641 Works

Carroll symmetry in gravity and string theory

I will discuss the small speed of light expansion of general relativity, utilizing the modern perspective on non-Lorentzian geometry. The leading order in the expansion leads to an action that corresponds to the electric Carroll limit of general relativity, of which I will highlight some interesting properties. The next-to-leading order will also be obtained, which exhibits a particular subsector that correspond to the magnetic Carroll limit, which features a solution that describes the Carroll limit...

Emergence of Supergroups from Junctions of M-branes

We study the boundary conditions in the topologically twisted Chern-Simons matter theories with the Lie 3-algebraic structure. We find that the supersymmetric boundary conditions and the gauge invariant boundary conditions can be unified as the complexified gauge invariant boundary conditions which lead to the supergroup WZW models. We examine the BPS indices of the supergroup WZW models which may describe certain junctions of M2-branes and M5-branes by identifying the vacuum configurations of the brane system...

Welcome and Opening Remarks

Quantum cosmology in Lorentz-violating gravity

Lorentz invariance is considered a fundamental symmetry of physical theories. However, while Lorentz violations are strongly constrained in the matter sector, constraints in the gravitational sector are weaker, allowing to contemplate the idea of Lorentz-violating gravity theories. In this talk I will discuss the effects of Lorentz violations in the quantum cosmology scenario by analyzing the properties of a simple anisotropic model in the framework of Horava-Lifshitz gravity and, if time permitting, some partial results...

Impact cratering and the evolution of planetary surfaces in the solar system – The Chicxulub impact

Impacts of asteroid and comets constitute major geologic processes shaping the surfaces and evolution of planetary bodies. Impacts produce deep transient cavities, with excavation to deep crustal levels, fragmentation, and removal of large rock volumes. Formation of complex craters involves high pressures and temperatures resulting in intense deformation, fracturing and melting. Here, we analyze the crater-forming impacts and their effects on the Earth´s climate, environment and life-support systems, in relation to the Cretaceous/Paleogene (K/Pg) boundary....

The chaotic evolution of Newton's universe

In this expository talk, I describe how "chaotic behavior" not only was discovered in the study of the Newtonian N-body problem, but also is responsible for several strange appearing motions. Then, a mathematical outline of the general evolution of the universe, under Newton's laws, is provided. No prior background in dynamics or the mathematics of the N-body problem is needed to follow this lecture

Relation of adiabatic QC to other models

More on adiabatic quantum computation

A variety of results in mathematical adiabatic quantum mechanics

Low energy QCD and ChPT tests at the NA48/2 experiment

In the last years, the NA48/2 experiment at the CERN SPS has recorded an unprecedented sample of charged kaon decays. From this, we report very precise measurements of fundamental parameters of Chiral Perturbation Theory (ChPT) and the study of low energy pi-pi scattering. Several rare and very rare decays have been studied. From more than 10^6 K+- -> pi+ pi0 gamma decays, a first measurement of the interference between Bremsstrahlung and Direct Emission amplitudes and...

The Diamond Lemma for (multiplicative) preprojective algebras

Bergman's Diamond Lemma for ring theory gives an algorithm to produce a (non-canonical) basis for a ring presented by generators and relations. After demonstrating this algorithm in concrete, geometrically-minded examples, I'll turn to preprojective algebras and their multiplicative counterparts. Using the Diamond Lemma, I'll reprove a few classical results for preprojective algebras. Then I'll propose a conjectural basis for multiplicative preprojective algebras. Finally I'll explain why the set is a basis in the case of...

Coxeter Lecture II - Stabilization of moduli in string theory I

Non-Anticommutative supersymmetry in two dimentions

We formulate non-anticommutative supersymmetry in two dimensions using differential operators acting on the component fields. We then use these operators to give a compact expression for the one-loop divergences in the non-anticommutative Kahler sigma model.

Quantum Materials Discovery: The Synthesis of Geometrically Frustrated Magnets

In the last few decades, there has been a marked rise in the diversity of compounds studied with frustrated networks of spins. This was clearly not the case in the early days of this field, where only a handful of “model” systems were being studied (ie. in two dimensions, the triangular or kagome lattices, and in three dimensions, the pyrochlore lattice).  Solid state chemists have played a major role in not only the identification of new geometrically...

Fractionalized Topological Insulators in Frustrated Magnets

Spin liquid phases in frustrated magnets may arise in a variety of forms. Here we discuss the possibility of topological insulators of spinons or the fractionalized excitations in spin liquids. These phases should be characterized by "both" of the two popular and different definitions of topological orders, namely the long-range entanglement and the symmetry-protected topological order. We show an explicit construction of such a state in frustrated magnets on the pyrochlore lattice and discuss novel...

Quasiprobability representations of qubits

Negativity in a quasi-probability representation is typically interpreted as an indication of nonclassical behavior.  However, this does not preclude bases that are non-negative from having interesting applications---the single-qubit stabilizer states have non-negative Wigner functions and yet play a fundamental role in many quantum information tasks. We determine what other sets of quantum states and measurements of a qubit can be non-negative in a quasiprobability representation, and identify nontrivial groups of unitary transformations that permute such...

Coordinate Charts on Character Varieties via Non-abelianization

Classical work by Thurston in the theory of surfaces gives symplectic co-ordinate charts on Teichmüller space, associated to quadratic differentials. Motivated by wall crossing in 4d field theories Gaiotto, Moore and Neitzke defined a generalization of these; giving maps from the moduli of one dimensional local systems on a spectral curve to the moduli space of n-dimensional local systems on a non-compact Riemann surface. I will...

Fundamental physics with 21cm observations


Entanglement Generation in Relativistic Quantum Fields

We present a general, analytic recipe to compute the entanglement that is generated between arbitrary, discrete modes of bosonic quantum fields by Bogoliubov transformations. Our setup allows the complete characterization of the quantum correlations in all Gaussian field states. Additionally, it holds for all Bogoliubov transformations. These are commonly applied in quantum optics for the description of squeezing operations, relate the modedecompositions of observers in different regions of curved spacetimes, and describe observers moving along...

On-chip Extraction of Quantum Correlations from the Vacuum

Far Infrared Study of Magnetic Field Induced Normal States of La1.94Sr0.06CuO4

We report on the ab-plane optical properties of the magnetic field inducednormal state of underdoped La1.94Sr0.06CuO4  (Tc=5.5 K), the first such study. We apply strong magnetic fields (4 T and 16 T) along the c-axis. We find that a 4 T field is strong enough to destroy the superconducting condensate.  However at higher fields we observed a gap-like depression in the optical conductivity at low frequency along with parallel growth of a broad absorption peak...

Effective Spin-1/2 Hamiltonians Determined for Er2Ti2O7 & Yb2Ti2O7 Through Inelastic Neutron Scattering

We used time-of-flight inelastic neutron scattering to measure the excitation spectra from field-polarized states of exotic frustrated magnets. A knowledge of these spin-wave excitations in various directions in reciprocal space allows a robust determination of exchange parameters in suitable model Hamiltonians.  We have taken this approach with two pyrochlores, Er2Ti2O7 and Yb2Ti2O7, whose magnetic properties have until this point been somewhat puzzling.  The model we use is an effective spin-1/2 exchange Hamiltonian that incorporates the full...

Detection of vacuum entanglement in an ion trap

Quantum information methods have been recently used for studying the properties of ground state entanglement in several many body and field theory systems. We will discuss a thought experiment wherein entanglement can be extracted from the vacuum of a relativistic field theory into a pair of arbitrarily spatially separated atoms. In order to simulate the detection process, we will consider the ground state of a linear chain of cooled trapped ions, and discuss a scheme...

Registration Year

  • 2022

Resource Types

  • Audiovisual


  • Perimeter Institute