Guest speaker: Markus Frembs
by William Schober
Hello everyone,
This afternoon at 13:30 in D1.14 we'll have a talk by Markus Frembs, a visitor to the group today. I apologize for the last-minute notification, this plan only came together in the last half hour or so! Markus' title and abstract are below.
Join us at 13:30 in D1.14 or online at https://meet.jit.si/cqi-demon-M6QW9V7YY
Best regards,
Will Schober
Title: Bipartite Entanglement and the arrow of time
Abstract:
Quantum correlations in general and quantum entanglement in particular embody both our continued struggle towards a foundational understanding of quantum theory as well as the latter’s advantage over classical physics in various information processing tasks. Consequently, the problems of classifying (i) quantum states from more general (non-signalling) correlations, and (ii) entangled states within the set of all quantum states, are at the heart of the subject of quantum information theory.
In this talk I will present two recent results (from https://doi.org/10.1103/PhysRevA.106.062420 and https://doi.org/10.1103/PhysRevA.107.022218) that shed new light on these problems, by exploiting a surprising connection with time in quantum theory:
First, I will sketch a solution to problem (i) for the bipartite case, which identifies a key physical principle obeyed by quantum theory: quantum states preserve time orientations—roughly, the unitary evolution in local subsystems.
Second, I will show that time orientations are intimately connected with quantum entanglement: a bipartite quantum state is separable if and only if it preserves arbitrary time orientations. As a variant of Peres's well-known entanglement criterion, this provides a solution to problem (ii).
1 year, 8 months
CQI seminar 22.3.2023 - Charles Bédard
by William Schober
Cari amici,
Spring greetings! I'd like to invite everyone to the "first" CQI seminar of the semester at 14:30 in D5.01, or online at https://meet.jit.si/cqi-demon-M6QW9V7YY (actually we've had several seminars already, just in the framework of the Information and Physics student seminar).
In this talk Charles Bédard will tell us about ZX calculus, a diagrammatic language for reasoning about quantum circuits in the style of Penrose's tensor notation. Title and abstract below.
Hoping to see everyone there,
Will Schober
Title: On Tensor Networks and ZX Calculus, or 'when vertical lines can be horizontalized'
Abstract: Tensor-network calculus can be done with drawings. Quantum circuits are drawn 'because' they are tensor networks. To foster the full power of diagrammatic simplifications in quantum circuits, some specific tensors and rules governing them are introduced: the ZX calculus. I shall introduce it, exemplify it with the teleportation circuit, and use it to prove the Gottesman-Knill theorem. This talk is based on a presentation by Julien Codsi, at the Bellairs Workshop in March 2023.
1 year, 8 months
Xxx
by lorenzo.laneve＠usi.ch
Yyy
1 year, 9 months
