Atom interferometer using two Stern-Gerlach magnets

Abstract

An atom interferometer using two Stern-Gerlach magnets as polariser and analyser is described. The interferometer was first operated with a thermal beam of ground state potassium atoms. In that case the beam splitters are two radiofrequency zones within a transverse homogeneous magnetic field building a coherent superposition of Zeeman states. Ramsey fringes are obtained by scanning the RF-frequency through the resonance profile. Pulsing the RF power allows to get the timeof-flight distribution of the beam. Atomic interference fringes ("Stern-Gerlach fringes") are observed when the magnitude of an inhomogeneous magnetic field located in between the beam splitters is scanned. When the inhomogeneous field is also pulsed, the scalar Bohm-Aharonov effect is observed. The use of metastable helium atoms (He * 2 3 S) in place of potassium atoms is proposed. In addition to the usual advantages provided by metastable atoms of high internal energy, this atom offers the specific advantage to behave as an ideal spin-one particle. This allows us to greatly simplify the polarisation scheme of the interferometer. Possible applications involving transversally inhomogeneous magnetic fields are given and limitations due to the finite source size and angular aperture are discussed. Ramsey interference pattern obtained by scanning the RF frequency around 2.307 MHz (resonance). The RF power is such that the atoms experience two subsequent π/2 -pulses. The absolute contrast of the fringes is about 30%.

Stern-Gerlach Interferometry with the Atom Chip

“…Finally, we briefly compare our experiments to previous work in an elaborate series of SGI experiments over a period of 15 years using metastable atomic beams [35][36][37][38][39][40][41][42]44] and, more recently, thermal and ultra-cold alkali atoms [43,45]. A detailed discussion is given in [64].…”

“…We obtain a high full-loop SGI visibility of 95% with a spin interference signal [18,19] by utilizing the highly accurate magnetic fields of an atom chip [6]. Notwithstanding the impressive endeavors of [35][36][37][38][39][40][41][42][43][44][45] this is, to the best of our knowledge, the first realization of a complete SG interferometer analogous to that originally envisioned a century ago.…”

Realization of a complete Stern-Gerlach interferometer: Toward a test of quantum gravity

“…We briefly compare our experiments to state-of-the-art SG interferometry ( 29 – 39 ). While these longitudinal beam experiments did show spin population interference fringes, the experiments presented here are very different.…”

Single photon beat note in an acousto-optic modulator-based interferometer

“…This experiment may be considered as a photonic analogue of early days atom interferometry setups using detuned separated oscillatory fields as beam splitters. These experiments searched for off-diagonal terms of the density matrix of thermal atomic beams [19][20][21]. Non stationary beam splitters induce energy transfer and thus produce mixing of different energy components in the incoming particles' spectrum.…”