Scientific Series

Certifying quantum properties with minimal assumptions is a fundamental problem in quantum information science. Self-testing is a method to infer the underlying physics of a quantum experiment only from the measured statistics. While all bipartite pure entangled states can be self-tested, little is known about how to self-test quantum states of an arbitrary number of systems. Here, we introduce a framework for network-assisted self-testing and use it to self-test any pure entangled quantum state of an arbitrary number of systems. The scheme requires the preparation of a number of singlets that scales linearly with the number of systems, and the implementation of standard projective and Bell measurements, all feasible with current technology. When all the network constraints are exploited, the obtained self-testing certification is stronger than what is achievable in any Bell-type scenario. Our work does not only solve an open question in the field but also shows how properly designed networks offer new opportunities for the certification of quantum phenomena.

In this seminar, I will explore the effect of quantum gravity on matter couplings within a (Functional) Renormalization Group framework. I will mainly focus on gravitational contribution to the flow of gauge couplings. In particular, I will focus on results obtained from a class of interpolating regulators that allow us to extract certain universal pieces from non-universal quantities. I will argue that gravity might induce the UV completion of an Abelian-gauge sector, despite an apparent vanishing contribution to its flow when we consider only universal pieces. This result might offer a new perspective on the differences between perturbative studies and Functional Renormalization Group studies.

Zoom Link: https://pitp.zoom.us/j/97277305442?pwd=d240TXhrNnZ0TlErbGQ0bCtGU1NCZz09

The patent system is designed to help innovators protect their intellectual property. In this colloquium, we will discuss logistical and strategic aspects of the patent process, to help you better understand how to leverage the patent system. Topics will include the anatomy of a patent, deadlines and procedural steps for filing patent applications, and strategic considerations in developing the claims and other components of a patent application.

Zoom Link: https://pitp.zoom.us/j/91402107798?pwd=UDRQV0IvY3JEUkVJeC9QR3JXVjZSdz09

I will discuss the large-N limit of two-dimensional symmetric product orbifolds. The goal is to single out which symmetric product orbifold theory could lead to a strongly coupled theory, whose dual could be a semi-classical theory of AdS_3 gravity, by quantifying the large-N limit of the BPS spectrum and the behaviour under exactly marginal deformations. From this analysis, I will propose an infinite family of new holographic CFTs.

Zoom Link: https://pitp.zoom.us/j/99948208493?pwd=RDRYclc2a05kMmNZL3ZhMWxMdWdNUT09

Muons are the archetypal ‘who ordered that?’ surprise discovered in cosmic rays and fittingly, recent muon measurements including g–2 could be challenging standard paradigms again. Remarkably, tau g–2 remains poorly constrained but can be 280 times more sensitive to new physics than the muon. Recently, ATLAS and CMS announced groundbreaking measurements of tau g–2 using the landmark observation of tau pairs created via photon collisions in LHC heavy-ion data. Beyond colliders, quantum sensing progress enables next-generation haloscopes to illuminate axion-like origins of dark matter above microwave frequencies. This motivates the Broadband Reflector Experiment for Axion Detection (BREAD) proposal at Fermilab and its interdisciplinary science program bridging astronomy, particle physics, and quantum technology.

Zoom Link: https://pitp.zoom.us/j/95937524952?pwd=eFVaTXVXOHBiNE9TZk9oMGNxRUwyQT09

Next generation cosmic microwave background (CMB) experiments and galaxy surveys will generate a wealth of new data with unprecedented precision on small scales. Correlations between CMB anisotropies and the galaxy density carry valuable cosmological information about the largest scales, creating novel opportunities for inference. It is possible to foresee a future where reconstruction of the gravitational weak-lensing potential, velocity fields and the remote quadrupole field will provide the most precise tests of fundamental physics. The use of the second-order effects in the CMB to extract this information motivate a strong push towards low noise, high resolution frontiers of the upcoming generation CMB experiments. In this talk, I will discuss the prospects to use small-scale kinetic and polarized Sunyaev Zel’dovich effects and the moving-lens effect, in cross-correlation with ongoing galaxy surveys, to extract cosmological information. 

Zoom Link: https://pitp.zoom.us/j/91455862792?pwd=M1hFRDgyOXVKU1U4Z0pLcm1wZGdRQT09

I review a recent approach to connecting quantum gravity and the real world by deconstantizing the constants of nature, and using their conjugate as a time variable. This is nothing but a generalization of unimodular gravity. The wave functions are then packets of plane waves moving in a space that generalizes the Chern-Simons functional. For appropriate states they link up with classical cosmology in the appropriate limit. There are however deviations, namely during the matter to Lambda transition, raising the possibility that quantum gravity could be in action here and now. At the other extreme I show how this approach can be used to resolve the cosmological singularity, and perhaps more.

Zoom Link: https://pitp.zoom.us/j/94010122575?pwd=L291eHNSOG1wZmpCL1lmWHVJaEwwdz09

Unlike conventional global symmetries that act on all of space, subsystem symmetries act only on rigid subspaces such as lines, planes or fractal regions. Such symmetries are of interest for their close connection to fracton physics and in their own right. In this talk, I discuss phenomena that can occur in two-dimensional systems with subsystem symmetry and anyon excitations, where the symmetry fractionalizes on anyon excitations. This turns out to be manifest in the mobility of the fractionalized excitations under dynamics that respect the symmetry. Such symmetry fractionalization was previously thought to be impossible, and indeed there are a number of differences from conventional symmetry fractionalization. I will present a general framework to describe subsystem symmetry fractionalization in two dimensions, and give a number of simple examples of this phenomenon in commuting Pauli Hamiltonians.

This talk is based on arXiv:2203.13244, work in collaboration with David Stephen, Arpit Dua, José Garre-Rubio and Dominic Williamson.

Zoom Link: https://pitp.zoom.us/j/93741883840?pwd=RlMrUGwwVEt5WFdoNGpkMmdSVXp5UT09

In this talk, I intend to give a pedagogical, nonetheless biased, introduction to String Cosmology. After briefly reviewing the Lambda-CDM model and motivating inflation, we will remind ourselves that early universe cosmology remains singular and waiting for alternatives. That will be our cue to consider string theory to define our gravity sector and string thermodynamics to define our matter sector. We will learn how that doesn't work unless we consider more string corrections (in fact, an infinity of them!). Once we are stringy enough, we will be able to build a full cosmological model that is non-singular and already poses itself as an alternative to inflation at the background level.

Zoom Link: https://pitp.zoom.us/j/98491655811?pwd=ZzArNjFVMmZIdE1STjd2TVNWSlZtZz09

Population studies of gravitational-wave events allow us to probe stellar evolution and formation mechanisms of compact binaries. Recent work has painted a conflicting portrait of the distribution of black hole spins in merging binaries. In this talk, I describe the emerging picture of black hole spin using observations from LIGO-Virgo–KAGRA with a new spin model. We find evidence for two subpopulations of binary black holes: 1) merging binaries containing black holes with negligible spin, 2) binaries preferentially aligned with the orbital angular momentum and rapidly spinning. These results are consistent with predictions from studies of angular momentum transport in stars and suggest that the subpopulation of spinning black holes may be spun up via tidal interactions. I will also share insights of the binary black hole population using the latest catalogue of gravitational-wave events.

Zoom Link: https://pitp.zoom.us/j/93713298741?pwd=eFo2Q1lSTVBESWcyZXJlcFVKZ2hRQT09

Quantum information science was initially motivated by questions about information processing. For example, what are the consequences of quantum mechanics for computation? Or for cryptography? More recently, quantum information has also become a perspective through which we can study questions in theoretical physics more broadly, including in condensed matter and quantum gravity. While quantum information considers the constraints of quantum mechanics, there are additional constraints on information implied by relativity. In particular, it is impossible to send information faster than the speed of light. In this talk, I consider constraints on information processing imposed by quantum mechanics and relativity together, and the consequences of these constraints for quantum gravity. Doing so reveals novel aspects of how gravitational degrees of freedom can be recorded into a quantum mechanical system, and how an extra dimension can be recorded into ``holographic'' field theories.

Zoom Link: https://pitp.zoom.us/j/99249375009?pwd=QWZyZzQrNXJwSGYyYTZheGwwaVRndz09

The sustained storage, transmission, or processing of quantum information will likely be a non-equilibrium process that requires monitoring the system and applying some form of feedback to produce fault-tolerance.  In this talk, I will discuss a class of models based on random quantum circuits with intermediate measurements that display a similar phenomenology to standard models for fault-tolerance, including the existence of a threshold, but with several helpful simplifications.  However, naïve realizations of the threshold require an exponential number of repetitions of the experiment to fully explore the output space of the intermediate measurements.  Recently, it has been proposed that this problem can be circumvented by developing efficient entanglement “decoders” that have close parallels to quantum error correction decoders.  We show how to leverage modern machine learning tools to devise a neural network decoder to detect the phase transition. We then study the complexity and scalability of this approach and discuss how it can be utilized to detect entanglement phase transitions in generic experiments.

Zoom Link: https://pitp.zoom.us/j/99123641139?pwd=VmkyR3BSNWF5bURVYmFVakp0ZkNRZz09