4,435 research outputs found
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
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
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
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
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 Li atoms. At the unitarity limit, the three-body loss coefficient
exhibits universality in the sense that it is independent of the
interaction strength and follows the predicted temperature scaling law of . 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
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
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
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
Quantitative analysis of -wave three-body losses via cascade process
We describe the three-body loss coefficient of identical fermions with
-wave interactions using a set of rate equations in which three-body
recombination happens via an indirect process. Our theoretical treatment
explains experimental results just above the universal scaling law regime of
weak interactions. Furthermore, we theoretically extend and experimentally
verify the rate equation model for the case of atoms trapped in two dimensions.
Moreover, we find that the three-body loss coefficient in a two-dimensional
trap is proportional to in the weakly interacting regime, where
is the scattering area. Our results are useful in understanding
three-body physics with -wave interactions.Comment: three figure
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