How to extend quantum experiments

Author(s): M. Arndt, M. Aspelmeyer, A. Zeilinger

Journal: Fortschritte Phys.

Volume: 57

Page(s): 1 - 10

Year: 2009

DOI Number: -


The counter-intuitive properties of quantum mechanics for individual systems have probably first been publicly discussed in Albert Einstein’s famous 1909 presentation in Salzburg to the Annual Meeting of the ‘Deutsche Gesellschaft der ¨Arzte und Naturforscher’ [1]. There, Einstein pointed to the conceptual

challenges related to the idea of light quanta if interference also persists on the level of individual photons. At Einstein’s time this fact was not yet experimentally confirmed, but today, interference of single photons,

or more generally single particles is standard practice in many laboratories world-wide. In all these

experiments, the predictions of quantum theory have been perfectly confirmed and even extended to multiparticle interference and entanglement. These results require a drastic revision of our intuitive world-view.

We argue that extending quantum experiments into hitherto untested parameter regimeswill help to sharpen our view on this question and will shed new light on our understanding of quantum theory – for example by closing remaining loopholes in existing Bell experiments, by providing even more drastic examples of

counter-intuitive quantum phenomena in the spirit of Schr¨odinger’s cat [2] or by establishing new incompatibility theorems in the spirit of Bell’s inequalities that are related to macroscopic properties [3]. In the

following we will discuss prospects for such extensions for quantum experiments with entangled photons, with matter waves and with massive mechanical resonators.

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Arndt Group Arndt Group , Aspelmeyer Group , Zeilinger Group