Wage-Experience Contracts and Employment Status

The objective of this paper is to study equilibrium in a labour market in which identical firms post wage-contracts and ex-ante identical workers search on the job. The main novelty of this paper is to generate dispersion in contract offers by allowing firms to condition their offers on workers' initial experience and employment status although these characteristics do not affect productivity. In this context I show that changes in firms' information set at the moment of recruiting can have strong effects on wage dispersion and turnover without changing the agents' payoffs. I construct an equilibrium in which firms compete in promotion contracts. Employed and more experience workers are offered better contracts with shorter time-to-promotion periods. This implies contract offers are disperse within and between experience levels. The earnings distribution within the firm is then such that workers who have acquired more 'outside' firm experience and more tenure are higher in the earnings scale. This generates workers cohort effects within a firm that depend on the level of experience at which they where hired

Recruitment Policy When Firms Observe Workers' Employment Status: an Equilibrium Search Approach

This paper considers an equilibrium search model, where firms use information on a worker's labour market status when recruiting new hires, and all workers search for a job. We show that firms segment their workforce in two. Unemployed workers are offered a lower wage than the workers they recruit from employment in a competing firm even when these workers have the same productivity. The unique equilibrium is given by the Diamond outcome in the market for unemployed workers and the Burdett and Mortensen (B-M) outcome in the market for employed workers. We show that the offer and earnings distributions derived in the model are first order stochastically dominated by the ones given in B-M and all workers are worse off. We also show that in this environment information on employment status is sufficient for firms to obtain the same profits as if they had complete information about workers' reservation wages and outside offers

Trade Blocks and the Gravity Model: Evidence from Latin American Countries

We apply the gravity model to examine the effects of the Andean Community and Mercosur on both intra-regional and intra-industrial trade in the period 1980-1997. After accounting for size and distance effects, the Andean Community preferential trade agreements had a significant effect on both the differentiated and reference products, in particular capital intensive goods. In contrast, Mercosur preferential trade agreements only had a positive effect on the capital intensive subcategory of the reference products

Non-reciprocal few-photon devices based on chiral waveguide-emitter couplings

We demonstrate the possibility of designing efficient, non reciprocal few-photon devices by exploiting the chiral coupling between two waveguide modes and a single quantum emitter. We show how this system can induce non-reciprocal photon transport at the single-photon level and act as an optical diode. Afterwards, we also show how the same system shows a transistor-like behaviour for a two-photon input. The efficiency in both cases is shown to be large for feasible experimental implementations. Our results illustrate the potential of chiral waveguide-emitter couplings for applications in quantum circuitry.Comment: Mathematica notebook attached for calculation of detection probabilitie

Quantum Spin Dynamics with Pairwise-Tunable, Long-Range Interactions

We present a platform for the simulation of quantum magnetism with full control of interactions between pairs of spins at arbitrary distances in one- and two-dimensional lattices. In our scheme, two internal atomic states represent a pseudo-spin for atoms trapped within a photonic crystal waveguide (PCW). With the atomic transition frequency aligned inside a band gap of the PCW, virtual photons mediate coherent spin-spin interactions between lattice sites. To obtain full control of interaction coefficients at arbitrary atom-atom separations, ground-state energy shifts are introduced as a function of distance across the PCW. In conjunction with auxiliary pump fields, spin-exchange versus atom-atom separation can be engineered with arbitrary magnitude and phase, and arranged to introduce non-trivial Berry phases in the spin lattice, thus opening new avenues for realizing novel topological spin models. We illustrate the broad applicability of our scheme by explicit construction for several well known spin models.Comment: 18 pages, 10 figure

Plasmon-polariton emission from a coherently p-excited quantum dot near a metal interface

We study the emission of surface plasmon polaritons by the decay of the lowest excited state of a quantum emitter when the system is excited by a laser in resonance with a higher excited state (p-shell excitation). By solving a master equation and by using the quantum-regression theorem, we show how the emission is enhanced by the Purcell effect due to the weak coupling between the emitter and the structured spectral density of plasmon-polariton states of a metal surface. Measurable magnitudes, as the spectrum and the second-order coherence function, are extremely affected by the coherent p-shell excitation. In many cases, such coherent excitation completely masks the physical features of the emission under study. The coexistence between coherent p-shell excitation in the first step of the process and weak coupling in the final step is very important and completely general for any structured reservoir of final states. The advantage of our system is that, just by changing the distance from the quantum emitter to the metal surface, one can access a very rich set of regimes as purely dissipative direct photon emission or emission of plasmon polaritonsThis work was supported by the Spanish MICINN under Contracts No. MAT2008-01555 and No. MAT2011-22997and by CAM under Contract No. S-2009/ESP-1503. C.S.-M. acknowledges a grant from the Universidad Autonoma de Madrid. A.G.-T. acknowledges an FPU Grant No. AP2008-00101 from the Spanish Ministry of Educatio

Two-photon spectra of quantum emitters

We apply our recently developed theory of frequency-filtered and time-resolved N-photon correlations to study the two-photon spectra of a variety of systems of increasing complexity: single mode emitters with two limiting statistics (one harmonic oscillator or a two-level system) and the various combinations that arise from their coupling. We consider both the linear and nonlinear regimes under incoherent excitation. We find that even the simplest systems display a rich dynamics of emission, not accessible by simple single photon spectroscopy. In the strong coupling regime, novel two-photon emission processes involving virtual states are revealed. Furthermore, two general results are unraveled by two-photon correlations with narrow linewidth detectors: i) filtering induced bunching and ii) breakdown of the semi-classical theory. We show how to overcome this shortcoming in a fully-quantized picture.Comment: 27 pages, 8 figure

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

Emitters of NN-photon bundles

We propose a scheme based on the coherent excitation of a two-level system in a cavity to generate an ultrabright CW and focused source of quantum light that comes in groups (bundles) of $N$ photons, for an integer $N$ tunable with the frequency of the exciting laser. We define a new quantity, the \emph{purity} of $N$-photon emission, to describe the percentage of photons emitted in bundles, thus bypassing the limitations of Glauber correlation functions. We focus on the case $1\le N\le3$ and show that close to 100% of two-photon emission and 90% of three-photon emission is within reach of state of the art cavity QED samples. The statistics of the bundles emission shows that various regimes---from $N$-photon lasing to $N$-photon guns---can be realized. This is evidenced through generalized correlation functions that extend the standard definitions to the multi-photon level.Comment: Introduce the n-th order N-photon correlation functions. Reorganized to emphasize the N-photon emitter, now extended to the antibunching regime, rather than only coherent emission as previsoul