Spontaneous Collapse Models From A Coarse-grained Deterministic And Non-unitary Dynamics

Abstract

We study the measurement process of a quantum system at Planck time resolution using trace dynamics. When a quantum system interacts with a classical apparatus the combined system is macroscopic and the non unitarity in the trace dynamics equations become important. In quantum mechanics we have a unitary and deterministic evolution of the wavefunction and therefore superpositions are preserved with time. However, in trace dynamics since non-unitarity is important, we investigate the non-unitary and deterministic evolution of a quantum system. To gain insights into this different kind of evolution, we consider a simple two-level qubit system. The motivation for pursuing this study was trace dynamics formulation in which quantum theory comes out as an emergent phenomena. We present, in this thesis, an overview of standard quantum formalism, the measurement problem, spontaneous collapse models and trace dynamics.