Quantum computing based on many different types of qubits has developed into an important field of research. A quantum computer with its entangled qubits should provide a much more efficient technique for specific tasks such as finding prime factors of large numbers and searching a non-structured data base. Our financial security uses the prime factors of large integers for encryption and these factors could be found much more quickly with a quantum computer. We are investigating the use of Josephson junctions in a SQUID configuration for these qubits. For success, the time for logic gate operations must be shorter than the coherence times of entangled qubits. In this talk the basic physics of Josephson junction qubits will be described and a review of our experiments to make better junctions and to study and eliminate the sources of decoherence will be presented. Investigations of coherence times via Rabi oscillations and the Ramsey effect will be described and the reasons for using a SQUID phase qubit will be discussed. We have obtained a significant improvement in coherence times during the last few months and these recent results will be presented.



More information on Prof. Anderson can be found on his website: http://umdphysics.umd.edu/anderson.html