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Steady State Entanglement beyond Thermal Limits
F. Tacchino, A. Auffèves, M. F. Santos, D. GeraceClassical engines turn thermal resources into work, which is maximized for reversible operations. The quantum realm has expanded the range of useful operations beyond energy conversion, and incoherent resources beyond thermal reservoirs. This is the case of entanglement generation in a driven-dissipative protocol, which we hereby analyze as a continuous quantum machine. We show that for such machines the more irreversible the process, the larger the concurrence. Maximal concurrence and entropy production are reached for the hot reservoir being at negative effective temperature, beating the limits set by classic thermal operations on an equivalent system.
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Investigating nonclassicality in nonlinear electronic spectroscopy
Saulo V. Moreira, Fernando L. SemiãoIn this work, we establish a connection between nonlinear electronic spectroscopy and quantum information protocols for the non-disturbance condition. The non-fulfillment of the later is a witness of nonclassicality. Our approach permits us to express the non-disturbance condition in terms of common observables in the context of electronic spectroscopy experiments, such as the induced polarization. We then provide the theoretical framework allowing one to infer nonclassicality from the detected signals in these experiments. A prominent feature of our proposal is then the model independence. In particular, for third-order nonlinear spectroscopies, such as the widely used two-dimensional electronic spectroscopy, we find that the induction of third-order polarization in systems satisfying inversion symmetry automatically implies nonclassicality.
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Quantum walks via quantum cellular automata
Pedro C. S. Costa, Renato Portugal, Fernando de MeloVery much as its classical counterpart, quantum cellular automata are expected to be a great tool for simulating complex quantum systems. Here we introduce a partitioned model of quantum cellular automata and show how it can simulate, with the same amount of resources (in terms of effective Hilbert space dimension), various models of quantum walks. All the algorithms developed within quantum walk models are thus directly inherited by the quantum cellular automata. The latter, however, has its structure based on local interactions between qubits, and as such it can be more suitable for present (and future) experimental implementations.
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Pulse engineering for population control under dephasing and dissipation
I. Medina, F. L. SemiãoWe apply reverse-engineering to find electromagnetic pulses that allow for the control of populations in quantum systems under dephasing and thermal noises. In particular, we discuss two-level systems given their importance in the description of several molecular systems as well as quantum computing. Such an investigation naturally finds applications in a multitude of physical situations involving the control of quantum systems. We present an analytical description of the pulse which solves a constrained dynamics where the initial and final populations are fixed a priori. This constrained dynamics is sometimes impossible and we precisely spot the conditions for that. One of our main results is the presentation of analytical conditions for the establishment of steady states for finite coherence in the presence of noise. This might naturally find applications in quantum memories.
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Relative phase shifts for metaplectic isotopies acting on mixed Gaussian states
Maurice A. de Gosson, Fernando NicacioWe address in this paper the notion of relative phase shift for mixed quantum systems. We study the Pancharatnam-Sjoeqvist phase shift for metaplectic isotopies acting on Gaussian mixed states. We complete and generalize previous results obtained by one of us while giving rigorous proofs. This gives us the opportunity to review and complement the theory of the Conley-Zehnder index which plays an essential role in the determination of phase shifts.
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Concentration phenomena in the geometry of Bell correlations
Cristhiano Duarte, Samuraí Brito, Barbara Amaral, Rafael Chaves -
Noncontextual Wirings
Barbara Amaral, Adán Cabello, Marcelo Terra Cunha, Leandro Aolita -
Machine learning non-local correlations
Askery Canabarro, Samuraí Brito, Rafael Chaves -
Probing quantum fluctuation theorems in engineered reservoirs
C Elouard, N K Bernardes, A R R Carvalho, M F Santos, A Auffèves -
Energy, momentum and production rate of photonic Cooper pairs
Filomeno S. de Aguiar Junior, Andre Saraiva, Marcelo F. Santos, Belita Koiller, Reinaldo de Melo e Souza, Arthur Patrocinio Pena, Raigna A. Silva, Carlos H. Monken, Ado Jorio -
Nonanomalous measure of realism-based nonlocality
V. S. Gomes, R. M. Angelo -
Unitary equivalence between the Green's function and Schrödinger approaches for quantum graphs
Fabiano M. Andrade, Simone Severini -
Information-reality complementarity: The role of measurements and quantum reference frames
P. R. Dieguez, R. M. Angelo -
Gradient target propagation
Tiago de Souza Farias, Jonas Maziero -
Weak quantum discord
P. R. Dieguez, R. M. Angelo
1 a 15 de 19 Preprints encontradas Ano: 2018