Talks

This is an introduction to background independent quantum theories of gravity, with a focus on loop quantum gravity and related approaches. Basic texts: -Quantum Gravity, by Carlo Rovelli, Cambridge University Press 2005 -Quantum gravityy with a positive cosmological constant, Lee Smolin, hep-th/0209079 -Invitation to loop quantum gravity, Lee Smolin, hep-th/0408048 -Gauge fields, knots and gravity, JC Baez, JP Muniain Prerequisites: -undergraduate quantum mechanics -basics of classical gauge field theories -basic general relativity -hamiltonian and lagrangian mechanics -basics of lie algebras

An expected 90 day robotic odyssey on Mars has stretched into a two year scientific marathon. Dr. Grant, a geologist with the Center for Earth and Planetary Studies, helped pick the landing sites and works on day-to-day operations of the Spirit and Opportunity Rovers. You’ll see the latest photos, learn what Martian mysteries have been uncovered and find out how scientists plan to push the limits of future robots in space. Dr. John A. Grant, III joined the Smithsonian in the fall of 2000 as a Geologist at the Center for Earth and Planetary Studies at the National Air and Space Museum. He has been a member of the Science Team for the Mars Exploration Rovers since 2002, is one of six Science Operations Working Group Chairs and is co-leading site selection activities for the 2009 Mars Science Laboratory mission to Mars. Since 2001, Dr. Grant has served as a Co-Investigator on the High Resolution Camera (HiRISE), which is being flown on the 2005 Mars Reconnaissance Orbiter, currently on its way to Mars. In addition, he is leading development of a ground-penetrating radar for possible future deployment on a Mars rover and conducts fundamental research related to the history of geologic processes on the Earth and Mars. He has been interested in Mars ever since reading Ray Bradbury’s The Martian Chronicles as a child. Dr. Grant earned his bachelor’s degree from the State University of New York College at Plattsburgh and received his master’s in geology at the University of Rhode Island and his doctorate in geology at Brown University. He maintains a strong connection to the classroom and has held several professorial and teaching posts at both Rhode Island College and SUNY College at Buffalo. He has authored or contributed to numerous articles in many professional journals, including Science, Geology, Geomorphology, and the Journal of Geophysical Research. Mission to Mars, John A Grant, Mars, exploration, red planet, NASA, Spirit Rover, hematite, geology, air and space, outcrop, Mars Reconnaissance Orbiter,

This is an introduction to background independent quantum theories of gravity, with a focus on loop quantum gravity and related approaches. Basic texts: -Quantum Gravity, by Carlo Rovelli, Cambridge University Press 2005 -Quantum gravityy with a positive cosmological constant, Lee Smolin, hep-th/0209079 -Invitation to loop quantum gravity, Lee Smolin, hep-th/0408048 -Gauge fields, knots and gravity, JC Baez, JP Muniain Prerequisites: -undergraduate quantum mechanics -basics of classical gauge field theories -basic general relativity -hamiltonian and lagrangian mechanics -basics of lie algebras

It is shown that inflationary cosmology may be used to test the statistical predictions of quantum theory at very short distances. Hidden-variables theories, such as the pilot-wave theory of de Broglie and Bohm, allow the existence of vacuum states with non-standard field fluctuations (“quantum non-equilibrium”). It is shown that such non-equilibrium vacua lead to statistical anomalies, such as a breaking of scale invariance for the primordial power spectrum. The results depend only weakly on the details of the de Broglie-Bohm dynamics. Recent observations of the cosmic microwave background are used to set limits on violations of quantum theory in the early universe.

The problem of associating beables (hidden variables) to QFT, in the spirit of what Bohm did for nonrelativistic QM, is not trivial. In 1984, John Bell suggested a way of solving the problem, according to which the beables are the positions of fermions, in a discretized version of QFT, and obey a stochastic evolution that simulates all predictions of QFT. In the continuum limit, it will be shown that the Bell model becomes deterministic and that it is related to the choice of the charge density as a beable. Moreover, the charge superselection rule is a consequence of the Bell model. The non-relativistic limit and the derivation of Bohm's first quantized interpretation in this limit are also studied. I will also consider whether the Bell model can be applied to bosons.

From the Quantum Field Theory point of view, matter and gauge fields are generally expected to be localised around branes (topological defects) occurring in extra dimensions. I will discuss a simple scenario where, by starting with a five dimensional SU(3) gauge theory, we end up with several 4-D parallel braneworlds with localised 'chiral' fermions and gauge fields to them. I will show that it is possible to reproduce the electroweak model confined to a single brane, allowing a simple and geometrical approach to the hierarchy problem. Some nice results of this construction are: Gauge and Higgs fields are unified at the 5-D level; and new particles are predicted: a left-handed neutrino (with zero-hypercharge) and a massive vector field coupling together the new neutrino to other leptons.

From Monday, January 30th to Thursday, February 2nd, Senarath (Shanta) de Alwis will give a four lecture mini-course on `Potentials for light moduli in N=1 supergravity and string theory'. In these lectures, Shanta will be describing some of the technical ingredients used in recent constructions of inflation in string theory. The lectures will be given at a level appropriate for advanced graduate students and will be held in the Bob Room at 11:00am each day. The topics to be covered include: Derivation of the potential for chiral scalars in N=1 supergravity; Weyl anomalies and the generation of non-perturbative terms in the superpotential; Derivation of moduli potentials from fluxes in type IIB and heterotic string theory; Derivation of potentials for light moduli by integrating out heavy moduli. Shanta is a faculty member in the Physics Department at the University of Colorado, Boulder who is spending his sabbatical year here at Perimeter.

I will discuss the design of degenerate quantum error correcting codes for an arbitrary Pauli channel. At noise levels slightly beyond those for which a random stabilizer code does not allow high fidelity transmission with a nonzero rate, our codes usually have a rate which is strictly positive. In fact, there exist Pauli channels for which our codes outperform a random stabilizer code whenever the random coding rate is less than 0.04, which is a couple of orders of magnitude larger than the previous examples of this effect. I'll also present a fairly straightforward explanation of why these codes work and discuss how their performance scales with block size and what this scaling suggests even better codes will look like.

From Monday, January 30th to Thursday, February 2nd, Senarath (Shanta) de Alwis will give a four lecture mini-course on `Potentials for light moduli in N=1 supergravity and string theory'. In these lectures, Shanta will be describing some of the technical ingredients used in recent constructions of inflation in string theory. The lectures will be given at a level appropriate for advanced graduate students and will be held in the Bob Room at 11:00am each day. The topics to be covered include: Derivation of the potential for chiral scalars in N=1 supergravity; Weyl anomalies and the generation of non-perturbative terms in the superpotential; Derivation of moduli potentials from fluxes in type IIB and heterotic string theory; Derivation of potentials for light moduli by integrating out heavy moduli. Shanta is a faculty member in the Physics Department at the University of Colorado, Boulder who is spending his sabbatical year here at Perimeter.

This is an introduction to background independent quantum theories of gravity, with a focus on loop quantum gravity and related approaches. Basic texts: -Quantum Gravity, by Carlo Rovelli, Cambridge University Press 2005 -Quantum gravityy with a positive cosmological constant, Lee Smolin, hep-th/0209079 -Invitation to loop quantum gravity, Lee Smolin, hep-th/0408048 -Gauge fields, knots and gravity, JC Baez, JP Muniain Prerequisites: -undergraduate quantum mechanics -basics of classical gauge field theories -basic general relativity -hamiltonian and lagrangian mechanics -basics of lie algebras

This is an introduction to background independent quantum theories of gravity, with a focus on loop quantum gravity and related approaches. Basic texts: -Quantum Gravity, by Carlo Rovelli, Cambridge University Press 2005 -Quantum gravityy with a positive cosmological constant, Lee Smolin, hep-th/0209079 -Invitation to loop quantum gravity, Lee Smolin, hep-th/0408048 -Gauge fields, knots and gravity, JC Baez, JP Muniain Prerequisites: -undergraduate quantum mechanics -basics of classical gauge field theories -basic general relativity -hamiltonian and lagrangian mechanics -basics of lie algebras

The information spectrum approach gives general formulae for optimal rates of codes in many areas of information theory. In this talk I shall relate the information spectrum approach to Shannon information theory and explore its relationship to ``entropic'' properties including subadditivity, chain rules, Araki-Lieb inequlities, and monotonicity.