1,411 research outputs found
Cram\'er-Rao bound for time-continuous measurements in linear Gaussian quantum systems
We describe a compact and reliable method to calculate the Fisher information
for the estimation of a dynamical parameter in a continuously measured linear
Gaussian quantum system. Unlike previous methods in the literature, which
involve the numerical integration of a stochastic master equation for the
corresponding density operator in a Hilbert space of infinite dimension, the
formulas here derived depends only on the evolution of first and second moments
of the quantum states, and thus can be easily evaluated without the need of any
approximation. We also present some basic but physically meaningful examples
where this result is exploited, calculating analytical and numerical bounds on
the estimation of the squeezing parameter for a quantum parametric amplifier,
and of a constant force acting on a mechanical oscillator in a standard
optomechanical scenario.Comment: 9 pages, 2 figure
Continuous-variable entanglement distillation and non-commutative central limit theorems
Entanglement distillation transforms weakly entangled noisy states into
highly entangled states, a primitive to be used in quantum repeater schemes and
other protocols designed for quantum communication and key distribution. In
this work, we present a comprehensive framework for continuous-variable
entanglement distillation schemes that convert noisy non-Gaussian states into
Gaussian ones in many iterations of the protocol. Instances of these protocols
include (a) the recursive-Gaussifier protocol, (b) the temporally-reordered
recursive-Gaussifier protocol, and (c) the pumping-Gaussifier protocol. The
flexibility of these protocols give rise to several beneficial trade-offs
related to success probabilities or memory requirements, which that can be
adjusted to reflect experimental demands. Despite these protocols involving
measurements, we relate the convergence in this protocols to new instances of
non-commutative central limit theorems, in a formalism that we lay out in great
detail. Implications of the findings for quantum repeater schemes are
discussed.Comment: published versio
The global reception of post-national literary fiction: the case of Gerald Murnane
This paper considers the situation of the changing global market for Australian literary fiction. In particular it uses the case of Gerld Murnane to examine ways in which these changes might be beneficial to at least some authors as we enter an era of 'post-national' literary fiction.The paper traces the international reception of Murnane's fiction and the subsequently the development of his global reputation. It incorporates Murnane's own observations (drawn from personal correspondence with the author) and suggests that although it has been argued that the impacts of globalisation will be detrimental for Australian literary fiction, there may also be some reasons for optimism
Juliana de Nooy. What’s France Got to Do with It?: Contemporary Memoirs of Australians in France.
Revie
Libraries, the Long Tail and the Future of Legacy Print Collections
Chris Anderson's concept of the 'long tail has evoked considerable interest and discussion from librarians. To date these discussions have largely accepted without question the veracity of Anderson's model and its applicability to library collections. The purpose of this article is to examine some elements of the model in order to firstly, determine if it can indeed be simply adopted for use when describing the library collecting environment; and secondly, if there is some divergence, what does this tell us about the future management of print collections
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