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We report a multiple-loop guided atom interferometer in which the atoms make 200 small-amplitude roundtrips, instead of one large single orbit. The approach is enabled by using ultracold 39K gas and a magnetic Feshbach resonance that can tune the s-wave scattering length across zero to significantly reduce the atom loss from cold collisions. This scheme is resilient against noisy environments, achieving 0.9 s interrogation time without any vibration noise isolation or cancellation. A form of quantum lock-in amplification can be used with the device to measure localized potentials with high sensitivity. We used this technique to measure the dynamic polarizability of the 39K ground state at 1064 nm. The interferometer may also be a useful approach to building a compact multiple-loop Sagnac atom interferometer for rotation sensing., Comment: 13 pages, 11 figures

An integrated coherent matter wave circuit is a single device, analogous to an integrated optical circuit, in which coherent de Broglie waves are created and then launched into waveguides where they can be switched, divided, recombined, and detected as they propagate. Applications of such circuits include guided atom interferometers, atomtronic circuits, and precisely controlled delivery of atoms. Here we report experiments demonstrating integrated circuits for guided coherent matter waves. The circuit elements are created with the painted potential technique, a form of time-averaged optical dipole potential in which a rapidly-moving, tightly-focused laser beam exerts forces on atoms through their electric polarizability. The source of coherent matter waves is a Bose-Einstein condensate (BEC). We launch BECs into painted waveguides that guide them around bends and form switches, phase coherent beamsplitters, and closed circuits. These are the basic elements that are needed to engineer arbitrarily complex matter wave circuitry., Comment: 18 pages, 9 figures. Replaced with the published version

Bessel beams are plane waves with amplitude profiles described by Bessel functions. They are important because of their property of limited diffraction and their capacity to carry orbital angular momentum. Here we report the creation of a Bessel beam of de Broglie matter waves. The Bessel beam is produced by the free evolution of a thin toroidal atomic Bose-Einstein condensate (BEC) which has been set into rotational motion. By attempting to stir it at different rotation rates, we show that the toroidal BEC can only be made to rotate at discrete, equally-spaced frequencies, demonstrating that circulation is quantized in atomic BECs. The method used here to generate matter wave Bessel beams with a Painted Potential can be viewed as a form of wavefunction engineering which might be extended to implement arbitrary cold atom matter wave holography.

We report the creation of a pair of Josephson junctions on a toroidal dilute gas Bose-Einstein condensate (BEC), a configuration that is the cold atom analog of the well-known dc superconducting quantum interference device (SQUID). We observe Josephson effects, measure the critical current of the junctions, and find dynamic behavior that is in good agreement with the simple Josephson equations for a tunnel junction with the ideal sinusoidal current-phase relation expected for the parameters of the experiment. The junctions and toroidal trap are created with the painted potential, a time-averaged optical dipole potential technique which will allow scaling to more complex BEC circuit geometries than the single atom-SQUID case reported here. Since rotation plays the same role in the atom SQUID as magnetic field does in the dc SQUID magnetometer, the device has potential as a compact rotation sensor., Comment: 5 pages, 4 figures. Replacement to match published version

We investigate the effect of a strong magnetic field on the structure of neutron stars in a model with perturbative $f(R)$ gravity. The effect of an interior strong magnetic field of about $10^{17 \sim 18}$ G on the equation of state is derived in the context of a quantum hadrodynamics (QHD) model. We solve the modified spherically symmetric hydrostatic equilibrium equations derived for a gravity model with $f(R)=R+\alpha R^2$. Effects of both the finite magnetic field and the modified gravity are detailed for various values of the magnetic field and the perturbation parameter $\alpha$ along with a discussion of their physical implications. We show that there exists a parameter space of the modified gravity and the magnetic field strength, in which even a soft equation of state can accommodate a large ($> 2$ M$_\odot$) maximum neutron star mass through the modified mass-radius relation.

We summarize several new developments in the nuclear equation of state for supernova simulations and neutron stars. We discuss an updated and improved Notre-Dame-Livermore Equation of State (NDL EoS) for use in supernovae simulations. This Eos contains many updates. Among them are the effects of 3- body nuclear forces at high densities and the possible transition to a QCD chiral and/or super-conducting color phase at densities. We also consider the neutron star equation of state and neutrino transport in the presence of strong magnetic fields. We study a new quantum hadrodynamic (QHD) equation of state for neutron stars (with and without hyperons) in the presence of strong magnetic fields. The parameters are constrained by deduced masses and radii. The calculated adiabatic index for these magnetized neutron stars exhibit rapid changes with density. This may provide a mechanism for star-quakes and flares in magnetars. We also investigate the strong magnetic field effects on the moments of inertia and spin down of neutron stars. The change of the moment of inertia associated with emitted magnetic flares is shown to match well with observed glitches in some magnetars. We also discuss a perturbative calculation of neutrino scattering and absorption in hot and dense hyperonic neutron-star matter in the presence of a strong magnetic field. The absorption cross-sections show a remarkable angular dependence in that the neutrino absorption strength is reduced in a direction parallel to the magnetic field and enhanced in the opposite direction. The pulsar kick velocities associated with this asymmetry comparable to observed pulsar velocities and may affect the early spin down rate of proto-neutron star magnetars with a toroidal field configuration., Comment: 6 pages, revised 1 figure, International Symposium "Exotic Nuclear Structure From Nucleons" (ENSFN 2012)

We calculate the spin deceleration of proto-neutron stars by asymmetric neutrino absorption in the context of a fully relativistic mean field theory. We calculate for the first time the spin deceleration of neutron stars due to asymmetric neutrino absorption in a toroidal magnetic field configurations. We find a surprising effect that the deceleration can much larger for asymmetric neutrino absorption in a toroidal magnetic field than the usually presumed braking due to magnetic dipole radiation. This may explain the observation that magnetars appear to have had a more rapid deceleration in the past., Comment: 13 pages, 1 figure, 1 table

We report on first evidence of wave activity during neutral beam heating in KSTAR plasmas: 40 kHz magnetic fluctuations with a toroidal mode number of n=1. Our analysis suggests this a beta-induced Alfven eigenmode resonant with the q=1 surface. A kinetic analysis, when coupled with electron temperature measurements from electron cyclotron emission and ion/electron temperature ratios from crystallography, enables calculation of the frequency evolution, which is in agreement with observations. Complementary detailed MHD modelling of the magnetic configuration and wave modes supports the BAE mode conclusion, by locating an n=1 mode separated from the continuum in the core region. Finally, we have computed the threshold to marginal stability for a range of ion temperature profiles. These suggest the BAE can be driven unstable by energetic ions when the ion temperature radial gradient is sufficiently large. Our findings suggest that mode existence could be used as a form of inference for temperature profile consistency in the radial interval of the mode, thereby extending the tools of MHD spectroscopy., Comment: 12 pages, 6 figures, submitted to Plasma Physics and Controlled Fusion

We have considered the antikaon condensation in a neutron star in the presence of strong magnetic fields by using the modified quark-meson coupling (MQMC) model. The structure of the neutron star is investigated with various magnetic fields and different kaon optical potentials, and the effects of the magnetic fields for kaon condensation is discussed. When employing strong magnetic fields inside a neutron star with hyperons and kaon condensation, the magnetic fields can cause the equation of state to be stiff; thus, a large maximum mass of the neutron star can be obtained., Comment: published in J. Korean Phys.Soc

We investigate medium effects due to density-dependent magnetic moments of baryons on neutron stars under strong magnetic fields. If we allow the variation of anomalous magnetic moments (AMMs) of baryons in dense matter under strong magnetic fields, AMMs of nucleons are enhanced to be larger than those of hyperons. The enhancement naturally affects the chemical potentials of baryons to be large and leads to the increase of a proton fraction. Consequently, it causes the suppression of hyperons, resulting in the stiffness of the equation of state. Under the presumed strong magnetic fields, we evaluate relevant particles' population, the equation of state and the maximum masses of neutron stars by including density-dependent AMMs and compare them with those obtained from AMMs in free space.

We investigate the change of magnetic moments of octet baryons in nuclear matter at a finite density and temperature. Quark-meson coupling models are employed in describing properties of octet baryons and their interactions. Magnetic moments of octet baryons are found to increase non-negligibly as density and temperature increase, and we find that temperature dependence can be strongly correlated with the quark-hadron phase transition. Model dependence is also examined by comparing the results from the quark-meson coupling (QMC) model to those by the modified QMC (MQMC) model where the bag constant is assumed to depend on density. Both models predict sizable dependence on density and temperature, but the MQMC model shows a more drastic change of magnetic moments. Feasible changes of the nucleon mass by strong magnetic fields are also reported in the given models., Comment: 12 pages

We investigate the properties of an antikaon in medium, regarding itas a MIT bag. We first construct the MIT bag model for a kaon with$\sigma^*$ and $\phi$ in order to describe the interaction of$s$-quarks in hyperonic matter in the framework of the modifiedquark-meson coupling model. The coupling constant $g'^{B_K}_\sigma$in the density-dependent bag constant $B(\sigma)$ is treated as afree parameter to reproduce the optical potential of a kaon in asymmetric matter and all other couplings are determined by usingSU(6) symmetry and the quark counting rule. With various values ofthe kaon potential, we calculate the effective mass of a kaon inmedium to compare it with that of a point-like kaon. We thencalculate the population of octet baryons, leptons and $K^-$ and theequation of state for neutron star matter. The results show thatkaon condensation in hyperonic matter is sensitive to the $s$-quarkinteraction and also to the way of treating the kaon. The mass andthe radius of a neutron star are obtained by solving theTolmann-Oppenheimer-Volkoff equation., Comment: 14 figures

There is a pressing need for robust and straightforward methods to create potentials for trapping Bose-Einstein condensates which are simultaneously dynamic, fully arbitrary, and sufficiently stable to not heat the ultracold gas. We show here how to accomplish these goals, using a rapidly-moving laser beam that "paints" a time-averaged optical dipole potential in which we create BECs in a variety of geometries, including toroids, ring lattices, and square lattices. Matter wave interference patterns confirm that the trapped gas is a condensate. As a simple illustration of dynamics, we show that the technique can transform a toroidal condensate into a ring lattice and back into a toroid. The technique is general and should work with any sufficiently polarizable low-energy particles., Comment: Minor text changes and three references added. This is the final version published in New Journal of Physics

We calculate the magnetic moments of hyperons in dense nuclear matter by using relativistic quark models. Hyperons are treated as MIT bags, and the interactions are considered to be mediated by the exchange of scalar and vector mesons which are approximated as mean fields. Model dependence is investigated by using the quark-meson coupling model and the modified quark-meson coupling model; in the former the bag constant is independent of density and in the latter it depends on density. Both models give us the magnitudes of the magnetic moments increasing with density for most octet baryons. But there is a considerable model dependence in the values of the magnetic moments in dense medium. The magnetic moments at the nuclear saturation density calculated by the quark meson coupling model are only a few percents larger than those in free space, but the magnetic moments from the modified quark meson coupling model increase more than 10% for most hyperons. The correlations between the bag radius of hyperons and the magnetic moments of hyperons in dense matter are discussed., Comment: substantial changes in the text, submitted to PLB

We present experimental results on a Bose gas in a quasi-2D geometry near the Berezinskii, Kosterlitz and Thouless (BKT) transition temperature. By measuring the density profile, \textit{in situ} and after time of flight, and the coherence length, we identify different states of the gas. In particular, we observe that the gas develops a bimodal distribution without long range order. In this state, the gas presents a longer coherence length than the thermal cloud; it is quasi-condensed but is not superfluid. Experimental evidence indicates that we observe the superfluid transition (BKT transition)., Comment: 5 pages, 6 figures

We have observed the persistent flow of Bose-condensed atoms in a toroidal trap. The flow persists without decay for up to 10 s, limited only by experimental factors such as drift and trap lifetime. The quantized rotation was initiated by transferring one unit, $\hbar$, of the orbital angular momentum from Laguerre-Gaussian photons to each atom. Stable flow was only possible when the trap was multiply-connected, and was observed with a BEC fraction as small as 15%. We also created flow with two units of angular momentum, and observed its splitting into two singly-charged vortices when the trap geometry was changed from multiply- to simply-connected., Comment: 1 file, 5 figures

Bragg spectroscopy is used to measure excitations of a trapped, quantum-degenerate gas of 87Rb atoms in a 3-dimensional optical lattice. The measurements are carried out over a range of optical lattice depths in the superfluid phase of the Bose-Hubbard model. For fixed wavevector, the resonant frequency of the excitation is found to decrease with increasing lattice depth. A numerical calculation of the resonant frequencies based on Bogoliubov theory shows a less steep rate of decrease than the measurements., Comment: 11 pages, 4 figures

We use the modified quark-meson coupling and the quantum hadrodynamics models to study the properties of neutron star. Coupling constants of both models are adjusted to reproduce the same saturation properties. The onset of kaon condensation in neutron star matter is studied in detail over a wide range of kaon optical potential values. Once the kaon condensation takes place, the population of kaons increases very rapidly, and kaons become the dominant component, possibly making the neutron star matter a kaonic matter if the kaon optical potential is large., Comment: 4 pages, 12 eps figures, contribution to the proceedings of IX International Conference on Hypernuclear and Strange Particle Physics, 10-14 October 2006, Mainz, Germany

We demonstrate the coherent transfer of the orbital angular momentum of a photon to an atom in quantized units of hbar, using a 2-photon stimulated Raman process with Laguerre-Gaussian beams to generate an atomic vortex state in a Bose-Einstein condensate of sodium atoms. We show that the process is coherent by creating superpositions of different vortex states, where the relative phase between the states is determined by the relative phases of the optical fields. Furthermore, we create vortices of charge 2 by transferring to each atom the orbital angular momentum of two photons., Comment: New version, 4 pages and 3 figures, accepted for publication in Physical Review Letters

We use the modified quark-meson coupling (MQMC) model to study the composition profile of neutron star matter and compare the results with those calculated by quantum hadrodynamics (QHD). Both MQMC and QHD model parameters are adjusted to produce exactly the same saturation properties so that we can investigate the model dependences of the matter composition at high densities. We consider the possibility of deep kaon optical potential and find that the composition of matter is very sensitive to the interaction strength of kaons with matter. The onset densities of the kaon condensation are studied in detail by varying the kaon optical potentials. We find that the MQMC model produces the kaon condensation at lower densities than QHD. The presence of kaon condensation changes drastically the population of octet baryons and leptons. Once the kaon condensation takes place, the population of kaons builds up very quickly, and kaons become the dominant component of the matter. We find that the $\omega$-meson plays an important role in increasing the kaon population and suppressing the hyperon population., Comment: Significant changes from previous version. Version to appear in PRC

It has recently been demonstrated that quantum degenerate gases of very weakly bound molecules can be produced by atomic gases with Feshbach resonances. More strongly bound molecules can be produced with Raman photoassociation of a quantum gas, although this process has not yet been shown to produce a quantum degenerate molecular gas. In principle, Feshbach resonance and Raman photoassociation can be quantum-mechanically reversible, and lead to collective coherent phenomena such as Rabi cycling between an atomic and a molecular gas. However, such atom-molecular coherence has only partly been realized experimentally. Effects that may limit coherence include thermalizing elastic collisions, inelastic collisions, spontaneous Raman scattering, and pairing field formation. Here, we demonstrate a method that circumvents these limitations, based on Raman photoassociation of atoms in an optical lattice and driven into a Mott insulator state. We find that the Raman photoassociation transition is resolved into discrete lines corresponding to the quantized lattice site occupancies, and demonstrate that this provides a new method to accurately determine the distribution of site occupancies and the atom-molecule scattering length. Furthermore, we observe a Raman-induced oscillation of the central core of the gas, containing about 30% of the atoms, between an atomic and a molecular gas., Comment: 14 pages, 4 figures

The in-medium mass of a $\thetaplus$, $\mtheta^*$, in cold symmetric nuclear matter is calculated by using the quark-meson coupling model. The $\Theta^+$ is treated as an MIT bag with the quark content $uudd\bar s$. Bag parameters for a free $\thetaplus$ are fixed to reproduce the observed mass of the $\thetaplus$. In doing so, we use three different values of the $s$-quark mass since the mass of the $s$-quark is not well known. As usual, the strengths of the $u$ and $d$ quark couplings to $\sigma$- and $\omega$-meson fields are determined to fit the nuclear saturation properties. However, the coupling constant $g_\sigma^s$ between the $s$-quark and the $\sigma$-meson cannot be fixed from the saturation properties, and thus we treat $g_\sigma^s$ as a free parameter and investigate how $\mtheta^*$ depends on $g_\sigma^s$. %$\mtheta^*$ is calculated up to 2.5 times the nuclear saturation density, %and we find that We find that $\mtheta^*$ depends significantly on the value of $g_\sigma^s$ but not on the mass of the $s$-quark. Chemical potentials of the $\Theta^+$ and the $K+N$ system are calculated to discuss the decay of a $\Theta^+$ in nuclear matter. We calculate the effective mass of a kaon in nuclear matter in two ways; using the optical potential of $K^-$ in matter and using quark model. By comparing the effective masses calculated from these two methods, we find the magnitude of the real part of the optical potential that is consistent with the usual quark model is about 100 MeV., Comment: 16 pages, 4 figures, 3 tables

We investigate the properties of the neutron star with relativistic mean field models. We incorporate in the quantum hadrodynamics and in the quark-meson coupling models a possible reduction of meson masses in nuclear matter. The equation of state for neutron star matter is obtained and is employed in Oppenheimer-Volkov equation to extract the maximum mass of the stable neutron star. We find that the equation of state, the composition and the properties of the neutron stars are sensitive to the values of the meson masses in medium., Comment: 18 pages, 5 figures and 2 tables. To be published in EPJA