Electrical Engineering

By
Alexander N. Korotkov
University of California, Riverside
Department of Electrical Engineering
on
Monday, November 26, 2007
11:00 am – 12:00 pm, A265 Bourns Hall

Abstract:  The starting point of the talk is a simple fundamental question: what happens to a solid-state qubit in the process of its continuous measurement by a detector? While for ensemble of qubits the measurement simply leads to decoherence, the evolution of a single qubit is significantly different: it depends on the noisy detector output and may be fully coherent, though non-unitary. The theory describing such evolution has been developed relatively recently and provides a number of experimentally testable predictions. As an example, nondecaying Rabi oscillations in a qubit can be maintained by using a quantum feedback loop. Other experimental proposals include qubit entanglement by measurement, quantum nondemolition squeezing of a nanomechanical resonator, and "wavefunction uncollapsing" after a partial measurement. The first experiment verifying the coherent non-unitary evolution of a superconducting qubit due to partial measurement was realized last year at UCSB, followed by recent demonstration of the wavefunction uncollapsing.


About the Speaker:  Prof. Alexander Korotkov received Ph.D. degree in Physics in 1991 from the Moscow State University. After that he worked at the Moscow State University, the State University of New York at Stony Brook, and since 2000 he joined the faculty of the University of California, Riverside, where at present he is a Professor of Electrical Engineering. His research interests include single-electronics, transport in semiconductor heterostructures, noise analysis, and quantum measurements for quantum computing. He is an author/coauthor of 90 journal papers, which have been cited nearly 2,000 times.