16 research outputs found
Electromagnetically induced transparency of ultralong-range Rydberg molecules
We study the impact of Rydberg molecule formation on the storage and
retrieval of Rydberg polaritons in an ultracold atomic medium. We observe
coherent revivals appearing in the retrieval efficiency of stored photons that
originate from simultaneous excitation of Rydberg atoms and Rydberg molecules
in the system with subsequent interference between the possible storage paths.
We show that over a large range of principal quantum numbers the observed
results can be described by a two-state model including only the atomic Rydberg
state and the Rydberg dimer molecule state. At higher principal quantum numbers
the influence of polyatomic molecules becomes relevant and the dynamics of the
system undergoes a transition from coherent evolution of a few-state system to
an effective dephasing into a continuum of molecular states.Comment: Submitted to PR
Free-Space Quantum Electrodynamics with a single Rydberg superatom
The interaction of a single photon with an individual two-level system is the
textbook example of quantum electrodynamics. Achieving strong coupling in this
system so far required confinement of the light field inside resonators or
waveguides. Here, we demonstrate strong coherent coupling between a single
Rydberg superatom, consisting of thousands of atoms behaving as a single
two-level system due to the Rydberg blockade, and a propagating light pulse
containing only a few photons. The strong light-matter coupling in combination
with the direct access to the outgoing field allows us to observe for the first
time the effect of the interactions on the driving field at the single photon
level. We find that all our results are in quantitative agreement with the
predictions of the theory of a single two-level system strongly coupled to a
single quantized propagating light mode. The demonstrated coupling strength
opens the way towards interfacing photonic and atomic qubits and preparation of
propagating non-classical states of light, two crucial building blocks in
future quantum networks
Photon Subtraction by Many-Body Decoherence
We experimentally and theoretically investigate the scattering of a photonic
quantum field from another stored in a strongly interacting atomic Rydberg
ensemble. Considering the many-body limit of this problem, we derive an exact
solution to the scattering-induced spatial decoherence of multiple stored
photons, allowing for a rigorous understanding of the underlying dissipative
quantum dynamics. Combined with our experiments, this analysis reveals a
correlated coherence-protection process in which the scattering from one
excitation can shield all others from spatial decoherence. We discuss how this
effect can be used to manipulate light at the quantum level, providing a robust
mechanism for single-photon subtraction, and experimentally demonstrate this
capability
Efficient visible luminescence of nanocrystalline silicon prepared from amorphous silicon films by thermal annealing and stain etching
Films of nanocrystalline silicon (nc-Si) were prepared from hydrogenated amorphous silicon (a-Si:H) by using rapid thermal annealing. The formed nc-Si films were subjected to stain etching in hydrofluoric acid solutions in order to passivate surfaces of nc-Si. The optical reflectance spectroscopy revealed the nc-Si formation as well as the high optical quality of the formed films. The Raman scattering spectroscopy was used to estimate the mean size and volume fraction of nc-Si in the annealed films, which were about 4 to 8 nm and 44 to 90%, respectively, depending on the annealing regime. In contrast to as-deposited a-Si:H films, the nc-Si films after stain etching exhibited efficient photoluminescence in the spectral range of 600 to 950 nm at room temperature. The photoluminescence intensity and lifetimes of the stain etched nc-Si films were similar to those for conventional porous Si formed by electrochemical etching. The obtained results indicate new possibilities to prepare luminescent thin films for Si-based optoelectronics
Experimental Study of Impact-Protective Elements for Unidirectional Ribs of Lattice Composite Aircraft Structures
Lattice structures based on unidirectional composite ribs is currently one of the most promising directions of research aiming to create lightweight and reliable structure of future aircrafts [1]. Hybrid structure concepts based on lattice layouts have been developed for a number of conventional and non-conventional civil aircraft configurations, giving up to 15-20% weight saving as compared to conventional composite structures based on laminated skin and stiffeners [2]. One of the most critical problems of load-bearing lattice composite structures is very high sensitivity to impact loads, which is even more crucial than for the laminated composite structures. At the same time, topology of lattice grid makes it possible to create reliable protective system for the ribs, which can be effective in terms of weight expenses