Symposium on Quantum Technologies August 28, 2006

Cambridge|MIT “Substantial advances in nanoscale science and engineering have made it possible to engineer a wide range of physical systems whose behaviour is governed by the laws of quantum mechanics. Quantum technologies seek to exploit these quantum effects to develop novel practical applications – from secure communications systems to novel computing devices more powerful [...]

Local Extraction of EPR Entanglement from Classical Systems July 27, 2006

Leeds|NUS Kaszlikowski and Vedral outline a novel method of entanglement extraction using independent probes that locally interact with two subsets of a macroscopic system. “Coherent states with large amplitudes are traditionally thought of as the best quantum mechanical approximation of classical behavior. Here we argue that, far from being classical, coherent states are in [...]

Backward Evolving Quantum States June 26, 2006

Tel-Aviv In quant-ph 0606208, Vaidman outlines the theoretical limitations on possible manipulations of a backward-evolving quantum state. “The basic concept of the two-state vector formalism, which is the time symmetric approach to quantum mechanics, is the backward evolving quantum state. However, due to the asymmetry of the memory’s arrow of time, the possible ways [...]

Generation and control of Greenberger-Horne-Zeilinger entanglement in superconducting circuits June 22, 2006

RIKEN In quant-ph 0510169, Wei, Liu, and Nori propose an efficient approach to generate and control quantum entanglement between three macroscopic coupled superconducting qubits. “By conditionally rotating, one by one, selected Josephson charge qubits, we show that their Greenberger-Horne-Zeilinger (GHZ) entangled states can be deterministically generated. The possibility of using the prepared GHZ correlations [...]

Measurement-Based Quantum Computing May 27, 2006

Spheres and connections represent qubits and entanglement bonds in (a) a two-dimensional cluster state. Coloured qubits show a compact CNOT gate, proceeding from the input qubits (yellow), through progression of Y-basis measurements (pink), to output qubits (light blue). (b) Activating additional collision cavities can create higher-dimensional topologies of entanglement such as this helical structure. Blythe [...]

Quantum Coherence, Noise and Decoherence in Nanostructures May 24, 2006

Max-Planck Institute “The modern field of nanoelectronics has brought about novel physical phenomena and created new challenges for their interpretation within quantum theory. Among the most fundamental concepts are quantum coherence and interference effects. An improved understanding of these phenomena is needed both from a fundamental point of view as well as for a [...]

Entanglement Distribution Revealed by Macroscopic Observations May 19, 2006

Vienna “Observation of quantum entanglement between increasingly larger macroscopic objects is one of the most promising avenues of experimental quantum physics. Eventually, all these developments will lead to a complete understanding of the simultaneous coexistence of a macroscopic classical world and an underlying quantum realm.“ In quant-ph 0603208, Kofler and Brukner compute multipartite entanglement [...]

Defense and Security Applications of Quantum Information April 27, 2006

SPIE Applied technologies that compute, store, and distribute information based upon quantum mechanical entanglement, superposition, and interference phenomena are currently being pursued and realized in multiple parallel architectures, with high-impact assessment in the fields of cryptography, communications, computation and metrology. The SPIE Defense and Security Symposium, the largest unclassified international meeting of its kind, [...]

High-Temperature Macroscopic Entanglement February 26, 2006

Entanglement as a function of effective coupling between light and mirror (k) and effective duration of coupling (x-axis). Maximal entanglement is shown in red.
PRL Via Raitio – Aires Ferreira, Ariel Guerreiro, and Vlatko Vedral have published novel results on high-temperature macroscopic entanglement in Phys. Rev. Lett. 96, 060407 [arXiv, physicsweb]. “Can entanglement [...]

Tunable flux qubit manipulated by fast pulses February 24, 2006

Tunable flux qubit. (A) Double SQUID with two control coils. (B) Potential of the double SQUID in the symmetric case, relative energy levels. (C) Potential in the asymmetric case. Chiarello, cond-mat 0602464.
MQC Group Chiarello evaluates the physical parameters for operation of a tunable flux qubit, calculating dissipation and decoherence factors, and discussing the potential for [...]