Particle Theory Group Events and Seminarshttps://www.theory.caltech.edu/calendar/rss/en-usFri, 25 Feb 2022 13:00:00 -0800Reinforcement learning for designing quantum protocolshttps://www.theory.caltech.edu/calendar/inqnet-seminar-12Alexey A. Melnikov, Terra Quantum AG, Valiev Institute of Physics and Technology of Russian Academy of Sciences
Abstract:Designing quantum protocols and algorithms is difficult and often clashes with our intuition. In our previous research, reinforcement learning was found to be successful in designing quantum optics experiments. Based on the previous success, we apply similar techniques in designing long-distance quantum communication protocols. The same approach allows one to ﬁnd improved solutions to long-distance communication problems, particularly when dealing with asymmetric situations where the channel noise and segment distance are nonuniform. This is of particular importance in developing long-distance communication schemes, and opens the way to using machine learning in the design and implementation of quantum networks.Join Zoom Meetinghttps://caltech.zoom.us/j/93304584361Meeting ID: 933 0458 4361INQNET (INtelligent Quantum NEtworks & Technologies, inqnet.caltech.edu) is a research program that aims to bring together academia, national laboratories, and industry to advance quantum science and technology and address relevant fundamental questions in physics.Mon, 24 Jan 2022 12:30:00 -0800INQNET Seminar@Mon Jan 24 12:30:00 2022@theory.sites.caltech.eduINQNET SeminarAnalyticity and Unitarity for Cosmological Correlatorshttps://www.theory.caltech.edu/calendar/high-energy-physics-seminar-12062022Victor Gorbenko, Stanford University
I will discuss the fundamentals of quantum field theory on a rigid de Sitter space. I will show that the perturbative expansion of late-time correlation functions to all orders can be equivalently generated by a non-unitary Lagrangian on a Euclidean AdS geometry. This finding simplifies dramatically perturbative computations, as well as allows us to establish basic properties of these correlators, which comprise a Euclidean CFT. This is used to infer the analytic structure of the spectral density that captures the conformal partial wave expansion of late-time four-point functions, to derive an OPE expansion, and to constrain the operator spectrum that appears in it. Generically, dimensions and OPE coefficients do not obey the usual CFT notion of unitarity. Instead, unitarity of the de Sitter theory manifests itself as the positivity of the spectral density. I will illustrate these properties by explicit calculations in a scalar theory by computing the exchange diagrams. An exchanged particle appears as a resonant feature in the spectral density which can be potentially useful in experimental searches.Contact theoryinfo@caltech.edu for Zoom link.Mon, 24 Jan 2022 16:00:00 -0800High Energy Physics Seminar@Mon Jan 24 16:00:00 2022@theory.sites.caltech.eduHigh Energy Physics SeminarMulti-messenger Studies of Relativistic Jets at the Owens Valley Radio Observatoryhttps://www.theory.caltech.edu/calendar/astronomy-colloquium-470Anthony (Tony) Readhead, Robinson Professor of Astronomy, Emeritus, California Institute of Technology
In spite of five decades of intensive observational effort across the electromagnetic spectrum, some of the most critical questions regarding relativistic jets remain unanswered, including how the jets are launched and the composition of the jets. Since 2008 we have been monitoring ~1800 blazars at 15 GHz, with the 40 m Telescope of the Owens Valley Radio Observatory, to address these questions. Now, with the advent of neutrino astronomy, a new avenue of attack has opened up. I will review the status of the search for neutrino-blazar associations and describe the unique role that the 40 m Telescope is playing in this area. In another multimessenger program, I will describe the discovery of the remarkable supermasssive black hole binary candidate, PKS 2131-021, and the unanticipated phenomenology it has presented. I will also review the status of our Symmetric Achromatic Variability gravitational lensing studies of PKS 1413+135. Finally, I will describe how the 40 m Telescope monitoring program led to the RoboPol program and the wide area linear optical polarimeter programs in Crete and South Africa, to determine the Galactic magnetic field through observations of the optical polarization in over 4 million stars over two-thirds of the sky.To view this talk via YouTube, please visit: https://www.youtube.com/playlist?list=PLb1880Rn0qkKzIavl-n_7RaMyDOiU9XHmWed, 26 Jan 2022 16:00:00 -0800Astronomy Colloquium@Wed Jan 26 16:00:00 2022@theory.sites.caltech.eduAstronomy ColloquiumDistinguishing (S)CFTshttps://www.theory.caltech.edu/calendar/high-energy-theory-seminar-619Jacques Distler, UT Austin
Given two theories, T₁ and T₂, how much information about them do I need to give you, in order for you to be able to conclude that they are isomorphic (conformal) field theories? I will explore this question, and make some conjectures about an answer, using theories of Class-S as a foil.For Zoom information, please email monica@caltech.eduFri, 28 Jan 2022 11:00:00 -0800High Energy Theory Seminar@Fri Jan 28 11:00:00 2022@theory.sites.caltech.eduHigh Energy Theory SeminarD-instanton Superpotential in String Theoryhttps://www.theory.caltech.edu/calendar/high-energy-theory-seminar-620Manki Kim, Massachusetts Institute of Technology
One of the profound challenges in string theory is to understand vacua of string theory with a small number of supercharges. As an intermediate step, one can first study four-dimensional N=1 supersymmetric compactifications of string theory to attain more computational control. In this context, we study non-perturbative superpotential generated by D(-1)-branes in type IIB compactifications on orientifolds of Calabi-Yau threefolds. To compute D-instanton superpotential, we utilize F-theory compactification on toric complete intersection elliptic Calabi-Yau fourfolds. To obtain the weakly coupled type IIB description, we take the Sen-limit, but at finite string coupling, with a restriction that all D7-brane stacks are carrying SO(8) gauge groups, which we call the global Sen-limit. In the global Sen-limit, the axio-dilaton is not varying in the compactification manifold. We compute the Picard-Fuchs equations of elliptic Calabi-Yau fourfolds in the global Sen-limit, and show that the Picard-Fuchs equations of the elliptic fourfolds split into that of the underlying Calabi-Yau threefolds and of the elliptic fiber. We then demonstrate that this splitting property of the Picard-Fuchs equation implies that the fourform period of the elliptic Calabi-Yau fourfolds in the global Sen-limit does not contain exponentially suppressed terms. With this result, we finally show that in the global Sen-limit, superpotential of the underlying type IIB compactification does not receive D(-1)-instanton contributions. Limited capacity in 469 LauritsenFor Zoom information, please email monica@caltech.eduFri, 28 Jan 2022 13:00:00 -0800High Energy Theory Seminar@Fri Jan 28 13:00:00 2022@theory.sites.caltech.eduHigh Energy Theory SeminarTurning the LHC to the Dark Side: The Standard Dark Matter Search Approach, Its Limitations, and How to Overcome Themhttps://www.theory.caltech.edu/calendar/high-energy-physics-seminar-12062023Matteo Cremonesi, University of Notre Dame
Limited attendance in 269 Lauritsen.The nature of Dark Matter (DM) is one of the most interesting open questions in modern physics. Though its existence is proven by astrophysical evidence, its properties are not yet understood. The experiments at LHC can help shed light on this mystery, bringing a unique and complementary perspective to the broader DM quest. In this talk the standard approach for DM searches at colliders is described, reviewing the analysis techniques used as well as the presentation and the interpretation of recent results. A discussion of the current limitations and of the improvements that can help mitigate them will also be presented.Contact theoryinfo@caltech.edu for Zoom link.Mon, 31 Jan 2022 16:00:00 -0800High Energy Physics Seminar@Mon Jan 31 16:00:00 2022@theory.sites.caltech.eduHigh Energy Physics SeminarAstronomy Colloquiumhttps://www.theory.caltech.edu/calendar/astronomy-colloquium-471Wed, 02 Feb 2022 16:00:00 -0800Astronomy Colloquium@Wed Feb 2 16:00:00 2022@theory.sites.caltech.eduAstronomy ColloquiumUnveiling the Higgs's secrets to unlock new physicshttps://www.theory.caltech.edu/calendar/physics-colloquium-11Caterina Vernieri, SLAC
The Higgs boson was discovered in 2012 by the ATLAS and CMS experiments at the world's most powerful particle collider, the Large Hadron Collider (LHC) in Geneva, Switzerland. This particle plays a unique role in fundamental physics. It gives all of the known elementary particles, including itself, their masses. While we now have a strong evidence that the Higgs field is indeed the unique source of mass for the known elementary particles, the next step is to search for new interactions that could also explain why the Higgs field has the properties required by the Standard Model of particle physics. We have no clear roadmap to this new theory but the Higgs boson plays a crucial role in this quest. This talk highlights the current experimental results of Higgs boson couplings to other particles and its self-coupling at the LHC and perspectives at future colliders. The goal of a next-generation collider is to carry out precision measurements to per-cent level of the Higgs boson properties that are not accessible at the LHC. The exploitation of the complementarity between LHC and future colliders will be the key to understanding fundamentally the Higgs boson and acquire sufficient proof that physics beyond the SM exists and which is its energy scale.Limited attendance in Feynman Lecture Hall, 201 E. Bridge to first 100 people. All attendees must show valid Caltech ID upon entry. Join via Zoom: https://caltech.zoom.us/j/89237465190. Meeting ID: 892 3746 5190Thu, 03 Feb 2022 16:00:00 -0800Physics Colloquium@Thu Feb 3 16:00:00 2022@theory.sites.caltech.eduPhysics ColloquiumTBDhttps://www.theory.caltech.edu/calendar/high-energy-theory-seminar-609Hubert Saleur, University of Southern California
Limited capacity in 469 LauritsenFor Zoom information, please email nbenjami@caltech.eduFri, 04 Feb 2022 11:00:00 -0800High Energy Theory Seminar@Fri Feb 4 11:00:00 2022@theory.sites.caltech.eduHigh Energy Theory SeminarUnlocking the CMS Experiment to Catch Long-lived Particleshttps://www.theory.caltech.edu/calendar/high-energy-physics-seminar-Feb072021Cristian Peña, Fermilab
Limited attendance in 269 Lauritsen.Enabling new long-lived particles (LLPs) searches at the LHC presents HEP research with unique opportunities. Introducing novel experimental techniques to identify and reconstruct LLPs will open up new possibilities for discoveries with striking signatures. I will present new long-lived particles searches, with a focus on the CMS Muon System result, which significantly pushed the envelope of LLP exploration. I will follow a detector-based path and discuss the current efforts and significant extensions. I will also discuss new ideas for increasing the acceptance and developing efficient triggers. As we enter the high luminosity era of the LHC, the CMS detector will be equipped with precision timing information in the form of two dedicated systems: the barrel timing layer and the endcap timing layer. These revolutionary upgrades will enable CMS with 4D-reconstruction for the first time, and thus significantly enhance the physics reach of the LHC.Contact theoryinfo@caltech.edu for Zoom link.Mon, 07 Feb 2022 16:00:00 -0800High Energy Physics Seminar@Mon Feb 7 16:00:00 2022@theory.sites.caltech.eduHigh Energy Physics SeminarAstronomy Colloquiumhttps://www.theory.caltech.edu/calendar/astronomy-colloquium-472Wed, 09 Feb 2022 16:00:00 -0800Astronomy Colloquium@Wed Feb 9 16:00:00 2022@theory.sites.caltech.eduAstronomy ColloquiumTBDhttps://www.theory.caltech.edu/calendar/physics-colloquium-6Marilena Loverde, University of Washington
Limited attendance in Feynman Lecture Hall, 201 E. Bridge to first 100 people. All attendees must show valid Caltech ID upon entry. Join via Zoom: https://caltech.zoom.us/j/89237465190. Meeting ID: 892 3746 5190Thu, 10 Feb 2022 16:00:00 -0800Physics Colloquium@Thu Feb 10 16:00:00 2022@theory.sites.caltech.eduPhysics ColloquiumHigh Energy Theory Seminarhttps://www.theory.caltech.edu/calendar/high-energy-theory-seminar-618Josephine Suh, KITP, UC Santa Barbara
Limited capacity in 469 LauritsenWe propose that the underlying context of holographic duality and the Ryu-Takayanagi formula is that the volume measure of spacetime is a probability measure constrained by quantum dynamics. In anti-de Sitter JT gravity, we define and analyze the quantum stochastic process induced by the boundary, and show Einstein's equations arise from the evolution of probability under the non-Markovian process. In particular, the area of compactified space in the gravitational theory can be identified as a probability distribution evolving under the quantum process. Extrapolating these and analogous results in flat JT gravity, we conjecture that general relativity arises in the semi-classical limit of the evolution of probability with respect to quantum stochastic processes.For Zoom information, please email monica@caltech.eduFri, 11 Feb 2022 11:00:00 -0800High Energy Theory Seminar@Fri Feb 11 11:00:00 2022@theory.sites.caltech.eduHigh Energy Theory SeminarAstronomy Colloquiumhttps://www.theory.caltech.edu/calendar/astronomy-colloquium-473Wed, 16 Feb 2022 16:00:00 -0800Astronomy Colloquium@Wed Feb 16 16:00:00 2022@theory.sites.caltech.eduAstronomy ColloquiumTBDhttps://www.theory.caltech.edu/calendar/physics-colloquium-7Eric Cornell, Cornell University
Limited attendance in Feynman Lecture Hall, 201 E. Bridge to first 100 people. All attendees must show valid Caltech ID upon entry. Join via Zoom: https://caltech.zoom.us/j/89237465190. Meeting ID: 892 3746 5190Thu, 17 Feb 2022 16:00:00 -0800Physics Colloquium@Thu Feb 17 16:00:00 2022@theory.sites.caltech.eduPhysics ColloquiumTBDhttps://www.theory.caltech.edu/calendar/high-energy-theory-seminar-614Eva Silverstein, Stanford University
Limited capacity in 469 LauritsenFor Zoom information, please email nbenjami@caltech.eduFri, 18 Feb 2022 11:00:00 -0800High Energy Theory Seminar@Fri Feb 18 11:00:00 2022@theory.sites.caltech.eduHigh Energy Theory SeminarAstronomy Colloquiumhttps://www.theory.caltech.edu/calendar/astronomy-colloquium-474Wed, 23 Feb 2022 16:00:00 -0800Astronomy Colloquium@Wed Feb 23 16:00:00 2022@theory.sites.caltech.eduAstronomy ColloquiumCold and ultra-cold molecules for quantum sciencehttps://www.theory.caltech.edu/calendar/physics-colloquium-postponedJohn Doyle, Harvard University
Polar molecules, due to their intrinsic electric dipole moment and their controllable complexity, are a powerful platform for precision measurement searches for physics beyond the standard model (BSM) and, potentially, for quantum simulation/computation. This has led to many experimental efforts to cool and control molecules at the quantum level. I will discuss our results on the laser cooling of molecules into the ultracold regime and future prospects for molecules in Quantum Science. In particular, I will discuss the creation of an optical tweezer array of ultracold CaF molecules, the study of ultracold CaF collisions, and the laser cooling of the polyatomic molecules SrOH, YbOH, CaOH and CaOCH3. Polyatomic molecules, perhaps much larger than those just listed, have attracted new focus as potential novel quantum resources that have distinct advantages (and challenges) compared to both atoms and diatomic molecules. I will discuss how some key features of polyatomic molecules can be used to enhance applications in quantum simulation/computation, the search for BSM physics. Finally, if time permits, I will discuss recent measurements indicating that it might be possible to laser cool much larger molecules, including phenols and napthols.Limited attendance in Feynman Lecture Hall, 201 E. Bridge to first 100 people. All attendees must show valid Caltech ID upon entry. Join via Zoom: https://caltech.zoom.us/j/89237465190. Meeting ID: 892 3746 5190Thu, 24 Feb 2022 16:00:00 -0800Physics Colloquium@Thu Feb 24 16:00:00 2022@theory.sites.caltech.eduPhysics ColloquiumTBDhttps://www.theory.caltech.edu/calendar/high-energy-theory-seminar-610Steven Rayan, University of Saskatchewan
Limited capacity in 469 LauritsenFor Zoom information, please email nbenjami@caltech.eduFri, 25 Feb 2022 11:00:00 -0800High Energy Theory Seminar@Fri Feb 25 11:00:00 2022@theory.sites.caltech.eduHigh Energy Theory SeminarTBDhttps://www.theory.caltech.edu/calendar/high-energy-theory-seminar-616Raphael Bousso, UC Berkeley
Limited capacity in 469 LauritsenFor Zoom information, please email nbenjami@caltech.eduFri, 25 Feb 2022 13:00:00 -0800High Energy Theory Seminar@Fri Feb 25 13:00:00 2022@theory.sites.caltech.eduHigh Energy Theory Seminar