Quantum Interference Effect Transistors PhysicsWeb Cardamone et al. propose a novel approach to single-molecule transistors, the quantum interference effect transistor, or QuIET. Each transistor consists of two electrodes attached to an organic ring molecule in one of two configurations: the presence or absence of quantum interference in the ring determines the state of the transistor. "One potential advantage of the QuIET approach is that it could work in aqueous environments, such as those inside living organisms, because it is made of organic molecules."



Schematic diagrams of two types of QuIET In each, base voltage modulates the coherent suppression of current between emitter (E) and collector (C) leads. In (a), base voltage controls the distance x between the benzene ring and base lead (B), for example an STM tip. This in turn controls the coupling of the ring to the base lead. In (b), a base complex is introduced between the ring and base lead. The electrostatic effect of the base lead's bias on this molecule alters its coupling to the benzene ring.


Quantum Game Theory arXiv Nash equilibria and game theory profoundly affected the outcome of the 20th Century – preventing escalation of Cold War conflict between the US and USSR, for example. Quantum game theoretic approaches similarly hold the potential to influence strategic developments in the coming century. Quantum communications networks are already operating in research laboratories across the globe. With the recent birth of the DARPA/BBN quantum internet, quantum game theory has left the realm of academia and entered the world of practical applications, showing promise to transform politics, economics, conflict and warfare in the decades to come. In a recent PhD thesis, Iqbal reviews the current state of the field. See also "Quantum Pseudo-Telepathy" by Brassard et al, "Classical Rules in Quantum Games" by van Enk, "Quantum Strategies" by Meyer.

Vision 2033

American Association for the Advancement of Science Science, technology and public policy planning for the next thirty years - PDF downloads of the proceedings

Interference in Bose-Einstein Condensates Science Javanainen comments on nondestructive measurement of relative phase difference between two separated BECs, recently conducted by Saba et al. within the Ketterle Group at MIT's Center for Ultra-Cold Atoms: "The experiments open up new ways to manipulate condensates, which are macroscopic objects, as if they were quantum mechanical entities. Measurement devices based on matter-wave interferometry are a potential application."

Quantum Interference in Time arXiv Paulus has posted a preprint of the recent temporal quantum interference experiments, widely reported earlier this month: "The conceptually most important interference experiment is the double-slit scheme, which has played a pivotal role in the development of optics and quantum mechanics. [...] We have realized an intriguing implementation of the double slit in the time domain. The observation of interference and its absence at the same time for the same electron is a beautiful demonstration of the principles of quantum mechanics."

Gaidarzhy Defends Quantized Displacement arXiv In cond-mat 0503502, Gaidarzhy et al. reply to Schwab's critical comments on the Mohanty Group's recently-reported experimental evidence of macroscopic quantum displacement in a nanomechanical oscillator: "In summary, both the objections and the premise of the comment, on the data interpretation, by Schwab et al. are not valid [...] A proper theoretical framework to understand quantized motion of a macroscopic mechanical system of 50 billion atoms, in presence of decoherence and dissipation, is yet to be developed."

Measurement Based Quantum Computation Vienna In Nature 434, Walther et al. report on the first experimental demonstration of Grover's search via one-way quantum computing on entangled photons. Following initialization of a highly-entangled 'cluster state,' irreversible single-qubit measurements are performed in a feedforward process that determines the output of the system. Raussendorf and Briegel's original paper is available via quant-ph 0010033.

AIST Quantum Cryptography Research Tokyo ATIP QUIST reports that AIST, the Japanese National Institute of Advanced Industrial Science and Technology, is establishing a national research center in quantum cryptography and communications this spring under direction of Hideki Imai, University of Tokyo. "Hiroyuki Yoshikawa, Director of AIST, is aiming to establish world-class technology which will contribute to establishing global standards for cryptography technology and procedures for its evaluation."