Format results

Talk

Horizon entropy and the Einstein equation  Lecture 20230302
Ted Jacobson University of Maryland, College Park

Horizon entropy and the Einstein equation  Lecture 20230228
Ted Jacobson University of Maryland, College Park

Horizon entropy and the Einstein equation  Lecture 20230223
Ted Jacobson University of Maryland, College Park

Horizon entropy and the Einstein equation  Lecture 20230221
Ted Jacobson University of Maryland, College Park


Probing extreme configurations in binary compact object mergers
Samuel Tootle Goethe University Frankfurt

Physical Observables in Canonical Quantum Gravity
Axel Maas University of Graz

Beyond the linear tide: impact of the nonlinear tidal response of neutron stars on gravitational waveforms from binary inspirals
Hang Yu California Institute of Technology (Caltech)  Division of Physics Mathematics & Astronomy

BMS Field Theories with u(1) Symmetry
Max Riegler Technische Universität Wien

Spin Signatures in VLBI Images of Supermassive Black Hole Accretion Flows
Daniel Palumbo Smithsonian Astronomical Observatory

Horizons are Watching You
Gautam Satishchandran Princeton University

Hypermassive neutron stars: from numerical relativity simulations to gammaray data
Cecilia Chirenti Universidade Federal do ABC

Talk


Simulating onedimensional quantum chromodynamics on a quantum computer: Realtime evolutions of tetra and pentaquarks
Christine Muschik Institute for Quantum Computing (IQC)
23060002 

Five short talks  see description for talk titles

Barbara Soda Perimeter Institute for Theoretical Physics

Dalila Pirvu Perimeter Institute for Theoretical Physics
 Leonardo Solidoro, Pietro Smaniotto, Kate Brown
23060004 




Language models for simulating the dynamics of quantum systems
Juan Carrasquilla Vector Institute for Artificial Intelligence
23060008


Partition function for a volume of space
Ted Jacobson University of Maryland, College Park

Horizon entropy and the Einstein equation
This minicourse of four lectures is an introduction, review, and critique of two approaches to deriving the Einstein equation from hypotheses about horizon entropy.
It will be based on two papers:
 "Thermodynamics of Spacetime: The Einstein Equation of State" arxiv.org/abs/grqc/9504004
 "Entanglement Equilibrium and the Einstein Equation" arxiv.org/abs/1505.04753
We may also discuss ideas in "Gravitation and vacuum entanglement entropy" arxiv.org/abs/1204.6349
Zoom Link: https://pitp.zoom.us/j/96212372067?pwd=dWVaUFFFc3c5NTlVTDFHOGhCV2pXdz09

Probing extreme configurations in binary compact object mergers
Samuel Tootle Goethe University Frankfurt
Numerical relativity continues to play a crucial role in interpreting gravitational wave detections as well as the first multimessenger detection of GW170817. More so, stateoftheart models for kilonvae, gravitational waves, and more rely on the thousands of numerical relativity simulations that have taken place over more than 20 years. Simulations of binary systems including neutron stars are particularly taxing due to the equation of state of matter being a significant unknown. In spite of this fact, there exists vast amount of literature on the independent influence mass asymmetry or spin can have on the merger and postmerger dynamics of neutron star binaries across a wide array of possible equations of state.
In this talk I will extend this topic to extremal configurations consisting of binaries that are not only asymmetric, but include appreciable spins on the component neutron stars. To do so I will give an introduction into the initial data problem for numerical relativity, it's complexities, and its importance to current and future research. Furthermore, I will discuss a collection of results for extremal binary configurations including neutron stars and why this line of research is important to enable the next generation of multimessenger models.
Zoom Link: https://pitp.zoom.us/j/99895521696?pwd=T1VtN0RGbjZrVTNleXB3V0FtQjhldz09

Physical Observables in Canonical Quantum Gravity
Axel Maas University of Graz
Canonical Quantum Gravity can be considered as a gauge theory of translations. Just like in other gauge theories this implies that physical observables need to be gaugeinvariant. Hence, quantities like the metric cannot be observables. This poses new challenges, as this requires to rephrase in the quantum theory how to characterize physics. Moreover, such observables are usually composite. To determine them, the FröhlichMorchioStrocchi mechanism from QFT can be borrowed, to have an augmented perturbative approach.
Zoom Link: https://pitp.zoom.us/j/97927004145?pwd=ekFJaUJSc21UUGdkcDZDWCtpSmdIUT09

Beyond the linear tide: impact of the nonlinear tidal response of neutron stars on gravitational waveforms from binary inspirals
Hang Yu California Institute of Technology (Caltech)  Division of Physics Mathematics & Astronomy
Tidal interactions in coalescing binary neutron stars modify the dynamics of the inspiral, and hence imprint a signature on their gravitationalwave (GW) signals in the form of an extra phase shift. We need accurate models for the tidal phase shift in order to constrain the supranuclear equation of state from observations. In previous studies, GW waveform models were typically constructed by treating the tide as a linear response to a perturbing tidal field. In this work, we incorporate nonlinear corrections due to hydrodynamic three and fourmode interactions and show how they can improve the accuracy and explanatory power of waveform models. We set up and numerically solve the coupled differential equations for the orbit and the modes, and analytically derive solutions of the system's equilibrium configuration. Our analytical solutions agree well with the numerical ones up to the merger and involve only algebraic relations, allowing for fast phase shift and waveform evaluations for different equations of state over a large parameter space. We find that, at Newtonian order, nonlinear fluid effects can enhance the tidal phase shift by >~ 1 radian at a GW frequency of 1000 Hz, corresponding to a 10−20% correction to the linear theory. The scale of the additional phase shift near the merger is consistent with the difference between numerical relativity and theoretical predictions that account only for the linear tide. Nonlinear fluid effects are thus important when interpreting the results of numerical relativity, and in the construction of waveform models for current and future GW detectors.
Zoom link: https://pitp.zoom.us/j/91730134841?pwd=U0JXNHhFbWdQYno3aUpDWHRxWEtkUT09

BMS Field Theories with u(1) Symmetry
Max Riegler Technische Universität Wien
Quantum field theories in two dimensions (2d) with an underlying Bondivan der BurgMetznerSachs (BMS) symmetry augmented by u(1) currents are expected to holographically capture features of charged versions of cosmological solutions in asymptotically flat 3d spacetimes called Flat Space Cosmologies (FSCs). I will present a study of the modular properties of these field theories and the corresponding partition function. Furthermore, I will derive the density of (primary) states and find the entropy and asymptotic values of the structure constants exploiting the modular properties of the partition function and the torus onepoint function. The expression for the asymptotic structure constants shows shifts in the weights and one of the central terms and an extra phase compared to earlier results in the literature for BMS invariant theories without u(1) currents present. The field theory results for the structure constants can be reproduced holographically by a bulk computation involving a scalar probe in the background of a charged FSC.
Zoom Link: https://pitp.zoom.us/j/99205444635?pwd=Tk02UlgvcjJCU3JSWWphY1JQSlhFQT09

It from Qubit 2023
The final meeting of It from Qubit: Simons Collaboration on Quantum Fields, Gravity, and Information will be devoted to recent developments at the interface of fundamental physics and quantum information theory, spanning topics such as
 chaos and thermalization in manybody systems and their realization in quantum gravity;
 informationtheoretic constraints on quantum field theories and their RG flows and symmetries;
 gravitational wormholes and their informationtheoretic implications;
 calculable lowerdimensional models of quantum gravity; the entanglement structure of semiclassical states in quantum gravity;
 quantum errorcorrecting codes in quantum field theory and quantum gravity;
 complexity in field theory and gravity;
 the blackhole information puzzle;
 quantum simulation of quantum field theories and quantum gravity.
Territorial Land Acknowledgement
Perimeter Institute acknowledges that it is situated on the traditional territory of the Anishinaabe, Haudenosaunee, and Neutral peoples.
Perimeter Institute is located on the Haldimand Tract. After the American Revolution, the tract was granted by the British to the Six Nations of the Grand River and the Mississaugas of the Credit First Nation as compensation for their role in the war and for the loss of their traditional lands in upstate New York. Of the 950,000 acres granted to the Haudenosaunee, less than 5 percent remains Six Nations land. Only 6,100 acres remain Mississaugas of the Credit land.
We thank the Anishinaabe, Haudenosaunee, and Neutral peoples for hosting us on their land.

Noncommutative Geometry and Physics
Noncommutative Geometry and Physics 
Spin Signatures in VLBI Images of Supermassive Black Hole Accretion Flows
Daniel Palumbo Smithsonian Astronomical Observatory
The Event Horizon Telescope has released total intensity images of the Messier 87* and Sagittarius A* accretion flows; polarized images have been released for M 87*, and are imminent for Sgr A*. These images are a rich source of theoretical constraints on the black hole accretion flow system, but a trustworthy measurement of either black hole's spin remains elusive. Spin nonetheless remains a high priority, as the black hole angular momentum is deeply linked to mechanisms of energy extraction and galactic coevolution. In my talk, I will discuss my work on providing theoretical traction on supermassive black hole spin, and will review the state of spin measurements using existing and future EHT data, including measurements of the black hole photon ring, inference of nearhorizon magnetic field structure, and nextgeneration spacetime/emissivity inference codes.
Zoom: https://pitp.zoom.us/j/95355525128?pwd=blczM1ZUMGs5RmNxMVNCV3hlRDA4UT09

Horizons are Watching You
Gautam Satishchandran Princeton University
We show that if a massive (or charged) body is put in a quantum superposition of spatially separated states in the vicinity of any (Killing) the mere presence of the horizon will eventually destroy the coherence of the superposition. This occurs because, in effect, the longrange fields sourced by the superposition registers on the horizon which forces the radiation of entangling soft gravitons/photons through the horizon. This allows the horizon to harvest “which path” information about the superposition. The electromagnetic decoherence arises only when the superposed particle carries electric charge. However, since all matter sources gravity, the quantum gravitational decoherence applies to all superpositions. We provide estimates of the decoherence time for such quantum superpositions. Additionally, we show that this decoherence is distinct fromand larger thanthe decoherence resulting from the presence of thermal radiation from the horizon (i.e. Hawking/BunchDavies/Unruh radiation). We believe that the fact that Killing horizons will eventually decohere any quantum superposition may be of fundamental significance for our understanding of the nature of black holes and horizons in quantum gravity. (Based on arXiv:2205.06279 and arXiv: 2301.00026).
Zoom link: https://pitp.zoom.us/j/95263116767?pwd=amZ6SkROV1lxckVpdzhNbFhYc1ZiQT09

Hypermassive neutron stars: from numerical relativity simulations to gammaray data
Cecilia Chirenti Universidade Federal do ABC
Gamma ray bursts (GRBs) are the most luminous electromagnetic events in the universe. Short GRBs, typically lasting less than 2 seconds, have already been associated with binary neutron star (BNS) mergers, which are also sources of gravitational waves (GWs). The ultimate fate of a BNS, after coalescence, is usually expected to be a black hole (BH) with 23 solar masses. However, numerical relativity simulations indicate the possible formation of a shortlived hypermassive neutron star (HMNS), lasting for tens to hundreds of milliseconds after the BNS merger and before gravitational collapse forms a BH. The HMNS is expected to emit GWs with kHz frequencies that will be detectable by third generation groundbased GW detectors in the 2030s. I will present results from a recent analysis that revealed evidence for HMNSs by looking for kHz quasiperiodic oscillations in gammaray observations obtained in the 1990s with the Compton Gamma Ray Observatory.
Zoom link: https://pitp.zoom.us/j/96687956901?pwd=MkgrUGlqY3IyRCs2bXJYVkhUVEpPZz09

Quantum Simulators of Fundamental Physics
This meeting will bring together researchers from the quantum technology, atomic physics, and fundamental physics communities to discuss how quantum simulation can be used to gain new insight into the physics of black holes and the early Universe. The core program of the workshop is intended to deepen collaboration between the UKbased Quantum Simulators for Fundamental Physics (QSimFP; https://www.qsimfp.org) consortium and researchers at Perimeter Institute and neighbouring institutions. The weeklong conference will consist of broadlyaccessible talks on work within the consortium and work within the broader community of researchers interested in quantum simulation, as well as a poster session and ample time for discussion and collaboration
Territorial Land AcknowledgementPerimeter Institute acknowledges that it is situated on the traditional territory of the Anishinaabe, Haudenosaunee, and Neutral peoples.
Perimeter Institute is located on the Haldimand Tract. After the American Revolution, the tract was granted by the British to the Six Nations of the Grand River and the Mississaugas of the Credit First Nation as compensation for their role in the war and for the loss of their traditional lands in upstate New York. Of the 950,000 acres granted to the Haudenosaunee, less than 5 percent remains Six Nations land. Only 6,100 acres remain Mississaugas of the Credit land.
We thank the Anishinaabe, Haudenosaunee, and Neutral peoples for hosting us on their land.

Partition function for a volume of space
Ted Jacobson University of Maryland, College Park
In their seminal 1977 paper, Gibbons and Hawking (GH) audaciously applied concepts of quantum statistical mechanics to ensembles containing black holes, finding that a semiclassical saddle point approximation to the partition function recovers the laws of black hole thermodynamics. In the same paper they insouciantly applied the formalism to the case of boundaryless de Sitter space (dS), obtaining the expected temperature and entropy of the static patch. To what ensemble does the dS partition function apply? And why does the entropy of the dS static patch decrease upon addition of Killing energy? I’ll answer these questions, and then generalize the GH method to find the approximate partition function of a ball of space at any fixed proper volume. The result is the exponential of the BekensteinHawking entropy of its boundary.
Zoom link: https://pitp.zoom.us/j/91961890091?pwd=R3lZWHNIQUUzSldzS3kyclJKR3JXdz09