Interference and dynamics of light from a distance-controlled atom pair in an optical cavity

Abstract

Interference is central to quantum physics and occurs when indistinguishable paths exist, like in a double-slit experiment. Replacing the two slits with two single atoms 1 introduces optical nonlinearities for which nontrivial interference phenomena are predicted [2][3][4][5][6] . Their observation, however, has been hampered by difficulties in preparing the required atomic distribution, controlling the optical phases and detecting the faint light. Here we overcome all of these experimental challenges by combining an optical lattice for atom localisation, an imaging system with single-site resolution, and an optical resonator for light steering. We observe resonator-induced saturation of resonance fluorescence 7,8 for constructive interference of the scattered light and nonzero emission with huge photon bunching for destructive interference. The latter is explained by atomic saturation and photon pair generation 3-5 . Our experimental setting is scalable and allows one to realize the Tavis-Cummings model 9 for any number of atoms and photons, explore fundamental aspects of light-matter interaction 10-14 , and implement new quantum information processing protocols [15][16][17][18] .A multitude of non-classical radiation effects like photon antibunching 19 and squeezing 20 were predicted in the resonance fluorescence of single quantum emitters. The experimental observations of these effects 21,22 are milestones in the development of quantum optics. However, the large mismatch between the light mode driven by an emitter in free space and the light mode detected by an observer makes such quantum effects unpractical for applications. The way out is to couple the emitter to an optical resonator which enhances the interaction strength of the emitter with a tailor-made light mode. In fact, the experimental realization of well-controlled atom-cavity systems with single atoms as emitters has propelled the application potential of quantum-optical phenomena 23 enormously and, in addition, has enabled the observation of fundamentally new quantum-mechanical radiation effects induced by the cavity [24][25][26] . When scaling these single-atom systems to multiple atoms, relative optical phases appear as a new degree of freedom. As those are determined by the spatial arrangement of the atoms, both, subwavelength localisation and precise knowledge about the relative positions of the atoms, are mandatory * e-mail: stephan.ritter@mpq.mpg.de Figure 1.Experimental setup. a, A two-dimensional optical lattice is formed by a retroreflected, red-detuned 1 ○ and a blue-detuned 2 ○ laser beam in a high-finesse optical resonator 3 ○. A microscope objective 4 ○ is used to image and deterministically remove individual atoms trapped in the lattice. An atom pair is driven coherently with a running-wave beam 5 ○ propagating transversally through the resonator. Scattering from this beam into the single-sided cavity is studied via transmission through the outcoupling mirror 6 ○ as a function of the atomic positions. b, A typical fluorescence image...

Controllable and fast quantum-information transfer between distant nodes in two-dimensional networks

“…As shown above, the required time for achieving the task is smaller than photon coherence time and the atom dephasing time. In recent experiments, a set of cavity quantum electrodynamics parameters ( g , κ , γ ) = 2 π  × (7.6, 2.8, 3.0) MHz is available in an optical cavity 55–57 . Thus, based on the recent cavity QED technique or the technique to be improved soon, the proposal might be realizable in the future.…”

Measurement-induced chaos and quantum state discrimination in an iterated Tavis-Cummings scheme

“…(19). With these initial conditions, both atoms interact with the electromagnetic field inside a cavity prepared in a coherent state |α .…”

“…In view of its possibilities to measure and control the interaction of individual atoms with a single mode of the quantized radiation field with high precision, the area of cavity quantum electrodynamics offers interesting perspectives for future experimental implementations in this direction [18,19]. Inspired by recent experimental advances which realize the Tavis-Cummings model [19], in our proposal an ensemble of identically prepared two-level atoms (qubits) which interact pairwise with a single mode of the radiation field is considered. Afterwards, one member of each pair and the corresponding cavity field are measured.…”

Collective multiphoton blockade in cavity quantum electrodynamics

“…Interesting new results include the saturation of resonance fluorescence for constructive interference, bunching photon emission for destructive interference, and suppression of super radiant behavior due to strong back reaction of the cavity [24]. If the atoms feel asymmetric coupling to the cavity field while these are driven symmetrically then one can obtain very large secondorder photon-photon correlation g (2) , which has been related to the predominance of two photon processes [23]. Since cavities allow the possibility of a wide range of parameters, the two atom system can in a different parameter domain exhibit hyper-radiance which is enhanced radiation beyond super-radiance [25].…”