Scientific Series

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From Pauli's Principle to Fermionic Entanglement

Matthias Christandl ETH Zurich
May 03, 2013

PIRSA:13050005
Quantum Physics

Quantum Physics
AMS02 results support the secondary origin of cosmic ray positrons

Kfir Blum
May 03, 2013

PIRSA:13050015
High Energy Physics
An Infalling Observer in AdS/CFT and the Information Paradox

Suvrat Raju
May 03, 2013

PIRSA:13050016
High Energy Physics
Unconventional Magnetism and Superconductivity in 3 Dimensional Doped Mott Insulators

Baskaran Ganapathy Institute of Mathematical Sciences
April 30, 2013

PIRSA:13040140
Condensed Matter
Quantum measurements constrained by symmetry

Leon Loveridge University of York
April 30, 2013

PIRSA:13040124
Quantum Physics
Gromov-Witten Invariants from 2D Gauge Theories

Joshua Lapan Harvard University
April 30, 2013

PIRSA:13040141
High Energy Physics
From topological insulator to weak scale flavor physics

Sichun Sun University of Washington
April 30, 2013

PIRSA:13040126
High Energy Physics
Transporting non-Gaussianity from sub- to super- horizon scales

David Mulryne Queen Mary University of London
April 30, 2013

PIRSA:13040128
Astrophysics
Laws of thermodynamics beyond the von Neumann regime

Oscar Dahlsten City University of Hong Kong
April 29, 2013

PIRSA:13040112
Quantum Physics
Loop quantization of a weak-coupling limit of Euclidean gravity

Casey Tomlin Pennsylvania State University
April 25, 2013

PIRSA:13040104
General Relativity & Quantum Cosmology
Constraining neutron star interior properties with transient events from accreting neutron stars and magnetars

Andrew Cumming McGill University
April 25, 2013

PIRSA:13040138
General Relativity & Quantum Cosmology
Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems
April 24, 2013

PIRSA:13040116
Condensed Matter

From Pauli's Principle to Fermionic Entanglement

Matthias Christandl ETH Zurich
May 03, 2013

PIRSA:13050005
Quantum Physics

Quantum Physics
The Pauli exclusion principle is a constraint on the natural occupation numbers of fermionic states. It has been suspected for decades, and only proved very recently, that there is a multitude of further constraints on these numbers, generalizing the Pauli principle. Surprisingly, these constraints are linear: they cut out a geometric object known as a polytope. This is a beautiful mathematical result, but are there systems whose physics is governed by these constraints? In order to address this question, we studied a system of a few fermions connected by springs. As we varied the spring constant, the occupation numbers moved within the polytope. The path they traced hugs very close to the boundary of the polytope, suggesting that the generalized constraints affect the system. I will mention the implications of these findings for the structure of few-fermion ground states and then discuss the relation between the geometry of the polytope and different types of fermionic entanglement.
AMS02 results support the secondary origin of cosmic ray positrons

Kfir Blum
May 03, 2013

PIRSA:13050015
High Energy Physics
We show that the recent AMS02 positron fraction measurement is perfectly consistent with a secondary origin for positrons, and does not require additional primary sources such as pulsars or dark matter. Within the secondary model the AMS02 data imply a cosmic ray propagation time in the
Galaxy of about one Myr and an average traversed interstellar matter density of about 1/cc at a rigidity of 300 GV. These results may hint that high energy cosmic rays are confined to a thin halo of scale height similar to the gaseous disk.
An Infalling Observer in AdS/CFT and the Information Paradox

Suvrat Raju
May 03, 2013

PIRSA:13050016
High Energy Physics
We reconstruct the experience of an infalling observer using the AdS/CFT correspondence. We write operators both outside and inside the black hole in terms of CFT operators. Our construction provides a natural realization of black hole complementarity, and a way of preserving information without the need for firewalls.
Unconventional Magnetism and Superconductivity in 3 Dimensional Doped Mott Insulators

Baskaran Ganapathy Institute of Mathematical Sciences
April 30, 2013

PIRSA:13040140
Condensed Matter
Utilizing a variety and also constraints offered by quantum and solid state chemistry, we discuss possibilities of unconventional quantum magnetism and superconductivity in doped 3 dimensional Mott insulators. Some of the possibilities are quantum spin liquid states having pseudo fermi surface coexisting with long range magnetic order, 3 dimensional emergent gauge fields and unconventional superconducting order parameter symmetry. We present a few realistic models to illustrate this and use our theory to understand anomalous behavior of certain double perovskite compounds.
Quantum measurements constrained by symmetry

Leon Loveridge University of York
April 30, 2013

PIRSA:13040124
Quantum Physics
The Wigner-Araki-Yanase (WAY) theorem delineates circumstances under which a class of quantum measurements is ruled out. Specifically, it states that any observable (given as a self adjoint operator) not commuting with an additive conserved quantity of a quantum system and measuring apparatus combined admits no repeatable measurements. I'll review the content of this theorem and present some new work which generalises and strengthens the existing results. The observation that the WAY constraint vanishes if the observable-to-be-measured is ``relativised'' (in a suitable sense) points to interesting links with quantum reference frames and superselection rules. I'll discuss some of these connections and raise some open questions.
Gromov-Witten Invariants from 2D Gauge Theories

Joshua Lapan Harvard University
April 30, 2013

PIRSA:13040141
High Energy Physics
It has been known for twenty years that a class of two-dimensional gauge theories are intimately connected to toric geometry, as well as to hypersurfaces or complete intersections in a toric varieties, and to generalizations thereof. Under renormalization group flow, the two-dimensional gauge theory flows to a conformal field theory that describes string propagation on the associated geometry. This provides a connection between certain quantities in the gauge theory and topological invariants of the associated geometry. In this talk, I will explain how recent results show that, for Calabi-Yau geometries, the partition function for each gauge theory computes the Kahler potential on the Kahler moduli of the associated geometry. The result is expressed in terms of a Barnes' integral and is readily evaluated in a series expansion around special points in the moduli space (e.g., large volume), providing a fairly efficient way to compute Gromov-Witten invariants of the associated geometry.
From topological insulator to weak scale flavor physics

Sichun Sun University of Washington
April 30, 2013

PIRSA:13040126
High Energy Physics
In this talk, I will start with briefly introducing some universal physics behind quantum hall and topological insulator , which inspired a BSM flavor model. It intimately relates deconstructed little Higgs to flavor structure: fermion masses, CKM etc. This new cousin of little Higgs, we call it little flavor, shares a 10-20 Tev cut-off scale with little Higgs, so as to explain flavor structure at surprisingly low scale without rising FCNC problem.
Transporting non-Gaussianity from sub- to super- horizon scales

David Mulryne Queen Mary University of London
April 30, 2013

PIRSA:13040128
Astrophysics
The non-Gaussian statistics of the primordial density perturbation have become a key test of the inflationary scenario of the very early universe. Currently many techniques are used to calculate the non-Gaussian signatures of a given model of inflation. In particular, simple super-horizon techniques such as the deltaN formalism are often used for models with more than one field, while more technical field theory techniques, referred to as the In-In formalism, are typically used for models where the quantum sub-horizon evolution is important. Recently we have been developing an alternative point of view, called the transport approach. This framework highlights the connections between these other techniques and unifies them. Moreover, since it reduces the problem of calculating the statistics to that of solving a set of coupled ODEs, numerical implementations of the system are extremely simple.
Laws of thermodynamics beyond the von Neumann regime

Oscar Dahlsten City University of Hong Kong
April 29, 2013

PIRSA:13040112
Quantum Physics
A recent development in information theory is the generalisation of quantum Shannon information theory to the operationally motivated smooth entropy information theory, which originates in quantum cryptography research. In a series of papers the first steps have been taken towards creating a statistical mechanics based on smooth entropy information theory. This approach turns out to allow us to answer questions one might not have thought were possible in statistical mechanics, such as how much work one can extract in a given realisation, as a function of the failure-probability. This is in contrast to the standard approach which makes statements about average work. Here we formulate the laws of thermodynamics that this new approach gives rise to. We show in particular that the Second Law needs to be tightened. The new laws are motivated by our main quantitative result which states how much work one can extract or must invest in order to affect a given state change with a given probability of success. For systems composed of very large numbers of identical and uncorrelated subsystems, which we call the von Neumann regime, we recover the standard von Neumann entropy statements.

Joint work with Egloff, Renner and Vedral

http://arxiv.org/abs/1207.0434
Loop quantization of a weak-coupling limit of Euclidean gravity

Casey Tomlin Pennsylvania State University
April 25, 2013

PIRSA:13040104
General Relativity & Quantum Cosmology
I will describe recent work in collaboration with Adam Henderson, Alok Laddha, and Madhavan Varadarajan on the loop quantization of a certain $G_{\mathrm{N}}\rightarrow 0$ limit of Euclidean gravity, introduced by Smolin. The model allows one to test various quantization choices one is faced with in loop quantum gravity, but in a simplified setting. The main results are the construction of finite-triangulation Hamiltonian and diffeomorphism constraint operators whose continuum limits can be evaluated in a precise sense, such that the quantum Dirac algebra of constraints closes nontrivially and free of anomalies. The construction relies heavily on techniques of Thiemann's QSD treatment, and lessons learned applying such techniques to the loop quantization of parameterized scalar field theory and the diffeomorphism constraint in loop quantum gravity. I will also briefly discuss the status of the quantum constraint algebra in full LQG, and how some of the lessons learned from the present model may guide us in that setting.
Constraining neutron star interior properties with transient events from accreting neutron stars and magnetars

Andrew Cumming McGill University
April 25, 2013

PIRSA:13040138
General Relativity & Quantum Cosmology
The last few years have seen new opportunities for constraining the physics of neutron star interiors. I will first discuss the current state of neutron star radius measurements and then go on to discuss thermal tomography as a probe of the nuclear, magnetic, and transport properties of neutron star crusts. In each case, I will emphasize the astrophysics that must be understood to make reliable inferences about the properties of dense matter from observations of neutron stars.
Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems
April 24, 2013

PIRSA:13040116
Condensed Matter
In one extreme, where the interactions are sufficiently weak compared to the interactions, electrons form a “Fermi liquid” – the state that accounts for the properties of simple metals. In the other extreme, where the interactions are dominant, the electrons form various “Mott” insulating or “Wigner crystalline” phases, often characterized by broken spatial and/or magnetic symmetries. Corresponding charge and/or magnetically ordered insulating phases are common in nature. Between these two extremes lie highly correlated electronic fluids, and correspondingly a host of interesting and perplexing materials, including such diverse systems as the cuprate and iron-based high temperature superconductors, the failed metamagnet Sr3Ru2O7, and a variety of quantum Hall fluids. Some insight into electron fluids in this rich intermediate coupling regime can be obtained from viewing them as partially melted electron solids, rather than as strongly interacting gases. Here, analogies with the liquid crystalline phases of complex classical fluids provide useful guidance for a new approach to this key problem in condensed matter physics.

Title	Speaker(s)	Date	Talk Type	Info link
From Pauli's Principle to Fermionic Entanglement	Matthias Christandl	2013-05-03	Scientific Series	View details
AMS02 results support the secondary origin of cosmic ray positrons	Kfir Blum	2013-05-03	Scientific Series	View details
An Infalling Observer in AdS/CFT and the Information Paradox	Suvrat Raju	2013-05-03	Scientific Series	View details
Unconventional Magnetism and Superconductivity in 3 Dimensional Doped Mott Insulators	Baskaran Ganapathy	2013-04-30	Scientific Series	View details
Quantum measurements constrained by symmetry	Leon Loveridge	2013-04-30	Scientific Series	View details
Gromov-Witten Invariants from 2D Gauge Theories	Joshua Lapan	2013-04-30	Scientific Series	View details
From topological insulator to weak scale flavor physics	Sichun Sun	2013-04-30	Scientific Series	View details
Transporting non-Gaussianity from sub- to super- horizon scales	David Mulryne	2013-04-30	Scientific Series	View details
Laws of thermodynamics beyond the von Neumann regime	Oscar Dahlsten	2013-04-29	Scientific Series	View details
Loop quantization of a weak-coupling limit of Euclidean gravity	Casey Tomlin	2013-04-25	Scientific Series	View details
Constraining neutron star interior properties with transient events from accreting neutron stars and magnetars	Andrew Cumming	2013-04-25	Scientific Series	View details
Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems		2013-04-24	Scientific Series	View details

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From Pauli's Principle to Fermionic Entanglement

AMS02 results support the secondary origin of cosmic ray positrons

An Infalling Observer in AdS/CFT and the Information Paradox

Unconventional Magnetism and Superconductivity in 3 Dimensional Doped Mott Insulators

Quantum measurements constrained by symmetry

Gromov-Witten Invariants from 2D Gauge Theories

From topological insulator to weak scale flavor physics

Transporting non-Gaussianity from sub- to super- horizon scales

Laws of thermodynamics beyond the von Neumann regime

Loop quantization of a weak-coupling limit of Euclidean gravity

Constraining neutron star interior properties with transient events from accreting neutron stars and magnetars

Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems

From Pauli's Principle to Fermionic Entanglement

AMS02 results support the secondary origin of cosmic ray positrons

An Infalling Observer in AdS/CFT and the Information Paradox

Unconventional Magnetism and Superconductivity in 3 Dimensional Doped Mott Insulators

Quantum measurements constrained by symmetry

Gromov-Witten Invariants from 2D Gauge Theories

From topological insulator to weak scale flavor physics

Transporting non-Gaussianity from sub- to super- horizon scales

Laws of thermodynamics beyond the von Neumann regime

Loop quantization of a weak-coupling limit of Euclidean gravity

Constraining neutron star interior properties with transient events from accreting neutron stars and magnetars

Electronic Liquid Crystalline Phases of Highly Correlated Electronic Systems