QM Talks@CBPF: Tobias Micklitz — 21.06, 16h00

Our series of seminars continues this week with Tobias Micklitz (CBPF). Tobias is an expert on many-body problems within condensed matter, especially on issues related to Anderson’s location. Recently, we’ve been discussing some ideas at the interface between condensed matter and quantum information. I’m sure something nice will come out of this interaction.

See the details of the talk below, and be sure to not miss it. See you there!

Title: Disordered Quantum Systems from Anderson- to many-body localization

Speaker: Tobias Micklitz (CBPF)

Coordinates: room 601C, CBPF. 21.06, 16h00

Abstract: Disorder is known to have dramatic effects on single particle-dynamics in low dimensional quantum systems. The absence of diffusion in dimensions smaller than three emerges within a single-particle picture where non-interacting particles, scattering off disorder, interfere with themselves and effectively get localized to a finite region in space. This ‘Anderson localization’ originates from the quantum-mechanical wave-nature of particles and is fundamentally different from classical trapping in deep valleys of a disorder potential. The impact of weak interactions on the single-particle localization problem can be subsumed as a fluctuating bath. The bath induces decoherence and thus suppresses localization. More strikingly, it has been recently proposed that (isolated) disordered quantum systems of interacting particles undergo a finite-temperature phase-transition which can be thought of as a many-body localization transition. The ‘many-body localized’ phase is characterized by the absence of ergodicity and the vanishing of transport coefficients. In the talk I will give a brief introduction into the phenomenon of (quantum) localization in disordered systems emphasizing recent trends, and then discuss a field-theory approach to the many-body localization problem.

QM Talks@CBPF: Yelena Guryanova– 12.02, 16h

We are all starting to gather for the Workshop on Quantum Information and Thermodynamics that will happen in two weeks. Many people is already around, and we take this chance to hear from Yelena Guryanova (Bristol). Her expertise is on foundations of quantum mechanics, and you can see how this connects to quantum thermodynamics, as nowadays we think both theories as informational theories.

Check the info below and be sure not to miss the talk… and the workshop! See you there and there.

Speaker: Yelena Guryanova

Title: Almost quantum correlations

Coordinates: room 601D, CBPF. 12.02, 16:00h

Abstract: Quantum theory as we know it constitutes a robust theoretical framework: slight variations usually lead to implausible consequences, for instance faster-than-light communication. It has even been argued that quantum theory may be special amongst possible theories which has propelled a field of study since the 1990s to try to find a principle which singles it out. In this talk, we show that at the level of correlations, quantum theory is not so special. We define the “almost quantum” set of correlations, and show that it strictly contains the set quantum set and analytically satisfies all-but-one of the five proposed principles to capture quantum correlations. Finally, we will comment on the appearance of this set in other work, including graph theory and quantum gravity.

O Pote de Ouro de Bell

Neste ano comemoramos as bodas de ouro, ou seja, os 50 anos da publicação do artigo “On the Einstein-Podolsky-Rosen Paradox”, por J. S. Bell [Physics 1, 195 (1964)]. Para celebrar esse evento, que segundo Henry Stapp é a “descoberta mais importante da ciência”, estamos organizando um pequeno encontro para discutir a essência e as implicações do teorema de Bell. Veja (e distribua!) o cartaz do evento.

Cada um dos palestrantes foi especialmente escolhido para analisar uma das várias perspectivas do teorema de Bell e suas implicações. Dessa forma esperamos que o evento seja acessível para uma grande gama de pessoas e com diversos interesses.

O evento é aberto e franqueado a todos! Pedimos, no entanto, que os interessados em participar do encontro “O pote de ouro de Bell” mandem e-mail para
bell50anos [at] gmail.com
com nome completo para que possamos liberar a entrada no CBPF.

Os seminários serão realizados no Auditório Ministro João Alberto, a partir de 13h da tarde do dia 5 de dezembro. Veja abaixo a programação:

Horário Palestrante Título
13:00 – 13:45 Ruynet M. Filho (UFRJ) Algumas considerações sobre a realidade da função de onda
13:45 – 14:30 Nelson Pinto (CBPF) A perspectiva de de Brolie-Bohm: teoria realista não-local
14:30 – 15:15 Lucas C. Céleri (UFG) Desafios experimentais das desigualdades de Bell
15:15 – 15:45 Coffee-break discussões livres!
15:45 – 16:30 Ivan S. Oliveira (CBPF) Emaranhamento e desigualdades de Bell com sistemas macroscópicos
16:30 – 17:15 Rafael Rabelo (UFMG) Mecânica quântica fora de contexto?
17:15 – 18:00 Ernesto Galvão (UFF) Não-localidade além da mecânica quântica

Nos vemos lá!!

Colloquium @CBPF: Gerardo Adesso — 07.08, 16h

Lucky for us Gerardo Adesso is already what we call here a “figurinha carimbada”, that is, someone nice that shows up very frequently. Gerardo has a Science without Borders grant with Diogo O. Soares-Pinto (IFSC-USP), and whenever he’s in Brazil we manage to bring him to Rio for a couple of days. This collaboration is both fun and productive! This time we invited Gerardo to deliver a colloquium, that for sure will be great. I hope to see you there! Here are the details:

Speaker: Gerardo Adesso (University of Nottingham)

Coordinates: Auditorium 6th, CBPF. 07.08, 16:00h

Title: Quantum technology beyond entanglement

Abstract: Quantum information theory is built upon the realisation that quantum resources such as superpositions and entanglement can be exploited for novel or enhanced ways of processing, encoding and manipulating information, such as quantum cryptography, teleportation, and quantum computing. We now know that there is potentially much more beyond entanglement behind the power of quantum processors. There are more general forms of quantum correlations, that have been identified in almost all quantum states, that can survive up to high temperatures and macroscopic scales, and have been linked to the speed-up of quantum devices over classical ones in the presence of noise. Their presence represents, among other things, a signature that quantumness extends far beyond the microworld. In this Colloquium I will give an overview of the current quest for a proper understanding and characterisation of the border between classical and quantum correlations in composite systems, and provide an outlook of the different applications in which quantumness beyond entanglement looks fit to play a key role.

QM Talks@CBPF: Bruno Juliá-Díaz — 28.04, 16h

Update (29.04.14): Here are the slides from the excellent talk given by Bruno. Lot’s of results and new ideas to work on!

bjulia-cbpf

Bruno, thank you for your talk and visit!

—————————————-
Our next QM Talk@CBPF will be given by Bruno Juliá-Diaz, from the University of Barcelona. Bruno is currently visiting the qig@CBPF, more specifically he is collaborating with Itzhak Roditi, and will stay here up to 05.05. You can find the details of his talk below.

See you there!

Speaker: Bruno Juliá-Diaz (U. Barcelona)

Coordinates: auditorium 5th floor, CBPF. 28.04, 16h

Title: Bosonic Josephson junctions: Spin-squeezing, fragmentation and shortcuts to adiabaticity

Abstract: I will consider a gas of ultracold atoms at zero temperature trapped in a double-well potential. In the simplest case the system can be described using just two modes. I ll go through the different quantum many-body correlations present in the ground state of the system depending on the character of the atom-atom interactions.
Afterwards, I ll discuss the presence of pseudo-spin squeezed states in the spectrum and a way to produce them in fast times using a protocol to shortcut the adiabatic following useful for the Hamiltonian describing the system.

References:

Shortcut to adiabaticity in internal bosonic Josephson junctions
A. Yuste, B. Juliá-Díaz, E. Torrontegui, J. Martorell, J. G. Muga, A. Polls
Phys. Rev. A 88, 043647 (2013)

Dynamic generation of spin-squeezed states in bosonic Josephson junctions
B. Juliá-Díaz, T. Zibold, M. K. Oberthaler, M. Melé-Messeguer, J. Martorell, A. Polls
Phys. Rev. A 86, 023615 (2012)

Macroscopic self trapping in BECs: analysis of a dynamical quantum phase transition
B. Julia-Diaz, D. Dagnino, M. Lewenstein, J. Martorell, A. Polls
Phys. Rev. A 81, 023615 (2010)

Short course @UFF: Marco Piani

Marco Piani, from university of Waterloo, Canada, will be lecturing a short course at UFF, starting 26.08. Below you can find more information.

Schedule: 26/08/2013 — 30/08/2013 (Monday to Friday, from 14:00 to 16:00).

Place: Instituto de Física da UFF, Sala 201, Campus da Praia Vermelha, Niterói, RJ.

Contact/Organization: Prof. Marcelo Sarandy (msarandy@if.uff.br) or Prof. Thiago Oliveira (tro@if.uff.br

Summary:

In this short course we will cover some basic concepts and tools in the study of the many aspects of the non-classicality of correlations. We will discuss quantum non-locality, quantum entanglement, and quantum discord, focusing on the conceptual and operational characterization of such properties. We will investigate how these properties are related, and how tools from quantum information theory—and in particular entanglement theory — lead to a better understanding of the general non-classicality of correlations. Topics will include:
– non-locality, non-local games, and device-independent verification of entanglement;
– entanglement and channel discrimination;
– discord and entanglement generation in local measurements;
– no-local broadcasting theorem, discord and the quantum-to-classical transition.