Le contenu de cette page n’est pas disponible en français. Veuillez nous en excuser.

# The Fourth Annual Canadian Quantum Information Students' Conference - 2007

The Fourth Annual Canadian Quantum Information Students' Conference

## Quantum Key Distribution Networks

Samedi juin 02, 2007
Speaker(s):

Current physical implementations of quantum key distribution (QKD) require communicating parties to be close together.  We will explore methods for allowing parties separated by long distances to communicate by combining many QKD links in a network and discuss the resulting security properties.

Scientific Areas:

## Towards the Production of Entangled Photon Pairs in Optical Fiber via Four-Wave Mixing

Samedi juin 02, 2007
Speaker(s):

Previous experiments on the production of entangled photon pairs directly in optical fiber via four-wave mixing (FWM) have used a single pump laser and produced signal and idler photons with similar wavelengths. We will present the first results of our investigation into the production of widely separated entangled photon pairs via FWM in optical fiber using multiple pump lasers also at widely separated wavelengths. This source will have important applications in quantum cryptography and computation.

Scientific Areas:

## Distributed phase reference schemes for QKD: Explicit attacks and security considerations

Samedi juin 02, 2007
Speaker(s):

"Distributed phase reference schemes are a new class of protocols for Quantum Key Distribution, in which the quantum signals have overall phase-relationships to each other. This is expected to protect against some loss-related attacks. However, proving the full security of these schemes is a new challenge for theorists, as one can no longer identify individual signals (such as qubits in BB84, for instance), and so the security proof techniques do not apply directly.

Scientific Areas:

## An Introduction to Decoherence-Free Subspaces

Samedi juin 02, 2007
Speaker(s):
Scientific Areas:

## Information Flow in the Heisenberg Picture

Samedi juin 02, 2007
Speaker(s):
Scientific Areas:

## Quantum Mechanics in Phase Space

Samedi juin 02, 2007

Many authors have proposed what are known as "phase-space" or "classical" representations of quantum mechanics.  A unifying framework is given which illustrates the relationship among these various theories.  Examples relevant to quantum computing will be given.

Scientific Areas:

## An Introduction to One-Way Patterns

Vendredi juin 01, 2007

The one-way measurement model is a model of quantum computation which is intriguing for its' potential as a means of implementing quantum computers, but also for theoretical purposes for the different way in which it allows quantum operations to be described. Instead of a sequence of unitary gates on an array of wires'', operations are described in terms of emph{patterns}, consisting of a graph of entanglement relations on a set of qubits, together with a collection of measurement angles for these qubits (except possibly for a subset which will support a final quantum state).

Scientific Areas:

## Cluster State Quatum Computing in Optical Fibres

Vendredi juin 01, 2007
Speaker(s):

In this presentation I will briefly explain the cluster state model of quantum computing. Then will talk about a scheme that uses polarization and time-bin degrees of freedom of photons in optical fibres for the optical realization of this model. We are currently working on the implementation of this scheme in our lab.

Scientific Areas:

## A New Protocol for Loss-Tolerant Quantum Coin Tossing

Vendredi juin 01, 2007

Quantum coin tossing is a cryptographic task in which two parties, Alice and Bob, wish to generate a shared random bit but do not necessarily trust each other. This task is completely impossible to realize with classical asynchronous communication but becomes at least partially feasible when quantum communication is also available. The best quantum protocol known so far, due to Ambainis, uses qutrits and is near optimal in the sense that either party can bias the outcome with at most a 75% probability of success.

Scientific Areas:

## Degradability of Bosonic Gaussian Channels

Vendredi juin 01, 2007
Speaker(s):

The notion of weak-degradability of quantum channels is introduced by generalizing the degradability definition given by Devetak and Shor.  Exploiting the unitary equivalence with beam-splitter/amplifier channels we then prove that a large class of one-mode Bosonic Gaussian channels are either weakly degradable or anti-degradable. In the latter case this implies that their quantum capacity Q is null.

Scientific Areas:

## LECTURES ON-DEMAND

### Roger Melko: Perimeter Institute and University of Waterloo

Speaker: Roger Melko