We give an extensive study of polarization dynamics in anisotropic fibers exhibiting a third-order index nonlinearity. The study is performed in the framework of the Stokes parameters with the help of the Poincaré sphere. Stationary states are determined, and their stability is investigated. The number of fixed points and their stability depend on the respective magnitude of the linear and nonlinear birefringence. A conservation relation analogous to the energy conservation in mechanics allows evidencing a close analogy between the movement of the polarization in the Poincaré sphere and the motion of a particle in a potential well. Two distinct potentials are found, leading to the existence of two families of solutions, according to the sign of the total energy of the equivalent mechanical system. The mechanical analogy allows us to fully characterize the solutions and also to determine analytically the associated beat lengths. General analytical solutions are given for the two families in terms of Jacobi’s functions. The intensity-dependent transmission of a fiber placed between two crossed polarizers is calculated. Optimal conditions for efficient nonlinear switching compatible with mode-locking applications are determined. The general case of a nonlinear fiber ring with an intracavity polarizer placed between two polarization controllers is also considered.

We consider the cloaking of a slab object in scalar wave theory within the first-order Born approximation. We show that in the forward direction cloaking is achieved for any transversally invariant, positively refracting, and absorbing object by using a lossy, negative-index metamaterial cloak. Cloaking is perfect and occurs for incident fields having any spatial structure and bandwidth. In the backward direction cloaking is found to be possible for self-imaging fields. In both cases the refractive-index distribution and dispersive properties of the cloak slab resemble those of the object slab. The method of object-dependent cloaking with weak scatterers may find useful applications.

We demonstrate the creation of vibrational wave packets on multiple electronic states of a molecule via strong-field ionization. Furthermore, we show that the relative contribution of the different electronic states depends on the shape of the laser pulse which launches the wave packets.

We investigate a two-species Fermi gas in which one species is confined in two parallel layers and interacts with the other species in the three-dimensional space by a tunable short-range interaction. Based on the controlled weak coupling analysis and the exact three-body calculation, we show that the system has a rich phase diagram in the plane of the effective scattering length and the layer separation. Resulting phases include an interlayer $s$-wave pairing, an intralayer $p$-wave pairing, a dimer Bose-Einstein condensation, and a Fermi gas of stable Efimov-like trimers. Our system provides a widely applicable scheme to induce long-range interlayer correlations in ultracold atoms.

Benedict et al. and Kenfack et al. advocated nonclassicality indicators based on the measurement of negativity of the Wigner distribution functions. These indicators have some applications in quantum mechanics and quantum optics. In this paper we define a nonclassicality indicator in terms of the interference in phase space, which is applicable to some real distribution functions including those of Wigner. As a special case one may reproduce the previous results using our indicator for the Wigner distribution functions. This indicator is examined for cases of the Schrödinger cat state and the thermal states and the results are compared with those obtained by previous methods. It seems that the physical behavior of nonclassicality indicators originates in the uncertainty principle. This is shown by an onto correspondence between these indicators and the uncertainty principle.

We study the quantum critical behavior of the $\mathit{XY}$ spin chain with multisite interaction by means of a fidelity susceptibility (FS) calculation. The key ingredients (e.g., finite-size scaling behavior, universality principle) of the quantum criticality near the critical point are investigated carefully. The results show that the FS calculation is reliable to characterize the quantum critical behavior and that the multisite interaction can induce the redistribution of the criticality region.

We study quantum compression and decompression of light pulses that carry quantum information using a photon-echo quantum memory technique with controllable inhomogeneous broadening of an isolated atomic absorption line. We investigate media with differently broadened absorption profiles, transverse and longitudinal, finding that the recall efficiency can be as large as unity and that the quantum information encoded into the photonic qubits can remain unperturbed. Our results provide insight into reversible light-atom interaction and are interesting in view of future quantum communication networks, where pulse compression and decompression may play an important role in increasing the qubit rate or in mapping quantum information from photonic carriers with large optical bandwidth into atomic memories with smaller bandwidth.

The fine structure of high-$L$ $n$ $=$ $19$ and $20$ Rydberg states of Ba${}^{+}$ has been measured precisely using the resonant excitation Stark ionization spectroscopy technique, allowing for a determination of the Ba${}^{2+}$ polarizability: ${\alpha }_D$(Ba${}^{2+}$) $=$ $10.75(10)$ a.u. This result, in combination with an improved model of the $K$ splittings in Ba Rydberg levels, allows for a more precise determination of the Ba${}^{+}$ dipole transition strengths connecting the $6$$\hspace{0.5em}{}^2{S}_{1/2}$ ground state to the $6$$\hspace{0.5em}{}^2{P}_{1/2}$ and $6$$\hspace{0.5em}{}^2{P}_{3/2}$ excited states. The results, in atomic units, are $\langle$$6$$\hspace{0.5em}{}^2{S}_{1/2}\hspace{0.5em}\left|\right|D\left|\right|\hspace{0.5em}6\hspace{0.5em}{}^2{P}_{1/2}\rangle$ $=$ $3.3251(21)$ and $\langle$6$\hspace{0.5em}{}^2{\mathrm{S}}_{1/2}\hspace{0.5em}\left|\right|D\left|\right|\hspace{0.5em}6\hspace{0.5em}{}^2{P}_{3/2}\rangle$ $=$ $4.7017(27)$.

We present the coherent excitation of a single Rubidium atom to the Rydberg state $58d_{3/2}$ using a two-photon transition. The experimental setup is described in detail, as are experimental techniques and procedures. The coherence of the excitation is revealed by observing Rabi oscillations between ground and Rydberg states of the atom. We analyze the observed oscillations in detail and compare them to numerical simulations which include imperfections of our experimental system. Strategies for future improvements on the coherent manipulation of a single atom in our settings are given.

In this work we characterize a state-insensitive dipole trap for cold cesium atoms, as realized by tightly focusing a single running laser beam at the magic wavelength. The use of trapping light at the magic wavelength of $935.6$ nm resulted in the same ac Stark shift for the ${}^6{S}_{1/2}$ ground state and the ${}^6{P}_{3/2}$ excited state. A complete characterization of the trap is given, which includes the dependence of the lifetime on the trap depth, an analysis of the important role played by a depumper beam, and a comparison with dipole trapping at different (nonmagic) wavelengths. In particular, we measured the differential light shift of the relevant optical transition as a function of the trapping light wavelength, and showed that it becomes zero at the magic wavelength. Our results are compared to previous realizations of state-insensitive dipole traps for cesium atoms. We also discuss the possible role of the state-insensitive trap, its limitations, and possible developments for the study of ground-state quantum coherence phenomena and related applications.

We study experimentally and numerically the equilibrium density profiles of a trapped two-dimensional ${}^{87}\mathrm{Rb}$ Bose gas and investigate the equation of state of the homogeneous system using the local density approximation. We find a clear discrepancy between in situ measurements and quantum Monte Carlo simulations, which we attribute to a nonlinear variation of the optical density of the atomic cloud with its spatial density. However, good agreement between experiment and theory is recovered for the density profiles measured after time of flight, taking advantage of their self-similarity in a two-dimensional expansion.

We propose a control mechanism for the stabilization of symmetry-broken modes in Bose-Einstein condensates and optical beams trapped in double-well potentials in the presence of symmetric or asymmetric noise. The control, based on periodic $\pi$ shifts of the phase in one well, is demonstrated for solitons and in the two-mode approximation. The latter setting is considered in both the mean-field and quantum (Bose-Hubbard) regimes.

An ultracold gas of heteronuclear alkali-metal dimer molecules with hyperfine structure loaded into a one-dimensional optical lattice is investigated. The hyperfine molecular Hubbard Hamiltonian (HMHH), an effective low-energy lattice Hamiltonian, is derived from first principles. The large permanent electric dipole moment of these molecules gives rise to long-range dipole-dipole forces in a dc electric field and allows for transitions between rotational states in an ac microwave field. Additionally, a strong magnetic field can be used to control the hyperfine degrees of freedom independently of the rotational degrees of freedom. By tuning the angle between the dc electric and magnetic fields and the strength of the ac field, it is possible to control the number of internal states involved in the dynamics as well as the degree of correlation between the spatial and internal degrees of freedom. The HMHH’s unique features have direct experimental consequences such as quantum dephasing, tunable complexity, and the dependence of the phase diagram on the molecular state.

We model the dynamics of two species of bosonic atoms trapped in an optical lattice within the Mott regime by mapping the system onto a spin model. A field gradient breaks the cloud into two domains. We study how the domain wall evolves under adiabatic and diabatic changes of this gradient. We determine the time scales for adiabaticity and study how temperature evolves for slow ramps. We show that after large, sudden changes of the field gradient, the system does not equilibrate on typical experimental time scales. We find interesting spin dynamics even when the initial temperature is large compared to the superexchange energy. We discuss the implication of our results for researchers wishing to use such a two-component system for thermometry or as part of a cooling scheme.

Fourier-expanded Maxwell-Liouville equations are employed to study the light pulse dynamics in atomic samples coherently driven by a standing-wave light field. Solutions are obtained by a suitable truncation of the Maxwell-Liouville equations that contain the number of spin and optical Fourier coherence components appropriate to the sample temperature. This approach is examined here for cold but thermal atoms where the Doppler broadening is still not negligible and familiar secular approximations no longer hold. In this temperature regime higher-order momentum Fourier coherence components are shown to be important for achieving excellent agreement with a recent experiment done in cold ${}^{87}\mathrm{Rb}$ clouds at several hundred microkelvins.

For a quantum system with broken parity symmetry, selection rules cannot hold and cyclic transition structures are generated. With these loop transitions we discuss how to achieve inversionless gain of the probe field by properly setting the control and auxiliary fields. Possible implementations of our generic proposal with specific physical objects with broken parities (e.g., superconducting circuits and chiral molecules) are also discussed.

Based on the theory of electromagnetically induced transparency, we study the formation of all-optical blazed transmission gratings in a coherently driven three-level atomic system using intensity-modulated images in coupling fields. Also, we analyze the feasibility of high-speed (megahertz) modulation for the induced gratings by means of image-bearing flat-top pulse trains. Consequently, continuous-wave probe fields can be efficiently and rapidly deflected in free space. When more sophisticated images are adopted, our scheme can provide further possibilities of all-optical beam splitting and fanning.

In this article, we consider the dynamic Casimir-Polder force between an atom and a conducting wall in a one-dimensional cavity. Using quasimode theory to describe the dissipation of the electromagnetic fields in the cavity, our investigation shows that the force oscillations are damped in a short time, and tend to a final, steady, negative value. We discuss in detail the effects on the force of the quasimode decay rate, the cavity size, and the atom-wall distance.

We investigate how various versions of the molecular strong-field approximation (MSFA) agree with the experiment by Grasbon et al. [Phys. Rev. A 63, 041402(R) (2001)], in which the suppression of the ionization yield in the low-energy spectrum of the ${\mathrm{O}}_2$ molecule, compared to the spectrum of its companion atom Xe, was observed. In this experiment, it was also found that the spectrum of the ${\mathrm{N}}_2$ molecule is comparable to the corresponding spectrum of its companion atom Ar. We show that the length-gauge version of the MSFA with the initial state dressed by the laser field gives the best agreement with the experimental data for both ${\mathrm{O}}_2$ and ${\mathrm{N}}_2$ molecules.