The quantum measurement process: an exactly solvable model

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dc.creatorAllahverdyan, A. E.
dc.creatorBalian, R.
dc.creatorNieuwenhuizen, Th. M.
dc.date2003-09-08
dc.date2003-10-02
dc.date.accessioned2026-07-07T02:53:20Z
dc.date.available2026-07-07T02:53:20Z
dc.descriptionAn exactly solvable model for a quantum measurement is discussed, that integrates quantum measurements with classical measurements. The z-component of a spin-1/2 test spin is measured with an apparatus, that itself consists of magnet of N spin-1/2 particles, coupled to a bath. The initial state of the magnet is a metastable paramagnet, while the bath starts in a thermal, gibbsian state. Conditions are such that the act of measurement drives the magnet in the up or down ferromagnetic state, according to the sign of s_z of the test spin. The quantum measurement goes in two steps. On a timescale 1/\sqrt{N} the collapse takes place due to a unitary evolution of test spin and apparatus spins; on a larger but still short timescale this collapse is made definite by the bath. Then the system is in a `classical' state, having a diagonal density matrix. The registration of that state is basically a classical process, that can already be understood from classical statistical mechanics.
dc.description4 pages, presented at the conference "Anomalies and Strange Behavior in Physics: Challenging the conventional", Napels, April, 2003. v2: Elaboration on the statistical interpretation of QM
dc.identifierhttps://arxiv.org/abs/cond-mat/0309188
dc.identifierhttp://arxiv.org/abs/cond-mat/0309188
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/22178
dc.subjectMesoscale and Nanoscale Physics
dc.subjectStatistical Mechanics
dc.subjectQuantum Physics
dc.titleThe quantum measurement process: an exactly solvable model
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