Estimating the reduction time of quantum states

Abstract

An effective description of microscopic measurements is given, in which the precise moment of probing is not determined. Within this scenario we propose a scheme that relies on an "attempt" to make a forbidden simultaneous measurement of two incompatible observables. Although bound to failure in what concerns this goal, the process can lead to experimentally accessible information on a possibly non-vanishing time δt elapsed in the collapsing of the wave function, even if the duration ∆t of the individual measurements is much larger than δt.

Investigation of the collapse of quantum states using entangled photons

“…In a scenario of non-instantaneous collapse the measurement postulate must be recast in some way. A recent proposal [10] that we will adopt here, with some modifications of nomenclature, reads :…”

“…This ongoing move is so important that, justifiably, it has been termed the second quantum revolution [3]. Examples of this process are the debate on the "reality" of quantum states, which has received special attention in the last year [4] (see also [5]), and the many facets of the measurement problem, in particular, the collapse of the state vector [6][7][8][9][10][11]. These two topics are intimately related since there is no collapse problem in the epistemic view, where a state is regarded as the experimenter's information on some aspects of reality.…”

“…In a previous work [10] we presented some basic assumptions that we will adopt here, along with a formal example, * Corresponding author: parisio@df.ufpe.br constituting a proof of principle of how one could investigate the collapse time of quantum states. This example involved a single, completely unspecified, system with a two-dimensional Hilbert space, where two almost simultaneous measurements of incompatible observables were required, a conceptual and practical difficulty.…”

Finite-time collapse process and non-local correlations are incompatible with non-signaling theories

“…The mean time of the collapse may bring a deep insight on the dynamics that rules it. This problem, which has already been considered and experimental tests to verify the duration of the collapse have been proposed [14][15][16], will be the central issue of this work.…”

Wavefunction collapse through backaction of counting weakly interacting photons

“…Alternatively, the particle could scatter light and mysteriously appear at a specific place and time with a collapsed wave function characterized by a small uncertainty in position and a large uncertainty in linear momentum in accordance with the measurement postulate, which gives us no insight into the mechanism by which the wavefunction evolved to this new state or how its position came to be correlated to the observed distribution of the scattered light. 15 Quantum mechanics does not seem to favor one alternative over the other.…”