Fellow 2010-11

Raffi Ohannes Budakian


Probing the Physics of the Fractional Vortex State in Novel Superconductors

For a quantum computer to function, the quantum bits or qubits must be strongly coupled to each other while remaining sufficiently isolated from random environmental fluctuations to prevent the stored information from decaying—a phenomenon known as decoherence. An ingenious scheme to overcome decoherence, proposed by Alexei Kitaev in 1997, is to encode quantum information using extended many-body states.

Currently only a few physical systems are thought to possess excitations with the exotic topological properties required to implement the Kitaev proposal. Professor Budakian’s research focuses on the search for one such topological entity: the half-quantum vortex state in the p-wave superconducting material Sr2RuO4 (SRO).

During his Center appointment, Professor Budakian will mentor students in the design and construction of a new ultra-low-temperature, high-resolution scanning SQUID microscope. This instrument will be used to image the magnetic field distribution of fractional vortices in SRO rings. The project also calls for construction of a small current-carrying loop, integrated into the tip of the microscope, that can be used to manipulate the vortices and test their topological properties.

These new methods should help to resolve open questions pertaining to the properties of fractional vortex states in SRO rings. The results have specific application to quantum computing and also advance our basic scientific understanding of this novel superconductor.