414 research outputs found
La crisi del dibattito pubblico nell'Italia contemporanea: il discorso populista
In this paper I discuss the current state of the so called populist political discourse in Italy. In particular my purpose is to shed light on some features of this kind of discourse in order to show the relation between language and policy in the discourse of populism. In this perspective I will follow the eight key points that, according to Diamanti & Lazar (2018), identify the actual populist movements, in order to verify if – and, in that case, which – linguistic traits characterize their discourse.The analysis will be focused on the semantic and argumentative aspects of the discourse of some of the most important political actors in contemporary Italy
A deeper insight into quantum state transfer from an information flux viewpoint
We use the recently introduced concept of information flux in a many-body
register in order to give an alternative viewpoint on quantum state transfer in
linear chains of many spins.Comment: 6 pages, 3 figures, RevTeX
Controllable Gaussian-qubit interface for extremal quantum state engineering
We study state engineering through bilinear interactions between two remote
qubits and two-mode Gaussian light fields. The attainable two-qubit states span
the entire physically allowed region in the entanglement-versus-global-purity
plane. Two-mode Gaussian states with maximal entanglement at fixed global and
marginal entropies produce maximally entangled two-qubit states in the
corresponding entropic diagram. We show that a small set of parameters
characterizing extremally entangled two-mode Gaussian states is sufficient to
control the engineering of extremally entangled two-qubit states, which can be
realized in realistic matter-light scenarios.Comment: 4+3 pages, 6 figures, RevTeX4. Close to published version with
appendi
Quantum state transfer in imperfect artificial spin networks
High-fidelity quantum computation and quantum state transfer are possible in
short spin chains. We exploit a system based on a dispersive qubit-boson
interaction to mimic XY coupling. In this model, the usually assumed
nearest-neighbors coupling is no more valid: all the qubits are mutually
coupled. We analyze the performances of our model for quantum state transfer
showing how pre-engineered coupling rates allow for nearly optimal state
transfer. We address a setup of superconducting qubits coupled to a microstrip
cavity in which our analysis may be applied.Comment: 4 pages, 3 figures, RevTeX
Entanglement control in hybrid optomechanical systems
We demonstrate the control of entanglement in a hybrid optomechanical system
comprising an optical cavity with a mechanical end-mirror and an intracavity
Bose-Einstein condensate (BEC). Pulsed laser light (tuned within realistic
experimental conditions) is shown to induce an almost sixfold increase of the
atom-mirror entanglement and to be responsible for interesting dynamics between
such mesoscopic systems. In order to assess the advantages offered by the
proposed control technique, we compare the time-dependent dynamics of the
system under constant pumping with the evolution due to the modulated laser
light.Comment: Published versio
Non-equilibrium readiness and accuracy of Gaussian Quantum Thermometers
The dimensionality of a thermometer is key in the design of quantum
thermometry schemes. In general, the phenomenology that is typical of
finite-dimensional quantum thermometry does not apply to infinite dimensional
ones. We analyse the dynamical and metrological features of non-equilibrium
Gaussian Quantum Thermometers: on one hand, we highlight how quantum
entanglement can enhance the readiness of composite Gaussian thermometers; on
the other hand, we show that non-equilibrium conditions do not guarantee the
best sensitivities in temperature estimation, thus suggesting the reassessment
of the working principles of quantum thermometry
Information-flux approach to multiple-spin dynamics
We introduce and formalize the concept of information flux in a many-body
register as the influence that the dynamics of a specific element receive from
any other element of the register. By quantifying the information flux in a
protocol, we can design the most appropriate initial state of the system and,
noticeably, the distribution of coupling strengths among the parts of the
register itself. The intuitive nature of this tool and its flexibility, which
allow for easily manageable numerical approaches when analytic expressions are
not straightforward, are greatly useful in interacting many-body systems such
as quantum spin chains. We illustrate the use of this concept in quantum
cloning and quantum state transfer and we also sketch its extension to
non-unitary dynamics.Comment: 7 pages, 4 figures, RevTeX
Detecting Gaussian entanglement via extractable work
We show how the presence of entanglement in a bipartite Gaussian state can be
detected by the amount of work extracted by a continuos variable Szilard-like
device, where the bipartite state serves as the working medium of the engine.
We provide an expression for the work extracted in such a process and
specialize it to the case of Gaussian states. The extractable work provides a
sufficient condition to witness entanglement in generic two-mode states,
becoming also necessary for squeezed thermal states. We extend the protocol to
tripartite Gaussian states, and show that the full structure of inseparability
classes cannot be discriminated based on the extractable work. This suggests
that bipartite entanglement is the fundamental resource underpinning work
extraction.Comment: 12 pages, 8 figure
Work statistics, irreversible heat and correlations build-up in joining two spin chains
We investigate the influences of quantum many-body effects, such as
criticality and the existence of factorisation fields, in the thermodynamic
cost of establishing a bonding link between two independent quantum spin
chains. We provide a physical interpretation of the behavior of irreversible
work spent in such process by linking the phenomenology of such quantities to
the properties of the spectrum of the systemComment: 9 pages, 8 figures. Contribution to the FQMT13 special volum
Nonlinearity and nonclassicality in a nanomechanical resonator
We address quantitatively the relationship between the nonlinearity of a
mechanical resonator and the nonclassicality of its ground state. In
particular, we analyze the nonclassical properties of the nonlinear Duffing
oscillator (being driven or not) as a paradigmatic example of a nonlinear
nanomechanical resonator. We first discuss how to quantify the nonlinearity of
this system and then show that the nonclassicality of the ground state, as
measured by the volume occupied by the negative part of the Wigner function,
monotonically increases with the nonlinearity in all the working regimes
addressed in our study. Our results show quantitatively that nonlinearity is a
resource to create nonclassical states in mechanical systems.Comment: 6 pages; 7 figures; RevTeX4-
- …