Mario Castagnino

The Self-Induced Approach to Decoherence in Cosmology

In this paper we will present the self-induced approach to decoherence, which does not require the interaction between the system and the environment: decoherence in closed quantum systems is possible. This fact has relevant consequences in cosmology, where the aim is to explain the emergence of classicality in the universe conceived as a closed (noninteracting) quantum system. In particular, we will show that the self-induced approach may be used for describing the evolution of a closed quantum universe, whose classical behavior arises as a result of decoherence.

Functional approach to quantum decoherence and the classical final limit

A quantum system with discrete and continuos evolution spectrum is studied. A final pointer basis is found, that can be defined in a presised mathematical way. This result is use to explain the quantum measurement in the system.

Self‐Induced Decoherence and the Classical Limit of Quantum Mechanics

In this paper we argue that the emergence of the classical world from the underlying quantum reality involves two elements: self‐induced decoherence and macroscopicity. Self‐induced decoherence does not require the openness of the system and its interaction with the environment: a single closed system can decohere when its Hamiltonian has continuous spectrum. We show that, if the system is macroscopic enough, after self‐induced decoherence it can be described as an ensemble of classical distributions weighted by their corresponding probabilities. We also argue that classicality is an emergent property that arises when the behavior of the system is described from an observational perspective.

Decoherence time in self-induced decoherence

A general method for obtaining the decoherence time in self-induced decoherence is presented. In particular, it is shown that such a time can be computed from the poles of the resolvent or of the initial conditions in the complex extension of the Hamiltonians spectrum. Several decoherence times are estimated:

The Cosmological origin of time asymmetry

{10}^{\ensuremath{-}13}\char21{}{10}^{\ensuremath{-}15}\phantom{\rule{0.3em}{0ex}}\mathrm{s}

The Riemannian Structure of Space‐Time as a Consequence of a Measurement Method

for microscopic systems, and

The Global Arrow of Time as a Geometrical Property of the Universe

{10}^{\ensuremath{-}37}\char21{}{10}^{\ensuremath{-}39}\phantom{\rule{0.3em}{0ex}}\mathrm{s}

Functional Approach to Quantum Decoherence and the Classical Final Limit: The Mott and Cosmological Problems

for macroscopic bodies. For the particular case of a thermal bath, the order of magnitude of our results agrees with that obtained by the einselection (environment-induced decoherence) approach.

The Arrow of Time: From Universe Time-Asymmetry to Local Irreversible Processes

In this paper, we address the problem of the arrow of time from a cosmological point of view, rejecting the traditional entropic approach that defines the future direction of time as the direction of the entropy increase: from our perspective, the arrow of time has a global origin and it is an intrinsic, geometrical feature of spacetime. Time orientability and the existence of a cosmic time are necessary conditions for defining an arrow of time, which is manifested globally as the time asymmetry of the universe as a whole, and locally as a time-asymmetric energy flux. We also consider arrows of time of different origins (quantum, electromagnetic, thermodynamic, etc) showing that they can be non-conventionally defined only if the geometrical arrow is previously defined.

A general theoretical framework for decoherence in open and closed systems

Following the graphical method of Marzke and Wheeler it is shown analytically that if we know the space‐time paths of all particles and light pulses we can deduce the connection and the metric of the space‐time manifold. Specifically if such space‐time paths fulfill some reasonable physical hypotheses, it is proved that space‐time is a Riemannian manifold. To reach this conclusion a new definition of parallelism is introduced, based only on ideal experiments. This parallelism is entirely different from the ordinary parallel transfers, if the manifold is non‐Riemannian; therefore it opens new ways of modifying gravitational theory.