We present an analysis of experimentally accessible magnetic Feshbach resonances in ultracold heteronuclear ${}^{85}\mathrm{Rb}\text{−}{}^{87}\mathrm{Rb}$ and ${}^6\mathrm{Li}\text{−}{}^{87}\mathrm{Rb}$ mixtures. Using recent experimental measurements of the triplet scattering lengths for ${}^6\mathrm{Li}\text{−}{}^{87}\mathrm{Rb}$ and ${}^7\mathrm{Li}\text{−}{}^{87}\mathrm{Rb}$ mixtures and Feshbach resonances for one combination of atomic states, we create model potential curves and fine-tune them to reproduce the measured resonances and to predict the location of several experimentally relevant resonances in Li-Rb collisions. To model ${}^{85}\mathrm{Rb}\text{−}{}^{87}\mathrm{Rb}$ collisions, we use accurate ${\mathrm{Rb}}_2$ potentials obtained previously from the analysis of experiments on ${}^{87}\mathrm{Rb}\text{−}{}^{87}\mathrm{Rb}$ collisions. We find resonances that occur at very low magnetic fields, below $10\mathrm{G}$, which may be useful for entanglement generation in optical lattices or atom chip magnetic traps.

An extended Dicke model, which includes atom-atom interactions and a driving classical laser field, is established for a Bose-Einstein condensate inside an ultrahigh-finesse optical cavity. A feasible experimental setup with a strong atom-field coupling is proposed, where most parameters are easily controllable and thus the predicted a second-order superradiant-normal phase transition may be detected by measuring the ground-state atomic population. More intriguingly, second-order phase transition from the superradiant phase to the “Mott” phase is also revealed. In addition, a rich and exotic phase diagram is presented.

Using a time-dependent linear (Rabi) coupling between the components of a weakly interacting multicomponent Bose-Einstein condensate (BEC), we propose a protocol for transferring the wave function of one component to the other. This “Rabi switch” can be generated in a binary BEC mixture by an electromagnetic field between the two components, typically two hyperfine states. When the wave function to be transferred is, at a given time, a stationary state of the multicomponent Hamiltonian, then, after a time delay (depending on the Rabi frequency), it is possible to have the same wave function on the other condensate. The Rabi switch can be used to transfer also moving bright matter-wave solitons, as well as vortices and vortex lattices in two-dimensional (2D) condensates. The efficiency of the proposed switch is shown to be 100% when interspecies and intraspecies interaction strengths are equal. The deviations from equal interaction strengths are analyzed within a two-mode model, and the dependence of the efficiency on the interaction strengths and on the presence of external potentials is examined in both 1D and 2D settings.

We investigate the dynamics of doubly charged vortices generated in dilute Bose-Einstein condensates by using the topological phase imprinting technique. We find splitting times of such vortices and show that thermal atoms are responsible for their decay.

In a recent paper [Kato et al., Phys. Rev. A 77, 062708 (2008)], optical oscillator strengths for the Lyman and Werner transitions of ${\mathrm{H}}_2$, extrapolated from the authors’ experimental generalized oscillator strengths, are compared with a suite of other values, several of which have been incorrectly derived from the literature. These significant errors are corrected and it is suggested that claiming the status of an “optical” oscillator strength for the extrapolated generalized oscillator strength associated with electron energy-loss spectra at $100–200\text{−}\mathrm{eV}$ impact energy is somewhat questionable.

We analyze the vortex core states of two-species (mass imbalanced) superfluid fermion mixtures as a function of two-body binding energy in two dimensions. In particular, we solve the Bogoliubov–de Gennes equations for a population balanced mixture of ${}^6\mathrm{Li}$ and ${}^{40}\mathrm{K}$ atoms at zero temperature. We find that the vortex core is mostly occupied by the light-mass $\left({}^6\mathrm{Li}\right)$ fermions and that the core density of the heavy-mass $\left({}^{40}\mathrm{K}\right)$ fermions is highly depleted. This is in contrast with the one-species (mass balanced) mixtures with balanced populations where an equal amount of density depletion is found at the vortex core for both pseudospin components.

We consider ramifications of the use of high-speed light modulators to questions of correlation and measurement of time-energy entangled photons. Using phase modulators, we find that temporal modulation of one photon of an entangled pair, as measured by correlation in the frequency domain, may be negated or enhanced by modulation of the second photon. Using amplitude modulators, we describe a Fourier technique for measurement of biphoton wave functions with slow detectors.

A simple phase estimation procedure is outlined and applied to solve standard quantum-mechanical problems. The procedure needs only one qubit to read off the eigenenergy obtained by iterative measurements, while the system qubits provides the corresponding eigenstates. No a priori information is needed about the system states and energies, therefore, the procedure may be launched from a completely random initial state.

We study the zero temperature properties of a trapped polarized Fermi gas at unitarity by assuming phase separation between an unpolarized superfluid and a polarized normal phase. The effects of the interaction are accounted for using the formalism of quasiparticles to build up the equation of state of the normal phase with the Monte Carlo results for the relevant parameters. Our predictions for the Chandrasekhar-Clogston limit of critical polarization and for the density profiles, including the density jump at the interface, are confirmed with excellent accuracy by the recent experimental results at MIT. The role of interaction on the radial width of the minority component, on the gap of spectral functions, and on the spin oscillations in the normal phase is also discussed. Our analysis points out the Fermi liquid nature of these strongly interacting spin-polarized configurations.

Confinement of electromagnetic energy into a single well-controlled oscillation of light is very important for generation of intense supercontinuum radiation. We find that the pulse breakup of few-cycle ultrashort laser pulses via resonant propagation effects can achieve this aim. By extracting such pulses and then focusing them to drive the He atoms, about $200\mathrm{eV}$ intense supercontinuum radiation can be generated, which is capable of supporting $\sim 20\text{attosecond}$ isolated pulse generation.

We present analytical solutions for the three-body problem with multichannel interactions and identify a class of quasibound Efimov states that can be viewed as three-body Fano-Feshbach resonances. Our method employs a multichannel generalization of the Fermi pseudopotential to model low-energy atom-atom interactions near a magnetically tunable Fano-Feshbach resonance. We discuss the conditions under which quasibound Efimov states may be supported and identify the interaction parameters that limit the lifetimes of these states. We speculate that it may be possible to observe these states using spectroscopic methods, perhaps allowing for the measurement of multiple Efimov resonances.

Doping helium nanodroplets with more than a single Mg atom leads to a shift of the atomic absorption from $279\mathrm{nm}\text{to}282\mathrm{nm}$. This behavior is stable against a change of the chosen droplet size. There is evidence that the interplay of the weak long-range potential between individual Mg atoms and the interaction with the surrounding quantum fluid leads to the formation of metastable very weakly bound complexes high above the global energy minimum. They resemble a bubble foam, where the individual Mg atoms are separated by a helium layer. The formation of compact Mg clusters is hindered by density variations within the superfluid solvent. The distance between the Mg atoms is substantially larger compared to the ground state. We estimate a value of roughly $10\mathrm{\AA }$ and the barrier, preventing the formation of compact Mg clusters to only a few kelvin. Upon laser excitation the metastable complexes collapse on a time scale of $20\mathrm{ps}$ as measured with a femtosecond pump-probe experiment.

We theoretically investigate the transmission of electromagnetic radiation through a metal plate with a zero-$ϵ$ metamaterial slit, where the permittivity tends towards zero over a given bandwidth. Our analytic results demonstrate that the transmission coefficient can be substantial for a broad range of slit geometries, including subwavelength widths that are many wavelengths long. This resonant effect has features quite unlike the Fabry-Perot-like resonances that have been observed in conductors with deep channels. We further reveal that ultranarrow zero-$ϵ$ channels can have significantly greater transmission compared to slits with no wave impedance difference across them.

We demonstrate that laser beam collapse in highly nonlinear media can be described, for a large number of experimental conditions, by the geometrical optics approximation within high accuracy. Taking into account this fact we succeed in constructing analytical solutions of the eikonal equation, which are exact on the beam axis and provide (i) a first-principles determination of the self-focusing position, thus replacing the widely used empirical Marburger formula, (ii) a mathematical condition for obtaining the filament intensity, (iii) a benchmark solution for numerical simulations, and (iv) a tool for the experimental determination of the high-order nonlinear susceptibility. Successful comparison with experiment is presented.

We investigate the effect of common bath decoherence on the qubits of Alice in the usual teleportation protocol. The system bath interaction is studied under the central spin model, where the qubits are coupled to the bath spins through isotropic Heisenberg interaction. We have given a more generalized representation of the protocol in terms of density matrices and calculated the average fidelity of the teleported state for different Bell state measurements performed by Alice. The common bath interaction differentiates the outcome of various Bell state measurements made by Alice. There will be a high fidelity teleportation for a singlet measurement made by Alice when both the qubits of Alice interact either ferromagnetically or antiferromagnetically with bath. In contrast if one of Alice’s qubits interacts ferromagnetically and the other antiferromagnetically then measurement of Bell states belonging to the triplet sector will give better fidelity. We have also evaluated the average fidelity when Alice prefers nonmaximally entangled states as her basis for measurement.

Antiferromagnetic condensates are generally believed not to display modulational instability and subsequent spin-domain formation. Here we demonstrate that in the presence of a homogeneous magnetic field antiferromagnetic spin-1 Bose-Einstein condensates can undergo spatial modulational instability followed by the subsequent generation of spin domains. Employing numerical simulations for realistic conditions, we show how this effect can be observed in sodium condensates confined in an optical trap. Finally, we link this instability and spin-domain formation with stationary modes of the condensate.

Spontaneous parametric downconversion produces entangled signal and idler fields that are in a zero-mean jointly Gaussian state whose postselected, low-brightness, low-flux limit is a biphoton. This paper applies Gaussian-state analysis to two biphoton-state quantum imaging scenarios: far field diffraction-pattern imaging; and broadband thin-lens imaging. It is shown that the spatial resolution behavior in both cases is controlled by the nonzero phase-sensitive cross correlation between the signal and idler fields. Thus, the same resolution can be achieved in these two configurations with classical-state signal and idler fields possessing a nonzero phase-sensitive cross correlation. In other words, the image formation process in these two scenarios is intrinsically classical coherence propagation.

In this work we relate the well-known no-go theorem that two nonorthogonal (mixed) quantum states cannot be perfectly discriminated, to the general principle in physics, the no-signaling condition. In fact, the minimum error in discrimination between two quantum states is derived from the no-signaling condition.

Grazing scattering of neutral atoms from insulator surfaces is investigated in the intermediate velocity range, in which interference effects have recently been observed. To describe this process we introduce a distorted-wave method based on the use of the eikonal wave function, which takes into account the phase of the scattering state along the classical projectile path. The eikonal theory is applied to evaluate the angular distribution of few-keV helium atoms after impinging on a LiF(001) surface along low-index crystallographic directions. The interest focuses on the role played by the projectile polarization produced by cations and anions of the crystal surface. For the considered collision system we found a polarization channel, corresponding to the direction ⟨110⟩, which is affected by this effect, while for incidence in the direction ⟨100⟩ the polarization contribution is nearly negligible. The proposed eikonal approach, including polarization effects, provides angular projectile spectra in good agreement with the experimental data.