Photon-Mediated Quantum Gate between Two Neutral Atoms in an Optical Cavity

Abstract

Quantum logic gates are fundamental building blocks of quantum computers. Their integration into quantum networks requires strong qubit coupling to network channels, as can be realized with neutral atoms and optical photons in cavity quantum electrodynamics. Here we demonstrate that the long-range interaction mediated by a flying photon performs a gate between two stationary atoms inside an optical cavity from which the photon is reflected. This single step executes the gate in 2 µs. We show an entangling operation between the two atoms by generating a Bell state with 76(2)% fidelity. The gate also operates as a CNOT. We demonstrate 74.1(1.6)% overlap between the observed and the ideal gate output, limited by the state preparation fidelity of 80.2(0.8)%. As the atoms are efficiently connected to a photonic channel, our gate paves the way towards quantum networking with multiqubit nodes and the distribution of entanglement in repeater-based long-distance quantum networks.

Optical Interferometry with Quantum Networks

“…We hope that our application further motivates such development of quantum networks. [51], which is on par with that of the Rb-cavity system used to demonstrate atom-photon gates [44] and two-qubit gates [45]. 4 Using proximal 13 C nucleus [50,52].…”

Pulsed atom-mechanical quantum non-demolition gate

“…7 Right now this direction is rapidly developing. Establishing quantum entanglement between atoms and another object or just between different atomic ensembles is the most common task close to experimental realization, [8][9][10][11] but solid-state systems are becoming competitive. 12 Works on hybrid mechanics include a wide range of studies like coupling with other systems, e.g.…”

“…[37][38][39] In addition, techniques to change the time profile of squeezed light while maintaining the squeezing magnitude are being developed. 40 After establishing quantum gates between atoms, 11,41 hybrid gates with other platforms become the next target. In the future, the possibility to achieve a fundamentally different type of interaction between atoms and mechanics is much more inspiring.…”

Making Diamond Qubits Talk to Light

“…The prevailing strategy for engineering an efficient, coherent optical interface is that of cavity quantum electrodynamics (QED), which enhances the interactions between atomic quantum memories and photons [6][7][8][9][10]. Nanophotonic cavity QED systems are particularly appealing, as the tight confinement of light inside optical nanostructures enables strong, high-bandwidth qubit-photon interactions [11][12][13].…”