The next Sydney Foundations of Physics seminar will be held on Thursday 5th 
September at 11:30am. Eric Cavalcanti from the School of Physics will speak 
about the status of the quantum state. Details below.
____________________________
Speaker. Eric Cavalcanti (Sydney).
Title. “No epistemic model can explain the indistinguishability of quantum 
states.”

Abstract. According to a recent no-go theorem (M. Pusey, J. Barrett and T. 
Rudolph, Nature Physics 8 475 (2012)), models in which quantum states 
correspond to probability distributions over the values of some underlying 
physical variables must have the following feature: the distributions 
corresponding to distinct quantum states do not overlap. This is significant 
because if the distributions do not overlap, then the quantum state itself is 
encoded by the physical variables. In such a model, it cannot coherently be 
maintained that the quantum state has a purely information theoretic character. 
The theorem, however, considers only models in which a certain condition holds, 
which is that the physical variables corresponding to independently prepared 
systems are independent. This work considers models that are defined for a 
single quantum system of dimension d, such that the independence condition does 
not arise. We prove a result in a similar spirit to the original no-go theorem, 
in the form of an upper bound on the extent to which the probability 
distributions can overlap, consistently with reproducing quantum predictions. 
In particular, models in which the quantum trace distance between pure states 
is equal to the classical trace distance between the corresponding probability 
distributions cannot reproduce the quantum predictions in any dimension d ≥ 3. 
The result is noise tolerant, and an experiment is motivated to distinguish the 
class of models ruled out from quantum theory. [Joint work with Jon Barrett, 
Ray Lal and Owen Maroney.]

Time. Thursday 5th September, 11:30-13:00.
Location. Philosophy Common Room S413, Main Quad - A14, University of Sydney.
___________________________

All are welcome!

Please note that we are seeking speakers for future seminars - any area related 
to foundational concepts in physics (e.g. space, time, matter, motion, 
probability, measurement, etc.) is welcome, whether theoretical, philosophical 
or methodological. If you'd like to give a talk, or know of any future visitors 
who would like to give a talk, please contact me at 
[email protected]<mailto:[email protected]>.

The schedule for SydFoP talks is available here: 
http://newagendasstudyoftime.wordpress.com/sydfop/

Details for how to subscribe to the SydFoP mailing list are here: 
http://lists.arts.usyd.edu.au/mailman/listinfo/sydfop


All the best
Matt
__________________________________________
DR MATT FARR | Postdoctoral Research Fellow
New Agendas for the Study of Time<http://newagendasstudyoftime.wordpress.com/> 
| Centre for Time
School of Philosophical and Historical Inquiry | Faculty of Arts and Social 
Sciences

UNIVERSITY OF SYDNEY
Room N494 | Quadrangle A14
University of Sydney | NSW | 2006

T +61 2 9114 0633<tel:%2B61%202%209114%200633> | F +61 2 9351 
3918<tel:%2B61%202%209351%203918>
E [email protected]<mailto:[email protected]>
W mattfarr.co.uk<http://mattfarr.co.uk/>
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