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R. Floreanini

Publications and source records attributed to R. Floreanini.

At least 73 records · Page 4Linked to original sources
arXiv2003

Complete positivity and dissipative factorized dynamics: some comments

After reviewing the main properties of time-evolutions of open quantum systems, some considerations about the positivity of factorized Markovian dynamics for bipartite systems are made. In particular, it is shown that the positivity of the whole time-evolution in general does not ask for the complete positivity of the single system time-evolutions, if they are allowed to differ. However, they must be completely positive if one is a small perturbation of the other, which is the typical situation for open systems in a heat bath.

quant-ph↗
arXiv2003

Neutral kaons in random media

The generalized dynamics describing the propagation of neutral kaons in randomly fluctuating media is derived and analyzed. It takes into account possible matter-induced effects leading to loss of phase coherence and dissipation. The study of selected neutral kaon observables indicates that these non-standard effects are amenable to a direct experimental analysis.

hep-ph↗
arXiv2003

About non-positive evolutions in open system dynamics

The long-time evolution of a system in interaction with an external environment is usually described by a family of linear maps g_t, generated by master equations of Block-Redfield type. These maps are in general non-positive; a widely adopted cure for this physical inconsistency is to restrict the domain of definition of the dynamical maps to those states for which g_t remains positive. We show that this prescription has to be modified when two systems are immersed in the same environment and evolve with the factorized dynamics g_t x g_t starting from an entangled initial state.

quant-ph↗
arXiv2002

Planck's scale dissipative effects in atom interferometry

Atom interferometers can be used to study phenomena leading to irreversibility and dissipation, induced by the dynamics of fundamental objects (strings and branes) at a large mass scale. Using an effective, but physically consistent description in terms of a master equation of Lindblad form, the modifications of the interferometric pattern induced by the new phenomena are analyzed in detail. We find that present experimental devices can in principle provide stringent bounds on the new effects.

quant-ph↗
arXiv2002

Complete positivity and entangled degrees of freedom

We study how some recently proposed noncontextuality tests based on quantum interferometry are affected if the test particles propagate as open systems in presence of a gaussian stochastic background. We show that physical consistency requires the resulting markovian dissipative time-evolution to be completely positive.

quant-ph↗
arXiv2002

Dissipation and decoherence in photon interferometry

The propagation of polarized photons in optical media can be effectively modeled by means of quantum dynamical semigroups. These generalized time evolutions consistently describe phenomena leading to loss of phase coherence and dissipation originating from the interaction with a large, external environment. High sensitive experiments in the laboratory can provide stringent bounds on the fundamental energy scale that characterizes these non-standard effects.

quant-ph↗
arXiv2001

Massless neutrino oscillations

Quantum dynamical semigroups provide a general framework for studying the evolution of open systems. Neutrino propagation both in vacuum and in matter can be analyzed using these techniques: they allow a consistent treatment of non-standard, dissipative effects that can alter the pattern of neutrino oscillations. In particular, initially massless neutrinos can give rise to a nonvanishing flavour transition probability, involving in addition the Majorana CP-violating mixing phase.

hep-ph↗
arXiv2001

Irreversibility and dissipation in neutral B-meson decays

The propagation and decay of neutral B-mesons can be described in terms of quantum dynamical semigroups; they provide generalized time-evolutions that take into account possible non-standard effects leading to loss of phase coherence and dissipation. These effects can be fully parametrized in terms of six phenomenological constants. A detailed analysis of selected B-meson decays shows that present and future dedicated experiments, both at colliders and B-factories, will be able to put stringent bounds on these non-standard parameters.

hep-ph↗
arXiv2000

Damped harmonic oscillators in the holomorphic representation

Quantum dynamical semigroups are applied to the study of the time evolution of harmonic oscillators, both bosonic and fermionic. Explicit expressions for the density matrices describing the states of these systems are derived using the holomorphic representation. Bosonic and fermionic degrees of freedom are then put together to form a supersymmetric oscillator; the conditions that assure supersymmetry invariance of the corresponding dynamical equations are explicitly derived.

hep-th↗
arXiv2000

Effective dissipative dynamics for polarized photons

In the framework of open quantum systems, the propagation of polarized photons can be effectively described using quantum dynamical semigroups. These extended time-evolutions induce irreversibility and dissipation. Planned, high sensitive experiments, both in the laboratory and in space, will be able to put stringent bounds on these non-standard effects.

hep-ph↗
arXiv2000

On the weak-coupling limit and complete positivity

We consider two non-interacting systems embedded in a heat bath. If they remain dynamically independent, physical inconsistencies are avoided only if the single-system reduced dynamics is completely positive also beyond the weak-coupling limit.

quant-ph↗
arXiv2000

Open system approach to neutrino oscillations

Neutrino oscillations are studied in the general framework of open quantum systems by means of extended dynamics that take into account possible dissipative effects. These new phenomena induce modifications in the neutrino oscillation pattern that in general can be parametrized by means of six phenomenological constants. Although very small, stringent bounds on these parameters are likely to be given by future planned neutrino experiments.

hep-ph↗
arXiv1999

CPT, dissipation, and all that

A phenomenological paradigm for the study of CPT-violating effects in the neutral kaon system is presented. Besides the familiar direct and indirect breakings, it encodes possible phenomena leading to irreversibility and dissipation, that could originate from quantum effects at Planck's scale. These new effects can be experimentally probed with great accuracy, in particular at phi-factories.

hep-ph↗
arXiv1999

Complete positivity and correlated neutral kaons

In relation with experiments on correlated kaons at phi-factories, it is shown that the request of complete positivity is necessary in any physically consistent description of neutral kaons as open quantum systems.

hep-ph↗
arXiv1999

Dissipative effects in semileptonic B decays

We study the time evolution and decay of the neutral B-meson system using quantum dynamical semigroups. New, nonstandard terms appear in the expression of relevant observables; they can be parametrized in terms of six phenomenological constants. Although very small, these parameters may be detected in the new generation of dedicated B-meson experiments.

hep-ph↗
arXiv1999

Dissipative contributions to epsilon'/epsilon

The time evolution and decay of the neutral kaon system can be described using quantum dynamical semigroups. Non-standard terms appear in the expression of relevant observables; they can be parametrized in terms of six, new phenomenological constants. We discuss how the presence of these constants affects the determination of the parameter epsilon'/epsilon.

hep-ph↗