Valleys in String Foam Suppress Quantum Coherence

TL;DR

This paper explores how valley trajectories in string world sheets, linked to quantum fluctuations in space-time foam, lead to non-Hamiltonian evolution and suppression of quantum coherence in the string's density matrix.

Contribution

It introduces a novel string contribution involving valley trajectories that cause non-Hamiltonian dynamics and decoherence effects in the string's quantum state.

Findings

Valley trajectories affect the $ d{S}$ matrix structure.

They induce non-Hamiltonian time evolution.

Off-diagonal density matrix elements are suppressed over time.

Abstract

We exhibit string contributions to the $\nd{S}$ matrix relating in- and out- state density matrices that do not factorize as a product of $S$ and $S^\dagger$ matrices. They are associated with valley trajectories between topological defects on the string world sheet, that appear as quantum fluctuations in the space-time foam. Through their ultraviolet cut-off dependences these valleys cause non-Hamiltonian time evolution and suppress off-diagonal entries in the density matrix at large times.