06 August 2010

Molecular Simulation with Superconducting Qubits 
"Because Nature isn't classical, damnit, and if you want to make a simulation of nature, you'd better make it quantum mechanical. " —Richard Feynman 
Georgia, UCSB In arXiv:1008.0701, Pritchett, Martinis et al. introduce a protocol for efficient simulation of molecular dynamics using superconducting qubits. "Recent experimental progress suggests that quantum simulation will be one of the first practical applications of quantum computation. We have shown how quantum computers of only a few qubits can simulate arbitrary quantum systems accurately and quickly, even before they reach the regime of fault tolerant quantum computation."

17 July 2010

Decoherence sources in coupled flux qubits NEC, RIKEN In Phys Rev B and concurrent arXiv preprints, Yoshihara, Nakamura and Tsai study decoherence in coupled superconducting flux qubits. "The microscopic origin of decoherence has been elusive so far. It is crucial to identify and eliminate the source of noise sources in order to improve the performance of these devices—the sensitivity of SQUIDs and coherence of qubits. We have quantified the correlations among flux noise and found that the dominant contribution is by local fluctuations."

18 June 2010

Superconducting qubits as artificial atoms
"The demonstrated resonance wave scattering indicates that superconducting quantum devices can be used as building blocks for controllable, quantum coherent, macroscopic artificial structures — in which a plethora of effects can be realized from quantum optics of atomic systems."
NEC 東京大学 This week's Qulink seminar by Yasunobu Nakamura (NEC) reports on recent developments in exploring the quantum optical properties of a superconducting flux qubit coupled to a 1d microwave transmission line. See also: Electromagnetically induced transparency on a single artificial atom (arXiv); Resonance fluorescence of a single artificial atom (Science); Ultimate on-chip quantum amplifier (Phys Rev Lett).

11 June 2010

Quantum Zeno effect with a superconducting qubit NTT In arXiv 1006.2133, Matsuzaki and Semba provide detailed analysis of the Quantum Zeno effect in superconducting qubits: "Superconducting qubits are a promising system to observe the Quantum Zeno effect. We have studied how a sequence of projective measurements can alter the dephasing process, and suggest experimental requirements to observe the Quantum Zeno effect in existing superconducting qubits. It would be possible to demonstrate our prediction utilizing current technologies."