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.
An unsolved problem in relativistic quantum information
research is how to model efficient, directional quantum communication between
localised parties in a fully quantum field theoretical framework. We propose a
tractable approach to this problem based on calculating expectation values of
localized field observables in the Heisenberg Picture. We illustrate our
approach by analysing, and obtaining approximate analytical solutions to, the
problem of communicating quantum states between an inertial sender, Alice and
In the Unruh effect, long-distance correlations in a pure
quantum state cause accelerated observers to experience the state as a thermal
bath. We discuss a similar phenomenon for quantum states that contain
correlations between the distant future and the distant past. Examples include
Minkowski half-space with a static mirror and an eternal black hole with an
unusual global structure behind the horizon. The question of utilising the
future-past correlations in quantum information tasks is raised.
After an introduction to generalized uncertainty
principle(s), we study uncertainty relations as formulated in a crystal-like
universe, whose lattice spacing is of order of
Planck length. For Planckian energies, the uncertainty relation for
position and momenta has a lower bound equal to zero. Connections of this
result with 't Hooft's deterministic quantization proposal, and with double
special relativity are briefly presented. We then apply our formulae to
This talk analyzes the limits that quantum mechanics imposes on the
accuracy to which spacetime geometry can be measured. By applying the
fundamental physical bounds to measurement accuracy ensembles of clocks
and signals, as in the global positioning system, I present a covariant
version of the quantum geometric limit, which states that the total
number of ticks of clocks and clicks of detectors that can be contained
in a four volume of spacetime of radius R and temporal extent is less
The bridge between continuous information and discrete information is provided by sampling theory. In this talk, I will discuss an application of covariant sampling theory to cosmology (see the previous talk by Dr. R. Martin). In cosmology, the two-point correlation function of a quantum field is of central importance because it is a measure of the size of the fluctuations of the quantum field and of the entanglement of the vacuum in a given spacetime. Furthermore, the two-point function is experimentally accessible through the cosmic microwave background.
A covariant ultra-violet cutoff on the modes of physical fields on a given space-time can be achieved by cutting off the spectrum of the D'Alembertian of the manifold. This cutoff is a natural generalization of the naive ultra-violet cutoff inEuclidean space which is obtained by simply projecting out frequencies greater in magnitude than a given maximum frequency. Here it is shown that for flat spacetime and expanding FRW spacetimes thiscutoff manifests itself as a decrease in temporal degrees of freedom for large spatial modes.
We show that entanglement harvested from a quantum field
by interaction with local detectors undergoing anti-parallel acceleration can
be used to measure the distance of closest approach between the two detectors.
Information about the separation is stored nonlocally in the phase of the joint
state of the detectors after the interaction; a single detector alone contains
none. We model the detectors as two-level quantum systems accelerating
uniformly through the Minkowski vacuum
Recently striking connections have been discovered between the research fields of black hole soultions in string theory and the one of entanglement measures in quantum entanglement theory.For the emerging research field the term The Black Hole/Qubit Correspondence has been coined. The basic idea is that wrapping configurations of extended objects in extra dimensions can give rise to interesting realizations of entangled systems and black holes at the same time. The geometry of the extra dimensions and the wrapping type determines the entangled system in question.