Since 2002 Perimeter Institute has been recording seminars, conference talks, and public outreach events using video cameras installed in our lecture theatres. Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities. Recordings of events in these areas are all available On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA). PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.
We attempt at characterizing the correlations present in the quantum computational model DQC1, introduced by Knill and Laflamme [Phys. Rev. Lett. 81, 5672 (1998)]. The model involves a collection of qubits in the completely mixed state coupled to a single control qubit that has nonzero purity. Although there is little or no entanglement between two parts of this system, it provides an exponential speedup in certain problems. On the contrary, we find that the quantum discord across the most natural split is nonzero for typical instances of the DQC1 ciruit.
The Cosmic Microwave Background (CMB) consists of a bath of photons
emitted when the universe was 380,000 years old. Carrying the imprint
of primordial fluctuations that seeded the formation of structure in
the universe, the CMB is one of the most valuable known tools for
studying the early universe. In our modern, post WMAP era, the utility
of studying temperature anisotropies in the CMB is clear and much of
the work has been done. I will describe two exciting new directions in
which the field is currently heading: small-scale secondary CMB
We derive a set of Bell inequalities using correlated random variables. Our inequalities are necessary conditions for the existence of a local realistic description of projective measurements on qubits. We analyze our inequalities for the case of two qubits and find that they are equivalent to the well known CHSH inequalities. We also discuss the sufficiency of our inequalities as well as their applicability to more than two qubits.
A class of operations distinct to entangled states shared between more than two parties is their conversion to entangled states shared between fewer parties. The extent to which these can be achieved in the regime of local operations and classical communication provides an operational characterisation of multiparty states, for example in the \"entanglement of assistance\" and related quantities. I will give a brief overview of this topic and discuss our results showing qualitatively different behaviour when the parties receiving the final state are not chosen beforehand.
Several finite dimensional quasi-probability representations of quantum states have been proposed to study various problems in quantum information theory and quantum foundations. These representations are often defined only on restricted dimensions and their physical significance in contexts such as drawing quantum-classical comparisons is limited by the non-uniqueness of the particular representation.
We have two strong reasons to argue that Einstein\'s theory of general relativity may be incomplete. First, given that it cannot be expressed within a consistent quantum field theory there is reason to expect higher energy corrections. Second, the observation that we are undergoing a current epoch of accelerated expansion might indicate that our understanding of gravity breaks down at the largest scales.