Computations in Science Seminars
Jul 2015
8
Wed 12:15
Peter Scherpelz and Hosung Seo, University of Chicago
e-mail:
Host: Giulia Galli
Organizer: Sayantan Majumdar ()
First-principles computational modeling of defect spins in semiconductors for solid-state quantum information processing

Although quantum mechanics has enabled astounding advances in semiconductor technology, these technologies still do not fully exploit aspects of quantum physics, such as entanglement. A second revolution in semiconductor technology will stem from the successful control and implementation of entanglement and other exotic features of quantum physics. In this seminar, we discuss two material platforms that may lead to new types of quantum electronics building upon mature semiconductor microelectronic technologies, and we describe how first-principles theoretical modeling techniques can be used to design these material systems and guide experimental efforts. First, we will discuss how scanning tunneling microscopy can be used to create systems of atomically precise defects. These defects can be used as long-lived quantum dot qubits, networks of interacting qubits, atomic-scale transistors, and more. We will show how computational methods can provide precise detail on the electronic structure of these defects, and identify new dopants and defect geometries. In the second part of the talk, we will discuss electronic spins bound to atom-like point defects in semiconductors. We will present our recent work on the quantum decoherence dynamics of the divacancy spins in silicon carbide using the cluster-correlation expansion method and our work on the exploration of new quantum defect spins in piezoelectric aluminum nitride using density functional theory.

Jul 2015
15
Wed 12:15
Bradford Benson, University of Chicago
e-mail:
Host: Leo Kadanoff ()
Organizer: Shiladitya Banerjee ()
“Measurements of the Cosmic Microwave Background"

Measurements of the cosmic microwave background (CMB) have driven spectacular advances in our understanding of the universe. This has led to a standard cosmological model (LCDM) that requires only six cosmological parameters to fit all cosmological data sets, which imply a universe dominated by dark matter and dark energy. Next-generation CMB experiments aim to answer some of the most exciting questions in cosmology: to understand the physical origin of dark energy, to test and constrain physics at Planck energy scales (1e16 GeV), to measure the sum of the neutrino masses at a level below the minimum mass expected from neutrino oscillations (<0.06 eV), and to precisely constrain the relativistic energy density of the universe and any "dark radiation" component. I will review some of the latest results from the CMB, and describe how CMB experiments use superconducting detectors to go from detector time-streams, to microwave maps of the sky, and finally to constraints on cosmology.

Jul 2015
22
Wed 12:15
OPEN
Jul 2015
29
Wed 12:15
Shiladitya Banerjee, University of Chicago
e-mail:
Host: Leo Kadanoff ()
How bacteria couple cell shape to growth and division

How cells maintain stable shapes and sizes through the cycles of birth and replication poses a fundamental question at the interface of physics and modern biology. Recent technological advances in single cell imaging have yielded unprecedented amounts of quantitative information about the shapes of single bacteria as they grow and divide. These single-cell studies are generating tremendous interest because they reveal unanticipated relationships between cell shape, growth rate and the timing of division events. To understand these relationships, we developed a general theoretical framework from a principle of minimal energy dissipation that relates cell geometry to the kinetics of growth and division. The model accounts for counterintuitive dependencies between growth and shape and gives rise to predictions that we verify in our experimental studies of the bacterium Caulobacter crescentus. In particular we describe how mechanical stresses regulate cell wall growth and drive shape transitions during cell wall constriction. Using our theoretical model and experimental data we further establish that cell growth and constriction are both driven by the synthesis of new cell wall material and are thus controlled by a single timescale. Our work brings new perspectives on how shapes of bacteria can impact their growth and survival.

Aug 2015
5
Wed 12:15
Radha Ramachandran, Eve Tulbert, University of Chicago, Freedom Games
e-mail:
Aug 2015
12
Wed 12:15
Stephane Perrard, University of Chicago
e-mail:
Host: William Irvine ()
Aug 2015
19
Wed 12:15
Sayantan Majumdar, University of Chicago
e-mail:
Host: Leo Kadanoff ()
Aug 2015
26
Wed 12:15
Kim Weirich, University of Chicago
e-mail:
Host: Leo Kadanoff ()
Sep 2015
30
Wed 12:15
Sarah Cobey, University of Chicago
e-mail:
Host: Michael Rust
Oct 2015
7
Wed 12:15
Zvonimir Dogic, Brandeis University
e-mail:
Host: William Irvine ()
Oct 2015
14
Wed 12:15
Michael Oppenheimer, Princeton
e-mail:
Host: Leo Kadanoff ()
Oct 2015
21
Wed 12:15
Kathleen Stebe, University of Pennsylvania
e-mail:
Host: Leo Kadanoff ()
Oct 2015
28
Wed 12:15
Tom Lubensky, University of Pennsylvania
e-mail:
Host: Leo Kadanoff ()
Nov 2015
4
Wed 12:15
Eric Siggia, Rockefeller University
e-mail:
Host: Greg Voth
Nov 2015
11
Wed 12:15
David Schuster, University of Chicago
e-mail:
Host: Leo Kadanoff ()
Nov 2015
18
Wed 12:15
OPEN
Dec 2015
2
Wed 12:15
OPEN
Dec 2015
9
Wed 12:15
Charles Kane, University of Pennsylvania
e-mail:
Host: Leo Kadanoff ()
Dec 2015
16
Wed 12:15
Jeremie Palacci, New York University
e-mail:
Host: William Irvine ()
Jan 2016
5
Tue 4:00 PM
Seth Lloyd, MIT
e-mail:
JFI TUESDAY SEMINAR - ROOM W301 - 4:00 PM
Jan 2016
6
Wed 12:15
Seth Lloyd, MIT
e-mail:
Host: Leo Kadanoff ()
Jan 2016
13
Wed 12:15
OPEN
Jan 2016
20
Wed 12:15
OPEN
Jan 2016
27
Wed 12:15
Jeffrey Harvey, University of Chicago
e-mail:
Host: Dan Holz ()
Feb 2016
3
Wed 12:15
OPEN
Feb 2016
10
Wed 12:15
Mark Bowick, Syracuse University
e-mail:
Host: William Irvine ()
Feb 2016
17
Wed 12:15
Chris Fang-Yen, University of Pennsylvania
e-mail:
Host: David Biron ()
Feb 2016
24
Wed 12:15
OPEN
Mar 2016
2
Wed 12:15
OPEN
Mar 2016
9
Wed 12:15
John Novembre, University of Chicago
e-mail:
Host: Leo Kadanoff ()
Mar 2016
16
Wed 12:15
OPEN
Mar 2016
23
Wed 12:15
OPEN
Mar 2016
30
Wed 12:15
OPEN
Apr 2016
6
Wed 12:15
OPEN
Apr 2016
13
Wed 12:15
OPEN
Apr 2016
20
Wed 12:15
OPEN
Apr 2016
27
Wed 12:15
OPEN
May 2016
4
Wed 12:15
OPEN
May 2016
11
Wed 12:15
OPEN
May 2016
18
Wed 12:15
OPEN
May 2016
25
Wed 12:15
OPEN
Jun 2016
1
Wed 12:15
OPEN
Jun 2016
8
Wed 12:15
OPEN