Tuning the adiabaticity of spin dynamics in diamond nitrogen vacancy centers.

We study the spin dynamics of diamond nitrogen vacancy (NV) centers in an oscillating magnetic field along the symmetry axis of the NV in the presence of transverse magnetic fields. It is well-known that the coupling between the otherwise degenerate Zeeman levels |= ±1⟩ due to strain and electric fields is responsible for a Landau-Zener process near the pseudo-crossing of the adiabatic energy levels when the axial component of the oscillating magnetic field changes sign. We derive an effective two-level Hamiltonian for the NV system that includes coupling between the two levels via virtual transitions into the third far-detuned level |= 0⟩ induced by transverse magnetic fields.

Dynamics of a Magnetic Needle Magnetometer: Sensitivity to Landau-Lifshitz-Gilbert Damping.

An analysis of a single-domain magnetic needle (MN) in the presence of an external magnetic field B is carried out with the aim of achieving a high-precision magnetometer. We determine the uncertainty ΔB of such a device due to Gilbert dissipation and the associated internal magnetic field fluctuations that give rise to diffusion of the MN axis direction n and the needle orbital angular momentum. The levitation of the MN in a magnetic trap and its stability are also analyzed.

Erratum: Dynamics of an electric dipole moment in a stochastic electric field [Phys. Rev. E 88, 022127 (2013)].

This corrects the article DOI: 10.1103/PhysRevE.88.

Molecules with an induced dipole moment in a stochastic electric field.

The mean-field dynamics of a molecule with an induced dipole moment (e.g., a homonuclear diatomic molecule) in a deterministic and a stochastic (fluctuating) electric field is solved to obtain the decoherence properties of the system.

Feshbach resonance without a closed-channel bound state.

The physics of Feshbach resonance is analyzed using an analytic expression for the s-wave scattering phase shift and the scattering length a which we derive within a two-channel tight-binding model. Employing a unified treatment of bound states and resonances in terms of the Jost function, it is shown that, for strong interchannel coupling, Feshbach resonance can occur even when the closed channel does not have a bound state. This may extend the range of ultracold atomic systems that can be manipulated by Feshbach resonance.

Dynamics of an electric dipole moment in a stochastic electric field.

The mean-field dynamics of an electric dipole moment in a deterministic and a fluctuating electric field is solved to obtain the average over fluctuations of the dipole moment and the angular momentum as a function of time for a Gaussian white-noise stochastic electric field. The components of the average electric dipole moment and the average angular momentum along the deterministic electric-field direction do not decay to zero, despite fluctuations in all three components of the electric field. This is in contrast to the decay of the average over fluctuations of a magnetic moment in a stochastic magnetic field with Gaussian white noise in all three components.

Spin decoherence due to fluctuating fields.

The dynamics of a spin in the presence of a deterministic and a fluctuating magnetic field is solved for analytically to obtain the averaged value of the spin as a function of time for various kinds of fluctuations (noise). Specifically, analytic results are obtained for the time dependence of the expectation value of the spin, averaged over fluctuations, for Gaussian white noise, Gaussian colored noise, and non-Gaussian telegraph noise. Fluctuations cause the decay of the average spin vector (decoherence).

The second generation and asthma: Prevalence of asthma among Israeli born children of Ethiopian origin.

Background: Immigrant populations moving from undeveloped countries with low asthma prevalence have shown increased asthma prevalence in their new Westernized environment. We compared the prevalence of asthma among Israeli born children of Ethiopian origin to that in non-Ethiopian children.

Methods: Cross sectional study.

Creating very slow optical gap solitons with a grating-assisted coupler.

We show that optical gap solitons can be produced with velocities down to 4% of the group velocity of light using a grating-assisted coupler, i.e., a fiber Bragg grating that is linearly coupled to a non-Bragg fiber over a finite domain.

Interference of Bose-Einstein condensates.

A formalism for describing the coherence and interference properties of two atomic clouds of Bose-Einstein condensates (BEC) is presented, which is applicable even in the opposite limits when the BEC clouds are initially coherent and when they are initially independent. First, we develop a mean-field theory wherein one mean-field mode is used, and then, for fragmented (i.e.

Optoacoustic solitons in Bragg gratings.

Optical gap solitons, which exist due to a balance of nonlinearity and dispersion due to a Bragg grating, can couple to acoustic waves through electrostriction. This gives rise to a new species of "gap-acoustic" solitons (GASs), for which we find exact analytic solutions. The GAS consists of an optical pulse similar to the optical gap soliton, dressed by an accompanying phonon pulse.

Interferences in the density of two Bose-Einstein condensates consisting of identical or different atoms.

The density of two initially independent condensates which are allowed to expand and overlap can show interferences as a function of time due to interparticle interaction. Two situations are separately discussed and compared: (1) all atoms are identical and (2) each condensate consists of a different kind of atoms. Illustrative examples are presented.

Nonlinear adiabatic passage from fermion atoms to boson molecules.

We study the dynamics of an adiabatic sweep through a Feshbach resonance in a quantum gas of fermionic atoms. Analysis of the dynamical equations, supported by mean-field and many-body numerical results, shows that the dependence of the remaining atomic fraction Gamma on the sweep rate alpha varies from exponential Landau-Zener behavior for a single pair of particles to a power-law dependence for large particle number N. The power law is linear, Gamma is proportional to alpha, when the initial molecular fraction is smaller than the 1/N quantum fluctuations, and Gamma is proportional to alpha(1/3) when it is larger.

Gap solitons in a medium with third-harmonic generation.

We find two-component optical solitons in a nonlinear waveguide with a Bragg grating, including Kerr effects and third-harmonic generation (THG). The model may be realized in temporal and in spatial domains. Two species of fundamental gap solitons (GSs) are found.

Conversion efficiency of ultracold fermionic atoms to bosonic molecules via Feshbach resonance sweep experiments.

We explain why the experimental efficiency observed in the conversion of ultracold Fermi gases of 40K and 6Li atoms into diatomic Bose gases is limited to 0.5 when the Feshbach resonance sweep rate is sufficiently slow to pass adiabatically through the Landau-Zener transition but faster than "the collision rate" in the gas, and increases beyond 0.5 when it is slower.

Elastic scattering loss of atoms from colliding bose-einstein condensate wave packets.

Bragg diffraction of atoms by light waves can create high momentum components in a Bose-Einstein condensate. Collisions between atoms from two distinct momentum wave packets cause elastic scattering that can remove a significant fraction of atoms from the wave packets and cause the formation of a spherical shell of scattered atoms. We develop a slowly varying envelope technique that includes the effects of this loss on the condensate dynamics described by the Gross-Pitaevski equation.

Four wave mixing in the scattering of Bose-Einstein condensates.

The nonlinear coupling term in the Gross-Pitiaevski equation which describes a Bose-Einstein condensate (BEC) can cause four- wave mixing (4WM) if three BEC wavepackets with momenta k1, k2, and k3 interact. The interaction will produce a fourth wavepacket with momentum k4 = k1 + k2. We study this process using numerical models and suggest that experiments are feasible.

Near-field and far-field propagation of beams and pulses in dispersive media.

We formulate an efficient exact method of propagating optical wave packets (and cw beams) in isotropic and nonisotropic dispersive media. The method does not make the slowly varying envelope approximation in time or space and treats dispersion and diffraction exactly to all orders, even in the near field. It can also be used to determine the partial differential wave equation for pulses (and beams) to any order as a power series in the partial derivatives with respect to time and space.