3,522 research outputs found
An Electronic Mach-Zehnder Quantum Eraser
We propose an electronic quantum eraser in which the electrons are injected
into a mesoscopic conductor at the quantum Hall regime. The conductor is
composed of a two-path interferometer which is an electronic analogue of the
optical Mach-Zehnder interferometer, and a quantum point contact detector
capacitively coupled to the interferometer. While the interference of the
output current at the interferometer is shown to be suppressed by the
which-path information, we show that the which-path information is erased by
the zero-frequency cross correlation measurement between the interferometer and
the detector output leads. We also investigate a modified setup in which the
detector is replaced by a two-path interferometer.We show that the path
distinguishability and the visibility of the joint detection can be controlled
in a continuous manner, and satisfy a complementarity relation for the
entangled electrons.Comment: 5 pages, 2 figure
Fine Details of the Nodal Electronic Excitations in BiSrCaCuO
Very high energy resolution photoemission experiments on high quality samples
of optimally doped BiSrCaCuO show new features in the
low-energy electronic excitations. A marked change in the binding energy and
temperature dependence of the near-nodal scattering rates is observed near the
superconducting transition temperature, . The temperature slope of the
scattering rate measured at low energy shows a discontinuity at ~. In the
superconducting state, coherent excitations are found with the scattering rates
showing a cubic dependence on frequency and temperature. The superconducting
gap has a d-wave magnitude with negligible contribution from higher harmonics.
Further, the bi-layer splitting has been found to be finite at the nodal point.Comment: 5 pages, 4 figure
Frictional Drag between Two Dilute Two-Dimensional Hole Layers
We report drag measurements on dilute double layer two-dimensional hole
systems in the regime of r_s=19~39. We observed a strong enhancement of the
drag over the simple Boltzmann calculations of Coulomb interaction, and
deviations from the T^2 dependence which cannot be explained by
phonon-mediated, plasmon-enhanced, or disorder-related processes. We suggest
that this deviation results from interaction effects in the dilute regime.Comment: 4 pages, 3 figures, accepted in Phys. Rev. Lett. Added single layer
transport dat
Magnetic Field Induced Insulating Phases at Large
Exploring a backgated low density two-dimensional hole sample in the large
regime we found a surprisingly rich phase diagram. At the highest
densities, beside the , 2/3, and 2/5 fractional quantum Hall states,
we observe both of the previously reported high field insulating and reentrant
insulating phases. As the density is lowered, the reentrant insulating phase
initially strengthens, then it unexpectedly starts weakening until it
completely dissapears. At the lowest densities the terminal quantum Hall state
moves from to . The intricate behavior of the insulating
phases can be explained by a non-monotonic melting line in the -
phase space
Third-order cosmological perturbations of zero-pressure multi-component fluids: Pure general relativistic nonlinear effects
Present expansion stage of the universe is believed to be mainly governed by
the cosmological constant, collisionless dark matter and baryonic matter. The
latter two components are often modeled as zero-pressure fluids. In our
previous work we have shown that to the second-order cosmological
perturbations, the relativistic equations of the zero-pressure, irrotational,
multi-component fluids in a spatially near flat background effectively coincide
with the Newtonian equations. As the Newtonian equations only have quadratic
order nonlinearity, it is practically interesting to derive the potential
third-order perturbation terms in general relativistic treatment which
correspond to pure general relativistic corrections. Here, we present pure
general relativistic correction terms appearing in the third-order
perturbations of the multi-component zero-pressure fluids. We show that, as in
a single component situation, the third-order correction terms are quite small
(~ 5 x10^{-5} smaller compared with the relativistic/Newtonian second-order
terms) due to the weak level anisotropy of the cosmic microwave background
radiation. Still, there do exist pure general relativistic correction terms in
third-order perturbations which could potentially become important in future
development of precision cosmology. We include the cosmological constant in all
our analyses.Comment: 20 pages, no figur
Sampling the canonical phase from phase-space functions
We discuss the possibility of sampling exponential moments of the canonical
phase from the s-parametrized phase space functions. We show that the sampling
kernels exist and are well-behaved for any s>-1, whereas for s=-1 the kernels
diverge in the origin. In spite of that we show that the phase space moments
can be sampled with any predefined accuracy from the Q-function measured in the
double-homodyne scheme with perfect detectors. We discuss the effect of
imperfect detection and address sampling schemes using other measurable
phase-space functions. Finally, we discuss the problem of sampling the
canonical phase distribution itself.Comment: 10 pages, 7 figures, REVTe
Multiple conducting carriers generated in LaAlO3/SrTiO3 heterostructures
We have found that there is more than one type of conducting carriers
generated in LaAlO3/SrTiO3 heterostructures by comparing the sheet carrier
density and mobility from optical transmission spectroscopy with those from
dc-transport measurements. When multiple types of carriers exist, optical
characterization dominantly reflects the contribution from the high-density
carriers whereas dc-transport measurements may exaggerate the contribution of
the high-mobility carriers even though they are present at low-density. Since
the low-temperature mobilities determined by dc-transport in the LaAlO3/SrTiO3
heterostructures are much higher than those extracted by optical method, we
attribute the origin of high-mobility transport to the low-density conducting
carriers.Comment: 3 figures, supplemental materia
Polarization Relaxation Induced by Depolarization Field in Ultrathin Ferroelectric BaTiO Capacitors
Time-dependent polarization relaxation behaviors induced by a depolarization
field were investigated on high-quality ultrathin
SrRuO/BaTiO/SrRuO capacitors. The values were
determined experimentally from an applied external field to stop the net
polarization relaxation. These values agree with those from the electrostatic
calculations, demonstrating that a large inside the ultrathin
ferroelectric layer could cause severe polarization relaxation. For numerous
ferroelectric devices of capacitor configuration, this effect will set a
stricter size limit than the critical thickness issue
Reconstructing baryon oscillations
The baryon acoustic oscillation (BAO) method for constraining the expansion
history is adversely affected by non-linear structure formation, which washes
out the correlation function peak created at decoupling. To increase the
constraining power of low z BAO experiments, it has been proposed that one use
the observed distribution of galaxies to "reconstruct'' the acoustic peak.
Recently Padmanabhan, White and Cohn provided an analytic formalism for
understanding how reconstruction works within the context of Lagrangian
perturbation theory. We extend that formalism to include the case of biased
tracers of the mass and, because the quantitative validity of LPT is
questionable, we investigate reconstruction in N-body simulations. We find that
LPT does a good job of explaining the trends seen in simulations for both the
mass and for biased tracers and comment upon the implications this has for
reconstruction.Comment: 9 pages, 8 figure
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