arXiv subjects

Emanuele Ciancio

Publications and source records attributed to Emanuele Ciancio.

4 recordsLinked to original sources

arXiv2005

Coupling bosonic modes with a qubit: entanglement dynamics at zero and finite-temperatures

We consider a system of two iso-spectral bosonic modes coupled with a single two-level systems i.e., a qubit. The dynamics is described by a mode-symmetric two-modes Jaynes-Cummings. The entanglement, induced between the two bosonic modes, is analyzed and quantified by negativity. We computed the time evolution of negativity starting from an initial thermal state of the bosonic sector for both zero and finite temperature. We also studied the entangling power of the interaction as a function of mode-qubit detuning and its resilience against temperature increase. Finally a two-qubit gates based on bosonic virtual subsystem is discussed.

quant-ph↗

arXiv2005

Quantum-transport theory for semiconductor nanostructures: A density-matrix formulation

A general density-matrix formulation of quantum-transport phenomena in semiconductor nanostructures is presented. More specifically, contrary to the conventional single-particle correlation expansion, we shall investigate separately the effects of the adiabatic or Markov limit and of the reduction procedure. Our fully operatorial approach allows us to better identify the general properties of the scattering superoperators entering our effective quantum-transport theory at various description levels, e.g., N electrons-plus-quasiparticles, N electrons only, and single-particle picture. In addition to coherent transport phenomena characterizing the transient response of the system, the proposed theoretical description allows to study scattering induced phase coherence in steady-state conditions. As prototypical example, we shall investigate polaronic effects in strongly biased semiconductor superlattices.

cond-mat.mtrl-sci↗

arXiv2005

Mode transformations and entanglement relativity in bipartite gaussian states

A proper choice of subsystems for a system of identical particles e.g., bosons, is provided by second-quantized modes i.e.,creation/annihilation operators. Here we investigate how the entanglement properties of bipartite gaussian states of bosons change when modes are changed by means of unitary, number conserving, Bogolioubov transformations. This set of "virtual" bi-partitions is then finite-dimensionally parametrized and one can quantitatively address relevant questions such as the determination of the minimal and maximal available entanglement. In particular, we show that in the class of bipartite gaussian states there are states which remain separable for every possible modes redefinition, while do not exist states which remain entangled for every possible modes redefinition

quant-ph↗

arXiv2001

Gauge-Invariant Formulation of Fermi's Golden Rule: Application to High-Field Transport in Semiconductors

A gauge-invariant formulation of Fermi's Golden rule is proposed. We shall rivisit the conventional description of carrier-phonon scattering in the presence of high electric fields by means of a gauge-invariant density-matrix approach. We show that the so-called Intracollisional Field Effect - as usually accounted for - does not exist: it is simply an artifact due to the neglect of the time variation of the basis states which, in turn, leads to a ill-defined Markov limit in the carrier-phonon interaction process. This may account for the surprisingly good agreement between semiclassical and rigorous quantum-transport calculations.

cond-mat.stat-mech↗