Aspects of nonideal Stern–Gerlach experiment and testable ramifications

Abstract

We critically examine the quantum-mechanical modelling of a measurement process using the Stern-Gerlach (SG) setup in the most general context, probing in particular for nonideal situations, the subtleties involved in the connection between the notion of 'distinguishability' of apparatus states defined in terms of the inner product and the spatial separation among the wave packets emerging from the SG setup. The quantitative studies highlighting some of the unexplored features of this relationship are presented in terms of an appropriately defined measure for the spatial separation between the emerging wave packets. It is also indicated how the effects arising from such departures from the idealness can be empirically tested for different values of the relevant parameters.

Proper time in atom interferometers: Diffractive versus specular mirrors

“…Potentials enabling specular reflection of matter waves have also been implemented by means of magnetic fields [26,[51][52][53] based on either current carying wires, magnetic surfaces or permanently magnetized micro-structures. Moreover, recently there have been significant advances in Stern-Gerlach interferometry with atoms [25], which has been a long standing challenge [54][55][56][57][58][59], leading to yet another method for facilitating an exponential potential. However, due to the experimental requirement for an optical access in direction of the atomic motion we focus in the following on an evanescent field mirror.…”

Stern-Gerlach dynamics with quantum propagators

“…Therefore we conclude that a vertical separation is not an automatic feature in a Stern-Gerlach configuration oriented along the z axis. The occurrence of such nonideal SGE features may have interesting ramifications [11].…”

“…This is not very surprising given the significance of SGE in quantum theory, but it highlights the need to clearly delineate the approximations. More recently, the possibility of probing Stern-Gerlach experiments beyond the region of validity of the approximations in order to uncover new (nonstandard) results and understand their quantum significance has been considered [10,11]. * bailey.c.hsu@gmail.com † berrondo@byu.edu ‡ vanhuele@byu.edu…”

Optimal violation of the Leggett–Garg inequality for arbitrary spin and emergence of classicality through unsharp measurements

“…After emerging from the field each beam is effectively described by a two dimensional Hilbert space, and evolves under the same unitary as above. Finally, the beam is subjected to a non-ideal Stern-Gerlach apparatus [31]. In this scenario the effective spin j observable is given by Q = λ((Γ z + Π)/ √ 2j + 1), where 0 < λ ≤ 1.…”