# Completely scrambled memory for quantum superposition

## TL;DR

This paper introduces a scheme for quantum memory that achieves complete scrambling and descrambling of quantum superpositions in atomic ensembles, enhancing security and fidelity without additional interferometers.

## Contribution

The authors propose and demonstrate a novel method to achieve 100% phase ambiguity in quantum memory, improving security and fidelity over previous partial scrambling techniques.

## Key findings

- Achieved 100% phase ambiguity in quantum superposition memory.
- Demonstrated secure information encoding without falsification.
- Enhanced quantum memory security and fidelity.

## Abstract

Although constructing a quantum computation device with multiple qubits is arguably a difficult task, several seconds of coherence time with tens of thousands of quantum particles has been demonstrated with a trapped atomic ensemble. As a practical application, a security-enhanced quantum state memory using atoms has been demonstrated. It was shown that the quantum superposition preserved in an atomic ensemble was scrambled and faithfully descrambled; however, the scrambled phase ambiguity remained at 50 %. To overcome this problem, we propose and demonstrate a scheme that achieves 100 % phase ambiguity without introducing an extra Ramsey interferometer. Moreover, this scheme can be used as a direct application to keep the choice between two values secret without falsification.