Talks

In this talk, I will provide an overview of neutron star (NS) mergers, highlighting the insights gained through numerical relativity simulations. I will mainly focus on the role of the cocoon shock breakout emission as a key early electromagnetic counterpart of NS mergers, with special relevance to events like GW170817. I will explore how the properties of the merger ejecta and the nature of the central engine influence the resulting emission. Additionally, I will present recent advancements in the development of our new general relativistic magnetohydrodynamics (GR-MHD) code GR-Athena++, and share ongoing research efforts on the evolution of magnetic fields in the post-merger remnant.

The Green-Schwarz anomaly cancellation condition says that the target space of heterotic string theory must come with a string structure for the theory to be consistent. In this talk we discuss a new tangential structure called string^h, first introduced by Devalapurkar, as a spin^c analogue of string. We will show that the spectrum of string^h has the notable property that it orients tmf_1(n), just like how the spectrum of string orients tmf, by the work of Ando-Hopkins-Rezk. Finally we will show that the anomaly of the partition function of type IIA, studied by Diaconescu-Moore-Witten induces a string^h structure on the target space of type IIA, in parallel to the Green-Schwarz anomaly for heterotic string theory, and discuss applications for anomaly cancellation. This is joint work in progress with Arun Debray.

In this talk, I shall recall the nonlocality transitivity problem, which concerns the possibility of inferring the Bell-nonlocality of certain marginals in a multipartite scenario based on other given marginals. Then, I explain how considering this problem has led to a more general class of problems known as resource marginal problems (RMPs). More precisely, RMPs concern the possibility of having a resource-free target subsystem compatible with a given collection of marginal density matrices. We briefly discuss how a resource theory for a collection of marginal density matrices naturally arises from any given RMP and present some general features of such a theory. After that, we focus on a special case of RMPs known as the entanglement transitivity problems and explain how our progress on this problem has led to progress in the original nonlocality transitivity problem.

Entanglement in quantum many-body systems is typically fragile to interactions with the environment. Generic unital quantum channels, for example, have the maximally mixed state with no entanglement as their unique steady state. However, we find that for a unital quantum channel that is `strongly symmetric', i.e. it preserves a global on-site symmetry, the maximally mixed steady state in certain symmetry sectors can be highly entangled. For a given symmetry, we analyze the entanglement and correlations of the maximally mixed state in the invariant sector (MMIS), and show that the entanglement of formation and distillation are exactly computable and equal for any bipartition. For all Abelian symmetries, the MMIS is separable, and for all non-Abelian symmetries, the MMIS is entangled. Remarkably, for non-Abelian continuous symmetries described by compact semisimple Lie groups (e.g. SU(2)), the bipartite entanglement of formation for the MMIS scales logarithmically ∼logN with the number of qudits N.

About the Event:

Perimeter Presents

About the Speaker:

Most people have a basic understanding of gravity as the fundamental force that keeps us tethered to the Earth. They've likely even heard the fabled story of Isaac Newton’s inspiration for the theory: an apple falling from a tree. But few people have spent as much time grappling with gravity as Claudia de Rham, Professor of Theoretical Physics at Imperial College London.

In her recently released book, The Beauty of Falling: A Life in Pursuit of Gravity, de Rham recounts not only her scientific investigations of gravity and the limits of Einstein’s general theory of relativity, but also her more practical encounters with gravity – as a diver, a pilot, and an astronaut candidate.

Many of de Rham’s ponderous flights took place in Waterloo Region, where she earned her pilot’s license during a postdoctoral fellowship at Perimeter from 2006 to 2009. She has remained connected to Perimeter over the years, including as a Visiting Fellow since 2018.

About the Event:

On Thursday, August 1 at 7:00 PM EDT, Perimeter presents a short talk with de Rham about her fascinating journey in pursuit of gravity’s true nature, followed by an in-depth conversation with Nahlah Ayed, host of CBC’s Ideas, and an audience Q&A.

Tickets:

Registration to attend this in-person event will be available on Monday, July 22 at 9:00 AM EDT.

Eventbrite

This event will not be livestreamed, but made available in the subsequent days on Perimeter’s YouTube channel. An edited version will also appear on CBC’s Ideas in the fall.

Tickets for this event are 100% free.