Quantum dots are typically formed from large groupings of atoms and thus may be expected to have appreciable many-body behavior under intense optical excitation. Nonetheless, they known exhibit discrete energy levels due quantum confinement effects. We show that, like single-atom or single-molecule two- three-level systems, single semiconductor can also interference phenomena when driven simultaneously by two fields. Probe absorption spectra obtained that Autler-Townes splitting the fields...

The Goos-H\"anchen shift is calculated when total internal reflection occurs at an interface between ``normal'' and negatively refractive media. negative, consistent with the direction of energy flow in medium.

We report on the coherent optical excitation of electron spin polarization in ground state charged GaAs quantum dots via an intermediate exciton (trion) state. Coherent fields are used for creation and detection Raman coherence between states dot. The measured decoherence time, which is likely limited by nature ensemble, approaches 10 ns at zero field. also show that beats caused not only usual stimulated interaction but simultaneous spontaneous radiative decay either excited trion to a...

A class of pulse functions is found for which analytic solutions to the problem two levels coupled by these obtained. The hyperbolic-secant coupling included in this leading Rosen-Zener solution, but all other pulses belonging function are asymmetric. asymmetric lead qualitatively new features solutions; general, it impossible have a zero-transition probability with such pulses.

We show that the probability distributions for number of Rydberg excitations in small ensembles cold atoms, excited using short (100 ns) laser pulses, can be highly sub-Poissonian. The phenomenon occurs if atom density and principal quantum level are sufficiently high. Our observations attributed to a blockade excitation.

Received 4 November 1965DOI:https://doi.org/10.1103/PhysRevLett.15.999©1965 American Physical Society

In the limit of a dipole-dipole interaction between neutral atoms and binary-collision approximation, we present theory pressure broadening in which multiplet structure atomic levels is considered. The appropriate Schr\"odinger equations for collision problem are numerically integrated to obtain solutions both resonant foreign gas broadening. presence radiation fields neglected first half paper, where collisional time rate change density matrix found. pertinent decay parameters extracted...

The electron spin state of a singly charged semiconductor quantum dot has been shown to form suitable single qubit for computing architectures with fast gate times. A key challenge in realizing useful architecture lies demonstrating the ability scale system many qubits. In this Letter, we report an all optical experimental demonstration entanglement between confined and polarization photon spontaneously emitted from dot's excited state. We obtain lower bound on fidelity...

It has been shown recently that molecular gas samples excited with coherent light can display a variety of transient phenomena, similar to those found in nuclear magnetic resonance. This article elucidates how these coherence effects be used isolate or unfold collision mechanisms normally remain hidden within the optical line shape. Elastic collisions, for example, are easily detected here two-pulse photon echo experiments $^{13}\mathrm{C}$${\mathrm{H}}_{3}$F vibration-rotation transition....

We report the development of an atom interferometer that uses optical standing waves as phase gratings and operates in time domain. The observed signal is entirely caused by wave nature atomic center-of-mass motion. opportunities to measure recoil frequency gravity acceleration are demonstrated.

It is shown that, as a result of the atomic recoil associated with absorption and emission radiation, resonances can appear in nonlinear spectroscopy. The theory illustrated by calculating line shapes nearly degenerate four-wave mixing pump-probe spectroscopy when laser fields interact an ensemble two-level atoms. recoil-induced should be observable for atoms cooled below Doppler limit cooling, may provide means measuring velocity distribution these

A quantum-mechanical transport equation (QMTE) is derived which should be applicable to a wide range of problems involving the interaction radiation with atoms or molecules are also subject collisions perturber atoms. The follows time evolution macroscopic atomic density matrix elements located at classical position $\stackrel{\ensuremath{\rightarrow}}{\mathrm{R}}$ and moving velocity $\stackrel{\ensuremath{\rightarrow}}{\mathrm{v}}$ It quantum mechanical in sense that all collision kernels...

The effect of velocity-changing collisions on the optical phase memory coherently prepared molecular gas samples is examined by method Stark-pulse switching. Experiments are interpreted through solution a transport equation, which extends earlier Fokker-Planck description known both in NMR and Dicke line narrowing. magnitude characteristic velocity jump for binary its cross section thereby obtained.

We present a theory of pressure effects in which the atomic center-of-mass motion is treated quantum mechanically. The quantum-mechanical calculation treats perturber-induced energy-level variations and velocity changes emitter caused by collisions on an equal basis. Specifically, we shall treat problem laser to first order field, allowing for fact that atoms are undergoing collisions, but our results will also be applicable cases stimulated emission or absorption. It sufficient carry out...

We describe the transient four-wave-mixing (FWM) response in systems where decay of optically induced coherence depends on excitation level system. Using modified optical Bloch equations, we show that excitation-induced dephasing due to phase-interrupting excited-state interactions qualitatively modifies temporal behavior and polarization dependence FWM signal.

It has been shown recently [see, for example, S.-Y. Zhu and M. O. Scully, Phys. Rev. Lett. 76, 388 (1996)] that a dynamical suppression of spontaneous emission can occur in three-level system when an external field drives transitions between metastable state two decaying states. What is unusual the decay scheme states are coupled directly by vacuum radiation field. dynamics required total necessarily implies level isomorphic to \ensuremath{\Lambda} system, which lower levels both each state....

Collisional processes occurring within an atomic vapor can be conveniently described in terms of collision kernels. The population kernel ${W}_{\mathrm{ii}}({\stackrel{\ensuremath{\rightarrow}}{\mathrm{v}}}^{\ensuremath{'}}\ensuremath{\rightarrow}\stackrel{\ensuremath{\rightarrow}}{\mathrm{v}})$ gives the probability density per unit time that "active" atom state $i$ undergoes a with perturber changes active atom's velocity from...

Recently, DeVoe and Brewer [Phys. Rev. Lett. 50, 1269 (1983)] observed a striking deviation from prediction of the optical Bloch equations by monitoring free-induction decay in impurity-ion crystal ${\mathrm{Pr}}^{3+}$:${\mathrm{LaF}}_{3}$. At low fields, ${\mathrm{Pr}}^{3+}$ dephasing time ${T}_{2}$ arises magnetic fluctuations local environment, but at elevated is no longer constant, as assumed equations, because line-broadening process quenched. Several theories have been developed to...

The theory of the interaction between radiation fields and atoms as applied to laser spectroscopy can be approached using either a bare-atom picture (BAP) or dressed-atom (DAP). In BAP, basis states are those free field while, in DAP, encompass some part atom-field interaction. saturation three-level systems is discussed both approaches. Whereas calculations usually more easily done one gain useful insight into underlying physical processes from DAP. Moreover, when strengths (in frequency...

A dipole blockade, in which Rydberg-atom-Rydberg-atom interactions inhibit all but a single collective Rydberg excitation, has been proposed as mechanism to store and manipulate quantum information mesoscopic ensembles. We investigate the excitation dynamics of collection few atoms show that they undergo an unexpected, qualitative change when number increases from two three. In particular, combined action three atoms, each pairwise would produce can break blockade.