QUROPE Quantum Information Processing and Communication in Europe

P. Böhi, M.F. Riedel, T.W. Hänsch and P. Treutlein, Method and device for sensing microwave magnetic field polarization components, patent pending.

We give new evidence that quantum computers -- moreover, rudimentary quantum computers built entirely out of linear-optical elements -- cannot be efficiently simulated by classical computers. In particular, we define a model of computation in which identical photons are generated, sent through a linear-optical network, then nonadaptively measured to count the number of photons in each mode. This model is not known or believed to be universal for quantum computation, and indeed, we discuss the prospects for realizing the model using current technology.

The New York Times on "Quantum Computing Reaches for True Power".

We demonstrate that Dirac fermions self-interacting or coupled to dynamic scalar fields can emerge in the low energy sector of designed bosonic and fermionic cold atom systems. We illustrate this with two examples defined in two spacetime dimensions. The first one is the self-interacting Thirring model. The second one is a model of Dirac fermions coupled to a dynamic scalar field that gives rise to the Gross-Neveu model.

Quantum mechanics offers new possibilities to process and transmit information. In recent years, algorithms and cryptographic protocols exploiting the superposition principle and the existence of entangled states have been designed. They should allow us to realize communication and computational tasks that outperform any classical strategy. Here we show that quantum mechanics also provides fresh perspectives in the field of random networks.

The presentation can be downloaded from the workshop web site.

Dear colleagues,

you and your group members are cordially invited to participate in the international conference on Quantum Information Processing and Communication (QIPC) 2011 to be held at ETH Zurich from September 5-9, 2011.

The program committee has selected an exciting range of speakers covering the diverse aspects of the field of quantum information science and technology. Detailed information about the conference can be found on the website www.qipc2011.ethz.ch.

We are pleased to announce that, by decision of the QUIE2T Coordination Steering Committee, following a recommendation of the QUIE2T External Advisory Board of Experts, the next international QIPC conference initiated by the Coordination Action QUIE2T will take place in Zurich, Switzerland, from Monday, Sept. 5 to Friday, Sept. 9, 2011.

More information will follow as soon as a web site for the conference is available.

A central problem in quantum computation is to understand which quantum circuits are useful for exponential speed-ups over classical computation. We address this question in the setting of query complexity and show that for almost any sufficiently long quantum circuit one can construct a black-box problem which is solved by the circuit with a constant number of quantum queries, but which requires exponentially many classical queries, even if the classical machine has the ability to postselect. We prove the result in two steps.

The original motivation to build a quantum computer came from Feynman who envisaged a machine capable of simulating generic quantum mechanical systems, a task that is believed to be intractable for classical computers. Such a machine would have a wide range of applications in the simulation of many-body quantum physics, including condensed matter physics, chemistry, and high energy physics.