A pulsed matter-wave interferometer for testing the mass limits of quantum mechanics
Dr. Jonas Rodewald (Fakultät für Physik der Universität Wien, Österreich)

According to the quantum superposition principle, massive particles can be delocalized and propagate though space as waves of matter. To date it is not known whether this principle holds for particles of all masses or if there exists a mass limit to its validity. We have designed and set up the optical timedomain matter-wave (OTIMA) interferometer, specifically to probe and exploit superposition states of large particles [1]. The experiment is of the Talbot Lau-type and utilizes three pulsed standing wave laser gratings. These imprint a periodic pattern onto the traversing matter waves through photo depletion of the particle density at the standing wave anti-nodes [2, 3]. Due to the high photon energy of 7,9 eV, the grating mechanism works universally for many different kinds of clusters, molecules and nanoparticles, largely independent of internal absorption resonances. Since the optical gratings interact non-dispersively with the interfering particles, the setup will enable interference experiments with increasingly large particles in a quest for novel decoherence effects or objective wavefunction collapse mechanism. I present experimental progress in characterizing the apparatus in conjunction with various different particle beam sources and discuss systematic effects on the interference contrast [3]. Proof of principle results of experiments with tailor made nanoparticles are presented and discussed in the context of high-mass matter-wave interferometry. On the applied side, I will outline schemes for recoil spectroscopy in the OTIMA interferometer [4]. [1] P. Haslinger, N. Dörre, P. Geyer, J. Rodewald, S. Nimmrichter, and M. Arndt, "A universal matter-wave interferometer with optical ionization gratings in the time domain", Nature Physics, vol. 9, pp. 144-148, feb 2013. [2] N. Dörre, J. Rodewald, P. Geyer, B. von Issendorff, P. Haslinger, and M. Arndt, "Photofragmentation Beam Splitters for Matter-Wave Interferometry", Physical Review Letters, vol. 113, p. 233001, dec 2014. [3] N. Dörre, P. Haslinger, J. Rodewald, P. Geyer, and M. Arndt, "Refined model for TalbotLau matter-wave optics with pulsed photodepletion gratings", Journal of the Optical Society of America B, vol. 32, p. 114, dec 2014. [4] J. Rodewald, P. Haslinger, N. Dörre, B. A. Stickler, A. Shayeghi, K. Hornberger, and M. Arndt, "New avenues for matter-wave-enhanced spectroscopy", Applied Physics B, vol. 123, p. 3, jan 2017.