Date: June 24, 2005

Time : 12 Midday

Who: Mile Gu

Seminar type: Research seminar

Abstract:
Given an arbitrary quantum algorithm described by a special unitary operator U, it would be impractical and very unlikely we are able to directly synthesise U by application of some constant Hamiltonian H such that U = exp(-iH) exactly. Thus, it is of most practical interest to ask how we may decompose U into products of operators that are easier to synthesis. In this seminar, I will describe to approach of Cartan Decompositions [1], a powerful mathematical tool for solving this problem.

The seminar is designed to approach this method from an intuitive and pedagogical perspective, where emphasis will be placed on lines of reasons rather than abstract mathematics. It should hopefully be accessible those who have no knowledge in Lie Algebra’s.

Suggested reading:

• [1] N. Khaneja, S. Glaser, quant-ph/0010100

Date: July 1, 2005

Time: 12 Midday

Who: Yeong-Cherng Liang

Seminar type: PhD Confirmation

Abstract:
Bell inequalities have long played a role in our understanding of the mysterious nature of quantum mechanics. The first Bell inequality, proposed in 1964 by John Bell, helped to clarify that the current quantum theory of physics is not compatible with local realism. The intuition behind local realism is that two separated physical systems can be fully described by local variables that determine the outcomes of experiments at each location independently of the choice of measurement at the distant location. Bell’s demonstration depends on entangled states of composite quantum systems for which he showed that no such description in terms of local hidden variables was possible.

Although it is well-known that all states violating Bell inequalities are entangled, not all entangled states violate a standard Bell inequality.
Indeed, very little is known about the class of quantum states that are inconsistent with local realism. In this seminar, we will first give a review of Bell inequalities and progress that has been made in classifying the class of quantum states violating a Bell inequality. This is then followed by presenting our approach and progress in solving the problem.

Date: Friday June 17, 2005

Who: Fernando Semiao, Universidade Estadual de Campinas (Unicamp) Brazil

Seminar type: Research Seminar

Abstract:
We demonstrate that a translation invariant chain of interacting quantum systems can be used for high efficiency transfer of quantum
entanglement and the generation of multi-particle entanglement over large distances and between arbitrary sites without the requirement of
precise spatial control. Such a ‘quantum data bus’ may prove useful in future solid state architectures for quantum information processing.

Date: Thursday June 16, 2005

Who: Fernando Semiao, Universidade Estadual de Campinas (Unicamp) Brazil

Seminar type: First Tutorial Seminar

First Seminar topic: Ion traps, laser cooling and detection of internal states.

Where: Conference Room 407, Physics Annexe

When: 4.00pm

Abstract:
In these tutorials, I will review the basics of ion trapping, cooling and manipulation by light fields in order to present some of the exciting theoretical and experimental progress made in recent years. I will be covering methods for creating and reconstructing quantum states of motion, quantum gates proposals, and the latest experimental achievements such as quantum teleportation.

Date: Tuesday 21 June, 2005

Who: Fernando Semiao, Universidade Estadual de Campinas (Unicamp) Brazil

Seminar type: Second Tutorial Seminar

Second Seminar topic: Interaction with light fields and generation/reconstruction of quantum states of motion.

Where: Conference Room 407, Physics Annexe

When: 4.00pm

Date: Tuesday 28 June, 2005

Who: Fernando Semiao, Universidade Estadual de Campinas (Unicamp) Brazil

Seminar type: Third Tutorial Seminar

Third Seminar topic: Quantum gates and a brief comment on the latest experimental results as quantum teleportation. Also, I will
point out some of the possibilities of using trapped ions within optical cavities for letting photons act as flying qubits.

Where: Conference Room 407, Physics Annexe

When: 4.00pm

Date: June 3, 2005

Time: 12 Midday

Who: Michael Nielsen

Seminar type: Research talk

Abstract:

Standard quantum error-correction is based on the idea of putting the information to be protected (e.g., a qubit) into a subspace of a large Hilbert space (e.g., a 7-qubit space). Recent work has generalized this idea, allowing information to be stored in a subsystem of a subspace.

In this talk, I’ll describe a theory of generalized quantum error-correction. You won’t need to understand standard error-correction for the talk to be comprehensible (I hope): I’ll cover the required background material, so it should all be quite self-contained!