Quantum Institute: Visitor Schedule

The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA-3, Building 123, Room 121.

The organizing committee includes Malcolm Boshier (P-21), Adolfo del Campo (T-4 & CNLS), Michael Di Rosa (C-PCS), Armin Rahmanisisan (T-4 & CNLS), Changhyun Ryu (P-21) , Nikolai Sinitsyn (T-4), Rolando Somma (T-4), Christopher Ticknor (T-1), and Wojciech Zurek (T-4).

For more information, or to nominate a speaker, contact Adolfo del Campo.

To add your name to the Quantum Lunch email list, contact Ellie Vigil.

Thursday, May 23, 2013
12:30 PM - 2:00 PM

Speaker: Pedram Roushan (UC Santa Barbara)

Technical Host: Armin Rahmanisisan

TOPIC: From Surface States of Topological Insulators to Semiconductor Nanowires: Candidates for Realizing Majorana Fermions

Abstract
Recently discovered topological insulators are promising candidates for novel quantum applications. In topological insulators, the spin texture of the surface states makes them distinct from conventional two-dimensional electron states, and leads to novel properties for these states. These surface states are expected to be immune to localization and to overcome barriers caused by material imperfections. We have used scanning tunneling microscopy and spectroscopy to study the topological surface states. By mapping the interference of the surface states scattering off random alloying disorder, we have demonstrated that despite strong atomic scale disorder, backscattering between states of opposite momentum and opposite spin is absent, resulting from the spin texture [1]. Furthermore, we have measured the transmission and reflection of topological surface states through atomic terraces. In contrast to Schottky surface states of noble metals, these surface states penetrate such barriers with high probability[2,3]. Concurrently and not fully independently from the advancements in our understanding of topological insulators, several theoretical proposals for realizing Majorana fermions in condensed matter systems have created much excitement in the community. I will discuss our experimental efforts in exploring the large parameter space of Majorana fermions, relevant for semiconductor nanowires.
[1] Roushan et al., Nature 460, 1106(2009)
[2] Seo, Roushan, et al., Nature 466, 343(2010)
[3] Beidenkopf, Roushan, et al., Nature Physics 7, 939(2011)