Relativistic Quantum Information
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.
Two different branches of theoretical physics, string theory and quantum information theory (QIT), share many of the same features, allowing knowledge on one side to provide new insights on the other. In particular the matching of the classification of stringy black holes and the classification of four-qubit entanglement provides a falsifiable prediction in the field of QIT.
Space offers a very unique
environment for quantum physics experiments at regimes for distance and
velocity not possible on ground. In the recent years there have been a range of
theoretical and experimental studies towards the feasibility of performing
quantum physics and quantum information science experiments in space.
We will explore different results on relativistic quantum information and general relativistic quantum optics whose aim is to provide scenarios where relativistic quantum effects can be experimentally accessible. Traditionally, relativistic quantum information has been far away from the experimental test, but the discipline is close to the transition point where experimental outcomes will soon arise.