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# Upcoming

in 3 days

Ian Moss
# QSimFP FVD Seminar: False vacuum decay in an ultracold spin-1 Bose gas

Abstract:
After some background on first order transitions in the early universe
I’ll describe a new physical system that might be used as a
laboratory analogue. The system is based on a spin 1 Bose gas
with Raman and RF induced interactions. It does not require
the Feshbach resonance and modulated interactions
of previous proposals. Based on work by Ian Moss, Tom Billam
and Kate Brown.
Biosketch:
Ian Moss is Professor of Theoretical Cosmology at Newcastle University.
He has been been researching early universe phase transitions for what
seems like forever and he is half of the Hawking-Moss instanton.
The seminar will last 1 hour including Q&A and be held at 3.00pm UK Time/10.00am Toronto Time.
This seminar will be held on Zoom.

https://zoom.us/j/97690810408
in 16 days

TBA
# QSimFP QBH Seminar: TBA

The seminar will last 1 hour including Q&A and be held at 3.00pm UK Time/10.00am Toronto Time.
This seminar will be held on Zoom.

in 31 days

Ulrich Schneider
# QSimFP FVD Seminar: Realizing discontinuous quantum phase transitions in a strongly-correlated driven optical lattice

Ulrich Schneider (Department of Physics, University of Cambridge, UK), on "Realizing discontinuous quantum phase transitions in a strongly-correlated driven optical lattice"
The seminar will last 1 hour including Q&A and be held at 3.00pm UK Time/10.00am Toronto Time.
This seminar will be held on Zoom.

in 115 days

TBA
# QSimFP FVD Seminar: TBA

TBA

in 128 days

TBA
# QSimFP QBH Seminar: TBA

TBA

in 143 days

TBA
# QSimFP FVD Seminar: TBA

TBA

in 163 days

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# QSimFP QBH Seminar: TBA

TBA

in 178 days

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# QSimFP FVD Seminar: TBA

TBA

in 191 days

TBA
# QSimFP QBH Seminar: TBA

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in 206 days

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# QSimFP FVD Seminar: TBA

TBA

# To be announced

# Past seminars

12 days ago

Maxime Jacquet
# Quantum vacuum excitation of a quasi-normal mode in an analog model of black hole spacetime

Maxime Jacquet (Laboratoire Kastler Brossel,Quantum Optics Group, Paris, France), on "Quantum vacuum excitation of a quasi-normal mode in an analog model of black hole spacetime"
Biosketch: Maxime is currently leading experimental and theoretical research in analogue gravity with quantum fluids of light in the Quantum Optics group at Laboratory Kastler Brossel, Sorbonne University and CNRS, France.
Abstract:
Analogue gravity enables the laboratory investigation of effects of quantum field theories on curved spacetimes. The archetypal example is the parametric amplification of vacuum quantum fluctuations of the field on the curved spacetime, as in the Hawking effect (the correlated emission of waves) at the event horizon.
In this talk, I will review theoretical work on the Hawking effect in transsonic, quantum fluids of microcavity polaritons [1]. Because of the driven-dissipative dynamics of the fluid, the system is out of thermal equilibrium. I will explain how this impacts correlated emission by the Hawking effect [2], and also show that dissipation may be harnessed to observe novel effects like the quantum vacuum excitation of quasi-normal modes of the acoustic field [3]. This, I will argue, opens a range of new questions pertaining to all quantum fields on black hole spacetimes beyond analogue models.
Refs: [1] arxiv:2002.00043, [2] arxiv:2201.02038, [3] arxiv:2110.14452.
The seminar will last 1 hour including Q&A and be held at 3.00pm UK Time/10.00am Toronto Time.
This seminar will be held on Zoom.

25 days ago

Dalila Pirvu
# Bubble Clustering in Cosmological First Order Phase Transitions

Abstract: False vacuum decay in quantum mechanical first order phase transitions is a phenomenon with wide implications in cosmology and presents interesting theoretical challenges. In the standard approach, it is assumed that false vacuum decay proceeds through the formation of bubbles that nucleate at random positions in spacetime and subsequently expand. In our work, we investigated the presence of correlations between bubble nucleation sites using a recently proposed semiclassical stochastic description of vacuum decay. The procedure sampled vacuum fluctuations which were evolved using classical lattice simulations. We computed the two-point function for bubble nucleation sites from an ensemble of simulations, demonstrating that nucleation sites cluster in a way that is qualitatively similar to peaks in random Gaussian fields. I will comment qualitatively on the phenomenological implications of bubble clustering in early Universe phase transitions, which include features in the power spectrum of stochastic gravitational waves and an enhancement or suppression of the probability of observing bubble collisions in the eternal inflation scenario. I finish by explaining briefly how our results can be tested empirically using a table-top analogue of vacuum decay.
Biosketch: Dalila Pirvu is a second year PhD student at the Perimeter Institute and University of Waterloo in Canada. She did her undergraduate at Imperial College London. Her work is focused on dynamical lattice simulations of phase transitions in quantum field theories.
The seminar will last 1 hour including Q&A and be held at 3.00pm UK Time/10.00am Toronto Time.
This seminar will be held on Zoom. Details to follow

40 days ago

Niayesh Afshordi
# Stimulating Hawking Radiation of Gravitational Waves

Abstract: I will outline the diverse theoretical arguments for why quantum mechanics of merging black holes should lead to the stimulation of Hawking Radiation of gravitational waves, which may manifest as delayed echoes in observations. I will then summarize the status and outlook of the observational program to search for these echoes.
Biosketch: Niayesh Afshordi is an Astrophysicist whose research spans from Early Universe Cosmology and Quantum Gravity, to Dark Matter, Dark Energy, Extragalactic Astronomy, Large Scale Structure of the Universe, and High Energy Astrophysics. He received his PhD at Princeton in 2004. He then did postdocs at Harvard College Observatory and Perimeter Institute for Theoretical Physics. He is currently a professor of Physics and Astronomy at the University of Waterloo. He is also an associate faculty at Perimeter Institute, and a founding faculty of the Waterloo Centre for Astrophysics.
The seminar will last 1 hour including Q&A and be held at 3.00pm UK Time/10.00am Toronto Time.
This seminar will be held on Zoom.

75 days ago

Maria Chiara Braidotti
# Measurement of Penrose superradiance in a photon fluid

Superradiance is the amplification ofwaves scattered by a rapidly rotating object, first proposed by Roger Penroseas a way to extract energy from rotating black holes. Despite being afundamental process in wave physics, astrophysical superradiance has not beenobserved yet due to the large distances involved. However, proposal based onanalogue gravity studies have demonstrated their versatility providing the firstmeasurement of superradiance in a hydrodynamic experiment.
Here we report the first measurementof Penrose superradiance in nonlinear optical systems, especially in a 2Dsuperfluid. A weak signal beam with orbital angular momentum is focused ontothe core of a pump vortex. In the scattering, a negative norm idler wave isgenerated and trapped inside the pump core, while the signal (positive normwave) gets amplified. Our results demonstrate the presence of Penrosesuperradiance in superfluids unveiling the key role of the negative norm modein the amplification process.
Maria Chiara Braidotti is a research associateat the School of Physics & Astronomy of the University of Glasgow (UoG),Scotland. She joined works in the ExtremeLight group lead by Prof. Faccio, UoG(http://www.physics.gla.ac.uk/XtremeLight/index.html). Her main expertise is theoretical andexperimental nonlinear optics, especially using it as a tool to testfundamental processes at the interface between gravitation and quantummechanics. In recent years, her research activity has focused on the test ofPenrose process and Zel’dovich effect both involving amplification ofelectromagnetic modes from the scattering with a rotating body.
She is author of more than 15 publications ininternational journals (with 2 publications on Physics Review Letters journal)and over 30 invited presentations to national and international conferences.