Full Protection of Superconducting Qubit Systems from Coupling Errors Munchen, Berkeley quant-ph/0407780 "Solid state qubits realized in superconducting circuits are potentially extremely scalable. However, strong decoherence may be transferred to the qubits by various elements of the circuits that couple individual qubits [...] We propose here an encoding that provides full protection against errors originating from these coupling elements ..."

Asymmetry and Decoherence in a Double-layer Persistent-current Qubit Kavli Institute Delft cond-mat/0405272 "We discuss a superconducting flux qubit design that exploits the symmetries of a circuit to protect the qubit from unwanted coupling to the noisy environment [...] Possibilities for prolonging the relaxation and decoherence times of the studied superconducting qubit are proposed on the basis of the obtained results."

Detection of Macroscopic Entanglement by Correlation of Local Observables University of Tokyo In quant-ph 0504086, Shimizu and Morimae propose a macroscopic entanglement index for unknown and mixed states. "We propose a correlation of local observables on many sites in macroscopic quantum systems. By measuring the correlation one can detect, if any, 'superposition of macroscopically distinct states,' which we call macroscopic entanglement, in arbitrary quantum states that are (effectively) homogeneous. Using this property, we also propose an index of macroscopic entanglement."

Spectroscopy on Two Coupled Superconducting Flux Qubits Kavli Institute Delft In PRL 94, 090501 (2005) Mooij et al. report on spectroscopy measurements of two coupled superconducting flux qubits: "The new results support the notion that superconducting flux qubits can be used to study entanglement in macroscopic quantum systems and for the development of nontrivial two-qubit gates [...] We demonstrate that two macroscopic flux qubits can be coupled to form a quantum mechanical four level system."

2005 Agilent Europhysics Prize Agilent Technologies The 2005 Agilent Technologies Europhysics Prize has been awarded to Awschalom, Dietl, and Ohno for their investigation of solid-state magnetic semiconductors and spin coherence. Spintronics is a promising candidate for scalable quantum computation. "We are proud to recognize these scientists for combining advanced materials engineering, insightful theoretical modeling, ingenious experimental techniques, and international collaboration to attain important breakthroughs in spintronics," said Jim Hollenhorst, director of molecular technology at Agilent Laboratories. Last year the award was shared by Mooij, Nakamura, Devoret and Esteve for their demonstration of superconducting circuits as qubits.

Nonlocal Measurements in Time-Symmetric Quantum Mechanics arXiv Vaidman and Nevo have posted a preprint on nonlocal demolition measurement of backward evolving quantum states which allows for the introduction of novel types of nonlocal variables. The work builds upon upon Aharonov's time-symmetric formalism, which contains the quantum state evolving backward in time from complete measurement performed in the future relative to the time in question. "Demolition measurements of nonlocal backward evolving quantum states require remarkably small resources. This is so because the combined operation of time reversal and teleportation of a local backward evolving quantum state requires only a single quantum channel and no transmission of classical information."