Quantum evolution broken by measurements

F. Fratini

Published Mar 6, 2021• 0 citations

Abstract

Quantum mechanics is characterized by features that are counterintuitive if looked at from the point of view of everyday's life experience. The most intriguing feature is perhaps the possibility, for a close-by object, to influence an object that stands far away, if the two objects were entangled in the past. Such a feature was named `spooky action at distance' by Einstein, so to underline that it was something he was not comfortable with. Notwithstanding such long distance influence, the No-Communication theorem -- which has been developed within the framework of Quantum Mechanics -- forbids instantaneous information transfer between distant observers. Within such a theorem, a measurement is considered a single act of extracting information from the quantum system at a particular instant of time. Any measurement process involves a wavefunction reduction (or collapse), which entails, for the quantum system, an abrupt and non-deterministic evolution which lies outside the domain of the Schrodinger equation. By exploiting this, here we show that, when more measurements are performed in a row, only the first one is subject to the No-Communication theorem, since the following ones are made on the quantum system that already underwent a non-deterministic evolution due to the first one. As example, we construct a thought experiment, with the aim to show how the spooky action at distance could be recorded.

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