This meeting was held at the Heriot-Watt University, in Room 304 in the Postgraduate Centre. For maps and directions, please see the maps here.

Attendance is free. For catering purposes, please email Dr Erika Andersson E.Andersson@hw.ac.uk by the 11th March 2011.

Timetable

Abstracts:

Sabrina Maniscalco: Non-Markovian CV Quantum Key Distribution

Yuting Ping: Generating distributed entanglement from electron currents
Abstract: Several recent experiments have demonstrated the viability of a passive device that can generate large spin-entangled currents in two separate leads. However, manipulation and measurement of individual flying qubits in a solid state system has never been achieved. This is particularly difficult when a macroscopic number of these indistinguishable qubits are present. In order to access such an entangled current resource, we therefore show how to use it to generate distributed, static entanglement. The spatial separation between the entangled static pair can be much higher (macroscopic) than that achieved conventionally by only exploiting the tunnelling effects between quantum dots. Our device is completely passive, and can rely on weak Coulomb interactions between static and flying spins. We show that the entanglement generated is robust to decoherence for large enough currents.

Mario Ziman: Quantum encryption schemes
Abstract: I will illustrate that quantum superdense coding, quantum teleportation and quantum private channels are special instances of different quantum generalizations of the one time pad cryptosystem.

Viv Kendon: Robust cluster state generation using ancilla-based systems
Abstract: Efficient generation of cluster states is crucial for engineering large-scale measurement-based quantum computers. Hybrid matter-optical systems offer a robust, scalable path to this goal. Such systems have an ancilla which acts as a bus connecting the qubits. We show that by generating smaller cluster ``Lego bricks'', reusing one ancilla per brick, the cluster can be produced with maximal efficiency, requiring fewer than half the operations compared with no bus reuse. By reducing the time required to prepare sections of the cluster, bus reuse more than doubles the size of the computational workspace that can be used before decoherence effects dominate. A row of buses in parallel provides fully scalable cluster state generation requiring only 20 CPhase gates per bus use.