Entanglement between light and an optical atomic excitation

A. Kuzmich

Truly functional quantum networks can be based on entanglement between light fields and optical collective excitations of an ultra-cold atomic gas created by deterministic Rydberg-level atomic interactions. Ultra-cold atoms are confined in an optical lattice with the same trapping potential for both the ground and the Rydberg atomic levels. The achieved separation of the external and internal atomic degrees of freedom is employed to entangle an optical atomic coherence and a light wavepacket, unconditionally, a priori, paving the way for the truly functional quantum networks.

Bouwmeester

Edwin Pedrozo-Peñafiel, Simone Colombo, Chi Shu +8 more

R. G. Dall, Sean S. Hodgman, Andrew Manning +1 more

In direct analogy to the textbook example of light guided in a few-mode fiber (FMF), we report the observation of the first excited mode of an optically guided atomic beam. We selectively excite the atomic analog of the LP₀₁ optical mode by controlling the energy distribution of ultracold atoms loaded into the guide, resulting in a modal structure dominated by a 47(2)% population in the first excited transverse mode. The ability to guide lower-order modes has been essential to demonstrating optical effects such as multimode interferometry, slow light, and entanglement, and an atomic analog to a FMF may lead to similarly useful applications.

David S. Simon, Gregg S. Jaeger, Alexander V. Sergienko

Giovanna Morigi, Jürgen Eschner, Stefano Mancini +1 more

The coherent interaction between a laser-driven single trapped atom and an optical high-finesse resonator allows one to produce entangled multiphoton light pulses on demand. The mechanism is based on the mechanical effect of light. The degree of entanglement can be controlled through the parameters of the laser excitation. Experimental realization of the scheme is within reach of current technology. A variation of the technique allows for controlled generation of entangled subsequent pulses, with the atomic motion serving as intermediate memory of the quantum state.