Nicholas Hadley was elected to a third term as the Chair of the US CMS Collaboration Board. In this position, he will represent and lead the nearly 700 scientists, from 49 universities and national laboratories in the United States, who are members of the CMS experiment at the Large Hadron Collider at CERN. The United States is the largest national group in the CMS collaboration. US groups have made significant contributions to nearly every aspect of the detector throughout all phases of the experiment including construction, installation and physics analysis.

The Large Hadron Collider at CERN smashes protons together at close to the speed of light with four times the energy of the most powerful accelerators built up to now. Some of the collision energy is turned into mass, creating new particles, which can be observed in the CMS particle detector. CMS data is analyzed by scientists around the world to build up a picture of what happened at the heart of the collision. This experiment will help us answer questions such as: "what is the Universe really made of and what forces act within it?" and "what gives everything substance?" Such research increases our basic understanding and may also spark new technologies.

Jake Taylor, Physics Adjunct Professor and JQI Fellow, has recently been nominated as a finalist for the 2012 Samuel J. Heyman Service to America Medal. There are a total of nine medals issued, and Taylor is one of three finalists for the Call to Service Medal. According to the Partnership for Public Service, this award is intended to “recognize a federal employee whose professional achievements reflect the important contributions that a new generation brings to public service.” The nomination specifically cites Taylor’s theoretical research efforts that relate to medical imaging and information transfer protocols. The Washington Post profiled Taylor as part of a series covering the nominees. Taylor works on a range of quantum information research projects and teaches atomic physics. The medal recipients will be announced on September 13, 2012.

Congratulations to Victor Galitski who welcomed a son into the world on Sunday, May 6, 2012! Michael "Micky" Galitski is doing great! 

The world is posed at the edge of a new technological revolution that will make the strange and unique properties of quantum physics relevant and exploitable in the context of information science and technology. Many think the key to crossing into this new world of quantum computing is something called a Majorana fermion.

Condensed matter physicists including Sankar Das Sarma’s group at the University of Maryland, have been in hot pursuit of Majorana fermions for decades. Originally predicted in 1937 by Ettore Majorana, these exotic particles serve as their own anti-particles. Das Sarma, the Richard E. Prange Chair in physics at Maryland and director of the university’s Condensed Matter Theory Center (CMTC), is among those leading quantum information scientists who believe that the realization of Majorana fermions would open powerful new possibilities in quantum computation.

Now a group at Delft University in the Netherlands led by L.P. Kouwenhoven has published experimental signatures of the elusive particle. The research, which appeared in Science Express on April 12, 2012, precisely follows theoretical proposals made in 2010 by Professor Das Sarma and his collaborators at the Joint Quantum Institute (JQI), which is a UMD-based collaboration between the University of Maryland and the National Institutes of Standards and Technology.

“This is certainly very exciting news,” says Das Sarma. “It is not often that a theoretical prediction for something totally new actually works out in the laboratory. One, however, has to be cautious because while this experiment from Delft has provided the likely necessary evidence for the existence of the Majorana, the sufficient conditions are more difficult to achieve and may take more time.”

The Delft University scientists observed evidence of the particle at the ends of one-dimensional (1D) nanowires. The wires are made of the semiconducting material indium antimonide. This substance has one of the necessary ingredients for supporting the Majorana fermions: strong spin-orbit coupling.

What is spin-orbit coupling? An electron, which can be roughly thought of as a tiny spinning top, lives in a natural environment of electric fields. These fields force a charged particle into motion. Due to the laws of electromagnetism, the moving charge gives rise to a magnetic field, which can in turn affect the behavior of the electron. Heavier elements are likely candidates for having strong spin-orbit interactions.

The wires are placed near a superconductor and the “proximity effect” causes a region of superconductivity to also form in the wire. The experimentalists combine the nanowire and superconductor on a microchip and begin the search at temperatures just above absolute zero. Das Sarma’s theory established that such a nanowire in the presence of an external magnetic field along the wire would lead to the Majorana fermions at low (~1K) temperatures, exactly as observed in the Delft experiment.

The JQI/CMTC research group has predicted different ways to observe these particles in semiconductor/superconductor systems. For instance, in a variation on their original 1D nanowire proposals, they showed the surprising result that the Majorana fermions in the wire are not so delicate and would survive even if the strict 1D restrictions were relaxed. In fact, the Majorana fermions can be stable, even in the presence of the imperfections and disorder that often exist in solid state materials. A very recent work from Das Sarma’s group, which appeared on the condensed matter archive on April 15, provided a detailed theoretical analysis of the Delft data, further enhancing the claim that the elusive Majorana particle may have finally been found in nature.

Related publications and links:

"Signatures of Majorana Fermions in Hybrid Superconductor-Semiconductor Nanowire Devices," V. Mourik, K. Zuo, S.M. Frolov, S.R. Plissard, E.P.A.M. Bakkers, and L.P. Kouwenhoven, Science DOI: 10.1126/science.1222360 (Published online April 12, 2012)

"Generic New Platform for Topological Quantum Computation Using Semiconductor Heterostructures" J. Sau, R. Lutchyn, S. Tewari, S. Das Sarma, Phys. Rev. Lett. 104, 040502 (2010)

"Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures," R. Lutchyn, J. Sau, S. Das Sarma Phys. Rev. Lett., 105, 077001 (2010)

"Non-Abelian quantum order in spin-orbit-coupled semiconductors: Search for topological Majorana particles in solid-state systems" J. Sau, S. Tewari, R. Lutchyn, T. Stanescu, S. Das Sarma, Phys. Rev. B 82, 214509 (2010)

“Zero bias conductance peak in Majorana wires made of semiconductor-superconductor hybrid structures” C.H. Lin, J.D. Sau, and S. Das Sarma, arXiv:1204.3085 (at arXiv.org)