# Experimentally feasible protocol for semiquantum key distribution

## TL;DR

This paper introduces a new semiquantum key distribution protocol that is experimentally feasible with current technology, using 4-level systems instead of qubits, and proves its robustness.

## Contribution

A novel SQKD protocol using 4-level systems that can be practically implemented and is proven to be robust.

## Key findings

- Protocol is experimentally feasible with current technology.
- The protocol is proven to be robust.
- Uses 4-level systems instead of qubits.

## Abstract

Quantum key distribution (QKD) protocols make it possible for two quantum parties to generate a secret shared key. Semiquantum key distribution (SQKD) protocols, such as "QKD with classical Bob" and "QKD with classical Alice" (that have both been proven robust), achieve this goal even if one of the parties is classical. However, existing SQKD protocols are not experimentally feasible with current technology. Here we suggest a new protocol, "Classical Alice with a controllable mirror", that can be experimentally implemented with current technology (using 4-level systems instead of qubits), and we prove it to be robust.