Date: July 22, 2005

Who: Mark de Burgh

Time: 12 Midday

Place: Interaction Room, Physics Annexe

Seminar type: PhD Confirmation

Abstract:
Accurate clock synchronization is essential to a diverse range of practical applications including global positioning, distributed computation, telecommunications and large science projects like very long base-line interferometry in radio-astronomy. Atomic clock technology is so advanced that the best atomic clocks drift only tens of nanoseconds in a year. The next generation of optical atomic clocks are predicted to perform 1000 times better. Can clock synchronization techniques be improved to provide complementary advances in technology?

Recently techniques of quantum optics have been applied to the problem of clock synchronization to achieve performance that is impossible classically. In this talk I will give a brief overview of this area before presenting our own clock synchronization algorithm. This clock synchronization algorithm based on the concept of “ticking qubits” performs better than the standard quantum limit, yet requires no entanglement or complicated collective measurements. We conjecture that this algorithm performs at the limit allowed by quantum mechanics for ticking qubit protocols.

Finally I will briefly describe the other research goals for my thesis “Optimal state preparations measurements and control in quantum technology”

Date: July 15, 2005

Who: Lluis Masanes

Seminar type: Research

Abstract:
By definition, entangled states cannot be prepared with local operations and classical communication. Despite this, not all of them seem to provide a nonclassical resource or behaviour. Some examples of this being: entangled states with a local variable model accounting for the outcomes of any measurement, nondistillable entangled states, etc. In this talk it is presented a protocol that allows for extracting quantum resources from all bipartite bound entangled states. For example, it is seen that for each bound entangled state \omega, there exists an other state \rho not being useful for conclusive teleportation such that after a joint operation on \omega\otimes\rho the resulting state can teleport.

Date: July 8, 2005

Time: 12 Midday

Where: Interaction Room, Physics Annexe

Who: Haidong Yuan

Seminar type: Research talk

Abstract:
In quantum computing and quantum information, often one wants to complete a quantum evolution in minimum time, due to the decoherence effect. In this talk, I’ll give a complete characterization of all the unitary quantum gates that can be synthesized in a given time for a system of coupled two-qubits in presence of general time varying coupling tensor, providing the local controls, with this characterization one can compute the minimum time required to synthesized any two-qubits quantum gate.