A Single Photon Can Simultaneously Excite Two or More Atoms

TL;DR

This paper demonstrates that a single photon can coherently and reversibly excite two or more atoms simultaneously via a resonant coupling mediated by virtual states, with potential applications in quantum information processing.

Contribution

It reveals a novel resonant mechanism allowing one photon to excite multiple atoms simultaneously, extending quantum Rabi oscillations to multi-atom systems in circuit QED.

Findings

One photon can excite two atoms with high probability.

The process is coherent and reversible, enabling joint emission.

Experimental parameters are feasible in circuit QED systems.

Abstract

We consider two separate atoms interacting with a single-mode optical resonator. When the frequency of the resonator field is twice the atomic transition frequency, we show that there exists a resonant coupling between \textit{one} photon and \textit{two} atoms, via intermediate virtual states connected by counter-rotating processes. If the resonator is prepared in its one-photon state, the photon can be jointly absorbed by the two atoms in their ground state which will both reach their excited state with probability close to one. Like ordinary quantum Rabi oscillations, this process is coherent and reversible, so that two atoms in their excited state will undergo a downward transition jointly emitting a single cavity photon. This joint absorption and emission processes can also occur with three atoms. The parameters used to investigate this process correspond to experimentally demonstrated values in circuit quantum electrodynamics systems.