Posts by: Hamish Johnston

Quantum Cheshire cat spotted in Grenoble

An illustration of a Cheshire cat

A most curious thing is the quantum Cheshire cat. (Courtesy: iStockphoto/koffeezilla)

By Hamish Johnston

Three months ago we ran a news article about a “quantum Cheshire cat” experiment that was proposed by Yakir Aharonov of Tel Aviv University and colleagues. Now, an international team of physicists has created a quantum Cheshire cat using polarized neutrons at the Institut Laue-Langevin (ILL) in Grenoble, France.

The work was done by Yuji Hasegawa and colleagues at the Vienna University of Technology, ILL, the University of Cergy-Pontoise and Chapman University.

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Lights, camera, action at Daresbury Laboratory

Daresbury Laboratory: SuperSTEM is the small, white building just right of centre and surrounded by trees (Courtesy: STFC)

Daresbury Laboratory: SuperSTEM is the small, white building right of centre and surrounded by trees. (Courtesy: STFC)

By Hamish Johnston

Recently I was in Liverpool with the Physics World camera crew to film a series of videos, including a feature about the NA62 experiment based at CERN. On the way back to Bristol we spent the afternoon at the Daresbury Laboratory in Cheshire, where we made videos about two major facilities at that lab.

Today, we are premiering the video that we made about Daresbury’s SuperSTEM, which is the UK’s national facility for aberration-corrected scanning transmission electron microscopy (STEM).

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Stretching and spinning droplets using sound

Mirror made from tiny polystyrene spheres (Courtesy: Grzegorczyk et al Phys Rev Lett 112) 023902

Mirror made from tiny polystyrene spheres. (Courtesy: Grzegorczyk et al., Phys. Rev. Lett. 112 023902)

By Hamish Johnston

There are two fantastic papers in Physical Review Letters this week that made me smile. Both of them are about controlling macroscopic objects using waves. While there are practical applications for both techniques, I can’t help thinking that the authors did the work for the sheer joy of it.

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Splitting sausages, immigration and the “Silence of the labs”

A hot topic this week. Courtesy: Shutterstock/indigolotos

A hot topic this week. (Courtesy: Shutterstock/indigolotos)

By Hamish Johnston

Why do sausages usually split lengthwise when cooked? That’s the subject of a fantastic article on Gizmodo that applies physics and maths to answer this important culinary question. Full of diagrams, a dozen equations and an evocation of Pascal’s principle, the article concludes that the “hoop stress” on the casing, which tends to cause lengthwise splits, is double that of the stress in the perpendicular direction. The article was adapted from a piece by the blogger Nick Berry about why pipes usually split lengthwise when frozen.

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Spies are keen on quantum computing, claims Washington Post

By Hamish Johnston

An article in the Washington Post claims that the US National Security Agency (NSA) is funding research into how quantum computers could be used to crack cryptography systems. While the article claims to be based on leaked secret documents, the revelation doesn’t seem to surprise several of the physicists quoted in the piece.

Scott Aaronson of the Massachusetts Institute of Technology (MIT) says that it’s unlikely that the NSA project is much further ahead of public quantum-computing research. His MIT colleague Seth Lloyd adds that it could be five years or more before the NSA or anyone else creates a quantum computer capable of breaking cryptographic systems.

Interestingly, Lloyd alludes to a space-race-like rivalry between the US, EU and Switzerland that is driving the development of code-busting quantum computers.

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Season’s greetings

Screenshot of Hubblecast 71: Visible echoes around RS Puppis.

A star glowing in the night. (Courtesy: ESA/Hubble)

By Hamish Johnston

Things are winding down for the holidays at Physics World and this afternoon the team will be enjoying our Christmas lunch at a local brewpub. Hopefully they will have a festive ale or two on tap! To brighten up this festive blog, we have chosen this stunning image of the variable star RS Puppis as our Christmas picture.  It was taken by the Hubble Space Telescope and shows starlight reverberating through the foggy environment around the star.

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Why do beer bottles foam when struck on top?

A foamy mess in the making (Courtesy: Javier Rodríguez-Rodríguez)

A foamy mess in the making. (Courtesy: Javier Rodríguez-Rodríguez)

By Hamish Johnston

We’ve all had a friend who does it – you’re deep in conversation at a party, beer bottle in hand, when someone sneaks up and taps the top of your bottle with theirs, causing a foamy mess to erupt from your bottle. And to add insult to injury, their bottle doesn’t foam.

Now, physicists in Spain and France have studied this curious effect and gained a better understanding of how it occurs. While their work won’t prevent wet shoes and slippery floors at university social gatherings, the researchers believe their work could provide insights into geological features such as oil reservoirs, mud volcanoes and “exploding lakes”.

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How to build a “memcomputer”

Is this a nascent memcomputer? (Courtesy: Oak Ridge National Laboratory)

Is this a nascent memcomputer? (Courtesy: Oak Ridge National Laboratory)

By Hamish Johnston

There is a fascinating paper this week in Nature Physics about chaotic behaviour that has been spotted in a ferroelectric material. It’s an unexpected discovery that the researchers claim could lead to the development of computers that resemble the human brain.

The story begins with Anton Ievlev and colleagues at Oak Ridge National Lab in the US using the tip of a scanning probe microscope (SPM) to draw patterns on the surface of a ferroelectric material. Ferroelectrics have a spontaneous electric polarization, the direction of which can be reversed by applying an electric field.

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Waiter, there’s a bug in my cocktail!

By Hamish Johnston

Just in time for Christmas, researchers at the Massachusetts Institute of Technology (MIT) have unveiled the ultimate “cocktail accessory”. It’s an edible self-propelled boat that whizzes around on the surface of an alcoholic drink.

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A new way to look for axions

The ADMX experiment being installed at the University of Washington (Courtesy: Mary Levin / University of Washington)

The ADMX experiment. (Courtesy: Mary Levin/University of Washington)

By Hamish Johnston

There’s an interesting preprint on the arXiv server that proposes a new way of detecting dark-matter particles. I’ve been thinking about dark matter because last week physicists working on the LUX experiment announced that the underground detector had failed to find any dark-matter particles in the first three months of its operation. LUX was designed to look for WIMPs (weakly interacting massive particles), but WIMPs are not the only game in town when it comes to dark matter. There are also axions, which are the quarry of this latest proposal by three physicists in the US.

Axions are hypothetical particles that were first postulated in the 1970s to help explain puzzling aspects of quantum chromodynamics, which is the theory that describes interactions between quarks and gluons. Axions are also interesting from a cosmological point of view because they have mass but do not interact strongly with electromagnetic radiation. These properties make them prime candidates for dark matter, a mysterious substance that appears to make up most of the matter in the universe.

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