2B: Fractional Quantum Hall States

Fractional quantum Hall states for topological quantum information processing

PL: W. Wegscheider

Involved PIs: K. Ensslin, T. Ihn, A. Imamoglu, D. Loss, R. Renner, M. Troyer,  D. Zumbühl

In specific fractional quantum Hall effect (FQHE) states, the quasi-particles that are confined to move in two dimensions are anticipated to exhibit novel quantum statistics, where the two-particle wave function acquires an arbitrary phase upon exchange (anyons). Even more remarkably, it is theoretically predicted that a number of FQHE states with degenerate ground states will transform non-trivially under exchange of particles, involving the action of a unitary matrix; experimentally, the most promising candidate for the observation of such non-Abelian quantum statistics is the 5/2 FQHE state. In addition to representing a most spectacular new state of matter, non-Abelian incompressible quantum systems would allow for topologically protected quantum computation, where unitary transformations that form the building blocks of a quantum algorithm could be completely insensitive to local perturbations. The observation of the 5/2 state requires a ultrahigh-mobility two-dimensional electron gas and temperatures below 20 mK.

With the combination of researchers assembled in this project, we will have a unique combination of exquisite sample growth, low-temperature transport experiments and optical spectroscopy, as well as theoretical support. We will explore the possibility to probe the excitations of the 5/2 state by a combination of transport and optical techniques on non-structured as well as on nano-patterned samples.

See also: FQHS seminar