Hall Effect on Noncommutative Phase Space

When phase space coordinates are noncommutative, especially including arbitrarily noncommutative momenta, the Hall effect is reinvestigated. A minimally gauge-invariant coupling of electromagnetic field is introduced by making use of Faddeev-Jackiw formulation for unconstrained and constrained systems. We find that the parameter of noncommutative momenta makes an important contribution to the Hall conductivity.Comment: 11 pages, no figures, uses ptptex.cl

Rigorous Bound on Energy Absorption and Generic Relaxation in Periodically Driven Quantum Systems

We discuss the universal nature of relaxation in isolated many-body quantum systems subjected to global and strong periodic driving. Our rigorous Floquet analysis shows that the energy of the system remains almost constant up to an exponentially long time in frequency for arbitrary initial states and that an effective Hamiltonian obtained by a truncation of the Floquet-Magnus expansion is a quasi-conserved quantity for long time scale. These two general properties lead to intriguing classification on the initial stage of relaxation, one of which is similar to the prethermalization phenomenon in quasi-integrable systems.Comment: 5+6 pages, 3 figures; typos correcte

Wigner's Formulation of Noncommutative Quantum Mechanics

When we have noncommutativity among coordinates (or conjugate momenta), we consider Wigner's formulation of quantum mechanics, including a new derivation of path integral formula. We also propose the Moyal star product based on the Dirac bracket in constrained systems.Comment: 10 pages, No figures, Late

Noncommutative Hall Effect

When coordinates are noncommutative, the Hall effect is reinvestigated. The Hall conductivity is expressed with noncommutative parameters, so that in the commutative limit it tends to the conventional result.Comment: 7 pages, no figure, uses ptptex.cl

Hall effect in Noncommutative spaces

In order to investigate whether space coordinates are intrinsically noncommutative, we make use of the Hall effect on the two-dimensional plane. We calculate the Hall conductivity in such a way that the noncommutative U(1) gauge invariance is manifest. We find that the noncommutativity parameter theta does not appear in the Hall conductivity itself, but the particle number density of electron depends on theta. We point out that the peak of particle number density differs from that of the charge density.Comment: 6 pages, no figure; v2: References added. Typos correcte

Tight-binding theory of surface spin states on bismuth thin films

The surface spin states for bismuth thin films were investigated using an $sp^3$ tight-binding model. The model explains the experimental observations using angle-resolved photoemission spectroscopy, including the Fermi surface, the band structure with Rashba spin splitting, and the quantum confinement in the energy band gap of the surface states. A large out-of-plane spin component also appears. The surface states penetrate inside the film to within approximately a few bilayers near the Brillouin-zone center, whereas they reach the center of the film near the Brillouin-zone boundary.Comment: 7 pages, 5 figure

Unitarity-limited behavior of three-body collisions in a p-wave interacting Fermi gas

We experimentally investigate the unitarity-limited behavior of the three-body loss near a p-wave Feshbach resonance in a single-component Fermi gas of $^6$Li atoms. At the unitarity limit, the three-body loss coefficient $L_{3}$ exhibits universality in the sense that it is independent of the interaction strength and follows the predicted temperature scaling law of $L_3 \propto T^{-2}$. When decreasing the interaction strength from the unitarity regime, the three-body loss coefficient as a function of the interaction strength and temperature can be described by the theory based on the association of an excited resonant quasibound state and its relaxation into a deep stable dimer by collision with a third atom in the framework of the standard Breit-Wigner theoretical approach. The results reported here are important to understand the properties of a resonant p-wave Fermi gas in the prospect of quantum few- and many-body physics.Comment: 5 pages, 3 figure

Two-body relaxation in a Fermi gas at a p-wave Feshbach resonance

We systematically studied the two-body loss in a two-component Fermi gas of $^6$Li atoms near a p-wave Feshbach resonance. The two-body loss rate constants were measured for various temperatures and magnetic fields using atoms trapped in three-dimensional and quasi-two-dimensional traps. Our results were nicely reproduced by a theoretical model that incorporates the two-body loss as an imaginary part to the inverse of the scattering volume in the scattering amplitude expression. The observed loss suppression in quasi-two-dimensional traps may provide a promising strategy to realize a p-wave superfluid in a system of ultracold atoms.Comment: 4 pages, 5 figure

Charge-exchange collisions between ultracold fermionic lithium atoms and calcium ions

Charge exchange collisions between ultracold fermionic 6Li atoms and 40Ca+ ions are observed in the mK temperature range. The reaction product of the charge exchange collision is identified via mass spectrometry during which the motion of the ions is excited parametrically. The cross-sections of the charge exchange collisions between 6Li atoms in the ground state and 40Ca+ ions in the ground and metastable excited states are determined. Investigation of the inelastic collision characteristics in the atom-ion mixture is an important step toward ultracold chemistry based on ultracold atoms and ions.Comment: 5 pages, 5 figure

Geodesic "curve"-of-sight formulae for the cosmic microwave background: a unified treatment of redshift, time delay, and lensing

In this paper, we introduce a new approach to a treatment of the gravitational effects (redshift, time delay and lensing) on the observed cosmic microwave background (CMB) anisotropies based on the Boltzmann equation. From the Liouville's theorem in curved spacetime, the intensity of photons is conserved along a photon geodesic when non-gravitational scatterings are absent. Motivated by this fact, we derive a second-order line-of-sight formula by integrating the Boltzmann equation along a perturbed geodesic (curve) instead of a background geodesic (line). In this approach, the separation of the gravitational and intrinsic effects are manifest. This approach can be considered as a generalization of the remapping approach of CMB lensing, where all the gravitational effects can be treated on the same footing.Comment: 40 pages, 3 figures; v2: published in JCAP, references added, typos corrected, a minor revision in sec. 4.