# Nuclear quantum memory and time sequencing of a single $\gamma$ photon

## TL;DR

This paper proposes a novel gamma-ray quantum memory using a Doppler frequency comb in nuclear ensembles, enabling reliable storage and time sequencing of single gamma photons, opening new avenues in quantum information science.

## Contribution

It introduces the first gamma-photon-nuclear-ensemble interface utilizing a Doppler frequency comb for quantum memory and photon time sequencing.

## Key findings

- Demonstrates a reliable gamma photon storage method.
- Enables on-demand gamma photon generation.
- Provides a technique for gamma photon time sequencing.

## Abstract

A $\gamma$-ray-nuclear quantum interface is suggested as a new platform for quantum information processing, motivated by remarkable progresses in $\gamma$-ray quantum optics. The main advantages of a $\gamma$ photon over an optical photon lie in its almost perfect detectability and much tighter, potentially sub-angstrom, focusability. Nuclear ensembles hold important advantages over atomic ensembles in a unique combination of high nuclear density in bulk solids with narrow, lifetime-broadening M\"ossbauer transitions even at room temperature. This may lead to the densest long-lived quantum memories and the smallest size photon processors. Here we propose a technique for $\gamma$ photon quantum memory through a Doppler frequency comb, produced by a set of resonantly absorbing nuclear targets that move with different velocities. It provides a reliable storage, an on-demand generation, and a time sequencing of a single $\gamma$ photon. This scheme presents the first $\gamma$-photon-nuclear-ensemble interface opening a new direction of research in quantum information science.