Subject: TALK:Monday 4-14-08 Quantum Information Processing Seminar
"Quantum-Mechanical Circuits."
Speaker: Michel Devoret
Speaker Affiliation: Yale
Host: Peter Shor
Host Affiliation: M.I.T.
Date: 4-14-2008
Time: 4:15 PM - 5:15 PM
Refreshments: 3:30 PM
Location: 36-428
Abstract: Can the collective variables that describe the state of a
radio-frequency circuit, in other words currents and voltages, behave
quantum-mechanically? Is it possible to have in a wire a quantum
superposition of currents flowing simultaneously in two opposite directions?
Integrated superconducting circuits employing Josephson junctions as purely
dispersive non-linear elements are sufficiently non-dissipative at low
temperatures that coherent effects of this kind can not only manifest
themselves, but dominate the dynamics of the circuit. Josephson junctions,
together with transmission lines and capacitors, form a basic "Lego set" for
the implementation of an arbitrary quantum Hamiltonian. In particular, the
quantization of energy levels of the circuit, together with interference
phenomena displayed by coherent population of these levels, can radically
differ from the usual manifestations of microscopic superconductivity and
emulate many situations encountered in quantu
m optics and NMR. We will give a short review of latest experiments in this
field, which saw recently the development of entangled solid-state qubits
and the observation of single photons in a microwave resonator. Finally, we
will discuss the prospects of these circuits for implementing a complete set
of primitives for a quantum information processor.
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