Deflection of resonant multilevel particles in a standing wave light field

We study the deflection of an atomic system with a resonant multilevel energy structure in classical and quantized wave light fields. We obtain that the shape of the momentum distribution is very sensitive to the energy level structure, whereas its moments are not. Comparison with a two-level case is made.     

Backward diffraction of electrons by a standing light wave

By means of a simple approximation we evaluate the Kapitza-Dirac diffraction probabilities for scattering of electrons in backward direction by a standing wave of intense coherent light.     

Deflection and internal dynamics of atoms dressed by a resonant standing wave

A unitary transformation to dress a two-level atom by the field of a resonant standing wave is shown to yield in a very simple way the main results of previous theories of deflection without using explicit analytical or numerical solutions of the Schrödinger equation. A generalization of Rabi precession induced by an inhomogeneous standing wave is obtained.     

Diffraction pattern of atoms in a resonant standing wave laser field

We illustrate the diffraction pattern of an atomic beam for a resonant standing wave laser field, and stress its dependence on the angle of incidence. A maximum spread of the atomic beam is found to occur for an incidence angle close to, but different from normal incidence.     

Resonant light pressure due to a strong standing wave

This paper calculates the light pressure force due to a standing wave, including the lowest order modification of the populations. The result is compared with that of the rate-equation approximation.     

Spectral line narrowing in a gas by atoms trapped in a standing light wave

This paper presents results of a theoretical analysis of a new method for eliminating the Doppler broadening of spectral lines and the broadening by the transit time of atoms through a light beam. The atomic motion in a one-dimensional standing wave is studied and the conditions for translational-to-vibrational motion transformation are found. The variation in the Doppler contour by the trapping effect is investigated. It is illustrated, in particular, that the width of the narrow peak at the line centre depends mainly on the finite transit time of the atoms through the light beam. Next it is shown that, by accumulating slow atoms in a three-dimensional standing wave, it is possible, in principle, to observe narrow peaks with their widths determined only by the natural line width. The possibility of experimentally detecting of the phenomenon is discussed.     

Dynamics of spontaneous radiation of atoms scattered by a resonance standing light wave

The scattering of atoms by a resonance standing light wave is considered under conditions when the lower of two resonance levels is metastable, while the upper level rapidly decays due to mainly spontaneous radiative transitions to the nonresonance levels of an atom. The diffraction scattering regime is studied, when the Rabi frequency is sufficiently high and many diffraction maxima are formed due to scattering. The dynamics of spontaneous radiation of an atom is investigated. It is shown that scattering slows down substantially the radiative decay of the atom. The regions and characteristics of the power and exponential decay are determined. The adiabatic and nonadiabatic scattering regimes are studied. It is shown that the wave packets of atoms in the metastable and resonance excited states narrow down during scattering. A limiting (minimal) size of the wave packets is found, which is achieved upon nonadiabatic scattering in the case of a sufficiently long interaction time.     

Stable localization of atoms in a standing light wave field

We demonstrate theoretically that atoms can be localized (trapped) for a long time in the minima of a periodic potential produced by a strong standing light wave when they are irradiated additionally by a weak traveling or standing light wave which cools atoms in the potential wells.     

Resonant light pressure forces in a strong standing laser wave

The light pressure forces acting on a two-level atom in a strong standing laser wave are calculated. It is shown that at strong saturation of a resonant atomic transition the velocity dependence of these forces include sharp variations due to multiphoton resonances. At small atomic velocities these multiphoton resonances may even change the sign of the forces. The results obtained are important for many applications of resonant light pressure, e.g. in cooling and trapping of atoms in standing laser waves.     

Time-resolved detection of atoms diffracted from a standing light wave

We present a time-resolved experimental observation of the diffraction of metastable helium atoms from a nearly resonant standing light wave. The application of a time-resolved detection technique and a pulsed source allows to resolve high diffraction orders, which are populated in the atom-light interaction. Furthermore, the rms momentum transfer from the light field on the atom as a function of the interaction time is investigated. Future applications of this technique may be the detailed investigation of the motion of atoms in standing light waves and the detection of correlations between spontaneously emitted photons and atoms.Dedicated to H. Walter on the occasion of his 60th birthday     

Proliferation of atomic wave packets at the nodes of a standing light wave

A quantum analysis is presented of the motion and internal state of a two-level atom in a strong standing-wave light field. Coherent evolution of the atomic wave-packet, atomic dipole moment, and population inversion strongly depends on the ratio between the detuning from atom-field resonance and a characteristic atomic frequency. In the basis of dressed states, atomic motion is represented as wave-packet motion in two effective optical potentials. At exact resonance, coherent population trapping is observed when an atom with zero momentum is centered at a standing-wave node. When the detuning is comparable to the characteristic atomic frequency, the atom crossing a node may or may not undergo a transition between the potentials with probabilities that are similar in order of magnitude. In this detuning range, atomic wave packets proliferate at the nodes of the standing wave. This phenomenon is interpreted as a quantum manifestation of chaotic transport of classical atoms observed in earlier studies. For a certain detuning range, there exists an interval of initial momentum values such that the atom simultaneously oscillates in an optical potential well and moves as a ballistic particle. This behavior of a wave packet is a quantum analog of a classical random walk of an atom, when it enters and leaves optical potential wells in a seemingly irregular manner and freely moves both ways in a periodic standing light wave. In a far-detuned field, the transition probability between the potentials is low, and adiabatic wave-packet evolution corresponding to regular classical motion of an atom is observed.     

Hydrodynamical equations for atomic motion in a resonant light wave

The hydrodynamical equations for atomic motion in a resonant light wave have been derived. The obtained equations are applied to analyze the atomic deceleration in counter propagating light beam.     

Deflection profiles of a monoenergetic atomic beam crossing a standing light wave

We calculate the shape of the deflection profile of a monoenergetic atomic beam crossing a laser standing wave, in a situation where many spontaneous emission processes occur during the interaction time. We predict that double peaked structures appear when the laser is detuned from resonance.     

Time evolution of atomic inversion in a standing wave light field

The interaction between an atomic beam of two-level atoms and a standing wave light field has been studied by the exact solution of a time-dependent quantum system developed recently. When the initial atomic state is choosen to be ground, we find that with the limit of zero detuning the atoms will oscillate between the upper and the lower levels with a decaying amplitude. The most interesting result obtained in this paper is when the initial atomic state is a particular superposition of the two levels, now the system does not oscillate at any time.     

Series solution of two trapped ions experiencing the standing wave of a resonant laser

Two identical two-level ions driven by a standing wave laser on resonance in a harmonic trap are investigated in the Lamb–Dicke limit and weak excitation regime. We present series solutions of such a system for the trap center staying at a node of the standing wave.     

Experimental study of light diffraction by standing ultrasonic wave with cylindrical symmetry

We report a new acousto-optic arrangement based on ultrasonic wave with cylindrical symmetry. The theory of light interaction with standing cylindrical ultrasonic wave is experimentally verified in the Fraunhofer region. A very good agreement of experimental results with numerical calculations based on the proposed theory is found. The diffraction pattern consists of ring-shaped diffraction orders which posses a fine structure. The time average light intensity of the whole zeroth diffraction order as a function of the Raman-Nath parameter is investigated. The modulation properties of presented system are examined by means of single photon counting technique. Finally, some potentially useful applications in the laser and fibre technology are suggested.