Spring 2012 Quantum Seminars

APRIL13

Third meeting

Posted on 04/11/2012

Science and Technology I, Room 306, 11am (+ lunch after noon)

QOB informal talk
Prof. Chenggang Tao, Virginia Tech
Visualizing fluctuations and electron scattering in nanostructures
Nanoscale structures have high surface-to-volume ratio and are susceptible to structural fluctuations. Direct imaging at the atomic scale using scanned probe techniques allows us to quantitatively characterize fluctuations using the tools of statistical mechanics. The impact of structural fluctuations on electronic devices will be illustrated for the case of electromigration, the biased displacement of mass by electron scattering when electrical current flows through a device. Using a combination of scanning tunneling microscopy and scanning electron microscopy, we directly observed electromigration of silver and silver-C60 nanostructures. I will show how the scattering force is determined. Possible mechanisms for the large force, including current crowding, charge transfer and local heating, will be discussed.

MARCH30

Postponed meeting

Posted on 03/27/2012

Cancelled

QOB informal talk
Dr. Khan W. Mahmud, JQI/NIST
Dynamics of noise correlations of ultracold bosons in an optical lattice

FEBRUARY10

Second meeting

Posted on 02/07/2012

Science and Technology I, Room 306, 11am (+ lunch after noon)

QOB informal talk
Dr. Satyan Bhongale, George Mason University
Satyan will discuss his recent work on dipolar condensates:
Bond order solid of two-dimensional dipolar fermions

JANUARY20

First meeting

Posted on 01/17/2012

Science and Technology I, …

Members of the Centers for Quantum Science

Faculty

Yuri Mishin

Professor
Planetary Hall 213, MSN 3F3, GMU (web page)

Ph.D: Moscow Institute of Steel and Alloys, Russia, 1985
Expertise: material science

Predrag Nikolic

Assistant Professor
Planetary Hall 363A, MSN 3F3, GMU (web page)

Ph.D: Massachusetts Institute of Technology, 2004
Expertise: condensed matter theory

Indu Satija

Professor
Planetary Hall 311, MSN 3F3, GMU (web page)

Ph.D: Columbia University, 1983
Expertise: condensed matter theory, nonlinear dynamics

Karen L. Sauer

Associate Professor
Planetary Hall 217, MSN 3F3, GMU (web page)

Ph.D: Princeton University, 1998
Expertise: experimental atomic and molecular physics

Mingzhen Tian

Assistant Professor
Planetary Hall 363B, MSN 3F3, GMU (web page)

Ph.D: Paris-Sud University, France, 1997
Expertise: experimental atomic, molecular and optical physics

Erhai Zhao

Assistant Professor
Planetary Hall 313, MSN 3F3, GMU (web page)

Ph.D: Northwestern University, 2005
Expertise: condensed matter theory

Research Staff and Affiliates

Updated on 07/30/2012

Satyan Bhongale

Postdoctoral Associate
Planetary Hall 2??, MSN 3F3, GMU (web page)

Ph.D: University of Colorado,Boulder, 2004
Expertise: theory of ultra-cold atomic gases

Graduate Students

Updated on 07/30/2012

Mahmoud Lababidi

condensed matter theory

Steve Keeling

condensed matter theory

Devin Vega

atomic physics experiment

Michael Malone

atomic physics experiment

Scientists cast doubt on renowned uncertainty principle

September 13, 2012 sjoy

Phys.org September 7, 2012

This is a general method for measuring the precision and disturbance of any system. The system is weakly measured before the measurement apparatus and then strongly measured afterwords. Credit: Lee Rozema, University of Toronto Werner Heisenberg’s uncertainty principle, formulated by the theoretical physicist in 1927, is one of the cornerstones of quantum mechanics. In its most familiar form, it says that it is impossible to measure anything without disturbing it. For instance, any attempt to measure a particle’s position must randomly change its speed.

Point-like defects in a quantum fluid behave like magnetic monopoles

Phys.org September 12, 2012 by Lisa Zyga

Experimental set-up showing the injection of a polariton fluid and the formation of half-solitons, which act like magnetic monopoles. Image credit: R. Hivet, et al. ©2012 Macmillan Publishers Limited (Phys.org)—No one has ever definitively observed a magnetic monopole, the hypothetical fundamental particle that has only a north or south magnetic pole, but not both like normal magnets do. However, scientists have observed a few types of monopole analogues – objects sometimes described as “quasiparticles” that behave like magnetic monopoles but don’t meet all the requirements to be one – such as excitations in spin-ice crystals and in one-dimensional magnetic nanowires. Now in a new study, scientists have observed a new type of monopole analogue in the form of tiny defects that arise in quantum states of matter called Bose-Einstein condensates (BECs). The discovery could help scientists better understand the fundamental nature of magnetism and may also lead to novel devices such as magnetronic circuits.

Advances in Condensed Matter Physics

Published Special Issues [5 issues]

Low-Dimensional Magnetic Systems
Guest Editors: Roberto Zivieri, Giancarlo Consolo, Eduardo Martinez, and Johan Åkerman
Tailoring Magnetic and Electronic Properties of Organic and Inorganic Nanostructures
Guest Editors: Emilia Annese, Rosa Lukaszew, Ivana Vobornik, and Kazuyuki Sakamoto
Multiferroic Magnetoelectric Composites and Their Applications
Guest Editors: Mirza Bichurin, Vladimir Petrov, Shashank Priya, and Amar Bhalla
Coherent States in Double Quantum Well Systems
Guest Editors: Yogesh Joglekar, Melinda Kellogg, Milica Milovanovic, and Emanuel Tutuc
Phonons and Electron Correlations in High-Temperature and Other Novel Superconductors
Guest Editors: Alexandre Sasha Alexandrov, Carlo Di Castro, Igor Mazin, and Dragan Mihailovic

Web Resources for Research

Quantum Science

Quantum Physics News: Phy.org

Condensed Matter

Cornell University Library new submissions

Atomic, Molecular and Optical Physics

High Energy Physics

About Center for Quantum Science

Director: Indubala Satija

Faculty: Yuri Mishin Phil Rubin Karen Sauer Ming Tian Predrag Nikolic Erhai Zhao Krishnamurthy Vemuru

The Center for Quantum Science at George Mason University gathers researhers from the School of Physics, Astronomy and Computational Sciences whose interests span condensed matter, atomic, molecular and optical physics. The main purpose of the Center is to stimulate the research productivity, interaction and collaboration among its members, create a collective mentoring environment for young researchers, and popularize its research areas to students and the public.

Research at the Center is funded by the National Science Foundation, Office of Navy Research, National Institute of Standards and Technology, Department of Energy, and the Air Force Office of Scientific Research.

Specific research areas include (but are not limited to):

condensed matter physics

superconductivity, quantum magnetism, topological insulators
quantum phase transitions and critical points
quantum field theory of interacting electrons
atomistic modeling and simulation of materials

atomic, molecular and optical physics

ultra-cold atoms, superfluidity, unitarity
optical lattices, quantum simulation, artificial gauge fields
magnetic resonance for materials characterization or for substance detection
quantum magnetometers
laser atomic spectroscopy, nonlinear and quantum optics

inter-disciplinary and applied physics

rare-earth based solid state quantum memory and quantum computation
quantum transport in spintronic and nano-electronic devices
non-linear dynamics

About CQS Research

Research areas:

( v) Condensed matter physics

(v) Atomic, molecular and optical physics

(v) Materials science

(v) High Energy Physics

Condensed matter physics

Condensed matter physics is a major fundamental branch of physics that studies the collective quantum dynamics of strongly interacting particles. Unlike high-energy physics, which focuses on elementary particles and forces as the fundamental building blocks of nature, condensed matter physics views the emergent phenomena arising from correlations and entanglement among many particles as the fundamental ones. Quantum field theory, on which both branches of physics rely, makes no distinction between these fundamental views. Examples of condensed matter researched at CQS are solid-state crystals, superfluids and superconductors, magnets, topological insulators, and ultra-cold gases of trapped atoms.

CQS theorists I.Satija, E.Zhao and P.Nikolic share a common interest in topological insulators. I.Satijahas been working on integer quantum Hall states in lattice potentials, with U(1) and SU(2) gauge symmetry groups, often placed in the context of ultra-cold atoms. Her collaborative work, which included the world-leading experimentalist Ian Spielman of NIST, E.Zhao, P.Nikolic and international collaborators, has resulted with the first proposals to experimentally measure Chern numbers in cold atom band-insulators, and create fermionic time-reversal-invariant topological insulators using cold atoms. She also explores novel topological quantum states that are …

Fractional Topological Insulators

A classical system can have multiple degrees of freedom whose properties can be measured independently and simultaneously with arbitray accuracy (limited only by the measuring device). However, quantum mechanics allows matter to exist in a “superposition” of different classical states. A quantum system in a “superposition” state will generally have properties whose measurements have random outcomes with predictable probabilities. Then, measuring different properties of the classical states that participate in the quantum superposition yields random, but correlated measurement outcomes. Such correlations are known as quantum entanglement.

A rather remarkable form of entanglement is that between a macroscopically large number of particles. The only forms of macroscopically entangled quantum matter that we have found so far in nature are superconductors and fractional quantum Hall states. The entanglement in superconductors is saddle and properly understood only when quantum fluctuations of the electromagnetic gauge field are taken into account (it is often ignored in literature). Apart from quantum Hall states, many other examples of entangled matter have been theoretically envisioned. The most notable example are spin liquids in quantum magnets, perhaps indirectly seen in a few experiments.

Quantum Hall effect and incompressible quantum liquids

Quantum Hall states are topological insulators without time-reversal symmetry. When …

Krishna Vemuru- SPACS Colloquium October 11, 2012

Magnetic Nanostructures Photo from Max Planck Institute of Microstructure Physics

Magnetic nanostructures

Thursday at 3:00 pm in Research Hall room 163

Vemuru abstract: Synthesis and characterization of magnetic nanostructures is an important aspect of research in nanoscience. In order to improve the characteristics of nanomaterials based devices, it is important to understand the structure property relation as well as the mechanism of the magnetic ordering. In this talk, I will introduce magnetic nanostructured materials with applications in high density magnetic data storage. Some of these are rodlike metallic iron and g-Fe2O3 nanoparticles, PZT thin films with Co nanostructures, FeRhPd/Co thin films, core-shell structured FePt, FePtCu, and FePtAu nanoparticles. I will present the details of the nanostructural characterization using small angle neutron scattering, and the element specific magnetic moment determination using x-ray magnetic circular dichroism spectroscopy.

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