939 research outputs found
Photonic high dimensional systems and their applications in fundamental quantum mechanics, quantum information and quantum communication
Photonic high dimensional systems and their applications in fundamental quantum mechanics, quantum information and quantum communication
For a few Euro more: Benefit Generosity and the Optimal Path of Unemployment Benefits
In this paper, we exploit the provision of higher UB at different points of the unemployment spell to shed light on the relative cost of insurance at different horizons after the job loss. First, we exploit a double cap system in an RDD setting to study the effect of higher benefit levels in the early part of unemployment spell on time on benefits and non-employment. We find that higher benefits increase the time spent on benefits and in non-employment, with no impact on new job quality. Second, we exploit an age-based discontinuity in benefit duration, which determines higher benefits later in the spell, to compare the behavioural and mechanical costs of these two variations in benefits. We find that the moral hazard costs are greater for higher benefit levels early in the spell. In addition, we provide evidence of a slight negative selection in long term unemployment and argue that the long-term unemployed face higher uncertainty in their employment prospects. These findings suggest that higher benefits later in the unemployment spell generate lower costs and would provide higher insurance. Our results question the optimality of strongly declining schedules for unemployment benefit levels
Photon spin-to-orbital angular momentum conversion via an electrically tunable -plate
Exploiting electro-optic effects in liquid crystals, we achieved real-time
control of the retardation of liquid- crystal-based -plates through an
externally applied voltage. The newly conceived electro-optic -plates can be
operated as electrically driven converters of photon spin into orbital angular
momentum, enabling a variation of the orbital angular momentum probabilities of
the output photons over a time scale of milliseconds.Comment: 4 pages, 5 figures, submitte
On the Analytic Structure of a Family of Hyperboloidal Beams of Potential Interest for Advanced LIGO
For the baseline design of the advanced Laser Interferometer
Gravitational-wave Observatory (LIGO), use of optical cavities with
non-spherical mirrors supporting flat-top ("mesa") beams, potentially capable
of mitigating the thermal noise of the mirrors, has recently drawn a
considerable attention. To reduce the severe tilt-instability problems
affecting the originally conceived nearly-flat, "Mexican-hat-shaped" mirror
configuration, K. S. Thorne proposed a nearly-concentric mirror configuration
capable of producing the same mesa beam profile on the mirror surfaces.
Subsequently, Bondarescu and Thorne introduced a generalized construction that
leads to a one-parameter family of "hyperboloidal" beams which allows
continuous spanning from the nearly-flat to the nearly-concentric mesa beam
configurations. This paper is concerned with a study of the analytic structure
of the above family of hyperboloidal beams. Capitalizing on certain results
from the applied optics literature on flat-top beams, a physically-insightful
and computationally-effective representation is derived in terms of
rapidly-converging Gauss-Laguerre expansions. Moreover, the functional relation
between two generic hyperboloidal beams is investigated. This leads to a
generalization (involving fractional Fourier transform operators of complex
order) of some recently discovered duality relations between the nearly-flat
and nearly-concentric mesa configurations. Possible implications and
perspectives for the advanced LIGO optical cavity design are discussed.Comment: 9 pages, 6 figures, typos corrected, Eqs. (24) and (26) change
Experimental investigation on the geometry of GHz states
Nonclassical correlations arising in complex quantum networks are attracting growing interest, both from afundamental perspective and for potential applications in information processing. In particular, in an entanglementswapping scenario a new kind of correlations arise, the so-called nonbilocal correlations that are incompatible withlocal realism augmented with the assumption that the sources of states used in the experiment are independent.In practice, however, bilocality tests impose strict constraints on the experimental setup and in particular to thepresence of shared reference frames between the parties. Here, we experimentally address this point showing thatfalse positive nonbilocal quantum correlations can be observed even though the sources of states are independent.To overcome this problem, we propose and demonstrate a scheme for the violation of bilocality that does notrequire shared reference frames and thus constitutes an important building block for future investigations ofquantum correlations in complex network
Device-independent certification of high-dimensional quantum systems
An important problem in quantum information processing is the certification
of the dimension of quantum systems without making assumptions about the
devices used to prepare and measure them, that is, in a device-independent
manner. A crucial question is whether such certification is experimentally
feasible for high-dimensional quantum systems. Here we experimentally witness
in a device-independent manner the generation of six-dimensional quantum
systems encoded in the orbital angular momentum of single photons and show that
the same method can be scaled, at least, up to dimension 13.Comment: REVTeX4, 5 pages, 2 figure
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