IMPRS Journal Club: Weak measurements, Superkicks and Superoscillations

Date

Jul 11, 2019

Time

10:00 AM - 11:00 AM

Speaker

Koen van Kruining

Affiliation

MPI-PKS

Series

IMPRS-MPSSE Seminar

Language

en

Main Topic

Physik

Other Topics

Physik

Description

This talk starts by revisiting the classic Stern-Gerlach experiment, by noticing that it sensu stricto does not measure atomic spin, but a deflection proportional which is dependent on the atomic spin. The atomic spin is then inferred from the observed deflection. By performing a $\it{weak}$ $\it{measurement}$, where the deflection is much smaller than the momentum spread of the incoming beam and then removing a large part of the outgoing beam with a second, strong, Stern-Gerlach experiment, it is possible to obtain deflections far bigger than expected from the magnitude of the atomic spin. A similar effect occurs for momentum. It is shown that an atom, when absorbing one photon, can experience a recoil larger than the momentum of the absorbed photon, a $\it{superkick}$. This is done by placing the atom in a region where the light field is $\it{superoscillatory}$, which means it changes on shorter length scales than its wavelength. As an example I will use an atom near a vortex core. Suggested reading: Y. Aharonov, D. Z. Albert & L. Vaidman, how the result of a measurement of a component of the spin of a spin 1/2 particle can turn out to be 100, Phys. Rev. Lett. 60 1351 S. M. Barnett & M. V. Berry, superweak momentum transfer near optical vortices, J. Opt. 15 125701

Last modified: Jul 11, 2019, 12:06:27 AM