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on 29-10-2014

... Dia 29 de Outubro de 2014 (quarta-feira), às 14h30m, na Sala B3-01

Post-Selected Measurements and The Arrow of Time in Classical and Quantum Physics

Janne Karimäki

Abstract: In 1932 Erwin Schrödinger pointed out a curious analogy between classical diffusion and the probabilistic formalism of quantum physics.
This analogy is further deepened, when post-selection of measurement data is considered. While classical diffusion (Wiener Process) is an irreversible physical process, with a clearly defined arrow of time, post-selection allows one to reveal a time-symmetric level (Bernstein Process) hidden in it.
Now, application of post-selection is becoming more and more important in both theoretical and experimental research in quantum physics. This is particularly important when studying entangled quantum systems, or performing experiments using the so-called weak measurement technique.
While the implications of the classical–quantum analogy discovered by Schrödinger, and further elaborated e.g. by Zambrini et al., are still somewhat unclear, there is hope that studying this property will shed light on many questions in Foundations of Physics, especially the role of time in physics, and many of the so-called ‘mysteries’ of quantum physics.
Further, a deepened understanding of this connection may also shed more light on the possibilities of practical applications in fields such as Quantum Computing & Quantum Cryptography.

Seminário financiado por Fundos Nacionais através da FCT – Fundação para a Ciência e a Tecnologia no âmbito do projeto PEst-OE/MAT/UI0208/2013

Instituto para a Investigação Interdisciplinar da Universidade de Lisboa
Av. Prof. Gama Pinto, 2
1649-003 Lisboa
Portugal More Information..

Functional Role of Tunneling in a Quantum Annealing Processor

on 24-10-2014

... Mohammad Amin, D-Wave

24/10/2014, 14:00
Room P9, Mathematics Building, IST

Quantum annealing has been proposed as a means to solve optimization problems using the laws of quantum mechanics. Despite many publications confirming the presence of quantum effects, especially entanglement, in D-Wave quantum annealing processors, the question of whether such effects can lead to a performance advantage still remains open. In this presentation, I start with introducing quantum annealing in general and the D-Wave implementation of it in particular. After a short review of some benchmarking attempts, I present the recent experimental results obtained in collaboration with Google and NASA. The data from the D-Wave II processor installed in NASA Ames clearly show that the processor employs multi-qubit coherent and incoherent tunneling to outperform all classical annealing approaches, including simulated annealing, path integral Monte Carlo, and spin vector Monte Carlo. I end with a brief description of our theoretical modeling of open quantum dynamics and show agreement between theoretical predictions and the experimental data.

Quantum Computation and Information Seminar

Support: Phys-Info (IT), SQIG (IT), CFIF and CAMGSD, with support from FCT, FEDER and EU FP7, namely via the Doctoral Programme in the Physics and Mathematics of Information (DP-PMI), and projects PEst-OE/EEI/LA0008/2013, CQVibes, Landauer (318287) and PAPETS (323901). More Information..