Unique Quantum Paths by Continuous Diagonalization of the Density Operator

In this short note we show that for a Markovian open quantum system it is always possible to construct a unique set of perfectly consistent Schmidt paths, supporting quasi-classicality. Our Schmidt process, elaborated several years ago, is the $\Delta t\to 0$ limit of the Schmidt chain constructed very recently by Paz and Zurek.Comment: 8 pages REVTe

Equation and test of possible delay time of Newton force

Recently, a simple heuristic modification of the Newton potential with a non-zero delay-time $\tau_G$ has been proposed. Our modification is largely suppressed for purely gravitational interactions, it becomes relevant under non-gravitational accelerations of the sources. We illustrate how the choice $\tau_G\sim1$ms may already influence the 5th digit of G determined by Cavendish experiments. Re-evaluation of old Cavendish experiments and implementing slightly modified new ones may confirm the proposal or, at least, put a stronger upper limit on $\tau_G$.Comment: 4 pp, 2 figs, based on talk at Int. Symp. Wigner 111 - Colourful & Deep (Budapest, 11-13 Nov, 2013

How to teach and think about spontaneous wave function collapse theories: not like before

A simple and natural introduction to the concept and formalism of spontaneous wave function collapse can and should be based on textbook knowledge of standard quantum state collapse and monitoring. This approach explains the origin of noise driving the paradigmatic stochastic Schr\"odinger equations of spontaneous localization of the wave function $\Psi$. It reveals, on the other hand, that these equations are empirically redundant and the master equations of the noise-averaged state $\hat\rho$ are the only empirically testable dynamics in current spontaneous collapse theories.Comment: Almost the published version p3-11 in "Collapse of the Wave Function", ed.: S Gao, Cambridge University Press, 201