Models of wave-function collapse, underlying theories, and experimental tests

Abstract

Quantum mechanics is an extremely successful theory that agrees with every experiment. However, the principle of linear superposition, a central tenet of the theory, apparently contradicts a commonplace observation: macroscopic objects are never found in a linear superposition of position states. Moreover, the theory does not explain why during a quantum measurement, deterministic evolution is replaced by probabilistic evolution, whose random outcomes obey the Born probability rule. In this article we review an experimentally falsifiable phenomenological proposal, known as Continuous Spontaneous Collapse: a stochastic non- *

A Comparison Between Models of Gravity Induced Decoherence

“…The CSL model is being subjected to stringent experimental tests, and various constraints have also been imposed on its parameters from astrophysical and cosmological observations [49]. It is hoped that in the coming decades tests will either verify or rule out this model.…”

“…Thus, the way things stand today, decoherence plus many worlds, Bohmian mechanics, and nonlinear quantum theory, are all valid explanations of observed quantum phenomena and the quantum measurement process. Only future investigations can decide as to which (if any) of these explanations is the correct one; and such investigations are of tremendous importance in helping decide the domain of validity of the standard theory [49].…”

Information and the Foundations of Quantum Theory

“…This is random determinism: randomness is a fundamental feature of the law of evolution; it does not in any way take away the primary importance of the 'it'. Today, technology is at a stage where CSL is being put to experimental tests in the laboratory, for in the mesoscopic and macroscopic range its predictions markedly differ from those of quantum theory [12]. If CSL is confirmed, then 'it' will reign supreme.…”

“…Such a modified quantum theory, which combines deterministic evolution with stochastic evolution, has been successfully developed by a group of physicists, since the eighties [6][7][8][9]. In its currently most advanced version it is known as 'Continuous Spontaneous Localization' [CSL] [10][11][12]. This is a stochastic nonlinear Schrödinger equation, in which the standard linear evolution is supplemented by a nonlinear stochastic part, described by a Weiner process.…”

Generating the Schrödinger cat state in a nanomechanical resonator coupled to a charge qubit

“…Generating large quantum superposition of the macroscopic objects is an essential task in the field of the macroscopic quantum mechanics [3][4][5][6], which provides a good platform to understand the mechanism of decoherence in macroscopic objects [7,8], to check the scope of application of quantum theory [9] and to observe the transition between quantum and classical physics [10]. To this end, the large quantum superposition, like the Schrödinger cat state (simply called 'cat state' in the following), has been realized in various systems, such as trapped ions [11], photons [12], superconducting qubits [13], macroscopic current [14], and NAMR [15].…”