Monday, March 9, 2015
(Refreshments served at 10:45am in HSCI-224)
Fig: A scanning Sagnac microscope
Symmetry is central to our understanding and description of natural phenomena. For example, conventional superconductors break only gauge symmetry, while a signature of an unconventional superconducting state is the breaking of additional symmetries. The breaking of time-reversal symmetry (TRS) is of particular interest since the condensate will have an overall magnetic moment due to either the spin or orbital (or both) parts of the pair wave function. To this end we have developed an optical technique for detecting broken TRS using a Sagnac interferometer, in which left and right circularly polarized lights propagate in opposite directions in the Sagnac loop and interact with the sample. The two lights, being time-reversal mirror image of each other, will gain a difference in phase due to broken TRS in the sample. And the achieved resolution is an unappreciated 10 nano radian at DC. In this talk, I will describe a few results we obtained with this Sagnac technique: (1) We used the Sagnac interferometer to identify TRS breaking in p-wave superconductor Sr2RuO4 across the superconducting transition; (2) We have identified in high temperature superconductors YBCO and LBCO broken TRS at temperatures tracking the so-called "Pseudo Gap" phase; (3) We have discovered that the ferromagnetism in ultra-thin perovskite films can be tuned with a patternable capping layer; (4) We are developing a functional brain imaging system based on Sagnac technology.
See the colloquium schedule and its archive of previous talks
Colloquia are scheduled to start Mondays at 11:15am sharp in Peterson Hall 2, Room 110 (PH2-110, map). Refreshments are served from 10:45am to 11:05am in Room HSCI-224 (next to the department office) and everyone is invited to mingle with faculty and students!
We acknowledge with gratitude donations and support from the following present sponsors:
We also acknowledge with gratitude our past donors: The Forty-Niner Shops, Inc., The Northrop Grumman Foundation, Sandra Dana, Anonymous.
If you wish to support the Colloquium, please contact the colloquium coordinator or the department chair. Thank you!
|Date||Title||Speaker and Affiliation|
|February 2,2015||Rapid Sequencing of Individual DNA Molecules with Graphene Nanogaps||Henk Postma, CSUN|
|February 9, 2015||Probing and Controlling Ultrafast Electron Motion with Attosecond Transient Absorption Spectroscopy||Michael Chini, UCF|
|February 11, 2015||Transparent Conducting Oxide Active Plasmonics and Metasurfaces: Ultrasmall and Ultrathin Optics||Howard Lee, Caltech|
|February 16, 2015||Nuclear Magnetic Resonance in Condensed Matter Physics: Unconventional Superconductivity, Quantum Magnetism, and Other Magnificent Tales||Georgios Koutroulakis, UCLA|
|February 18, 2015||Few-body Physics in Ultracold Atoms: Observation of Geometric Scaling Symmetry in Li-Cs-Cs Efimov States||Shih-Kuang Tung, NU|
|February 23, 2015||Molding Light with Flat Optics||Myoung Hwan Kim, Columbia U.|
|February 25, 2015||Quantum Phenomena and Layered Heterostructures||Claudia Ojeda-Aristizabal, UCB|
|March 9, 2015||What is a Sagnac interferometer and what can it do?||Jing Xia, UC Irvine.|