701 research outputs found
Experimental Test of Tracking the King Problem
In quantum theory, the retrodiction problem is not as clear as its classical
counterpart because of the uncertainty principle of quantum mechanics. In
classical physics, the measurement outcomes of the present state can be used
directly for predicting the future events and inferring the past events which
is known as retrodiction. However, as a probabilistic theory,
quantum-mechanical retrodiction is a nontrivial problem that has been
investigated for a long time, of which the Mean King Problem is one of the most
extensively studied issues. Here, we present the first experimental test of a
variant of the Mean King Problem, which has a more stringent regulation and is
termed "Tracking the King". We demonstrate that Alice, by harnessing the shared
entanglement and controlled-not gate, can successfully retrodict the choice of
King's measurement without knowing any measurement outcome. Our results also
provide a counterintuitive quantum communication to deliver information hidden
in the choice of measurement.Comment: 16 pages, 5 figures, 2 table
Projectable Horava-Lifshitz gravity in a nutshell
Approximately one year ago Horava proposed a power-counting renormalizable
theory of gravity which abandons local Lorentz invariance. The proposal has
been received with growing interest and resulted in various different versions
of Horava-Lifshitz gravity theories, involving a colourful potpourri of new
terminology. In this proceedings contribution we first motivate and briefly
overview the various different approaches, clarifying their differences and
similarities. We then focus on a model referred to as projectable
Horava-Lifshitz gravity and summarize the key results regarding its viability.Comment: 8 pages, no figures, to appear in the proceedings of First
Mediterranean Conference on Classical and Quantum Gravity Conference (MCCQG),
Kolymbari (Crete, Greece), September 14-18, 200
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