This series covers all areas of research at Perimeter Institute, as well as those outside of PI's scope.
The success of gauge theory descriptions of Nature follows simply, in hindsight, from Lorentz symmetry, quantum mechanics, and the existence of interacting massless particles with spin. Yet, remarkably, the most generic type of massless particle spin has never been seriously examined: Wigner's so-called "continuous spin" particles (CSPs), which have a tower of polarization states carrying all integer or half-integer helicities that mix under boosts.
A fascinating aspect of the two dimensional
world is the possible existence of anyons, particles which obey 'fractional'
statistics different from fermionic and bosonic statistics. In this colloquium,
following an introduction to fractional particles in the context of quantum
Hall systems, some of the tantalizing experiments for detecting the fractional
charge of these particles will be described.
Probes of fractional statistics in these systems will be discussed,
Despite its feeble in strength, gravity plays a pivotal role in shaping our Universe and the things in it. Ever since Newton formulated his universal law of gravitation the recognition that all things gravitate has been nearly sacrosanct. Repeatedly, apparent gravitational anomalies have either foretold the existence of new physics or a misunderstanding of gravity itself, from the existence of nuclear forces to Einstein's general relativity. Eighty years ago gravity betrayed the existence of dark matter, and fifteen years ago gravity demanded dark energy from reluctant cosmologists.
Ordinary differential equations become much less ordinary
when they are allowed to have singularities.
Solving them naively in formal power series, one often obtains divergent
series, just as in the perturbation series for physical observables in quantum
In 1982, Richard Feynman proposed the concept of a quantum computer as a means of simulating physical systems that evolve according to the Schrödinger equation. I will explain various quantum algorithms that have been proposed for this simulation problem, including my recent work (jointly with Dominic Berry and Rolando Somma) that significantly improves the running time as a function of the precision of the output data.
In 2004, Kim and Chan reported torsional
oscillator experiments on 4He crystals which showed evidence of
“non-classical rotational inertia”, the mass decoupling expected for a
long-sought “supersolid” state. It soon
became clear that this behavior is not a property of perfect crystals – defects
are involved. In 2007, we made elastic
measurements which showed, to our surprise, that the shear modulus of solid 4He
increases dramatically below 0.2 K, with the same dependence on temperature,
Alan Turing was one of our great 20th century
mathematicians, and a pioneer of computer science. However, he may best be
remembered as one of the leading code breakers of Bletchley Park during World
War II. It was Turing's brilliant insights and mathematical mind that helped to
break Enigma, the apparently unbreakable code used by the German military. We
present a history of both Alan Turing and the Enigma, leading up to this
fascinating battle of man against machine - including a full demonstration of
Superfluidity and superconductivity are two remarkable
phenomena in which, at low temperatures, materials abruptly gain the ability to
flow without friction. Microscopic quantum theories of these phases of matter
were constructed in blockbuster papers of Lev Landau (1940) and John Bardeen,
Leon Cooper, and J. Robert Schrieffer
(1957). The actual explanation of
the flow, however, is rooted in a
Einstein paper of 1924 that introduces a condensate, a quantum configuration describing a finite
Gamma-ray bursts are
the most luminous and energetic explosions known in the universe. They
appear in two varieties: long- and short-duration. The long GRB
result from the core-collapse of massive stars, but until recently the origin
of the short GRBs was shrouded in mystery. In this talk I will present
several lines of evidence that point to the merger of compact objects binaries
(NS-NS and/or NS-BH) as the progenitor systems of short GRBs. Within this
framework, the observational data also allow us to independently determine the
Despite being one of the most abundant constituents of the Universe and more than a half a century of study, some of the most fundamental properties of the neutrino have only been recently uncovered, and others still remain unresolved. I will discuss important developments in the phenomenon of neutrino oscillations, a transmutation process that allows neutrinos to change between three types as they propagate in time.