[QIP-Sem] QIP seminar, Mon 4/14, 4:15pm, 36-428, Michel Devoret

[Peter Shor]

MIT Quantum Information Processing seminar
Monday 4/14 at 4:15pm in 36-428
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Michel Devoret (Yale)

Quantum-Mechanical Circuits

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 quantum 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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