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Implementation of New Quantum Technologies and Experiments Exploring the Foundations of Quantum Physics with Single Trapped Ions

Dr Winfried Hensinger

FOCUS Research Fellow, Department of Physics, University of Michigan, USA

3.30pm, Friday 22 October 2004, AR103 Seminar Room, Graduate Research Centre

Ion trapping technology provides an experimental setting that can be used to implement new powerful quantum technologies while at the same time being essential in exploring the very foundations of quantum physics. In this talk I will give an overview of state-of-the-art ion trapping technology and discuss how this technology may be used to build devices whose operation is inherently based on quantum principles. I will also show how one can address very fundamental problems such as nonlocality, the nature of entanglement and the essence of quantum measurement.

Coupling the trapped ion system with the scalability of semiconductor fabrications methods that are available due to recent advances in nanotechnology provides a clear pathway to build a scalable quantum computer. I will report some recent breakthroughs in the fabrication of micron-scale planar ion traps. These trap structures are fabricated from silicon doped gallium arsenide grown via molecular beam epitaxy and shaped with chemical and electrochemical etching techniques. I will also present new results concerning a T-junction multi-trap geometry, that may allow complex entangling and shuttling operations to be performed for scalable quantum computation in multiple separate trapping regions. I will also discuss experiments featuring the creation of Schrödinger cat states, cooling a single ion to the zero-point using resolved sideband simulated Raman transitions and finally the probabilistic entanglement between a single photon and a single trapped cadmium ion, the first direct observation of entanglement between stationary and "flying" qubits.

Finally I will present perspectives for new directions in ion trapping such as exploring the quantum nature of electromechanical nano-devices, and accessing the strong coupling regime in cavity QED experiments featuring unprecedented atomic localization.

This work is supported by the U.S. National Security Agency and Advanced Research and Development Activity under Army Research Office contract, and the National Science Foundation ITR Program.

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