Measurement of nonlocal Bohmian trajectories of photons in a double slit interferometer

Jan Dziewior, Maria Galli, Lukas Knips, Jasmin Meinecke, and Harald Weinfurter

Bohmian mechanics, a hidden-variable interpretation of quantum mechanics, ascribes reality to the positions and momenta of quantum particles at the cost of a non local ontology. Thus, contrary to standard quantum mechanics it allows to conceive of definite particle trajectories, while being fully compatible with the standard theory in all empirical predictions. Nevertheless, the plausibility of the Bohmian picture has been called into question with a double slit Gedankenexperiment by Englert et al. [1], which initiated a lively controversy. While most of the proponents of Bohmian mechanics agreed with the predictions of Englert et al., the conclusions have been criticized.

Here, the experimental realization of this Gedankenexperiment is presented. The conditions for the occurrence of so called “surrealistic” trajectories are realized by using a pair of entangled photons, where one of the photons is sent into an optical double slit interferometer. The average trajectories are recorded using a method inspired by weak measurements [2,3]. By avoiding a measurement of the second photon as long as the trajectories of the first one are measured, the unique conditions for the alleged surrealistic case are realized.

[1] Englert, B., Scully, M., Süssmann G., Walther, H., Surrealistic Bohm Trajectories, Zeitschrift für Naturforschung A, 47, 1175-1186 (1992). [2] Wiseman, H. M., Grounding Bohmian mechanics in weak values and bayesianism, New Journal of Physics, 9, 165 (2007). [3] Mahler, D., Rozema, L., Fisher, K., Vermeyden, L., Resch, K. J., Wiseman, H. M., Steinberg, A., Experimental nonlocal and surreal Bohmian trajectories Science Advances, 2 (2016).