Collapse dynamics and Hilbert-space stochastic processes.

Spontaneous collapse models of state vector reduction represent a possible solution to the quantum measurement problem. In the present paper we focus our attention on the Ghirardi-Rimini-Weber (GRW) theory and the corresponding continuous localisation models in the form of a Brownian-driven motion in Hilbert space. We consider experimental setups in which a single photon hits a beam splitter and is subsequently detected by photon detector(s), generating a superposition of photon-detector quantum states. Through a numerical approach we study the dependence of collapse times on the physical features of the superposition generated, including also the effect of a finite reaction time of the measuring apparatus. We find that collapse dynamics is sensitive to the number of detectors and the physical properties of the photon-detector quantum states superposition.

Experimental test of the collapse time of a delocalized photon state.

We investigate whether the collapse of the quantum state of a single photon split between two space-like separated places takes a nonvanishing time. We realize this by using a source of heralded single photons, then splitting the resulting single photon state and letting it propagate over distances much larger than the experimental time resolution times the speed of light c. We find no additional delay within our accuracy and set a lower limit for the speed of collapse of the quantum state to 1550c.

Sudden ST elevation with angina-like pain in myocarditis. An uncommon course of a common disease: strategic role of cardiac magnetic resonance.

A case of a young man with myocarditis simulating acute coronary syndrome is reported. The possibility of vasospasm is discussed. The use of cardiac magnetic resonance imaging (MRI) is highlighted.