62 research outputs found
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
Experimental observation of impossible-to-beat quantum advantage on a hybrid photonic system
Quantum resources outperform classical ones for certain communication and
computational tasks. Remarkably, in some cases, the quantum advantage cannot be
improved using hypothetical postquantum resources. A class of tasks with this
property can be singled out using graph theory. Here we report the experimental
observation of an impossible-to-beat quantum advantage on a four-dimensional
quantum system defined by the polarization and orbital angular momentum of a
single photon. The results show pristine evidence of the quantum advantage and
are compatible with the maximum advantage allowed using postquantum resources.Comment: REVTeX4, 5 pages, 2 figure
A FULLY IMPLICIT MATERIAL RESPONSE CODE WITH ABLATION AND PYROLYSIS FOR SIMULATION OF THERMAL PROTECTION SYSTEMS
The purpose of this paper is to introduce and describe a 2-D fully implicit numerical simulation tool capable of evaluating the behaviour of an ablative charring thermal protection system during atmospheric entry. In particular, the computational tool can model the heat transfer inside a solid porous material and the decomposition of the latter, pyrolysis gas density, pressure and speed distributions and surface recession. The governing equations are fully coupled and are integrated using a time-implicit scheme. The grid can contract to simulate the recession phenomenon and the recession rate can be evaluated using different ablation models, depending on the problem and on the available data. Spatial and temporal convergence tests demonstrated that the tool is second order accurate in space and time and comparisons with available numerical results are shown here for code verification
Experimental entanglement activation from discord in a programmable quantum measurement
In quantum mechanics, observing is not a passive act. Consider a system of two quantum particles A and B: if a measurement apparatus M is used to make an observation on B, the overall state of the system AB will typically be altered. When this happens, no matter which local measurement is performed, the two objects A and B are revealed to possess peculiar correlations known as quantum discord. Here, we demonstrate experimentally that the very act of local observation gives rise to an activation protocol which converts discord into distillable entanglement, a stronger and more useful form of quantum correlations, between the apparatus M and the composite system AB. We adopt a flexible two-photon setup to realize a three-qubit system (A, B, M) with programmable degrees of initial correlations, measurement interaction, and characterization processes. Our experiment demonstrates the fundamental mechanism underpinning the ubiquitous act of observing the quantum world and establishes the potential of discord in entanglement generation
Tunable Two-Photon Quantum Interference of Structured Light
Structured photons are nowadays an important resource in classical and quantum optics due to the richness of properties they show under propagation, focusing, and in their interaction with matter. Vectorial modes of light in particular, a class of modes where the polarization varies across the beam profile, have already been used in several areas ranging from microscopy to quantum information. One of the key ingredients needed to exploit the full potential of complex light in the quantum domain is the control of quantum interference, a crucial resource in fields like quantum communication, sensing, and metrology. Here we report a tunable Hong-Ou-Mandel interference between vectorial modes of light. We demonstrate how a properly designed spin-orbit device can be used to control quantum interference between vectorial modes of light by simply adjusting the device parameters and no need of interferometric setups. We believe our result can find applications in fundamental research and quantum technologies based on structured light by providing a new tool to control quantum interference in a compact, efficient, and robust way
Resilience of hybrid optical angular momentum qubits to turbulence
Recent schemes to encode quantum information into the total angular momentum
of light, defining rotation-invariant hybrid qubits composed of the
polarization and orbital angular momentum degrees of freedom, present
interesting applications for quantum information technology. However, there
remains the question as to how detrimental effects such as random spatial
perturbations affect these encodings. Here, we demonstrate that alignment-free
quantum communication through a turbulent channel based on hybrid qubits can
be achieved with unit transmission fidelity. In our experiment, alignment-free
qubits are produced with q-plates and sent through a homemade turbulence
chamber. The decoding procedure, also realized with q-plates, relies on both
degrees of freedom and renders an intrinsic error-filtering mechanism that
maps errors into losses
Hybrid ququart-encoded quantum cryptography protected by Kochen-Specker contextuality
Quantum cryptographic protocols based on complementarity are nonsecure
against attacks in which complementarity is imitated with classical resources.
The Kochen-Specker (KS) theorem provides protection against these attacks,
without requiring entanglement or spatially separated composite systems. We
analyze the maximum tolerated noise to guarantee the security of a KS-protected
cryptographic scheme against these attacks, and describe a photonic realization
of this scheme using hybrid ququarts defined by the polarization and orbital
angular momentum of single photons.Comment: REVTeX4-1, 5 pages, 2 figure
Deterministic qubit transfer between orbital and spin angular momentum of single photons
In this work we experimentally implement a deterministic transfer of a
generic qubit initially encoded in the orbital angular momentum of a single
photon to its polarization. Such transfer of quantum information, completely
reversible, has been implemented adopting a electrically tunable q-plate device
and a Sagnac interferomenter with a Dove's prism. The adopted scheme exhibits a
high fidelity and low losses.Comment: 3 pages, 2 figure
Predominant VH1-69 IgBCR Clones Show Higher Expression of CD5 in Heterogeneous Chronic Lymphocytic Leukemia Populations
The immunoglobulin B cell receptor (IgBCR) expressed by chronic lymphocytic leukemia (CLL) B cells plays a pivotal role in tumorigenesis, supporting neoplastic transformation, survival, and expansion of tumor clones. We demonstrated that in the same patient, two or more CLL clones could coexist, recognized by the expression of different variable regions of the heavy chain of IgBCR, composing the antigen-binding site. In this regard, phage display screening could be considered the easier and most advantageous methodology for the identification of small peptide molecules able to mimic the natural antigen of the tumor IgBCRs. These molecules, properly functionalized, could be used as a probe to specifically identify and isolate single CLL subpopulations, for a deeper analysis in terms of drug resistance, phenotype, and gene expression. Furthermore, CLL cells express another surface membrane receptor, the CD5, which is commonly expressed by normal T cells. Piece of evidence supports a possible contribution of CD5 to the selection and maintenance of autoreactivity in B cells and the constitutive expression of CD5 on CLL cells could induce pro-survival stimuli. In this brief research report, we describe a peptide-based single-cell sorting using as bait the IgBCR of tumor cells; in the next step, we performed a quantitative analysis of CD5 expression by qRT-PCR related to the expressed IgBCR. Our approach could open a new perspective for the identification, isolation, and investigation of all subsets of IgBCR-related CLL clones, with particular attention to the more aggressive clones
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