552 research outputs found
Fractional statistics and duality: strong tunneling behavior of edge states of quantum Hall liquids in the Jain sequence
While the values for the fractional charge and fractional statistics coincide
for fractional Hall (FQH) states in the Laughlin sequence, they do not for more
general FQH states, such as those in the Jain sequence. This mismatch leads to
additional phase factors in the weak coupling expansion for tunneling between
edge states which alter the nature of the strong tunneling limit. We show here
how to construct a weak-strong coupling duality for generalized FQH states with
simple unreconstructed edges. The correct dualization of quasiparticles into
integer charged fermions is a consistency requirement for a theory of FQH edge
states with a simple edge. We show that this duality also applies for weakly
reconstructed edges.Comment: 4+epsilon page
Colored noise in the fractional Hall effect: duality relations and exact results
We study noise in the problem of tunneling between fractional quantum Hall
edge states within a four probe geometry. We explore the implications of the
strong-weak coupling duality symmetry existent in this problem for relating the
various density-density auto-correlations and cross-correlations between the
four terminals. We identify correlations that transform as either ``odd'' or
``anti-symmetric'', or ``even'' or ``symmetric'' quantities under duality. We
show that the low frequency noise is colored, and that the deviations from
white noise are exactly related to the differential conductance. We show
explicitly that the relationship between the slope of the low frequency noise
spectrum and the differential conductance follows from an identity that holds
to {\it all} orders in perturbation theory, supporting the results implied by
the duality symmetry. This generalizes the results of quantum supression of the
finite frequency noise spectrum to Luttinger liquids and fractional statistics
quasiparticles.Comment: 14 pages, 3 figure
Entanglement Complexity in Quantum Many-Body Dynamics, Thermalization and Localization
Entanglement is usually quantified by von Neumann entropy, but its properties
are much more complex than what can be expressed with a single number. We show
that the three distinct dynamical phases known as thermalization, Anderson
localization, and many-body localization are marked by different patterns of
the spectrum of the reduced density matrix for a state evolved after a quantum
quench. While the entanglement spectrum displays Poisson statistics for the
case of Anderson localization, it displays universal Wigner-Dyson statistics
for both the cases of many-body localization and thermalization, albeit the
universal distribution is asymptotically reached within very different time
scales in these two cases. We further show that the complexity of entanglement,
revealed by the possibility of disentangling the state through a
Metropolis-like algorithm, is signaled by whether the entanglement spectrum
level spacing is Poisson or Wigner-Dyson distributed.Comment: Minor revision
Out-of-equilibrium dynamical fluctuations in glassy systems
In this paper we extend the earlier treatment of out-of-equilibrium
mesoscopic fluctuations in glassy systems in several significant ways. First,
via extensive simulations, we demonstrate that models of glassy behavior
without quenched disorder display scalings of the probability of local two-time
correlators that are qualitatively similar to that of models with short-ranged
quenched interactions. The key ingredient for such scaling properties is shown
to be the development of a critical-like dynamical correlation length, and not
other microscopic details. This robust data collapse may be described in terms
of a time-evolving Gumbel-like distribution. We develop a theory to describe
both the form and evolution of these distributions based on a effective
sigma-model approach.Comment: 20 pages, RevTex, 9 figure
Income uncertainty and household savings in China
China's urban household saving rate has increased markedly since the mid-1990s and the age-savings profile has become U-shaped. To understand these patterns, we analyze a panel of urban Chinese households over the period 1989–2009. We document a sharp increase in income uncertainty, largely due to an increase in the variance in household income attributed to transitory idiosyncratic shocks. We then calibrate a buffer-stock savings model to obtain quantitative estimates of the impact of rising household-specific income uncertainty as well as another shock to household income—the pension reforms that were instituted in the late 1990s. Our calibrations suggest that rising income uncertainty and pension reforms lead younger and older households, respectively, to raise their saving rates significantly. These two factors account for two-thirds of the increase in China's urban household saving rate and the U-shaped age-savings profile.We are grateful to Loren Brandt, Robert Moffitt, two anonymous referees, as well as participants at the NBER Summer Institute, China Economics Summer Institute, IMF Research Seminar, and the Workshop on China's Macroeconomy at the University of Toronto for comments and suggestions. We thank Lei (Sandy) Ye for research assistance. The views expressed in this paper are those of the authors and do not necessarily reflect those of the institutions the authors are affiliated with.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.jdeveco.2013.07.01
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