Eur. Phys. J. D 63, 25-32 (2011)
https://doi.org/10.1140/epjd/e2011-10705-4

Regular Article

Massive spin-momentum entanglement measured in an atomic beam spin echo experiment

Physikalisches Institut Universität Heidelberg, Philosophenweg 12, 69120 Heidelberg, Germany

^a e-mail: maarten@physi.uni-heidelberg.de

Received: 13 December 2010
Received in final form: 14 June 2011
Published online: 17 June 2011

Abstract

In this paper we present an experiment performed with an atomic beam spin echo interferometer, in which massive intraparticle entanglement is demonstrated. In the longitudinal Stern-Gerlach arrangement the nuclear spin and linear momentum of ³He particles are inextricably linked, such that the overall system state cannot be written as the tensor product of the corresponding Hilbert spaces. The measured data show maximal entanglement between ℋ_I and ℋ_p. This hybrid system of one quantum and one classical degree of freedom is a textbook example of entanglement between discrete and continuous observables.