900 research outputs found
The Welfare Cost of Business Cycles in an Economy with Nonclearing Markets
In this paper we measure the welfare cost of fluctuations in a simple representative agent economy with nonclearing markets. The market friction we consider involves price rigidities and a voluntary exchange rationing scheme. These features are incorporated into an otherwise standard neoclassical growth model. We show that the frictions we introduce make the losses from fluctuations much bigger than in a frictionless environment.Cost of business cycles, Nonclearing markets, Dynamic general equilibrium
The welfare cost of business cycles in an economy with nonclearing markets
In this paper we measure the welfare cost of fluctuations in a simple representative agent economy with nonclearing markets. The market friction we consider involves price rigidities and a voluntary exchange rationing scheme. These features are incorporated into an otherwise standard neoclassical growth model. We show that the frictions we introduce make the losses from fluctuations much bigger than in a frictionless environment
The welfare cost of fluctuations in representative agent economies
In this paper we quantify the welfare cost of fluctuations in a representative agent dynamic equilibrium framework. In doing so, we argue that two key features of Intertemporal Stochastic General Equilibrium Models should not be forgotten: non-linearities and dynamics. We think that these features are often disregarded in the existing literature. We propase a structural measure of the welfare cost of fluctuations, and quantify the role played by dinamics and non-linearities in assessing this cost for some versions of the one sector stochastic growth model. We find that non-linearities do not magnify the cost of fluctuations for walrasian growth models, and our structural measure is close to what has been measured in the literature. That difference becomes sharply larger in non-walrasian cases, where fluctuations magnify equilibrium inefficiencies
Noise dephasing in the edge states of the Integer Quantum Hall regime
An electronic Mach Zehnder interferometer is used in the integer quantum hall
regime at filling factor 2, to study the dephasing of the interferences. This
is found to be induced by the electrical noise existing in the edge states
capacitively coupled to each others. Electrical shot noise created in one
channel leads to phase randomization in the other, which destroys the
interference pattern. These findings are extended to the dephasing induced by
thermal noise instead of shot noise: it explains the underlying mechanism
responsible for the finite temperature coherence time of the
edge states at filling factor 2, measured in a recent experiment. Finally, we
present here a theory of the dephasing based on Gaussian noise, which is found
in excellent agreement with our experimental results.Comment: ~4 pages, 4 figure
Robust quantum coherence above the Fermi sea
In this paper we present an experiment where we measured the quantum
coherence of a quasiparticle injected at a well-defined energy above the Fermi
sea into the edge states of the integer quantum Hall regime. Electrons are
introduced in an electronic Mach-Zehnder interferometer after passing through a
quantum dot that plays the role of an energy filter. Measurements show that
above a threshold injection energy, the visibility of the quantum interferences
is almost independent of the energy. This is true even for high energies, up to
130~eV, well above the thermal energy of the measured sample. This result
is in strong contradiction with our theoretical predictions, which instead
predict a continuous decrease of the interference visibility with increasing
energy. This experiment raises serious questions concerning the understanding
of excitations in the integer quantum Hall regime
Tuning decoherence with a voltage probe
We present an experiment where we tune the decoherence in a quantum
interferometer using one of the simplest object available in the physic of
quantum conductors : an ohmic contact. For that purpose, we designed an
electronic Mach-Zehnder interferometer which has one of its two arms connected
to an ohmic contact through a quantum point contact. At low temperature, we
observe quantum interference patterns with a visibility up to 57%. Increasing
the connection between one arm of the interferometer to the floating ohmic
contact, the voltage probe, reduces quantum interferences as it probes the
electron trajectory. This unique experimental realization of a voltage probe
works as a trivial which-path detector whose efficiency can be simply tuned by
a gate voltage
Finite bias visibility of the electronic Mach-Zehnder interferometer
We present an original statistical method to measure the visibility of
interferences in an electronic Mach-Zehnder interferometer in the presence of
low frequency fluctuations. The visibility presents a single side lobe
structure shown to result from a gaussian phase averaging whose variance is
quadratic with the bias. To reinforce our approach and validate our statistical
method, the same experiment is also realized with a stable sample. It exhibits
the same visibility behavior as the fluctuating one, indicating the intrinsic
character of finite bias phase averaging. In both samples, the dilution of the
impinging current reduces the variance of the gaussian distribution.Comment: 4 pages, 5 figure
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