Posted: April 7, 2009 
Keeping a quantum state alive in an optimal way 
(Nanowerk News) One of the main challenges in the practical realization of quantum computing is the tendency of many quantum systems to become classical, nonquantum, over time. This process is called decoherence. For any given mechanism of decoherence, researchers usually manually construct strategies to overcome them to the largest possible extent.

New research from the Institute for Quantum Computing (IQC) involving visiting graduate student Patrick Rebentrost, Postdoc Dr. Ioana Serban, and PI Dr. Frank K. Wilhelm published in Physical Review Letters takes a more systematic approach ("Optimal Control of a Qubit Coupled to a NonMarkovian Environment"). It applies a systematic optimization method to literally explore all possible strategies to overcome decoherence, and find the best one.

For a model ubiquitous to decoherence in qubits based on nanoelectronics, they show how a known strategy can be taken to a new level, improving quantum coherence by several orders of magnitude. This method should find wide applications in quantum computing devices from now on.
