1,875 research outputs found
Credit Supply versus Demand: Bank and Firm Balance-Sheet Channels in Good and Crisis Times
Abstract: Banking crises involve periods of persistently low credit and economic growth. Banksâ balance sheets are then weak but so are those of non-financial corporate borrowers. Hence, a crucial question is whether credit growth is low due to supply or to demand factors. However convincing identification has been elusive due to a lack of detailed loan application-, bank-, and firm-level data. Access to a dataset of loan applications in Spain that is matched with complete bank and firm balance-sheet data covering the period from 2002 to 2010 allows us to identify bank and firm balancesheet channels. We find robust evidence showing that bank balance-sheet strength determines the success of loan applications and the granting of loans in crisis times. The heterogeneity in firm balance-sheet strength determines loan granting in both good and crisis times, although the potency of this firm balance-sheet channel is the largest in the latter period. Our findings therefore hold important implications for both theory and policy.bank lending channel;credit supply;business cycle;credit crunch;capital;liquidity
Rabi lattice models with discrete gauge symmetry: Phase diagram and implementation in trapped-ion quantum simulators
We study a spin-boson chain that exhibits a local Z2 symmetry. We investigate the quantum phase diagram of the model by means of perturbation theory, mean-field theory, and the density matrix renormalization group method. Our calculations show the existence of a first-order phase transition in the region where the boson quantum dynamics is slow compared to the spin-spin interactions. Our model can be implemented with trapped-ion quantum simulators, leading to a realization of minimal models showing local gauge invariance and first-order phase transitions
Convolutional Goppa Codes
We define Convolutional Goppa Codes over algebraic curves and construct their
corresponding dual codes. Examples over the projective line and over elliptic
curves are described, obtaining in particular some Maximum-Distance Separable
(MDS) convolutional codes.Comment: 8 pages, submitted to IEEE Trans. Inform. Theor
Conical emission, pulse splitting and X-wave parametric amplification in nonlinear dynamics of ultrashort light pulses
The precise observation of the angle-frequency spectrum of light filaments in
water reveals a scenario incompatible with current models of conical emission
(CE). Its description in terms of linear X-wave modes leads us to understand
filamentation dynamics requiring a phase- and group-matched, Kerr-driven
four-wave-mixing process that involves two highly localized pumps and two
X-waves. CE and temporal splitting arise naturally as two manifestations of
this process
Dynamics of the excitations of a quantum dot in a microcavity
We study the dynamics of a quantum dot embedded in a three-dimensional
microcavity in the strong coupling regime in which the quantum dot exciton has
an energy close to the frequency of a confined cavity mode. Under the
continuous pumping of the system, confined electron and hole can recombine
either by spontaneous emission through a leaky mode or by stimulated emission
of a cavity mode that can escape from the cavity. The numerical integration of
a master equation including all these effects gives the dynamics of the density
matrix. By using the quantum regression theorem, we compute the first and
second order coherence functions required to calculate the photon statistics
and the spectrum of the emitted light. Our main result is the determination of
a range of parameters in which a state of cavity modes with poissonian or
sub-poissonian (non-classical) statistics can be built up within the
microcavity. Depending on the relative values of pumping and rate of stimulated
emission, either one or two peaks close to the excitation energy of the dot
and/or to the natural frequency of the cavity are observed in the emission
spectrum. The physics behind these results is discussed
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