QUROPE Quantum Information Processing and Communication in Europe

From 2011-10-01 to 2014-09-30 Objective IQIT will develop and demonstrate novel routes towards scaling up physical devices for quantum information science (QIS) with particular attention to communication between different parts of a quantum processor by means of a quantum bus.

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 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.

Two-qubit interactions are at the heart of quantum information processing. For single-spin qubits in semiconductor quantum dots, the exchange gate has always been considered the natural two-qubit gate. The recent integration of a magnetic field or g-factor gradients in coupled quantum dot systems allows for a one-step, robust realization of the controlled-phase (C-phase) gate instead.

We present a scheme for achieving coherent spin squeezing of nuclear spin states in semiconductor quantum dots. The nuclear polarization dependence of the electron spin resonance generates a unitary evolution that drives nuclear spins into a collective entangled state. The polarization dependence of the resonance generates an area-preserving, twisting dynamics that squeezes and stretches the nuclear spin Wigner distribution without the need for nuclear spin flips. Our estimates of squeezing times indicate that the entanglement threshold can be reached in current experiments. 

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QUTIS develops interdisciplinary research in:

• Quantum Information
• Quantum Technologies
• Quantum Optics
• Superconducting Circuits
• Quantum Biomimetics

This is the traditional QIPC cluster reviews. The program is as follows:

The EU sponsored research initiative QESSENCE (Quantum Interfaces, Sensors, and Communication based on Entanglement) with a 3-year budget of €4.7 million to explore quantum entanglement, is in its final year. The research outcomes are expected to make significant impact on future disruptive technologies and provide enabling physics for larger scale quantum computers in the longer-term.

Just to name a few, the recent highlights of research within the consortium include:

A call for proposals for the next QUIE2T sponsored QIPC conference has been published.