385 research outputs found
Non-Markovianity of a quantum emitter in front of a mirror
We consider a quantum emitter ("atom") radiating in a one-dimensional (1D)
photonic waveguide in the presence of a single mirror, resulting in a delay
differential equation for the atomic amplitude. We carry out a systematic
analysis of the non-Markovian (NM) character of the atomic dynamics in terms of
refined, recently developed notions of quantum non-Markovianity such as
indivisibility and information back-flow. NM effects are quantified as a
function of the round-trip time and phase shift associated with the atom-mirror
optical path. We find, in particular, that unless an atom-photon bound state is
formed a finite time delay is always required in order for NM effects to be
exhibited. This identifies a finite threshold in the parameter space, which
separates the Markovian and non-Markovian regimes.Comment: 7 pages, 4 figures. Fig. 3 featured in Phys. Rev. A Kaleidoscope
Images: July 201
Signatures of the term in ultrastrongly-coupled oscillators
We study a bosonic matter excitation coupled to a single-mode cavity field
via electric dipole. Counter-rotating and terms are included in the
interaction model, being the vector potential of the cavity
field. In the ultrastrong coupling regime the vacuum of the bare modes is no
longer the ground state of the Hamiltonian and contains a nonzero population of
polaritons, the true normal modes of the system. If the parameters of the model
satisfy the Thomas-Reiche-Kuhn sum rule, we find that the two polaritons are
always equally populated. We show how this prediction could be tested in a
quenching experiment, by rapidly switching on the coupling and analyzing the
radiation emitted by the cavity. A refinement of the model based on a
microscopic minimal coupling Hamiltonian is also provided, and its consequences
on our results are characterized analytically.Comment: 11 pages, 5 figure
Shaping Emotions: a Study about the Feeling of Loneliness through the Material Interaction with Surfaces
This contribution aims to investigate how design culture can foster new models of emotional, social and cultural interaction that find in the pleasantness of the surface the creation of valuable experiences for users. In particular, the
research examines interaction design from a different point of view, studying the relation of emotions and surfaces in a product-based interaction experience.
Specifically, the contribution presents the results of a workshop called shaping emotions: a formal exercise based on the understanding of how user sensations - without precise references on a particular product - can play a decisive role in defining strategies that embrace the aesthetic and typological sphere of use and meanings. This study has highlighted the transfer of intangible psycho-cognitive aspects into tangible elements whose syntax and semiotics is driven by a phenomenological approach to the formal interpretation of an emotional concept. Emotions that occur from experiential states place the feelings of the human being as a focus of the project; through the design culture, the study tries to interpret experiences and desires as components of mixed emotions
Quantum non-Gaussianity witnesses in the phase space
We address detection of quantum non-Gaussian states, i.e. nonclassical states
that cannot be expressed as a convex mixture of Gaussian states, and present a
method to derive a new family of criteria based on generic linear functionals.
We then specialise this method to derive witnesses based on -parametrized
quasiprobability functions, generalising previous criteria based on the Wigner
function. In particular we discuss in detail and analyse the properties of
Husimi Q-function based witnesses and prove that they are often more effective
than previous criteria in detecting quantum non-Gaussianity of various kinds of
non-Gaussian states evolving in a lossy channel.Comment: 9 pages, 6 figure
Quantum Correlations in Multipartite Quantum Systems
We review some concepts and properties of quantum correlations, in particular
multipartite measures, geometric measures and monogamy relations. We also
discuss the relation between classical and total correlationsComment: to be published as a chapter of the book "Lectures on general quantum
correlations and their applications" edited by F. Fanchini, D. Soares-Pinto,
and G. Adesso (Springer, 2017
Dynamics of spontaneous emission in a single-end photonic waveguide
We investigate the spontaneous emission of a two-level system, e.g. an atom
or atomlike object, coupled to a single-end, i.e., semi-infinite,
one-dimensional photonic waveguide such that one end behaves as a perfect
mirror while light can pass through the opposite end with no back-reflection.
Through a quantum microscopic model we show that such geometry can cause
non-exponential and long-lived atomic decay. Under suitable conditions, a bound
atom-photon stationary state appears in the atom-mirror interspace so as to
trap a considerable amount of initial atomic excitation. Yet, this can be
released by applying an atomic frequency shift causing a revival of photon
emission. The resilience of such effects to typical detrimental factors is
analyzed.Comment: 6 pages, 4 figure
- …