TL;DR

This paper demonstrates a novel spatially varying ac-Stark effect technique to perform arbitrary phase modulation of spin-wave states in quantum memory, enabling adaptive measurements and high-dimensional information processing.

## Contribution

It introduces a flexible method for spatial phase modulation of spin-waves in quantum memory, enhancing high-dimensional quantum information processing capabilities.

## Key findings

- Successful arbitrary 1D phase modulation of spin-waves.
- Far-field and near-field phase profile characterizations.
- Demonstration of coherence between separated partial readouts.

## Abstract

Utilization of the spatial degree of freedom vastly enhances informational capacity of light at the cost of stringent requirements on the processing devices. Multi-mode quantum memories constitute a viable candidate for quantum and classical information processing; however, full utilization of the assets of high-dimensionality requires a flexible processing technique. We employ a spatially varying ac-Stark effect to perform arbitrary 1D phase modulation of a coherent spin-wave state stored in a wavevector-multiplexed quantum memory. A far-field and an interferometric near-field characterizations of the introduced phase profiles are presented. Additionally, coherence between temporally separated partial readouts of a single coherent spin-wave state is demonstrated, offering possible applications in adaptive measurements via conditional spin-wave modulation.