Online Seminar by Muxin Han

Speaker: Muxin Han
Place: 241 Nicholson
Date: Thursday, March 28
Time: 1:30 PM
 

Title: Emergent Gravity from Spinfoam Models

Abstract: Recently, many new insights of quantum gravity are brought by the program of emergent gravity from quantum information. An idea in this program is that gravity, which is geometrical and smooth, might emerge as low energy excitations from fundamentally entangled qubits (or generally qudits), which are algebraic and discrete. In this talk, I demonstrate that spinfoam models, on one hand, are made fundamentally by entangled qudits, while on the other hand, emerge smooth gravitational fields in a low energy limit. The result suggests the spinfoam model to be a working example of the above idea in the emergent gravity program.

Online Seminar by Suzanne Lanery

Speaker: Suzanne Lanery

Place: 241 Nicholson

Date: Thursday March 21th

Time: 13:30

Title: Projective State Spaces for Loop Quantum Cosmology

Online Seminar by Philip Hoehn

Speaker: Philip Hoehn

Place: 241 Nicholson

Date: 14.03.198

Time: 10:30 AM

Title:  From quantum reference systems to quantum general covariance

Abstract: Reference frames (or, more generally, systems) provide the vantage points from which to describe the remaining physics. Treating them fundamentally as quantum systems is inevitable in quantum gravity, where coordinates are a priori unavailable, but also in quantum foundations once accepting that all frames are physical systems. Both fields thus face the question of how to describe physics from the perspective of quantum reference systems and how the descriptions relative to different such choices are related. I will summarize a recent systematic method for such switches, which works in analogy to coordinate changes on a manifold, except that these `quantum coordinate changes' proceed between different Hilbert spaces. This method relies on a new quantum reduction procedure, relating Dirac and reduced quantization, sets the stage for a quantum version of general covariance and applies to both temporal and spatial reference systems. In particular, I will illustrate how one can use this method to switch between different relational clocks in the quantum theory and thereby address the so-called "multiple choice problem of time". (Based on arXiv:1809.00556, 1809.05093, 1810.04153, 1811.00611.)

Online Seminar by Eugenio Bianchi

 

Speaker: Eugenio Bianchi

Place: 241 Nicholson

Date: Thursday Feburary 7th

 Time: 1:30 PM

Title: Entanglement entropy of Bell-network states in LQG

Speaker: Scott Baldridge, LSU
Place: 241 Nicholson
Date: Thursday November 29th
Time: 11am

Title: Graphs and cohomology invariants

Talk by Javier Olmedo

Speaker: Javier Olmedo, LSU
Place: 241 Nicholson
Date: Thursday November 15th
Time: 11am

Title: Power spectrum of primordial perturbations for an emergent universe in quantum reduced loop gravity

Seminar by 

Jonathan Engle

"Deriving loop quantum cosmology from diffeomorphism invariance" 

Loop quantum gravity is an approach to the quantization of general relativity in which Einstein’s principle of diffeomorphism covariance plays a central role. Loop quantum cosmology is a theory in which the principles of loop quantum gravity are applied in the homogeneous, and optionally isotropic, context, leading to predictions for the cosmic microwave background which are the best chance for testing, through observation, the principles of loop quantum gravity. Several results over the years, including a few results by the speaker and collaborators over the last year, have demonstrated (1.) how the Hilbert space of states of loop quantum cosmology and action of basic operators thereon is uniquely determined by the requirement of diffeomorphism covariance, and (2.) the degree to which the dynamics of loop quantum cosmology is similarly determined. This talk will summarize these results.