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Friday, October 18, 2002
Physics Building, Room 204
Note special time.
[Host: B. Shivaram]
Department of Physics and Astronomy, University of Kansas
"Superconducting Schrodingers Cat and its Application to Quantum Computing"
Since the beginning days of quantum mechanics the
possibility of having coherent superposition of macroscopic quantum
states, e.g., Schrodingers Cat, has stimulated much theoretical
debates. The idea can actually be tested out experimentally in
superconducting electronic devices called Josephson junctions (JJs)
and SQUIDs. Ill show that when sufficiently isolated from
environments a current biased JJ is a very well characterized and
controllable macroscopic quantum system and that Rabi oscillations
can be utilized to create coherent superposition of macroscopic
quantum states. In a recent experiment, we have succeeded in placing
a JJ in the superposition of its ground (alive) and excited (dead)
states and observing its time evolution as it oscillates coherently
between the alive and dead states of the junction [Y. Yu
Science 296, p889 (May 2002)]. The coherence time, estimated from
the exponentially decaying amplitude of the oscillations, is about 5
s which is very promising for quantum computing using the phase
qubits (JJs) or flux qubits (SQUIDs).
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