Triangle Seminars
Monday, 23 Oct 2006
Integrability in gauge theory and string theory I
Nick Dorey
(Cambridge/Imperial Maths Institute)
Abstract:
This the first of a series of lectures in which I will introduce the concept of integrability and study its realisation in the context of gauge theory and string theory. In particular, I plan to review recent progress in computing the spectrum of operator dimensions in N=4 supersymmetric Yang-Mills theory and the dual problem of determining the spectrum of string theory on AdS5 x S5.
This the first of a series of lectures in which I will introduce the concept of integrability and study its realisation in the context of gauge theory and string theory. In particular, I plan to review recent progress in computing the spectrum of operator dimensions in N=4 supersymmetric Yang-Mills theory and the dual problem of determining the spectrum of string theory on AdS5 x S5.
Posted by: IC
Wednesday, 25 Oct 2006
Geometry and Duality: T-folds and Non-Geometric Backgrounds in String Theory
📍 London
Christopher Hull
(Imperial College London)
When cooler is not better: Stochastic Resonance Phenomena in Quantum Many-Body Systems
Susana Huelga
(University of Hertfordshire)
Abstract:
The presence of noise is normally associated with a decrease in the optimal performance of any detection or information processing scheme. However, this is not always the case, as illustrated by the phenomenon of stochastic resonance where the response of a non-linear system displays a resonant-like dependence on the noise strength.
I will discuss stochastic resonance (SR) effects in weakly driven coupled quantum systems. I will show that both dynamical and information theoretic measures of the system's response can be introduced that exhibit a non-monotonic behaviour as a function of the noise strength. The relation between lack of monotonicity in the response and the presence of quantum correlations will be analyzed, showing that there are parameter regimes where the breakdown of a linear response can be associated to the presence of entanglement. I will also argue that a chain of coupled spin systems can exhibit a form of array-enhanced response, where the sensitivity of a single resonator to a weak driving signal is enhanced as a result of the nearest-neighbour coupling. These results enlarge the domain where SR effects exist and should be observable in state-of-the-art arrays of superconducting qubits.
The presence of noise is normally associated with a decrease in the optimal performance of any detection or information processing scheme. However, this is not always the case, as illustrated by the phenomenon of stochastic resonance where the response of a non-linear system displays a resonant-like dependence on the noise strength.
I will discuss stochastic resonance (SR) effects in weakly driven coupled quantum systems. I will show that both dynamical and information theoretic measures of the system's response can be introduced that exhibit a non-monotonic behaviour as a function of the noise strength. The relation between lack of monotonicity in the response and the presence of quantum correlations will be analyzed, showing that there are parameter regimes where the breakdown of a linear response can be associated to the presence of entanglement. I will also argue that a chain of coupled spin systems can exhibit a form of array-enhanced response, where the sensitivity of a single resonator to a weak driving signal is enhanced as a result of the nearest-neighbour coupling. These results enlarge the domain where SR effects exist and should be observable in state-of-the-art arrays of superconducting qubits.
Posted by: CityU
Thursday, 26 Oct 2006
Pure Spinor Strings and Non-Critical Strings
Pietro Antonio Grassi
(Alessandria (Univ. Piemonte Orientale))