The Experts below are selected from a list of 43632 Experts worldwide ranked by ideXlab platform

A O Caldeira - One of the best experts on this subject based on the ideXlab platform.

  • entanglement versus quantum discord in two coupled double quantum dots
    New Journal of Physics, 2010
    Co-Authors: F F Fanchini, L K Castelano, A O Caldeira
    Abstract:

    We study the dynamics of quantum correlations of two coupled double quantum dots containing two excess electrons. The dissipation is included through the contact with an oscillator bath. We solve the Redfield master equation in order to determine the dynamics of the quantum discord (QD) and the entanglement of formation (EoF). Based on our results, we find that the QD is more resistant to dissipation than the EoF for such a system. We observe that this characteristic is related to whether the oscillator bath is common to both qubits or not and to the form of the Interaction Hamiltonian. Moreover, our results show that the QD might be finite, even for higher temperatures in the asymptotic limit.

  • entanglement versus quantum discord in two coupled double quantum dots
    arXiv: Quantum Physics, 2009
    Co-Authors: F F Fanchini, L K Castelano, A O Caldeira
    Abstract:

    We study the dynamics of quantum correlations of two coupled double quantum dots containing two excess electrons. The dissipation is included through the contact with an oscillator bath. We solve the Redfield master equation in order to determine the dynamics of the quantum discord and the entanglement of formation. Based on our results, we find that the quantum discord is more resistant to dissipation than the entanglement of formation for such a system. We observe that this characteristic is related to whether the oscillator bath is common to both qubits or not and to the form of the Interaction Hamiltonian. Moreover, our results show that the quantum discord might be finite even for higher temperatures in the asymptotic limit.

Lawrence M Glasser - One of the best experts on this subject based on the ideXlab platform.

  • indirect Interaction of solid state qubits via two dimensional electron gas
    Physical Review Letters, 2001
    Co-Authors: Dima Mozyrsky, Vladimir Privman, Lawrence M Glasser
    Abstract:

    We propose a mechanism of long-range coherent coupling between nuclear spin qubits in semiconductor-heterojunction quantum information processing devices. The coupling is via localized donor electrons which interact with the two-dimensional electron gas. An effective Interaction Hamiltonian is derived and the coupling strength is evaluated. We also discuss mechanisms of decoherence and consider gate control of the Interaction between qubits. The resulting quantum computing scheme retains all the control and measurement aspects of earlier approaches, but allows qubit spacing at distances of the order of 100 nm, attainable with the present-day semiconductor device technologies.

H S Sherif - One of the best experts on this subject based on the ideXlab platform.

  • relativistic calculations for photonuclear reactions ii nonrelativistic reductions and nuclear medium effects
    Nuclear Physics, 1995
    Co-Authors: Mohammad Hedayatipoor, J I Johansson, H S Sherif
    Abstract:

    Abstract The relativistic amplitude for the direct knock-out contribution to (γ, p ) reactions on nuclei is reduced to a nonrelativistic form using an effective Pauli reduction scheme. The reduction is carried out to second order in the inverse nucleon mass. It is found that the Interaction Hamiltonian appearing in the nonrelativistic amplitude has significant dependence, starting at second order, on the vector and scalar mean nuclear potentials. These strong medium modifications are absent in traditional nonrelativistic calculations. Detailed comparisons show that these modifications are crucial to understanding the differences between relativistic and nonrelativistic models. These differences are also examined through reduction of the relativistic amplitude via the Foldy-Wouthuysen transformation. Similar medium modifications are obtained in this case as well. We discuss the implications of these medium modifications for the consistency of existing nonrelativistic calculations.

  • comparison of relativistic and non relativistic amplitudes for photonuclear reactions
    Physics Letters B, 1994
    Co-Authors: Mohammad Hedayatipoor, H S Sherif
    Abstract:

    Abstract The relativistic DWBA amplitude for direct knock-out in (γ, p) reactions on nuclei is subjected to an effective two-component Pauli reduction. The resulting Interaction Hamiltonian exhibits strong dependence on the nuclear vector and scalar potentials. The leading term in a 1/( E + M ) expansion recovers the standard non-relativistic form of the amplitude. Large differences exist between the relativistic and non-relativistic calculations, particularly for polarization observables at intermediate energies. Calculations carried out to second order clearly indicate the crucial importance of taking into account the medium modifications, via the strong vector and scalar potentials, of the Interaction Hamiltonian.

S Stringari - One of the best experts on this subject based on the ideXlab platform.

  • quantum tricriticality and phase transitions in spin orbit coupled bose einstein condensates
    Physical Review Letters, 2012
    Co-Authors: Lev P Pitaevskii, S Stringari
    Abstract:

    We consider a spin-orbit coupled configuration of spin-$1/2$ interacting bosons with equal Rashba and Dresselhaus couplings. The phase diagram of the system at $T=0$ is discussed with special emphasis on the role of the Interaction treated in the mean-field approximation. For a critical value of the density and of the Raman coupling we predict the occurrence of a characteristic tricritical point separating the spin mixed, the phase separated, and the zero momentum states of the Bose gas. The corresponding quantum phases are investigated analyzing the momentum distribution, the longitudinal and transverse spin polarization, and the emergence of density fringes. The effect of harmonic trapping as well as the role of the breaking of spin symmetry in the Interaction Hamiltonian are also discussed.

F F Fanchini - One of the best experts on this subject based on the ideXlab platform.

  • entanglement versus quantum discord in two coupled double quantum dots
    New Journal of Physics, 2010
    Co-Authors: F F Fanchini, L K Castelano, A O Caldeira
    Abstract:

    We study the dynamics of quantum correlations of two coupled double quantum dots containing two excess electrons. The dissipation is included through the contact with an oscillator bath. We solve the Redfield master equation in order to determine the dynamics of the quantum discord (QD) and the entanglement of formation (EoF). Based on our results, we find that the QD is more resistant to dissipation than the EoF for such a system. We observe that this characteristic is related to whether the oscillator bath is common to both qubits or not and to the form of the Interaction Hamiltonian. Moreover, our results show that the QD might be finite, even for higher temperatures in the asymptotic limit.

  • entanglement versus quantum discord in two coupled double quantum dots
    arXiv: Quantum Physics, 2009
    Co-Authors: F F Fanchini, L K Castelano, A O Caldeira
    Abstract:

    We study the dynamics of quantum correlations of two coupled double quantum dots containing two excess electrons. The dissipation is included through the contact with an oscillator bath. We solve the Redfield master equation in order to determine the dynamics of the quantum discord and the entanglement of formation. Based on our results, we find that the quantum discord is more resistant to dissipation than the entanglement of formation for such a system. We observe that this characteristic is related to whether the oscillator bath is common to both qubits or not and to the form of the Interaction Hamiltonian. Moreover, our results show that the quantum discord might be finite even for higher temperatures in the asymptotic limit.