ELFT HÍRADÓ

[Máté Zoltán <mate AT atomki.mta.hu>]

Az MTA Atommagkutató Intézet előadótermében
(Debrecen, Bem tér 18/c. 12. ép. III. em.)
2013. szeptember 24-én, KEDDEN 11:00-kor


               R. O. Barrachina
   (Centro Atómico Bariloche - Instituto Balseiro 
        San Carlos de Bariloche, Argentina)

               A Quantum Heresy:
  Vortices in Positron – Atom Ionization Collisions

                  
címmel előadást tart.

Az előadás előtt 10:30-tól tea, vendégeket szívesen látunk.


                                           Máté Zoltán

Abstract:
In 1987 John Stuart Bell wrote [1]:
“In 1952 I saw the impossible done […]. Bohm showed explicitly how […] the 
indeterministic description could be transformed into a deterministic one. 
More importantly, in my opinion, the subjectivity of the orthodox version, 
the necessary reference to the ‘observer,’ could be eliminated… But […] why 
is the pilot wave picture ignored in text books? Should it not be taught, not 
as the only way, but as an antidote to the prevailing complacency? To show us 
that vagueness, subjectivity, and indeterminism, are not forced on us by 
experimental facts, but by deliberate theoretical choice?”
Only recently, starting with the Quantum Trajectory method [2] and the Weak 
Measurements technique [3], both the de Broglie – Bohm theory [4] and the 
Hydrodynamic interpretation of Madelung [5] have recovered their lost 
momentum, and in particular are starting to be employed for the study of 
Atomic Collision processes.
In this talk we propose an unorthodox analysis of the ionization of atoms by 
the impact of positrons. The time evolution of the corresponding electron - 
positron - ion system is equivalent to the flow of a perfect fluid that is 
irrotational everywhere, except at vortices where the corresponding density 
vanishes. During the ionization process, vortices emerge as closed 
submanifolds of co-dimension 2 or in pairs of opposite circulation. They may 
collapse at later times, but some can survive up to macroscopic distances and 
manifest themselves as zeros of the multiple differential cross section.
Vortices are ubiquitous in classical and quantum systems with large 
(macroscopic) number of particles. They are routinely observed in connection 
with superfluidity, superconductivity, or Bose-Einstein condensation. The 
main qualitative differences of these examples with the vortices investigated 
here are, on one hand the extreme simplicity of the present three-body 
system, consisting of an electron, a positron and an ion. Additionally, the 
time-evolution is governed exactly by the Schrödinger equation with Coulomb 
interactions, with no ad-hoc potential models or nonlinear terms. 
Furthermore, they occur at impact energies that make an experimental 
observation feasible. Even their circulation might be at reach by means of 
weak pre- and post-selected measurements.
We finally comment on the exploration of the full vortex submanifold beyond 
the cut of minimum dimensionality imposed by the collinear geometry employed 
in this work, a study which represents the next obvious step in the quest for 
understanding the topology and dynamics of these fascinating few-body quantum 
structures.
REFERENCES
[1] J. S. BELL, SPEAKABLE AND UNSPEAKABLE IN QUANTUM MECHANICS (CAMBRIDGE 
UNIVERSITY PRESS, 1987) P. 160.
[2] R. E. WYATT: QUANTUM DYNAMICS WITH TRAJECTORIES (SPRINGER, BERLIN, 2005).
[3] S KOCSIS, B BRAVERMAN, S RAVETS, M J STEVENS, R P MIRIN, L K SHALM AND A 
M STEINBERG, SCIENCE 332, 1170 (2011).
[4] D. BOHM, PHYS. REV. 85, 166, 180 (1952).
[5] E. MADELUNG, Z. PHYS. 40, 332 (1926)