Relação entre paradoxos envolvendo valores fracos e uma interpretação realista de medições quânticas

Abstract

Weak measurements are a measurement protocol for quantum systems that consists in a weak coupling between the quantum system and the measurement device for preselected and post selected ensembles, such that the results of the measurements, called weak values, may lay far from the range of allowed or expected values, and from which many paradoxes have arisen. In fact, the original weak measurements paper already shows a paradox, since it is entitled “How the Result of a Measurement of a Component of the Spin of a spin-½ Particle Can Turn Out to be 100ℏ”. Since then many other quantum paradoxes were proposed based on the weak values. In the three-boxes paradox, for instance, it is stated that one particle can be found with certainty in two different boxes. In the quantum Cheshire cat paradox, it stated that a photon can be separated from its polarization. In the quantum pigeonhole principle, it is stated that we can put three particles into two boxes without two particles being in the same box. And there are many other examples. The aim of this work is to show how the realistic interpretation of the weak value, which is at the origin of all cited quantum paradoxes, is equivalent to a realistic interpretation of quantum measurements, that would reveal an underlying reality of the system that continues the same after the measurement is performed. We demonstrate that, by attributing reality to the preselect and postselected states at the same time, one always finds the same conclusions as with the assumption of a reality in the cited paradoxes, as in others. In this way, a simple way to avoid all cited paradoxes is to deny a realistic interpretation for the weak value.