Loss of coherence and dressing in QED

Abstract

The dynamics of a free charged particle, initially described by a coherent wave packet, interacting with an environment, i.e. the electromagnetic field characterized by a temperature T , is studied. Using the dipole approximation the exact expressions for the evolution of the reduced density matrix both in momentum and configuration space and the vacuum and the thermal contribution to decoherence, are obtained. The time behaviour of the coherence lengths in the two representations are given. Through the analysis of the dynamic of the field structure associated to the particle the vacuum contribution is shown to be linked to the birth of correlations between the single momentum components of the particle wave packet and the virtual photons of the dressing cloud.

Redundant information encoding in QED during decoherence

“…Eqs. (8,A12) in [10]; a similar derivation can be found also in [14]) and is given in the interaction picture by:…”

“…The decoherence process in this model has been extensively studied in [10] with the whole of the radiation traced out. The results can be easily generalized to our situation where only a portion F unob of the modes is neglected.…”

“…Quantum information theory approach to open quantum systems has been a subject of an active research recently, with an advent of such new and exciting research areas as thermodynamics of meso-and nanoscale systems [1][2][3] and quantum Darwinism [4][5][6], to name just two. Here we consider quantum electrodynamics (QED) from an open system's perspective ( see [7][8][9][10] and the references therein), treating the electromagnetic field as the environment for the charge. We use quantum information concepts to study information gained by portions of the (initially thermal) field about the charge during the evolution.…”

Electron decoherence in a semiconductor due to electron‐phonon scattering

“…3 Results Let us now analyze the dynamics of the electronic decoherence in our 1D model for the electronphonon interaction. In agreement with previous works [13], as initial condition we take a quantum state with no correlation between the particle and the phonon field. The corresponding initial WF is decoupled and reads:…”

Soft theorems from boundary terms in the classical point particle currents

“…The question of how soft gauge bosons cause decoherence of matter states can also be related to asymptotic states. In QED, studies of decoherence are quite old [59,60]; more recent work on both soft photon and soft graviton decoherence [27,61,62] indicates that matter states are almost completely decohered over long times except under very special circumstances, although the problem is not completely resolved [63,64]; the connection with asymptotic states can be understood in various ways [27,62]. In this context it is interesting that scattering using dressed states [62] seems to exhibit interference terms which are more in line with what is seen in finite time experiments.…”