1,260 research outputs found
Spitzer Space Telescope IRAC and MIPS observations of the interacting galaxies Ic 2163 and NGC 2207: clumpy emission
Peer reviewe
Boiling a Unitary Fermi Liquid
We study the thermal evolution of a highly spin-imbalanced, homogeneous Fermi
gas with unitarity limited interactions, from a Fermi liquid of polarons at low
temperatures to a classical Boltzmann gas at high temperatures. Radio-frequency
spectroscopy gives access to the energy, lifetime, and short-range correlations
of Fermi polarons at low temperatures . In this regime, we observe a
characteristic dependence of the spectral width, corresponding to the
quasiparticle decay rate expected for a Fermi liquid. At high , the spectral
width decreases again towards the scattering rate of the classical, unitary
Boltzmann gas, . In the transition region between the quantum
degenerate and classical regime, the spectral width attains its maximum, on the
scale of the Fermi energy, indicating the breakdown of a quasiparticle
description. Density measurements in a harmonic trap directly reveal the
majority dressing cloud surrounding the minority spins and yield the
compressibility along with the effective mass of Fermi polarons.Comment: Accepted version at PR
Unconventional conductance plateau transitions in quantum Hall wires with spatially correlated disorder
Quantum transport properties in quantum Hall wires in the presence of
spatially correlated random potential are investigated numerically. It is found
that the potential correlation reduces the localization length associated with
the edge state, in contrast to the naive expectation that the potential
correlation increases it. The effect appears as the sizable shift of quantized
conductance plateaus in long wires, where the plateau transitions occur at
energies much higher than the Landau band centers. The scale of the shift is of
the order of the strength of the random potential and is insensitive to the
strength of magnetic fields. Experimental implications are also discussed.Comment: 5 pages, 4 figure
The Peierls substitution in an engineered lattice potential
Artificial gauge fields open new possibilities to realize quantum many-body
systems with ultracold atoms, by engineering Hamiltonians usually associated
with electronic systems. In the presence of a periodic potential, artificial
gauge fields may bring ultracold atoms closer to the quantum Hall regime. Here,
we describe a one-dimensional lattice derived purely from effective
Zeeman-shifts resulting from a combination of Raman coupling and radiofrequency
magnetic fields. In this lattice, the tunneling matrix element is generally
complex. We control both the amplitude and the phase of this tunneling
parameter, experimentally realizing the Peierls substitution for ultracold
neutral atoms.Comment: 6 pages, 5 figure
Conductance plateau transitions in quantum Hall wires with spatially correlated random magnetic fields
Quantum transport properties in quantum Hall wires in the presence of
spatially correlated disordered magnetic fields are investigated numerically.
It is found that the correlation drastically changes the transport properties
associated with the edge state, in contrast to the naive expectation that the
correlation simply reduces the effect of disorder. In the presence of
correlation, the separation between the successive conductance plateau
transitions becomes larger than the bulk Landau level separation determined by
the mean value of the disordered magnetic fields. The transition energies
coincide with the Landau levels in an effective magnetic field stronger than
the mean value of the disordered magnetic field. For a long wire, the strength
of this effective magnetic field is of the order of the maximum value of the
magnetic fields in the system. It is shown that the effective field is
determined by a part where the stronger magnetic field region connects both
edges of the wire.Comment: 7 pages, 10 figure
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