Making Quantum Computers Fault Tolerant

SPEAKER: Dr. Ben Reichardt, Postdoctoral Fellow, California Institute of TechnologyABSTRACT: The biggest experimental obstacle to manipulating quantum information and realizing quantum computers is noise, or decoherence. Entangled quantum states are typically difficult to prepare without accumulating errors, and are highly susceptible to noise that collapses them down to merely classical states. General quantum fault-tolerance techniques, invented about a decade ago, can in theory solve both problems, but often require unrealistically low noise rates before they kick in.Over the last few years we have seen a renaissance in fault-tolerance schemes. These new schemes rely on quantum phenomena such as quantum teleportation to isolate the data from errors. I will describe these schemes that simulations indicate may tolerate as much as 3-6% noise per operation! However, as classical simulations of quantum systems are difficult, it is also important to develop rigorous methods to determine if, and how well, these schemes will really work. I will describe a new technique for analyzing these schemes---maintaining analytic control over large, noisy quantum systems---that leads to a rigorous proof that 0.1% gate depolarizing noise is tolerable (in a nonlocal gate model), lending support to the simulations. If the noise model is known, then the rigorous bound is as high as 1%. BIO: Ben Reichardt is a postdoctoral fellow at the Institute for Quantum Information, at the California Institute of Technology. He has a B.S. in mathematics from Stanford University, and a Ph.D. in computer science from the University of California, Berkeley. He studies quantum fault tolerance and quantum algorithms.http://www.its.caltech.edu/~breic/HOST: Todd Brun, tbrun@usc.edu

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 248

Audiences: Everyone Is Invited

Contact: Mayumi Thrasher