Computations in Science Seminars
Nov
5
Wed 12:15
seminar cancelled
Nov
12
Wed 12:15
Mogens Hogh Jensen, University of Copenhagen
e-mail:
Host: Leo Kadanoff ()
Life in Turbulence

Satellite pictures indicate that plankton-life in the oceans exhibit 'foliated' structures on many length scales clearly influenced by the turbulent flows in the water. We formulate a particle model where plankton are advected in a model field of strong turbulence. The model indicates a huge drop in the carrying capacity due high concentrations in the stagnation points of the flow. For two neutral alleles, we find that the presence of turbulence diminishes the fixation time significantly. We further study the fixation time as a function of various flow parameters and obtain analytical expressions for the fixation probability without flows. Simulations of the model in zero and one dimensions give good agreement with theoretical predictions both when species experience competitive exclusions and when they co-exist under mutualistic behavior. We also briefly discuss some general properties of turbulence and shell models.

Nov
19
Wed 12:15
Emil Martinec, University of Chicago
e-mail:
Black Holes and Phases of Matter and Geometry

Black holes are an exquisite testing ground for our understanding of quantum gravity. Particularly vexing puzzles have arisen in trying to understand how and why black holes behave as thermodynamic objects, having a temperature proportional to Planck's constant, and therefore by the first law an entropy inversely proportional to it. Hawking's calculation of the black hole blackbody spectrum raises further issues about how locality and causality can be consistent with quantum mechanical unitarity. After briefly reviewing these properties, I will present an overview of how string theory is answering these challenges using exotic phases of matter only available in a theory of extended objects inhabiting extra dimensions of space, and the additional topological complexity such geometries afford.

Dec
3
Wed 12:15
Susan Coppersmith, University of Wisconsin
e-mail:
Host: Leo Kadanoff ()
Compressed optimization of device architectures

Recent advances in nanotechnology have enabled researchers to control individual quantum mechanical objects with unprecedented accuracy, opening the door for both quantum and extreme-scale conventional computing applications. As these devices become larger and more complex, the ability to design them for simple control becomes a daunting and computationally infeasible task. Here, motivated by ideas from compressed sensing [1,2], we introduce a protocol for Compressed Optimization of Device Architectures (CODA) [3]. It leads naturally to a metric for benchmarking device performance and optimizing device designs, and provides a scheme for automating the control of gate operations and reducing their complexity. Because CODA is both experimentally and computationally efficient, it is readily extensible to large systems. We demonstrate the CODA benchmarking and optimization protocols through simulations of up to eight quantum dots in devices that are currently being developed experimentally for quantum computation.

[1] E. J. Cand├Ęs, J. K. Romberg, and T. Tao, Communications on Pure and Applied Mathematics, 59, 1207 (2006) [2] D. Donoho, IEEE Transactions on Information Theory, 52, 1289 (2006) [3] A. Frees et al., arXiv:1409.3846

Dec
10
Wed 12:15
Igor Aronson, Argonne
e-mail:
Host: Leo Kadanoff ()
Jan 2015
7
Wed 12:15
Henry Cohn, Microsoft
e-mail:
Host: Leo Kadanoff ()
Jan 2015
14
Wed 12:15
Osvanny Ramos, University Claude Bernard Lyon 1
e-mail:
Host: Heinrich Jaeger
Jan 2015
21
Wed 12:15
OPEN
Jan 2015
28
Wed 12:15
Seth Lloyd, MIT
e-mail:
Host: Leo Kadanoff ()
Feb 2015
4
Wed 12:15
Zheng-Tian Lu, Argonne
Host: Daniel Holz ()
Feb 2015
11
Wed 12:15
OPEN
Feb 2015
18
Wed 12:15
Heinrich Jaeger, University of Chicago
e-mail:
Host: Leo Kadanoff ()
Feb 2015
25
Wed 12:15
OPEN
Mar 2015
4
Wed 12:15
OPEN
Mar 2015
11
Wed 12:15
OPEN
Mar 2015
18
Wed 12:15
OPEN
Mar 2015
25
Wed 12:15
OPEN
Apr 2015
1
Wed 12:15
Andrea Bertozzi, UCLA
e-mail:
Host: Leo Kadanoff ()
Apr 2015
8
Wed 12:15
OPEN
Apr 2015
15
Wed 12:15
Michael Brenner, Harvard
e-mail:
Host: Leo Kadanoff ()
Apr 2015
22
Wed 12:15
Joseph Vallino, Marine Biological Labortory
e-mail:
Host: Leo Kadanoff ()
Apr 2015
29
Wed 12:15
Michael Rubenstein, Harvard
e-mail:
Host: Leo Kadanoff ()
May 2015
6
Wed 12:15
Tim Sanchez, Harvard
e-mail:
Host: Leo Kadanoff ()
May 2015
13
Wed 12:15
OPEN
May 2015
20
Wed 12:15
OPEN
May 2015
27
Wed 12:15
OPEN
Jun 2015
3
Wed 12:15
Alisa Bokulich, Boston University
e-mail:
Host: Leo Kadanoff ()
Jun 2015
10
Wed 12:15
OPEN
Jun 2015
17
Wed 12:15
OPEN
Jun 2015
24
Wed 12:15
OPEN