1,152 research outputs found
Electrostatic control of quantum dot entanglement induced by coupling to external reservoirs
We propose a quantum transport experiment to prepare and measure
charge-entanglement between two electrostatically defined quantum dots.
Coherent population trapping, as realized in cavity quantum electrodynamics,
can be carried out by using a third quantum dot to play the role of the optical
cavity. In our proposal, a pumping which is quantum mechanically
indistinguishable for the quantum dots drives the system into a state with a
high degree of entanglement. The whole effect can be switched on and off by
means of a gate potential allowing both state preparation and entanglement
detection by simply measuring the total current.Comment: 5 pages, 4 figures, Latex2e with EPL macros, to appear in Europhysics
Letter
Linear and nonlinear coupling of quantum dots in microcavities
We discuss the topical and fundamental problem of strong-coupling between a
quantum dot an the single mode of a microcavity. We report seminal quantitative
descriptions of experimental data, both in the linear and in the nonlinear
regimes, based on a theoretical model that includes pumping and quantum
statistics.Comment: Proceedings of the symposium Nanostructures: Physics and Technology
2010 (http://www.ioffe.ru/NANO2010), 2 pages in proceedings styl
Electroproduction of the d* dibaryon
The unpolarized cross section for the electroproduction of the isoscalar
di-delta dibaryon is calculated for deuteron target using a
simple picture of elastic electron-baryon scattering from the and the components of the deuteron. The calculated
differential cross section at the electron lab energy of 1 GeV has the value of
about 0.24 (0.05) nb/sr at the lab angle of 10 (30) for the
Bonn B potential when the dibaryon mass is taken to be 2.1 GeV. The cross
section decreases rapidly with increasing dibaryon mass. A large calculated
width of 40 MeV for combined with a small
experimental upper bound of 0.08 MeV for the decay width appears to have
excluded any low-mass model containing a significant admixture of the
configuration.Comment: 11 journal-style pages, 8 figure
Scaling of the conductance in gold nanotubes
A new form of gold nanobridges has been recently observed in ultrahigh-vacuum
experiments, where the gold atoms rearrange to build helical nanotubes, akin in
some respects to carbon nanotubes. The good reproducibility of these wires and
their unexpected stability will allow for conductance measurements and make
them promising candidates for future applications . We present here a study of
the transport properties of these nanotubes in order to understand the role of
chirality and of the different orbitals in quantum transport observables. The
conductance per atomic row shows a light decreasing trend as the diameter
grows, which is also shown through an analytical formula based on a one-orbital
model.Comment: 5 pages, 6 figure
MAGIC sensitivity to millisecond-duration optical pulses
The MAGIC telescopes are a system of two Imaging Atmospheric Cherenkov
Telescopes (IACTs) designed to observe very high energy (VHE) gamma rays above
~50 GeV. However, as IACTs are sensitive to Cherenkov light in the UV/blue and
use photo-detectors with a time response well below the ms scale, MAGIC is also
able to perform simultaneous optical observations. Through an alternative
system installed in the central PMT of MAGIC II camera, the so-called central
pixel, MAGIC is sensitive to short (1ms - 1s) optical pulses. Periodic signals
from the Crab pulsar are regularly monitored. Here we report for the first time
the experimental determination of the sensitivity of the central pixel to
isolated 1-10 ms long optical pulses. The result of this study is relevant for
searches of fast transients such as Fast Radio Bursts (FRBs).Comment: Proceedings of the 35th International Cosmic Ray Conference (ICRC
2017), Bexco, Busan, Korea (arXiv:1708.05153
Anomalous diffusion in correlated continuous time random walks
We demonstrate that continuous time random walks in which successive waiting
times are correlated by Gaussian statistics lead to anomalous diffusion with
mean squared displacement ~t^{2/3}. Long-ranged correlations of the
waiting times with power-law exponent alpha (0<alpha<=2) give rise to
subdiffusion of the form ~t^{alpha/(1+alpha)}. In contrast correlations
in the jump lengths are shown to produce superdiffusion. We show that in both
cases weak ergodicity breaking occurs. Our results are in excellent agreement
with simulations.Comment: 6 pages, 6 figures. Slightly revised version, accepted to J Phys A as
a Fast Track Communicatio
Dynamics of formation and decay of coherence in a polariton condensate
We study the dynamics of formation and decay of a condensate of microcavity
polaritons. We investigate the relationship between the number of particles,
the emission's linewidth and its degree of linear polarization which serves as
the order parameter. Tracking the condensate's formation, we show that, even
when interactions are negligible, coherence is not determined only by
occupation of the ground state. As a result of the competition between the
coherent and thermal fractions of the condensate, the highest coherence is
obtained some time after the particle number has reached its maximum
Polarization entanglement visibility of photon pairs emitted by a quantum dot embedded in a microcavity
We study the photon emission from a quantum dot embedded in a microcavity.
Incoherent pumping of its excitons and biexciton provokes the emission of leaky
and cavity modes. By solving a master equation we obtain the correlation
functions required to compute the spectrum and the relative efficiency among
the emission of pairs and single photons. A quantum regime appears for low
pumping and large rate of emission. By means of a post-selection process, a two
beams experiment with different linear polarizations could be performed
producing a large polarization entanglement visibility precisely in the quantum
regime.Comment: 13 pages and 6 figure
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