Infoptics seminar @UFF – Pedro Silva Correa, Friday September 18th,11:00

quantum Rio

Date and time: September 18th 2020, 11am

Link:https://meet.google.com/tqh-dzwe-fap

Speaker: Pedro Silva Correa (CBPF)

Title:  Macro-to-micro quantum mapping and the emergence of nonlinearity

Abstract: As a universal theory of physics, quantum mechanics must assign states to every level of description of a system, and also describe the interconnections among them. Assuming that we only have a coarse-grained access to a macroscopic system, here we show how to assign to it a microscopic description that abides by all macroscopic constraints. In order to do that, we employ general coarse-graining maps, allowing our approach to be used even when the split between system and environment is not obvious. As a by-product, we show how effective nonlinear dynamics can emerge from the linear quantum evolution, and we readily apply it to a state discrimination task.

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QM Talks@CBPF: Bill Poirier 21/01, 14h30

Title: Quantum Mechanics Without Wavefunctions

Speaker: Bill Poirier (Texas Tech University)

Coordinates: sala 601C, CBPF. 21/01, 14h30

Abstract: In David Bohm’s causal/trajectory interpretation of quantum mechanics, a physical system is regarded as consisting of BOTH a particle and a wavefunction, where the latter “pilots” the trajectory evolution of the former. In this presentation, we show that it is possible to discard the pilot wave concept altogether, thus developing a complete mathematical formulation of time-dependent quantum mechanics directly in terms of real-valued trajectories alone. Moreover, by introducing a kinematic definition of the quantum potential, a generalized action extremization principle can be derived. The latter places very severe a priori restrictions on the set of allowable theoretical structures for a dynamical theory, which is shown to include both classical mechanics and quantum mechanics, and a few other possibilities. Beneficial numerical ramifications of the above, “trajectories only” approach are also discussed.

Artigo em Ciência Hoje sobre supremacia computacional quântica

quantum Rio

Pesquisadores Leandro Aolita (IF-UFRJ) e Fernando de Melo (CBPF) escrevem artigo de divulgação sobre o recente experimento de supremacia quântica da Google e sobre a panorama geral de computação quântica como tecnologia potencialmente disruptiva no mundo e na America Latina.

Pra quem quiser saber um pouco sobre o tema sem tecnicismos e numa linguagem simples, aqui o link ao artigo: Supremacia quântica na Ciência Hoje

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QM Talks@CBPF: Nelson Pinto 05/12, 16h30

Title: On the geometrical hypotheses underlying wave functions and their emerging dynamics

Speaker: Nelson Pinto (CBPF)

Coordinates: auditório do 6o andar, CBPF 05/12, 16h30.

Abstract: Classical mechanics for individual physical systems and quantum mechanics of non-relativistic particles are shown to be exceptional cases of a generalized dynamics described in terms of maps between two manifolds, the source being configuration space. The target space is argued to be 2-dimensional and flat, and their orthogonal directions are physically interpreted. All terms in the map equation have a geometrical meaning in the target space, and the pull-back of its rotational Killing one-form allows the construction of a velocity field in configuration space. Identification of this velocity field with tangent vectors in the source space leads to the dynamical law of motion. For a specific choice of an arbitrary scalar function present in the map equation, and using Cartesian coordinates in the target space, the map equation becomes linear and can be reduced to the Schrödinger equation. We link the bi-dimensionality of the target space with the essential non-locality of quantum mechanics. Many extensions of the framework here presented are immediate, with deep consequences yet to be explored.

Defesa de mestrado (HOJE): Isadora B. L. Veeren

Candidata: Isadora Barbosa Lima Veeren,

Título da dissertação: Entropic uncertainty relations and classicality

Coordenadas: 30 de Abril às 16h. CBPF, auditório do sexto andar.

Banca: Fernando de Melo (CBPF), Bárbara Amaral (UFSJ*), Daniel Schneider Tasca (UFF), Ivan de Oliveira (CBPF) e Roberto Sarthour (CBPF).

Estão todxs convidadxs!

*não poderá participar.

QM Talks@CBPF: Leandro Aolita 04/04, 16h00

Título: Como confiar nas tecnologias quânticas de muitos corpos?

Palestrante: Mario Leandro Aolita (UFRJ)

Coordenadas: sala 601C, CBPF. 04/04, 16h00

Resumo: Recentemente houve um progresso experimental impressionante em tecnologias quânticas de muitos corpos. No entanto, ainda não temos ferramentas práticas de certificação que nos permitam garantir se os dispositivos quânticos experimentais que construímos funcionam adequadamente. De fato, uma vez que a simulação clássica de sistemas quânticos é uma tarefa computacionalmente difícil — exponencial no número de partículas — o paradigma usual de “predizer e comparar com o experimento” torna-se inaplicável. Este é um dos maiores obstáculos para as tecnologias quânticas de grande escala. Neste seminário, falarei sobre avanços recentes na validação de computadores quânticos e simuladores quânticos de muitos corpos. Em particular, discutirei testemunhas de fidelidade para simulações quânticas de bosons e para cadeias de spins, computação quântica verificável e tomografia de estado quântico assistida por redes neurais nativas de aprendizado de máquina sem supervisão.

VII Paraty Quantum Information School and Workshop: Registration is now open

quantum Rio

Dear colleague,

We would like to announce the “VII Paraty Quantum Information School and Workshop” (http://2019.paratyquantum.info/) that will take place in Paraty, Brazil from August 05 to 16, 2019.

We would be grateful if you could spread the word and bring the event to the attention of your group and to anyone else that might be interested. Click on the above picture to get the poster!

As in previous editions, the idea is to merge high level scientific exchange and a very pleasant atmosphere. The event will be held at the idyllic setting of Paraty, on Rio de Janeiro’s Costa Verde. The school runs from 5 to 9 August while the workshop takes place between 12 and 16 August 2019.

Come and be part of this story!

Courses of the school:

Quantum-assisted machine learning in near-term quantum devices
Alejandro Perdomo-Ortiz (University College London)

Entangled Structures in Classical and…

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New article: Spin-entanglement wave in a coarse-grained optical lattice

Title: Spin-entanglement wave in a coarse-grained optical lattice

Authors: Pedro Silva Correia, Fernando de Melo

Link: https://arxiv.org/abs/1902.08574

Abstract: In the present work we explore a suitable coarse graining channel as a tool to describe entanglement spreading in a coarse-grained spin-chain with different degrees of resolution. Comparing with the experimental realizations performed with ultracold atoms, our results suggest that even if we are not able to fully resolve the system, entanglement can still be detected for some coarse graining levels. Furthermore, we show that it is possible to have some information about the “microscopic” entanglement, even if we have access only to the system’s coarse graining description. We show that the amount of entanglement decays exponentially with the lack of system resolution. The lack of experimental resolution might thus lead to a classical effective description.

QM Talks@CBPF: Alexis Hernández — 06/12, 16h00

The year is about to finish… but we continue full power. This week our series of seminars QM Talks@CBPF, have the pleasure to welcome Alexis Hernández, from the Federal University of Rio de Janeiro. Alexis has many interests within physics (and outside of it as well!). This time he’ll tell us about a nonlinear description of Hall voltages. See details below.

Title: Investigating transverse Hall voltages using two-terminal setups

Speaker: Alexis Hernández (UFRJ)

Coordinates: room 601C, CBPF. 06/12, 16h00

Abstract: In this talk, we present a method to numerically study transverse Hall voltages using an alternative quantity in two-terminal setups. Using nonlinear transport concepts, we find that the Hall voltage dependence on the model parameters can be investigated from the difference between the injectivities of each terminal. The method is suitable to work with nonequilibrium Green’s functions as well as for scattering matrix approaches. We illustrate the proposed idea by studying the quantum spin Hall effect in graphene with disordered spin-orbit scattering centers induced by adatoms. We use two distinct models: a finite-difference implementation of the Dirac Hamiltonian and a tight-binding Hamiltonian combined with the scattering matrix approach and the nonequilibrium Green’s functions approach, respectively.

III Quantum Rio Workshop

quantum Rio

Despite of all difficulties of the present, and uncertainties of the future, it is time to gather the quantum info community/family from Rio. The quantum Rio Workshop, now in its third edition, will take place at CBPF from the 5th to the 6th of November. See the tentative schedule below. More information at https://quantumrio.wordpress.com/iii-quantum-rio-workshop/

We hope to see all the family there!

Coordinates: Auditorium 6th floor, CBPF.

Dates: 05/11 and 06/11

Program:

Monday (05/11)	Tuesday (06/11)
10h00 — 10h30	Welcome Coffee	Welcome Coffee
10h30 — 11h00	José Augusto	Fernando Nicácio
11h00 — 11h30	Frederico B. Brito	Reinaldo Faria
11h30 — 12h00	Alexandre Martins	Thiago Guerreiro
12h00 — 14h00	Lunch	Lunch
14h00 — 14h30	Ranieri Nery	Ernesto Galvão
14h30 — 15h00	Carlos Eduardo	Alfredo Ozorio
15h00 — 16h00	coffee-break + poster	coffee-break + poster
16h00h — 16h30	Stephen Walborn	Eduardo Duzzioni
16h30h — 17h00	Fernando de Melo	Antônio Zelaquett

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