[SydPhil] Foundations of Physics, 5 September: Eric Cavalcanti on the quantum state

Matthew Farr matt.farr at sydney.edu.au
Tue Aug 27 00:08:53 AEST 2013

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 matt.farr at sydney.edu.au<mailto:matt.farr at sydney.edu.au>.

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
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

Room N494 | Quadrangle A14
University of Sydney | NSW | 2006

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