ELFT HÍRADÓ

[Kormányos Andor <andor.kormanyos AT ttk.elte.hu>]

ELTE TTK Fizikai Intézet / ELTE Institute of Physics


ORTVAY KOLLOKVIUM / ORTVAY COLLOQUIUM

(https://physics.elte.hu/ortvayseminar)


Thursday, 10th November  2022, 15:00h.


Pócza Jenő Classroom,  Physics Building 1.71

Pázmány Péter sétány 1/A, 1117 Budapest.


Tamás Kiss (Wigner FK SZFI)
What does light teach us about the predictability of events? (Nobel Prize 
2022: Alain Aspect, John Clauser, and Anton Zeilinger )

The great promise of natural sciences is that they can predict future events. 
Can these predictions always be certain, at least in principle? In classical 
mechanics and electrodynamics the answer is yes, while quantum mechanics 
suggests that we have to give up either locality or certainty of predictions.
The Nobel Prize in physics this year acknowledges a series of optical 
experiments carried out in the past 50 years, aiming at testing these rather 
spooky predictions of quantum mechanics at a more and more precise level. In 
these tests, Aspect, Clauser and Zeilinger wanted to check the strange 
probabilistic correlations of events at distant locations. The nonclassical 
correlations are predicted by quantum mechanics through the phenomenon of 
entanglement (Schrödinger, 1935).  The spookiness of distant quantum 
correlations were pointed out by Einstein, Podolsky and Rosen in 1935 and 
quantitatively first described by John Bell in 1964. We show, how loopholes 
in testing the Bell-inequalities could gradually be closed in the experiments.
The practical implications of being able to manipulate quantum entanglement 
with high accuracy will also be discussed. Quantum communication, and 
especially quantum key distribution (QKD), is primarily based on quantum 
optics. We give a short overview of this field and present new experiments 
realizing device independent QKD. Quantum optics plays a prominent role in 
the field of quantum computing as well. One of the first experiments claiming 
quantum advantage, Gaussian boson sampling, was performed in an optical 
setup. We report on some other nontrivial quantum protocols, such as quantum 
walks or iterated nonlinear quantum evolution, which were also realized in 
photonic experiments.


The seminar can also be followed via Microsoft Teams:

https://teams.microsoft.com/l/meetup-join/19%3a6da57784c96d45fe89d6571fb65154d6%40thread.tacv2/1667119390851?context=%7b%22Tid%22%3a%22b366dbcd-4fc3-4451-82d2-e239564302c3%22%2c%22Oid%22%3a%22560bcc66-85b7-4700-9055-41903a3659ca%22%7d

Best regards,
Andor Kormányos
coordinator