Deflection Of Atoms Research Articles

Optical Stern–Gerlach effect via a single traveling-wave light

In this paper, we propose a simplified model of the optical Stern–Gerlach effect based on coherent coupling between the clock transition of alkaline-earth single atoms and a traveling-wave light. It is demonstrated that spin–orbit coupling-induced chiral motion in atom deflection appears under strong atom–light interaction. The strong optical driving removes the perturbation from the Doppler effect and back-action effect to access the coherent system. In this process, the superposition of distant matter waves connected to the arbitrary distribution of the atom internal state could be predicted, which is important for the realization of atom interferometry and quantum-state operation. The influence of atom relaxation and atom–atom interactions is discussed. The basic conditions for the experimental design are given at the end of this work.

Quantum atomic lithography via cross-cavity optical Stern–Gerlach setup

We present a fully quantum scheme to perform 2D atomic lithography based on a cross-cavity optical Stern-Gerlach setup: an array of two mutually orthogonal cavities crossed by an atomic beam perpendicular to their optical axes, which is made to interact with two identical modes. After deriving an analytical solution for the atomic momentum distribution, we introduce a protocol allowing us to control the atomic deflection by manipulating the amplitudes and phases of the cavity field states.

Optical pumping of a lithium atomic beam for atom interferometry

We apply optical pumping to prepare the lithium beam of our atom interferometer in a single hyperfine-Zeeman sublevel: we use two components of the D1-line for pumping the 7Li atoms in a dark state F,mF=+2 (or -2) sublevel. The optical pumping efficiency has been characterized by two techniques: state-selective laser atom deflection or magnetic dephasing of the atom interferometer signals. The first technique has not achieved a high sensitivity, because of a limited signal to noise ratio, but magnetic dephasing signals have shown that about 95% of the population has been transferred in the aimed sublevel, with similar results for three mean velocities of the atomic beam covering the range 744-1520m/s.

Visualization of superposition states and Raman processes with two-dimensional atomic deflection

The deflection of atoms in a $\ensuremath{\Lambda}$-type configuration passing through two crossed standing light waves is proposed for the probing and visualization of atomic superposition states. For this goal, we use both the large-dispersive and Raman-resonant regimes of atom-field interaction, giving rise to position-dependent phase shifts of fields, and perform double simultaneous spatial measurements on an atom. In this way, it is demonstrated that the deflection spatial patterns of atoms in a $\ensuremath{\Lambda}$-configuration passing through modes of standing waves are essentially modified if the atoms are initially prepared in coherent superpositions of their low-level states as well as when the superposition states are created during the process of deflection. There are similar results for the joint momentum distributions of atoms. Furthermore, considering both one-photon- and two-photon-excitation regimes of $\ensuremath{\Lambda}$ atoms, we also illustrate that the two-dimensional patterns of defected atoms qualitatively reflect the efficiency of the Raman processes.

Atomic deflection conditioned by entangled light waves

We investigate deflection of atomic beams on two co-propagating standing waves excited in a bimodal cavity. The novelty is that the standing waves are in an entangled, photon-number correlated state and interactions with three-level atoms of V-type and Λ-type configurations are considered. The splitting of atomic states, quantum interference effects and spatial atomic localization due to phase measurements is investigated on the framework of both the conditional position distributions of atomic wave packets as well as the Wigner functions for atomic translation variables. It is demonstrated that these quantities for V-type atoms passing the cavity are essentially modified when entangled states of standing waves are used instead of statistically independent waves. The deflection patterns and the Wigner functions are also modified if atoms are initially prepared in a superposition of low-level states. It is best demonstrated for the Λ-type configuration, where transition through the Raman resonance is realized, and proposed for testing superposition states in a new non-spectroscopic manner.

Spatial entanglement and sub-wavelength structures in atomic deflection

The deflection of V-level atomic beam in two mode quantized cavity field in a twin-photon state is investigated. Depending on the atom-light interaction scheme, two-dimensional position patterns in a sub-wavelength range as well as the effects of spatial entanglement are reported.

Spatially entangled atomic deflections in twin-photon light beams

We investigate deflections, spatial entanglement, and localization of an atomic beam due to its interaction with two modes of a standing electromagnetic field in an optical cavity. It is demonstrated that the deflection properties of an atom passing through two crossed standing light waves are crucially modified when photon-number correlated states of light are used instead of independent waves. Depending on the atom-light interaction scheme, various periodic two-dimensional patterns in a subwavelength regime are reported.

Probing Heliospheric Asymmetries with an MHD-Kinetic model

New solar wind data from the Voyager 1 and Voyager 2 spacecraft, together with the SOHO SWAN measurements of the direction that neutral hydrogen enters into the inner heliosheath and neutral helium measurements provided by multiple observations are expected to provide more reliable constraints on the ionization ratio of the local interstellar medium (LISM) and the direction and magnitude of the interstellar magnetic field (ISMF). In this paper we use currently the most sophisticated numerical model of the heliospheric interface, which is based on an MHD treatment of the ion flow and kinetic modeling of neutral particles, to analyze an ISMF-induced asymmetry of the heliosphere in the presence of the interplanetary magnetic field and neutral particles. It is shown that secondary hydrogen atoms modify the LISM properties leading to its shock-free deceleration at the heliopause. We determine the deflection of hydrogen atoms from their original trajectory in the unperturbed LISM and show that it occurs not only in the plane defined by the ISMF and LISM velocity vectors, but also, to a lesser extent, perpendicular to this plane. We also consider the possibility of using 2-3 kHz radio emission data to further constrain the ISMF direction.

Spin: Nonlinear zero dynamics of orbital motion

A formal proof is given to show that the prevailing historical view of treating the Schrödinger’s wave mechanics as a spinless theory is a great misunderstanding and that finding the fourth quantum number outside the Schrödinger equation is indeed superfluous. The spin dynamics inherent in the Schrödinger equation has long been overlooked since the inception of wave mechanics. We point out that from the original viewpoint of the Schrödinger equation without any additional interpretation, spin is not a motion with new degree of freedom beyond orbital motion; instead, it is the zero dynamics of orbital angular momentum. To manifest this point, the experiment performed in 1927 by Phipps and Taylor about the beam deflection of hydrogen atoms is revisited here to show how the Schrödinger equation correctly predicts the existence of the spin angular momentum ± ℏ/2 when the orbital quantum number l is zero. Apart from spin angular momentum, the Schrödinger equation also provides us with the nonlinear dynamics describing both the spin and orbital motion, from which spin quantization can be derived and the interaction between spin and orbital motions can be clearly demonstrated. This discovery allows us to include and analyze spin effect in any non-relativistic quantum mechanical systems by merely using the nonlinear dynamics derived from the Schrödinger equation.

Deflecting, focusing, and funnelling atoms by near-field light

We describe atom deflection with a slit-type deflector as an elemental technique of precise atom control using near-field light. In the demonstration experiments, cold Rb atoms deflected by repulsive near-field light induced in a 200?nm-wide slit are detected by means of two-step photoionization. Then, we consider a near-field-light lens of atomic de Broglie waves by developing the atom deflector. The feasibility of nanofocusing is shown by numerical analyses with Fourier atom optics. Finally, we describe atom funnels with evanescent light to generate a cold atomic beam required for atom manipulation using nanometric near-field light. The flux intensity of cold Rb atoms outputted from a 240??m outlet is estimated to be 7.5 ? 107?atom?cm?2?s?1 at a blue detuning of 1.2?GHz. In order to increase the flux intensity to 1012?atom?cm?2?s?1, we develop a Si-made funnel with a micron-sized outlet.

Atomic Deflection by the two Dimensional Traveling-wave and Standing-wave Vacuum Modes

We analyze the interaction of an two-state atom with two dimensional cavity modes in the strong coupling regime, with the quantized atomic center of mass motion taken into account. By choosing proper initial condition for the atomic transverse momentum and the cavity detuning, we can control the atomic transverse momentum distribution in two dimensions. We have analyzed the two-dimensional momentum distribution of the excited atom fully quantum mechanically, which interacts with two independent pairs of counterpropagating traveling-wave modes, one pair of folded traveling-wave modes, two independent crossed standing-wave modes and one folded standing-wave mode, respectively.

One-sided atomic deflection in the optical Stern-Gerlach effect and coherent trapping

In the optical Stern-Gerlach effect, the interaction of a traveling two-level atom with the electromagnetic field of an optical cavity causes a splitting of the atomic trajectory. One may ask if it is possible to single out particular initial configurations of the system that will lead to selective scattering, in which the atoms follow only one trajectory. We show that these configurations consist of a coherent superposition of the atomic internal states, and of a field phase state or a field coherent state, with a precise phase relation between the two subsystems: The same configurations which produce the so-called atomic coherent trapping in the Jaynes-Cummings model.

High Spatial Resolution Atom Detector with Two-Color Optical Near Fields

We describe a slit-type detector for ground-state atoms with nanometer optical near fields. The detector with a slit width of 70 nm and a slit length of 100 µm is fabricated by processing a silicon-on-insulator wafer with photolithography and anisotropic etching. Measurement with a fiber probe of the intensity distribution on the slit reveals that the spatial resolution is 96 nm. Rubidium atoms can be selectively detected by means of two-step photoionization. The detection efficiency is estimated at 25% for Rb atoms with a mean velocity of 10 m/s. The atom detector can be used for atom deflection experiments with a fiber probe.

Controlled hole burning in the photon-number distribution of field states in a cavity

A feasible experimental scheme to generate states of a field mode in a high-Q cavity possessing holes in their photon-number distributions at controlled positions is proposed. Such kind of states may be of interest to optical data storage and communications with a possible readout system consisting of an atomic deflection setup.

Deflection of krypton Rydberg atoms in the field of anelectric dipole

The controlled deflection of Rydberg atoms in aninhomogeneous electric field is demonstrated and shown to be in agreement withpredictionsbased on a well-defined Stark map.Krypton atoms in a supersonic beam are excited in a two-colourmultiphoton process to selected Stark states with n = 16-19 andundergo deflections in the field of an electrostatic dipole. Thespatial distribution of the deflected atoms is monitored by ionimaging. The atoms travelling ~10 cm in the beamdirection after excitation are deflected from the beam axis bydistances of up to 3 mm, the interaction with the field takingplace over 40 µs. Simulations of the trajectories agree wellwith the experimental results, demonstrating that the detectedRydberg atoms are those which have not undergone decay processesin the 40 µs applied field.

Control of atomic and molecular motion via the Stark effect in Rydberg states

A novel theoretical study of the control of translational motion of atomic and molecular Rydberg states in inhomogeneous static electric fields is presented. Simulations have been carried out demonstrating that, under realistic conditions, the deflection and focusing of Rydberg atoms and molecules should be achievable. Advantage is taken of the high susceptibility of the Rydberg states to external electric fields, allowing the use of much smaller fields than would be necessary for ground state neutrals. The simulations presented are for trajectories of Rydberg states with n = 18-20 in the fields of an electric dipole, quadrupole and hexapole. A deflection of 7 mm is predicted for n = 18 Rydberg states travelling parallel to the dipole after 100 µs time of flight. In the hexapole n = 20 Rydberg states are refocused to a spot size of the order of the laser beam waist (10 µm) after 20 µs. It is demonstrated that the hexapole can also act as a cylindrical lens if its axis is perpendicular to the Rydberg beam direction. Spontaneous emission and black-body decay rates are also calculated, and their variation with the applied field is investigated. The potential applications of this work might include the use of focusing and deflection for controlled low-energy collisions of Rydberg molecules with surfaces.

Atomic beam guide by a one-dimensional magneto-optical trap

The fine control of a neutral atomic beam by radiation pressure has opened a new field called atom lithography. In particular, a direct writing method, which focuses an atomic beam with a standing-wave light field into narrow lines, has been demonstrated. A velocity-controlled and isotope-selected atomic beam is essential for improving the performance of this lithography method. An atomic deflection technique using radiation pressure is indispensable for producing such an atomic beam. Here we report on an atomic beam guide using a one-dimensional magneto-optical trap (1D-MOT). First we decelerate atoms whose velocities lie in the range between 250 and 320 m/s. A diode laser (780 nm) is used as the light source for deceleration and its injection current is modulated at 2 MHz. Then the decelerated beam is deflected by a tilted 1D-MOT, which consists of four copper rods and four rectangular mirrors.

A novel spectrometer combining laser and electron excitation and deflection of atoms and molecules

A new spectrometer is described which combines electron impact excitation and deflection studies of atoms and molecules with laser spectroscopy. The spectrometer initially excites ground state atomic or molecular targets to a metastable state by employing an electron beam well defined in direction and energy. These metastable targets are then further excited to high Rydberg states (n⩾20) by employing resonant laser radiation derived from a frequency doubled pulsed dye laser. The high-n Rydberg targets are subsequently field ionized by a pulsed electric field and are detected as a function of both laser wavelength and electron impact energy, allowing state selected differential cross section measurements to be ascertained. The momentum transferred to the target by the electron impact can be exploited to provide additional information about the atomic or molecular state excited by electron impact.

Pulsed standing wave deflection of sodium atoms

We study the deflection of sodium atoms by a resonantly tuned pulsed standing wave of high field intensity. The effects of the phase fluctuations of the pulsed laser field on the momentum distribution of the deflected atoms are experimentally determined. The results are explained using a theoretical model based on the generalized density matrix formalism of two-level atoms.

Production and decay of excited quasiprojectiles in peripheral and semiperipheral35Cl+197Aureactions in Fermi energy domain

The peripheral and semiperipheral reactions in ${}^{35}\mathrm{Cl}{+}^{197}\mathrm{Au}$ have been studied at 30 and 43 MeV/nucleon. The nonequilibrium $\ensuremath{\alpha}$ and IMF components have been observed in the experiment. The fraction of nonequilibrium emission decreases with an increase in the atomic number of the projectilelike fragments but, for a given projectilelike fragment, it increases with the charge of the emitted particles. The characteristics of quasiprojectiles reconstructed from their decay products reveal several features reminiscent of damped reactions at lower bombarding energies. The atomic number and deflection angle of projectilelike fragments depend strongly on their kinetic energy or dissipated energy. At 30 MeV/nucleon, the experimental data can be explained by a deep inelastic transfer model. One-body dissipation is still the main mechanism for the energy and angular momentum dissipation. However, at 43 MeV/nucleon, deep inelastic transfer models can predict only the experimental tendency. Two-body dissipation plays a more important role at higher incident energies. The similarity observed in the decay product distributions, as a function of excitation energy, suggests that the excited quasiprojectiles formed in binary collisions might approach thermal equilibrium for both incident energies. The decay products have been analyzed with sequential-binary and simultaneous-disassembly statistical decay models. Both statistical models are able to provide good agreement with the experimental observables except for the mean kinetic energy of the products.