Category: Weird ‘n’ spooky
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Human eye could detect spooky action at a distance
It’s almost a year since Nicolas Gisin and colleagues at the University of Geneva announced that they had calculated that a human eye ought to be able to detect entangled photons. “Entanglement in principle could be seen,” they concluded. That’s extraordinary because it would mean that the humans involved in such an experiment would become…
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2D image created from a single pixel sensor
Ghost imaging is a curious phenomenon that has had numerous physicists scratching their heads in recent years. It works like this: take two beams of entangled photons and aim the first at an object. The transmitted photons from the object are then collected by a single pixel detector. The second beam is aimed at a…
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Quantum direct communication: secrecy without key distribution
An interesting development in the world of quantum encryption. In the last couple of years, we’ve seen a number of quantum key distribution systems being set up that boast close-to-perfect security (although they’re not as secure as the marketing might imply). These systems rely on two-part security. The first is the quantum part which reveals…
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Loop quantum cosmology: a brief overview
Abhay Ashtekar, a physicist at the Pennsylvania State University is one of the founders of loop quantum cosmology and also a part-time populariser of science. Today, he uses both of these attributes to produce a fascinating overview of loop quantum cosmology that non-specialists will find enlightening. A recommended read. Ref: arxiv.org/abs/0812.0177: Loop Quantum Cosmology: An…
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Quantum test found for mathematical undecidability
It was the physicist Eugene Wigner who discussed the “unreasonable effectiveness of mathematics” in a now famous paper that examined the profound link between mathematics and physics. Today, Anton Zeilinger and pals at the University of Vienna in Austria reveal this link at its deepest. Their experiment involves the issue of mathematical decidability. First, some…
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Quantum cloaking makes molecules invisible
Cloaking is surely the zeitgeist topic of the moment and for proof, you need look no further than the work of Jessica Fransson from the University of Upssala in Sweden and colleagues. This is a group who have who have applied the ideas of cloaking to the quantum world and come up trumps. the result…
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Solving a quantum conundrum
“Can one be convinced of the correctness of the computation of every quantum circuit, namely, every quantum experiment that can be conducted in the laboratory?” ask Dorit Aharonov and colleagues from the Hebrew University of Jerusalem in Israel. That’s an interesting question of quantum computer science. If you can’t simulate the answer to calculation on…
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Entangled photons to produce better quantum images
A while back, we saw how quantum imaging had been put on a firmer theoretical footing, thanks to some new thinking by Seth Lloyd at MIT. Quantum imaging involves sending one of a pair of entangled photons towards an object while holding on to the other. For a long while nobody was quite sure what…
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Loophole found in quantum cryptography photon detectors
If you’re hoping to secure your data using quantum cryptography, you might want to find a shoulder to cry on. Quantum cryptography ought to be 100 percent secure. In theory , it provides perfect security against eavesdroppers. But in practice, a number of loopholes have emerged (see here and here). And today, Vadim Makarov and…
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How to measure macroscopic entanglement
If macroscopic objects become entangled, how can we tell? The usual way to measure entanglement on the microscopic level is to carry out a Bell experiment, in which the quantum states of two particles are measured. If the results of these measurements fall within certain bounds, the particles are considered to be entangled. These kinds…