In a paper from 2006, Couder and Fort [1] describe a version of the famous
double slit experiment performed with drops bouncing on a vibrated fluid
surface, where interference in the particle statistics is found even though it
is possible to determine unambiguously which slit the "walking" drop passes. It
is one of the first papers in an impressive series, showing that such walking
drops closely resemble de Broglie waves and can reproduce typical quantum
phenomena like tunneling and quantized states [2-13]. The double slit
experiment is, however, a more stringent test of quantum mechanics, because it
relies upon superposition and phase coherence. In the present comment we first
point out that the experimental data presented in [1] are not convincing, and
secondly we argue that it is not possible in general to capture quantum
mechanical results in a system, where the trajectory of the particle is
well-defined.Comment: 4 pages, 1 figur
