Fourth meeting

Posted on 11/30/2009

Stephen Keeling volunteered to give us a short overview of what we learned so far. Then, Erhai Zhao gave a gentle overview of the topological insulators and superconductors found in papers:
•  Andreas P. Schnyder, Shinsei Ryu, Akira Furusaki, Andreas W. W. Ludwig;
Phys. Rev. B 78, 195125 (2008) and arXiv:0905.2029, AIP Conf. Proc. 1134, 10 (2009)
•  Alexei Kitaev, “Periodic table for topological insulators and superconductors”, arXiv:0901.2686
The interest for these subjects is motivated by possible applications in quantum computing.

NOVEMBER20

Third meeting

Posted on 11/30/2009

Dr. Kai Sun from the Joint Quantum Institute (JQI) at the University of Maryland gave a technical but very educational overview of topological insulators. We learned how to characterize topological properties, how topological protection works, and much more (Power Point presentation). Dr. Sun is an expert on quantum liquid crystals and topological phases. He got his PhD from the University of Illinois at Urbana-Champaign in 2009 working with Edurado Fradkin. His papers can be found here.

NOVEMBER13

Second meeting

Posted on 11/16/2009

We discussed the first real topological insulator (invariant under time-reversal) which was proposed to occur and later found to exist in CdTe/HgTe quantum wells. Parag Ghosh led the discussion of the Science article by B. Andrei Bernevig et.al. A …

1

Second meeting

Posted on 02/19/2010

Science and Technology I, Room 306, 9am-11am

Indu and Parag will open the discussion on topological Anderson insulators. The relevant papers are:     •  Topological Anderson Insulator,
•  Theory of the Topological Anderson Insulator,
•  Numerical study of the topological Anderson insulator in HgTe/CdTe quantum wells.

FEBRUARY15

First meeting

Posted on 02/04/2010

We had brief reports by Erhai and Predrag on the freshest research developments communicated at the“Exotic Insulating States of Matter” conference which took place at Johns Hopkins University in January 2010.

Then, Mahmoud presented the new developments in topologically protected insulators with a few papers highlighting the superconductor properties gained by doping Bi2Se3 with Cu. We looked at the material structure, the resistivity and magnetization dependence on temperature, and STM images of a sample.

We focused on the results in this paper:
•  Superconductivity in CuxBi2Se3 and its implications for pairing in the undoped topological insulator,
but also mentioned the following papers:
•  Observation of unconventional band topology in a superconducting doped topological insulator, Cu(x)Bi2Se3: Topological Superconductor or non-Abelian superconductor?
•  Odd-Parity Topological Superconductors: Theory and Application to Cu(x)Bi2Se3$

Quantum Happy Hour (Fall 2011)

Research I, Room 202, 3pm

Announcement:

We invite you to join us for informal lectures, presented by one of our physics faculty or an outside guest scientist, engaged in research in frontiers of quantum physics. These stimulating discussion style lectures will be followed by happy hour where we will continue our conversation on various current topics in quantum physics. We encourage our graduate and advanced undergraduates, particularly those interested in Quantum Physics, to participate and contribute to the excitement.

SEPTEMBER23

Bunching-Antibunching of Quantum Particles:
from Astrophysics to AMO

Indu Satija, GMU

Young’s double slit setup, introduced about two hundred years ago, is one of the most versatile tools to demonstrate the interference phenomena for both the light and the matter waves in physics. In contrast to this amplitude interferometry, there is also an intensity interferometry, discovered by Hanbury Brown and Twiss (HBT) about half a century ago, where correlations of signal intensities, rather than amplitudes was used to measure the angular sizes of astronomical objects. Instead of the two slits, the intensity interferometry involves two detectors and measures the probability of simultaneous arrival of particles in the detectors. In view of the strange unclassical character of the identical particles, this detection …

Fifth meeting

Posted on 04/27/2011

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

QOB informal talk
Dr. Satyan Bhongale, GMU

Fermionic dipolar molecules on a square lattice
Recent trapped atom experiments are able to generate an ultra-cold gas of heteronuclear molecules with a sufficiently large dipole moment to allow for the occurrence of rich many-body physics leading to exotic quantum phases. A key role is played by the anisotropic and long range nature of the dipole-dipole interaction. We study the system of fermionic dipolar molecules in a 2D optical lattice. Previous studies for homogeneous configurations have revealed the possibility of s-wave CDW and the p-wave BCS phase. In our study we take an unbiased approach by following the functional RG technique. This method allows us to look at the flow of various channels as one approaches the Fermi surface in the RG sense. We find an intriguing interplay between the s-wave CDW and the p-wave superfluid phases.

APRIL15

Fourth meeting

Posted on 04/12/2011

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

QOB informal talk
Dr. Bin Wang, University of Maryland

Time-Evolving-Block-Decimation Studies on Ultracold Atoms in 1D Optical Lattices
Time-Evolving-Block-Decimation (TEBD) algorithm is a powerful tool for the study of ground state and dynamical properties of …

Fall 2011

Announcement:

We invite you to join us for informal lectures, presented by one of our physics faculty or an outside guest scientist, engaged in research in frontiers of quantum physics. These stimulating discussion style lectures will be followed by happy hour where we will continue our conversation on various current topics in quantum physics. We encourage our graduate and advanced undergraduates, particularly those interested in Quantum Physics, to participate and contribute to the excitement.

DECEMBER8

Seventh meeting

Posted on 12/06/2011

Science and Technology I, Room 306, 4:30pm

QOB informal talk
Dr. Krishnamurthy Vemuru, GMU
X-ray magnetic circular dichroism spectroscopy of ferromagnetic materials

NOVEMBER4

Sixth meeting

Posted on 11/02/2011

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

QOB informal talk
Prof. Ana Maria Rey, JILA
Quantum Magnetism with Ultra Cold Polar Molecules

OCTOBER14

Fifth meeting

Posted on 10/12/2011

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

QOB “journal club”
Indu will discuss non-equilibrium topological states based on her preliminary work using kicked 2D lattices in magnetic fields. Related papers are:

Topological characterization of periodically driven quantum systems
Floquet topological insulator in semiconductor quantum wells

OCTOBER5

Fourth meeting

Posted on 10/03/2011

Science and Technology I, Room 306, 4pm

QOB informal talk
Prof. Shmuel Fishman, Technion University, Israel
Hyper-transport in potentials that are random in space and time

SEPTEMBER16

Third …

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, …