[institut] SEMINAR

[Branko Kolarić]

Dear colleagues,

The  Nanophotonics Lab and Photonics section of the Society of Physical 
Chemists of Serbia organized a joint event in the framework of the 
Photonics Center seminar, which will be held on Thursday, 9th April 2026 
at 15:00, in the library reading room "Dr. Dragan Popović" of the 
Institute of Physics Belgrade.

The talk, entitled "Where Does the Quantum Particle Go? Quantum Paths 
and Probability Flow," will be given by Dr. Mohamed Hatifi, Research 
Scientist at Institut Fresnel and Adjunct Lecturer at Centrale 
Méditerranée, Aix-Marseille Univ, France.

The abstract of the talk:

Quantum theory has changed how we interpret what was commonly called 
”physical reality”. In the Copenhagen interpretation of quantum 
mechanics, properties of a quantum system, such as position, are not 
assigned definite values before measurement. In 1927, during the Solvay 
conference, Louis de Broglie proposed an alternative response to this 
tension. He aimed to restore determinism and realism, and to bring the 
notion of trajectory back to the foreground. David Bohm later 
rediscovered and extended this idea, leading to the pilot-wave 
formulation of quantum mechanics, famously praised by John Bell as a 
striking way to rewrite quantum dynamics in deterministic terms. The 
talk then develops a unifying ”probability-flow” viewpoint in which 
quantum dynamics is organized around a probability density ρ and an 
associated current J linked by a continuity equation. Trajectories arise 
as the natural flow lines of this current, or in stochastic variants as 
paths generated by drift and diffusion that reproduce the same 
continuity structure. In this language, the Born rule ρ = |ψ|2 is not 
treated as an external measurement axiom, but as a distinguished 
equilibrium distribution that is transported consistently by the 
trajectory dynamics, meaning that it is preserved in time. The 
conceptual status of quantum equilibrium is discussed in terms of 
typicality arguments and dynamical relaxation mechanisms. The same 
construction carries over across markedly different regimes: 
nonrelativistic matter waves governed by the Schro ̈dinger equation; 
relativistic spin-1/2 dynamics governed by the Dirac equation; 
diffusion-based trajectory theories in the spirit of Nelson; and wave or 
field settings where, in suitable field descriptions, energy-flow lines 
provide a path-like account for photons.

You are all kindly invited to Dr. Mohamed Hatifi's lecture.

Best Regards,

Branko Kolaric on behalf of Nanophotonics Lab