The big challenge in quantum computing is to realize scalable multi-qubit systems with cross-talk free addressability and efficient coupling of arbitrarily selected qubits. Quantum networks promise a solution by integrating smaller qubit modules to a larger computing cluster. Such a distributed architecture, however, requires the capability to execute quantum-logic gates between distant qubits. Here we experimentally realize such a gate over a distance of 60m. We employ an ancillary photon that we successively reflect from two remote qubit modules, followed by a heralding photon detection which triggers a final qubit rotation. We use the gate for remote entanglement creation of all four Bell states. Our non-local quantum-logic gate could be extended both to multiple qubits and many modules for a tailor-made multi-qubit computing register.
@article{arxiv.2103.13095,
title = {A Quantum-Logic Gate between Distant Quantum-Network Modules},
author = {Severin Daiss and Stefan Langenfeld and Stephan Welte and Emanuele Distante and Philip Thomas and Lukas Hartung and Olivier Morin and Gerhard Rempe},
journal= {arXiv preprint arXiv:2103.13095},
year = {2021}
}