Cavity-Modified Collective Rayleigh Scattering of Two Atoms

Abstract

We report on the observation of cooperative radiation of exactly two neutral atoms strongly coupled to the single mode field of an optical cavity, which is close to the lossless-cavity limit. Monitoring the cavity output power, we observe constructive and destructive interference of collective Rayleigh scattering for certain relative distances between the two atoms. Because of cavity backaction onto the atoms, the cavity output power for the constructive two-atom case (N=2) is almost equal to the single-emitter case (N=1), which is in contrast to free-space where one would expect an N^{2} scaling of the power. These effects are quantitatively explained by a classical model as well as by a quantum mechanical model based on Dicke states. We extract information on the relative phases of the light fields at the atom positions and employ advanced cooling to reduce the jump rate between the constructive and destructive atom configurations. Thereby we improve the control over the system to a level where the implementation of two-atom entanglement schemes involving optical cavities becomes realistic.

Unambiguous atomic Bell measurement assisted by multiphoton states

“…Nevertheless, it is an unambiguous protocol as there are four successful events that lead to postselection of four different Bell states. The scheme is based on basic properties of the two-atom TavisCummings model [26] and on resonant matter-field interactions which are already under experimental investigation [27,28,29,30]. These considerations make our scheme compatible with a quantum repeater or a quantum relay based on coherent multiphoton states, atomic qubits and resonant matter-field interaction.…”

“…(11) The quantity α − τ |α is evaluated in Appendix B and an approximate expression is given in Eq. (29).…”

“…This could be realized, for instance, by transporting and positioning the atomic qubits in separate cavities. Current experimental realizations report coherent transport and controlled positioning of neutral atoms in optical cavities [29,30,42,43], where a dipole trap is used as a conveyor belt to displace them. Two trapped ions have also been reported to be coupled in a controlled way to an optical resonator [27,28].…”

Manipulating nanoscale atom–atom interactions with cavity QED

“…In general,there is a possibility of cavity-photon mediated long-range interaction [9,10,11,12,13,14,15] between atoms. This occurs due to transitions at a singleatom level.…”

Multiphoton-state-assisted entanglement purification of material qubits

“…The proposed scheme can be already implemented in a one-atom maser setup. However, other implementations may include condensed-matter qubits which are coupled to single-mode radiation fields [41], trapped ions inside a cavity [42], and neutral atoms coherently transported into an optical resonator [43].…”