3,918 research outputs found

    Non-equilibrium dynamics of bosonic atoms in optical lattices: Decoherence of many-body states due to spontaneous emission

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    We analyze in detail the heating of bosonic atoms in an optical lattice due to incoherent scattering of light from the lasers forming the lattice. Because atoms scattered into higher bands do not thermalize on the timescale of typical experiments, this process cannot be described by the total energy increase in the system alone (which is determined by single-particle effects). The heating instead involves an important interplay between the atomic physics of the heating process and the many-body physics of the state. We characterize the effects on many-body states for various system parameters, where we observe important differences in the heating for strongly and weakly interacting regimes, as well as a strong dependence on the sign of the laser detuning from the excited atomic state. We compute heating rates and changes to characteristic correlation functions based both on perturbation theory calculations, and a time-dependent calculation of the dissipative many-body dynamics. The latter is made possible for 1D systems by combining time-dependent density matrix renormalization group (t-DMRG) methods with quantum trajectory techniques.Comment: 17 pages, 14 figure

    Human Capital Spillovers, Productivity and Growth in the Manufacturing Sector of Pakistan

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    Manufacturing is an important sector of Pakistan’s economy. The main focus of this paper is to analyse the major factors of value-added growth and productivity in the manufacturing sector by using Translog Production Technology over the period 1971-72 to 2004-05. The empirical findings show that the contribution of productivity and human capital is around one- third of the total value-added growth in manufacturing sector which is less than the contribution attributed to these factors in developed and many other developing countries. Conventional factors like capital and labour are still the mainstay in the value-added growth of Pakistan’s manufacturing sector.Human Capital Spillovers, Total Factor Productivity, Absolute and Relative Shares

    Measuring entanglement growth in quench dynamics of bosons in an optical lattice

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    We discuss a scheme to measure the many-body entanglement growth during quench dynamics with bosonic atoms in optical lattices. By making use of a 1D or 2D setup in which two copies of the same state are prepared, we show how arbitrary order Renyi entropies can be extracted using tunnel-coupling between the copies and measurement of the parity of on-site occupation numbers, as has been performed in recent experiments. We illustrate these ideas for a Superfluid-Mott insulator quench in the Bose-Hubbard model, and also for hard-core bosons, and show that the scheme is robust against imperfections in the measurements.Comment: 4+ pages plus supplementary materia

    Quantum Spin Dimers from Chiral Dissipation in Cold-Atom Chains

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    We consider the non-equilibrium dynamics of a driven dissipative spin chain with chiral coupling to a 1D bosonic bath, and its atomic implementation with a two-species mixture of cold quantum gases. The reservoir is represented by a spin-orbit coupled 1D quasi-condensate of atoms in a magnetized phase, while the spins are identified with motional states of a separate species of atoms in an optical lattice. The chirality of reservoir excitations allows the spins to couple differently to left and right moving modes, which in our atomic setup can be tuned from bidirectional to purely unidirectional. Remarkably, this leads to a pure steady state in which pairs of neighboring spins form dimers that decouple from the remainder of the chain. Our results also apply to current experiments with two-level emitters coupled to photonic waveguides.Comment: Replaced by published version (6 pages + 8 pages supplemental material

    Raman response of Stage-1 graphite intercalation compounds revisited

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    We present a detailed in-situ Raman analysis of stage-1 KC8, CaC6, and LiC6 graphite intercalation compounds (GIC) to unravel their intrinsic finger print. Four main components were found between 1200 cm-1 and 1700 cm-1, and each of them were assigned to a corresponding vibrational mode. From a detailed line shape analysis of the intrinsic Fano-lines of the G- and D-line response we precisely determine the position ({\omega}ph), line width ({\Gamma}ph) and asymmetry (q) from each component. The comparison to the theoretical calculated line width and position of each component allow us to extract the electron-phonon coupling constant of these compounds. A coupling constant {\lambda}ph < 0.06 was obtained. This highlights that Raman active modes alone are not sufficient to explain the superconductivity within the electron-phonon coupling mechanism in CaC6 and KC8.Comment: 6 pages, 3 figures, 2 table

    Die Entwicklungsproblematik im Spiegel ihres europäisch-abendländischen Erbes. Auf der Wegsuche von der "alten" zur "neuen" Weltwirtschaftsordnung

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    Cost-effectiveness analysis of the use of immunotherapy in metastatic solid tumours in Austria by applying the ESMO-magnitude of clinical benefit scale (ESMO-MCBS) version 1.1

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    BACKGROUND: Immune checkpoint inhibitors (ICIs) treatment is a breakthrough in managing metastatic solid tumours, but its use is associated with a high financial burden for public health care systems. Validated tools such as the European Society for Medical Oncology-Magnitude of Clinical Benefit Scale (ESMO-MCBS) are frameworks that might help to better assess the clinical benefit of these novel innovative cancer drugs. METHODS: Here, we systematically analysed the number of European Medicines Agency-approved ICIs labels with an ESMO-MCBS grade <4 and the impact of the ICIs on incremental costs, gain of life years (LYs), quality-adjusted life years (QALYs) and the incremental cost-effectiveness ratio in the Austrian population. RESULTS: Of 23 ICIs treatment settings, we identified three clinical scenarios in metastatic solid cancers with an ESMO-MCBS grade <4 with no otherwise approved alternatives. In triple-negative breast cancer (TNBC), the addition of first-line atezolizumab increased QALYs by 0.33 compared with nab-paclitaxel only, with an incremental cost per QALY of €143 853. In small-cell lung cancer (SCLC), the addition of first-line atezolizumab increased the QALY by 0.09, with an incremental cost per QALY of €373 256, and the addition of first-line durvalumab increased the QALYs by 0.11, with an incremental cost per QALY of €589 527. CONCLUSIONS: Overall, most of the approved ICIs carry significant clinical benefit (≥4). Although TNBC and SCLC are challenging treatment scenarios, currently approved ICIs with an ESMO-MCBS grade <4 substantially increase the cost of medical treatment, and under a willingness-to-pay threshold of €100 000, they do not have a cost-effective comparative benefit

    Thermal vs. Entanglement Entropy: A Measurement Protocol for Fermionic Atoms with a Quantum Gas Microscope

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    We show how to measure the order-two Renyi entropy of many-body states of spinful fermionic atoms in an optical lattice in equilibrium and non-equilibrium situations. The proposed scheme relies on the possibility to produce and couple two copies of the state under investigation, and to measure the occupation number in a site- and spin-resolved manner, e.g. with a quantum gas microscope. Such a protocol opens the possibility to measure entanglement and test a number of theoretical predictions, such as area laws and their corrections. As an illustration we discuss the interplay between thermal and entanglement entropy for a one dimensional Fermi-Hubbard model at finite temperature, and its possible measurement in an experiment using the present scheme
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