We compare two different tests of quantum nonlocality, both in theoretical terms and with respect to a possible implementation in a mesoscopic circuit: Hardy’s test [L. Hardy, Phys. Rev. Lett. 68, 2981 (1992)] and the Clauser-Horne-Shimony-Holt (CHSH) test, the latter including a recently discovered inequality relevant for experiments with three possible outcomes [D. Collins and N. Gisin, J. Phys. A 37, 1775 (2004)]. We clarify the geometry of the correlations defined by Hardy’s equations with respect to the polytope of causal correlations, and show that these equations generalize to the CHSH inequality if the slightest imperfections in the setup need to be taken into account. We propose a mesoscopic circuit consisting of two interacting Mach-Zehnder interferometers in a Hall bar system for which both Hardy’s test and the CHSH test can be realized with a simple change of gate voltages, and evaluate the robustness of the two tests in the case of fluctuating experimental parameters. The proposed setup is remarkably robust and should work for fluctuations of beam splitter angles or phases up to the order of 1 radian, or single particle loss rates up to about 15%.

We experimentally realize the $1\to 2$ optimal universal quantum cloning machine for arbitrary qubits and the ancilla-free $1\to 3$ optimal phase-covariant quantum cloning machine for $x\text{−}y$ equatorial qubits, which were constructed by Zou et al. [Phys. Lett. A 366, 36 (2007)]. The qubits are represented by the polarization states of photons prepared from the process of spontaneous parametric down-conversion. The copies of each machine are shown to have almost equal fidelities conditioned on fourfold coincidences.

I present an experimental realization of a coherent-feedback control system that was recently proposed for testing basic principles of linear quantum stochastic control theory [M. R. James, H. I. Nurdin, and I. R. Petersen, e-print arXiv:quant-ph/0703150v2, IEEE Transactions on Automatic Control (to be published)]. For a dynamical plant consisting of an optical ring resonator, I demonstrate $\sim 7\mathrm{dB}$ broadband disturbance rejection of injected laser signals via all-optical feedback with a tailored dynamic compensator. Comparison of the results with a transfer function model pinpoints critical parameters that determine the coherent-feedback control system’s performance.

We illustrate how to apply modern effective field theory techniques and dimensional regularization to factorize the various scales that appear in nonrelativistic bound states at finite temperature. We focus here on the simplest case: the hydrogen atom. We discuss in detail the interplay of the hard, soft, and ultrasoft scales of the nonrelativistic system at zero temperature with the additional scales induced at finite temperature. We also comment on the implications of our results for heavy quarkonium bound states in the quark gluon plasma.

Theoretical antiproton and proton cross sections for ionization and excitation of hydrogen molecules as well as energy spectra of the ionized electrons were calculated in the impact-energy range from $8\text{to}4000\mathrm{keV}$. The cross sections were computed with the close-coupling formulation of the semiclassical impact-parameter method. The target was described using a one-active electron model centered on the target and assuming a fixed internuclear distance during the collision process. The dependence of the ionization cross sections on the internuclear distance is examined. The present cross sections are compared with experimental and theoretical data from the literature. For impact energies $E⩾90\mathrm{keV}$ the obtained results for ionization by antiproton impact are comparable to the experimental data while they disagree for energies $E<80\mathrm{keV}$.

Neutral impact collision ion scattering spectroscopy allows to determine concentration depth profiles. The method makes use of the energy loss of projectiles passing through matter to gain the depth information. The energy losses of the projectiles obey a statistical distribution, the energy-loss straggling. The energy-loss spectra are mainly given by the energy-loss straggling and the concentration depth profiles. Knowing the energy-loss straggling quantitatively makes it possible to deconvolute the energy-loss spectra. Here we use the Poisson distribution to describe the energy-loss straggling. The Poisson distribution and a previously developed method are used to deconvolute the energy-loss spectra of iodide of aqueous LiI solutions with concentrations between 5 and $7.2m$. The iodide concentration depth profiles of these highly concentrated solutions are monotonous and do not show a local maximum near the surface.

Doubly excited core-hole states of carbon monoxide in the photon energy region of $300–305\mathrm{eV}$, i.e., directly above the C $1s$ ionization threshold, have been studied using both angle-resolved ion-yield and high-resolution resonant Auger spectroscopies. The leading configurations of the most prominent doubly excited Rydberg states are assigned by careful analysis of the ion-yield spectra and the final-state spectra to C $1s^{-1}$ $(5{\sigma }^{-1}2{\pi }^{1}S=1)$ $3s\sigma$ $(v^{\prime }=0,1,2)$, C $1s^{-1}$ $(5{\sigma }^{-1}2{\pi }^{1}S=0)$ $3s\sigma$ $(v^{\prime }=0,1,2)$, and C $1s^{-1}$ $(5{\sigma }^{-1}2{\pi }^{1}S=1)$ $4s\sigma$ $(v^{\prime }=0,1)$, which can only be populated via a conjugate shake-up process. Analysis of the resonant Auger spectra provides an assignment of several two-hole–one-electron $\left(2h\text{−}1e\right)$ final states.

Quantum tomography based on high-order-harmonic generation in molecules is potentially a powerful technique to image electron orbitals. However, many assumptions are needed to reconstruct the spatial orbital structure from the harmonic spectrum. With two-dimensional model calculations, we examine several of these assumptions and find their validity depends strongly on the orbital symmetry and reconstruction axis. In fact, for certain symmetries we cannot find a reconstruction procedure that gives good results. We compare the length and velocity forms of the dipole interaction and find that the form of the dipole strongly affects the quality of the orbital reconstruction. For all of the wave functions studied, the velocity form works as well or better than the length form and may be the best method for quantum tomography. Moreover, in many cases, using the harmonic radiation polarized perpendicular to the molecular axis gives much better results than the parallel polarization. Finally, we examine the minima in the harmonic spectra as a function of angle and find that they cannot always be interpreted as a two-center interference effect.

The superfluid phase diagrams of a two-dimensional cold polarized Fermi gas in the BCS-BEC crossover are systematically and analytically investigated. In the BCS-Leggett mean-field theory, the transition from unpolarized superfluid phase to normal phase is always of first order. For a homogeneous system, the two critical Zeeman fields and the critical population imbalance are analytically determined in the whole coupling parameter region, and the superfluid-normal mixed phase is shown to be the ground state between the two critical fields. The density profile in the presence of a harmonic trap calculated in the local-density approximation exhibits a shell structure, a superfluid core at the center, and a normal shell outside. For weak interaction, the normal shell contains a partially polarized cloud with constant density difference surrounded by a fully polarized state. For strong interaction, the normal shell is in a fully polarized state with a density profile depending only on the global population imbalance. The difermion bound states can survive in the whole highly imbalanced normal phase.

We rigorously prove that when a bounded light beam is incident on an interface, a part of its plane wave components propagate according to the reverse mode of the ordinary reflection and transmission. Based on the two propagation modes, we propose the definition of the generalized reflection and transmission. With this definition, we solve the controversy about the Goos-Hänchen shift approaching the grazing incidence limit, and release the angular expansion method from the precondition which requires that the beam spread angle should not exceed the complement of the incident angle. Then the spectrum superposition effect is investigated for the incidence circumstance whose beam spread angle exceeds the complement of the incident angle.

Random quasi-phase-matching (RQPM) of the second-harmonic generation process is investigated experimentally and theoretically in a strongly randomized spontaneously grown nonlinear photonic crystal structure of strontium tetraborate. The thickness of domains in the structure is measured and employed in calculations of angular and spectral dependences of random quasi-phase-matching. Despite the great scale of randomness, the RQPM effect is preserved. The calculated enhancement factor due to RQPM is in excellent agreement with experiment, and good agreement between calculations and experiment is obtained for the shape of the angular dependence of RQPM. The calculated spectral dependence of RQPM consists of a number of narrow peaks, and a maximum enhancement factor is attained in the near ultraviolet. The band structure of randomized nonlinear photonic crystal is calculated.

We investigate the violation of Bell-type inequalities for two-qubit Werner-like states parametrized by the positive parameter $0⩽p⩽1$. We use an unbalanced homodyne detection scheme to obtain the quantum mechanical probabilities. A violation of the Bell-Wigner and Janssens inequalities is obtained for a large range of the parameter $p$. The range given by these inequalities is greater than the one given by the Clauser-Horne inequality. The range in which a violation is attained actually coincides with the range where the Werner-like states are known to be nonseparable, i.e., for $p>1∕3$. However, the improvement over the Clauser-Horne inequality is achieved at the price of restricting the class of possible local hidden variable theories.

We consider entanglement swapping for certain mixed states. We assume that the initial states have the same singlet fraction and show that the final state can have a singlet fraction greater than that of the initial states. We also consider two subsequent teleportations and show that entanglement swapping can increase teleportation fidelity. Finally, we show how this effect can be demonstrated with linear optics.

Fully relativistic, four-component density-functional-theory calculations were performed on $M{\mathrm{O}}_4$ ($M=\mathrm{Ru}$, Os, and element 108, Hs). Implementation of the noncollinear spin-polarized approximation in the method and the usage of large optimized sets of numerical basis functions have resulted in a high accuracy of the calculated molecular properties, especially the molecular polarizabilities. The calculated properties were used to determine the adsorption energy of $\mathrm{Hs}{\mathrm{O}}_4$ on inert surfaces using a physisorption model. The calculated $-\Delta H_{\mathrm{ads}}\left(\mathrm{Hs}{\mathrm{O}}_4\right)=45.4\pm 1\mathrm{kJ}∕\mathrm{mol}$ on quartz is in excellent agreement with the experimental value of $46\pm 2\mathrm{kJ}∕\mathrm{mol}$. Our calculations indicate a reversal of the trend in the volatility of $M{\mathrm{O}}_4$ (as desorption from the surface) in group 8, $\mathrm{Ru}{\mathrm{O}}_4<\mathrm{Os}{\mathrm{O}}_4>\mathrm{Hs}{\mathrm{O}}_4$, a trend that is also observed experimentally. Although inclusion of relativistic effects is crucial for obtaining accurate energetics, the general trends in the properties (e.g., volatility) of the $M{\mathrm{O}}_4$ compounds are already reproduced within a nonrelativistic treatment.

We analyze second-order $M1\text{−}M1$ and $M1\text{−}E2$ effects on the hyperfine structure (HFS) of the lowest-energy $P$ states of alkali-metal atoms arising from the coupling of the two $(J=1∕2,3∕2)$ fine-structure levels through the hyperfine interaction. We find these effects to be especially sizable in Li, leading to a $9\sigma$ correction to the most accurate reported experimental value of the $A\left(P_{1∕2}\right)$ HFS constant of ${}^7\mathrm{Li}$ [Das and Natarajan, J. Phys. B 41, 035001 (2008)]. For the remaining alkali-metal systems, the results tabulated within may be referenced as higher precision is sought in experimental determination of the HFS constants.

We have studied heteronuclear and homonuclear excited-state–ground-state collisions by loading both ${}^{85}\mathrm{Rb}$ and ${}^{87}\mathrm{Rb}$ into a far off resonant trap (FORT). Because of the relatively weak confinement of the FORT, we expect the hyperfine structure of the different isotopes to play a crucial role in the collision rates. This dependence on hyperfine structure allows us to measure collisions associated with long-range interatomic potentials of different structures, such as long and short ranged; or such as purely attractive, purely repulsive, or mixed attractive and repulsive. We observe significantly different loss rates for different excited-state potentials. Additionally, we observe that some collisional channels’ loss rates are saturated at our operating intensities $(15\mathrm{mW}∕{\mathrm{cm}}^2)$. These losses are important limitations in loading dual isotope optical traps.

The Stark deceleration of OH radicals in both low-field-seeking and high-field-seeking levels of the rovibronic ${}^2\Pi _{3∕2}$, $v=0$, $J=3∕2$ ground state is demonstrated using a single experimental setup. Applying alternating-gradient focusing, OH radicals in their low-field-seeking ${}^2\Pi _{3∕2}$, $v=0$, $J=3∕2$, $f$ state have been decelerated from $345\text{to}239\mathrm{m}∕\mathrm{s}$, removing 50% of the kinetic energy using only 27 deceleration stages. The alternating-gradient decelerator allows one to independently control longitudinal and transverse manipulation of the molecules. Optimized high-voltage switching sequences for the alternating-gradient deceleration are applied, in order to adjust the dynamic focusing strength in every deceleration stage to the changing velocity over the deceleration process. In addition we have also decelerated OH radicals in their high-field-seeking ${}^2\Pi _{3∕2}$, $v=0$, $J=3∕2$, $e$ state from $355\text{to}316\mathrm{m}∕\mathrm{s}$. For the states involved, a real crossing of hyperfine levels occurs at $640\mathrm{V}∕\mathrm{cm}$, which is examined by varying a bias voltage applied to the electrodes.

We study the two-component repulsive Fermi gas with imbalanced populations in one dimension. Starting from the Bethe ansatz solution we calculate analytically the phase diagram for the homogeneous system. We show that three phases appear: the balanced phase, the fully polarized phase, and the partially polarized phase. By means of the local density approximation and the equation of state for the homogeneous system we calculate the density profile for the harmonically confined case. We show that a two-shell structure appears: at the center of the cloud we find the partially polarized phase and at the edges the fully polarized one. The radii of the inner and outer shells are calculated for different values of the polarization and the coupling strength. We calculate the dependence of the magnetization on the polarization for different values of the coupling strength and we show that the susceptibility is always finite.

The absorption spectrum is considered for a two-level atom coherently driven by a laser field and incoherently perturbed by stochastic noise. In the noise-dominated regime where incoherent perturbation far exceeds coherent excitation, the amplifying and dispersionlike components in the standard absorption spectrum [B. R. Mollow, Phys. Rev. A 5, 2217 (1972); F. Y. Wu et al., Phys. Rev. Lett 38, 1077 (1977)] develop into an absorption peak and a narrow dip, respectively. The modified absorption spectrum is attributed to the quantum interference induced by stochastic noise.