Quantum Computation with Josephson Junctions

John Martinis, University of Colorado, Boulder

The Josephson junction is an ideal solid-state system for building electrical "atoms" that can function as quantum bits for a quantum computer. I will discuss recent experimental work based on "phase" qubits made from large area (10 µm by 10 µm) current-biased Josephson junctions. Recent experiments have demonstrated qubit state preparation and measurement with a fidelity of 85%, as well as manipulation of the qubit state via the observation of Rabi oscillations with a coherence time of approximately 40 ns. Presently, experiments in this system are aimed at achhieving both coherence times greater than ~1 µs and coupling of qubits. If achieved, the construction of a quantum computer with 20–100 qubits may be reasonably straightforward since scaling up is based on existing optical-lithography fabrication processes.

The P/T Colloquium is
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Thursday, 3:45–5:00 PM.
Refreshments are served
at 3:15 PM.