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Based on the model of the Λ-type three-level atomic system, the principle, the evolutionary equations and the resonance line characteristics of the coherent population trapping (CPT) are analyzed by means of ensemble-averaged density matrix approach. The paper presents a schematic illustration of practical realization and a block scheme of comprehensive analysis of the CPT system. Using vertical-cavity...
In a three-level lambda system, a destructive interference between excitation pathways at laser excitation can provide the resonant reduction of fluorescence and absorption (“dark resonance”). The dark resonances in rubidium vapor excited by a femtosecond laser or laser with frequency shifted feedback have been studied theoretically and experimentally.
A multiple quantum well (MQW) transistor vertical-cavity surface-emitting laser (T-VCSEL) is designed and numerically modeled. The quantum capture/escape process is simulated using a quantum-trap model. Both the steady state and frequency response of the T-VCSEL are calculated by a numerical and analytical approach.
The success in cooling and trapping atomic gases to the point of quantum degeneracy has prompted a quest to create ultracold molecular gases. Atomic techniques can not be applied to molecular gases due to their richer internal structure. Effort has been applied to converting ultracold atoms to ultracold molecules. This should be done without the use of spontaneous decay to attain the coldest possible...
We create Bose-Einstein Condensates of 52Cr atoms in an optical trap. Intense radio-frequency fields are used to induce degeneracy between the Zeeman sub-states of the ground state atoms in the BEC despite an ambient static field of 100 mG. We demonstrate this effect by analyzing atom trajectories under the influence of dressed magnetic potentials. We investigate the problem of adiabaticity in the...
The aim of this paper is to study experimentally the dynamics of atoms in various 2D or 3D optical potentials. In particular, we would like to be able to detect the existence of chaotic individual trajectories. We access the collective signatures through simulations of the atomic dynamics in different optical lattices: a standard square potential, which is either red or blue detuned, and a lattice...
We report on the successful experimental realization of a quantum ratchet for ultracold atoms in a driven spatially asymmetric optical lattice. Ratchets are usually considered as a tool, which rectify an otherwise undirected, for instance oscillating or fluctuating, motion of particles or objects. In order to observe a directed transport of atoms one has to break the space-time symmetry of the system...
Optomechanical interactions in high-finesse cavities offer a new promising route for the ongoing experimental efforts to achieve and to control the quantum regime of massive mechanical systems using the available toolbox of quantum optics. For example, they allow to cool mechanical degrees of freedom of movable mirrors via radiation-pressure backaction, in principle even into their quantum ground...
The summary form only given. We will discuss our work towards controlling light-matter interactions that make use of sub-wavelength localization of optical fields. Our approach combines the ideas of quantum optics with those of electronics and plasmonics. It can be used to create an efficient quantum interface between individual optical emitters and individual surfaces plasmons, to develop novel kinds...
The paper studies the second kind of entanglement distribution scheme. Entangled photon pairs are generated using the type-II spontaneous parametric down-conversion process (SPDC) in a PPKTP crystal. The source is tunable to both D-P transitions at 850 and 854 nm in 40Ca+ ions. The photon pairs are split by a polarizing beam splitter and one photon mode is coupled into a filtering line, consisting...
Quantum effects of radiation pressure are expected to limit the sensitivity of second-generation gravitational-wave interferometers. Using a high-finesse optical cavity and a classical intensity noise, radiation-pressure induced correlations between two optical beams sent into the same moving mirror cavity is demonstrated. The intensity fluctuations of the first, high-power, signal beam are imprinted...
In this paper, the motion of a silicon micro-mechanical resonator is optically monitored with a very high-finesse optical cavity down to a quantum-limited sensitivity at the 10-19 m/radicHz level. The high resonance frequency of the resonator (in the MHz range), its low mass (below 1 mg) and the extreme sensitivity open the way to radiation pressure-driven quantum optics experiments. Here, direct...
The mechanical interaction of light with small but macroscopic oscillators, mediated by radiation pressure, has been investigated since the '70ies. Several theoretical studies have proposed schemes exploiting such interaction at the quantum level. The phenomena analyzed include pondero-motive squeezing, quantum non-demolition measurements, entanglement between radiation field and mechanical oscillators...
Atomic ensembles have gained a lot of interest in the last decade for their prospective use as quantum memories, in precision measurements and other applications in quantum information processing. The atomic part of the interface presented here is an all-optically trapped atomic ensemble of 87Rb at a temperature of 25 muK. The ensemble consists of 106 atoms and has an elongated shape with an aspect...
This work considers an atom-light interface consisting of pulses of polarized light that interacts with an ensemble of 106 cold 87Rb in dipole trap. Measurements of polarization changes in the light is used in probing the atomic state. In such polarization-based atom-light interface, a Hamiltonian nonlinear in the Stokes operators can be produced through optical nonlinearities. This work investigates...
The paper reports on the first observation of nonlinear Faraday rotation (NFR) with cold atoms prepared in a magneto- optical trap (MOT) at ~100 muK temperature. The nonlinearity of rotation results from long-lived coherence of ground-state Zeeman sublevels, which makes NFR a candidate for the study and sensitive detection of qubits.
The quantum behavior of cold matter interacting with photons confined in high-finesse cavities is a subject of high interest for quantum communication, for studying properties of ultra-cold quantum gases, as well as for precision measurements. In particular promising schemes for enhanced laser cooling based on cavity feedback have been extensively studied both theoretically and experimentally. The...
Our goal is to realize a scalable cluster of entangled atoms trapped in fully controllable arrays of optical tweezers. The optical-tweezers array we are currently implementing consists of a freely configurable two-dimensional array of dipole-force traps, which we obtain by imaging the intensity pattern from a spatial-light modulator (SLM) into our apparatus. In every dipole trap, the intensity gradient...
We will discuss the implementation of high fidelity entangling operations based on a global interaction of a single laser beam with a string of trapped ions.
Optical tweezers are typically used on transparent dielectric particles. Particles with optical resonances should experience a larger trapping force near resonance. We present a numerical and experimental study of trapping force on such particles.
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