2179030
Weyl superfluidity in a three-dimensional dipolar Fermi gas.
Weyl superconductivity or superfluidity, a fascinating topological state of matter, features novel phenomena such as emergent Weyl fermionic excitations and anomalies. Here we report that an anisotropic Weyl superfluid state can arise as a low temperature stable phase in a 3D dipolar Fermi gas. A crucial ingredient of our model is a direction-dependent two-body effective attraction generated by a rotating external field. Experimental signatures are predicted for cold gases in radio-frequency spectroscopy. The finite temperature phase diagram of this system is studied and the transition temperature of the Weyl superfluidity is found to be within the experimental scope for atomic dipolar Fermi gases.
118417209
Cyclotron dynamics of interacting bosons in artificial magnetic fields
We study theoretically quantum dynamics of interacting bosons in artificial magnetic fields as engineered in recent ultracold atomic experiments, where quantum cyclotron orbital motion has been observed. With exact numerical simulations and perturbative analyses, we find that interactions induce damping in the cyclotron motion. The damping time is found to be dependent on interaction and tunneling strengths monotonically, while its dependence on magnetic flux is non-monotonic. Sufficiently strong interactions would render bosons dynamically localized inhibiting the cyclotron motion. The damping predicted by us can be construed as an interaction-induced quantum decoherence of the cyclotron motion.
118410842
$p$-wave chiral superfluidity from an $s$-wave interacting atomic Fermi gas
X iv :1 40 2. 59 95 v1 [ co nd -m at .q ua nt -g as ] 24 F eb 2 01 4 p-wave chiral superfluidity from an s-wave interacting atomic Fermi gas Bo Liu , Xiaopeng Li , Biao Wu, and W. Vincent Liu Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA 2 Condensed Matter Theory Center, University of Maryland, Co llege Park, MD 20742, USA Joint Quantum Institute, University of Maryland, College P ark, MD 20742, USA International Center for Quantum Materials, Peking University, Beijing 100871, China Collaborative Innovation Center of Quantum Matter, Beijin g, China (Dated: February 26, 2014) Abstract Chiralp-wave superfluids are fascinating topological quantum stat e of matter that have been found in the liquid 3He-A phase and arguably in the electronic Sr 2RuO4 superconductor. They are shown fundamentally related to the fractional 5/2 quantum Hall state which supports fractional exotic excita tions. A common understanding is that such states require spin-triplet pai ring of fermions due top-wave interaction. Here we report by controlled theoretical approximation that a cent er-of-mass Wannier p-wave chiral superfluid state can arise from spin-singlet pairing for an s-wave interacting atomic Fermi gas in an optical lattice. De spite a conceptually different origin, it shows topological prop erties similar to the conventional chiral p-wave state. These include a non-zero Chern number and the appeara nc of chiral fermionic zero modes bounded to domain walls. Several signature quantities are calculat ed for the cold atom experimental condition.
118637791
Topological orbital ladders
Synthetic quantum orbital materials, such as the recent double-well optical lattices loaded with s and p orbital atoms [1, 2], open an avenue to exploit symmetries beyond natural crystals. Exotic superfluid states were reported for bosons. Here, we unveil a topological phase of interacting fermions on a two-leg ladder of unequal parity orbitals, derived from the experimentally realized double-well lattices by dimension reduction. Z2 topological invariant originates simply from the staggered phases of sp-orbital quantum tunneling, requiring none of the previously known mechanisms such as spin-orbit coupling or artificial gauge field. Another unique feature is that upon crossing over to two dimensions with coupled ladders, the edge modes from each ladder form a parity-protected flat band at zero energy, opening the route to strongly correlated states controlled by interactions. Experimental signatures are found in density correlations and phase transitions to trivial band and Mott insulators. The uneven double-well potential formed by laser light has been developed into a powerful tool for quantum gases by numerous groups [1–6]. For instance, controls of atoms on the sand p-orbitals of the checkerboard [1] and hexagonal [6] optical lattices have been demonstrated, and correlation between these orbitals tends to give exotic quantum states [6, 7]. Motivated by these developments, we consider a lattice of uneven double-wells where fermionic atoms are loaded up to the sand porbital levels of the shallow and deep wells respectively, as shown in Fig. 1. The spatial symmetry of the orbital wave function dictates the complex hopping amplitudes between nearby sites. Under certain circumstances, as for the uneven double wells, the orbital hopping pattern is sufficient for producing topologically nontrivial band structures [8]. We will first focus on a one-dimensional ladder system illustrated in Fig. 1b and 1c. This corresponds to the quasi-one dimensional limit of a standard double-well optical lattice, with the optical potential given by
118504130
Gravitational deflection of light in Rindler-type potential as a possible resolution to the observations of Bullet Cluster 1E0657-558
The surface density Σ-map and the convergence κ-map of Bullet Cluster 1E0657-558 show that the center of baryonic matters separates from the center of gravitational force, and the distribution of gravitational force do not possess spherical symmetry. This hints that a modified gravity with difference to Newtonian inverse-square law at large scale, and less symmetry is worth investigating. In this paper, we study the dynamics in Randers-Finsler spacetime. The Newtonian limit and gravitational deflection of light in a Rindler-type potential is focused in particular. It is shown that the convergence in Finsler spacetime could account for the observations of Bullet Cluster.
54218524
Quadrupole-octopole alignment of CMB related to the primordial power spectrum with dipolar modulation in anisotropic spacetime
The WMAP and Planck observations show that the quadrupole and octopole orientations of the CMB might align with each other. We reveal that the quadrupole-octopole alignment is a natural implication of the primordial power spectrum in an anisotropic spacetime. The primordial power spectrum is presented with a dipolar modulation. We obtain the privileged plane by employing the "power tensor" technique. At this plane, there is maximum correlation between quadrupole and octopole. The probability for the alignment is much larger than that in the isotropic universe. We find that this model would lead to deviations from the statistical isotropy only for low-e multipoles.
118403311
Geometry and optics calibration of WFCTA prototype telescopes using star light
The Large High Altitude Air Shower Observatory project is proposed to study high energy gamma ray astronomy ( 40 GeV-1 PeV ) and cosmic ray physics ( 20 TeV-1 EeV ). The wide field of view Cherenkov telescope array, as a component of the LHAASO project, will be used to study energy spectrum and compositions of cosmic ray by measuring the total Cherenkov light generated by air showers and shower maximum depth. Two prototype telescopes have been in operation since 2008. The pointing accuracy of each telescope is crucial to the direction reconstruction of the primary particles. On the other hand the primary energy reconstruction relies on the shape of the Cherenkov image on the camera and the unrecorded photons due to the imperfect connections between photomultiplier tubes. UV bright stars are used as point-like objects to calibrate the pointing and to study the optical properties of the camera, the spot size and the fractions of unrecorded photons in the insensitive areas of the camera.
118446762
Neutron–proton effective mass splitting in neutron-rich matter at normal density from analyzing nucleon–nucleus scattering data within an isospin dependent optical model
Abstract The neutron–proton effective mass splitting in asymmetric nucleonic matter of isospin asymmetry δ and normal density is found to be m n − p ⁎ ≡ ( m n ⁎ − m p ⁎ ) / m = ( 0.41 ± 0.15 ) δ from analyzing globally 1088 sets of reaction and angular differential cross sections of proton elastic scattering on 130 targets with beam energies from 0.783 MeV to 200 MeV, and 1161 sets of data of neutron elastic scattering on 104 targets with beam energies from 0.05 MeV to 200 MeV within an isospin dependent non-relativistic optical potential model. It sets a useful reference for testing model predictions on the momentum dependence of the nucleon isovector potential necessary for understanding novel structures and reactions of rare isotopes.
118130623
Quantum resonance scheme to measure the gravitational constant G