QUROPE Quantum Information Processing and Communication in Europe

Following QIPC2009 in Rome and QIPC2011 in Zurich we have the pleasure to announce another edition of the QUANTUM INFORMATION PROCESSING AND COMMUNICATION CONFERENCE – QIPC2013.

The reports are available for public download at the WP2 deliverables page. They contain a detailed description of the features that are integrated in the qurope.eu web site, that allow a classification and analysis of the database material that is relevant to QIPC.

The update is expected for the end of the QUIE2T project, i.e. Feb 2013. It is expected that the QIPC Roadmap and the Quantum Information Classification Scheme are going to see a new major revision within the next few months.

The next conference on quantum cryptography in the QCRYPT series will take place at the Institute for Quantum Computing, Waterloo, Ontario, Canada on August 5-9, 2013.

Details on deadlines and registration will be available later this year at http://2013.qcrypt.net/

Welcome to Waterloo in 2013.

title abbreviation: NIC@QS13

dates of the conference: October 6-12, 2013

title of the conference: Noise, Information and Complexity at Quantum Scale

place: Ettore Majorana Centre, Erice (Sicily), Italy

www address: http://events.phys.unicam.it/nic-at-qs13/

brief description of the Conference:

Accurately controlling a quantum system is a fundamental requirement in quantum information processing and the coherent manipulation of molecular systems. The ultimate goal in quantum control is to prepare a desired state with the highest fidelity allowed by the available resources and the experimental constraints. Here we experimentally implement two optimal high-fidelity control protocols using a two-level quantum system comprising Bose–Einstein condensates in optical lattices.

We report on the observation of quantum interference of the emission from two separate nitrogen vacancy (NV) centers in diamond. Taking advantage of optically induced spin polarization in combination with polarization filtering, we isolate a single transition within the zero-phonon line of the non-resonantly excited NV centers. The time-resolved two-photon interference contrast of this filtered emission reaches 66%. Furthermore, we observe quantum interference from dissimilar NV centers tuned into resonance through the dc Stark effect.

Initialization and read-out of coupled quantum systems are essential ingredients for the implementation of quantum algorithms1, 2. Single-shot read-out of the state of a multi-quantum-bit (multi-qubit) register would allow direct investigation of quantum correlations (entanglement), and would give access to further key resources such as quantum error correction and deterministic quantum teleportation1. Although spins in solids are attractive candidates for scalable quantum information processing, their single-shot detection has been achieved only for isolated qubits3, 4, 5, 6.

We investigate spin-dependent decay and intersystem crossing (ISC) in the optical cycle of single negatively charged nitrogen-vacancy (NV) centres in diamond. We use spin control and pulsed optical excitation to extract both the spin-resolved lifetimes of the excited states and the degree of optically induced spin polarization. By optically exciting the centre with a series of picosecond pulses, we determine the spin-flip probabilities per optical cycle, as well as the spin-dependent probability for ISC.

We experimentally demonstrate single-spin magnetometry with multipulse sensing sequences. The use of multipulse sequences can greatly increase the sensing time per measurement shot, resulting in enhanced ac magnetic field sensitivity. We theoretically derive and experimentally verify the optimal number of sensing cycles, for which the effects of decoherence and increased sensing time are balanced. We perform these experiments for oscillating magnetic fields with fixed phase as well as for fields with random phase.