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Tag archives: quantum mechanics

Quantum quartet is on the cards

Quantum pair: Wolfgang Pauli and Werner Heisenberg (Courtesy: Sabine Hossenfelder)

Quantum pair: Wolfgang Pauli and Werner Heisenberg (Courtesy: Sabine Hossenfelder)

By Hamish Johnston

Theoretical physicist and blogger Sabine Hossenfelder has created a lovely set of cards featuring pioneering quantum physicists. You can see my two favourites above.

Resembling football or baseball cards, they each feature a portrait plus a fact or two about the physicist – including a salacious aspect of Erwin Schrödinger’s personal life. You will have go to Hossenfelder’s blog to learn more about that – and see the rest of the cards, including a feline “Bra-ket” as the joker of the deck.

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Why is quantum physics so hard to write about?

Live at Leeds: George Musser riffs on writing about quantum mechanics (Courtesy: H Johnston)

Live at Leeds: George Musser riffs on writing about quantum mechanics (Courtesy: H Johnston)

By Hamish Johnston

Why is quantum physics so hard to write about?

That was the theme of George Musser’s keynote talk at a seminar for science communicators held this week at the University of Leeds. Musser – who has written extensively on topics such as quantum entanglement and string theory – gave several reasons and here are a few that stuck in my mind.
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A century ago Einstein sparked the notion of the laser

Another brilliant idea: laser beams illuminate fog (Courtesy: CC BY 2.0/ Jeff Keyzer)

Another brilliant idea: laser beams illuminate fog. (CC BY 2.0/ Jeff Keyzer)

By Philip Ball 

I just got back from having my broken wrist X-rayed (it’s doing fine, thanks), and noticed that a laser beam was used to position and align the X-ray source. Hardly the most sophisticated use of these optical devices, it’s true, but a little reminder that there’s probably hardly a day goes by in the life of an average urbanite without the laser’s beam of coherent photons impinging on it. From supermarket barcode scanning to broadband fibre-optic telecommunications, lasers are everywhere.

The fundamental idea behind this mainstay of modern life was published one hundred years ago by Albert Einstein. But blink and you’ll miss it in his seminal paper, “The quantum theory of radiation”, published in German in Physikalische Zeitschrift 18 121 (English translation here). Einstein is trying to work out what Max Planck’s “quantum hypothesis” – that the energy of an oscillator must take discrete values equal to some integer multiple of the oscillation frequency times a constant h – implies for the way light interacts with matter.

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Looking toward the quantum-technology landscape of the future

Looking to the future: Sir peter Knight opening the Quantum technology for the 21st Century conference at the RSC (Courtesy: Tushna Commissariat)

Futuristic views: Peter Knight opening the conference at the Royal Society in London. (Courtesy: Tushna Commissariat)

By Tushna Commissariat

Not a week goes by here at Physics World that we don’t cover some advance in quantum mechanics – be it another step towards quantum computing or error correction, or a new type of quantum sensor, or another basic principle being verified and tested at new scales. While each advance may not always be a breakthrough, it is fair to say that the field has grown by leaps and bound in the last 20 years or so. Indeed, it has seen at least two “revolutions” since it first began and is now poised on the brink of a third, as scientific groups and companies around  the world race to build the first quantum computer.

With this in mind, some of the stalwarts of the field – including Peter Knight, Ian Walmsley, Gerard Milburn, Stephen Till and Jonathan Pritchard – organized a two-day discussion meeting at the Royal Society in London, titled “Quantum technology for the 21st century“, which I decided to attend. The meeting’s main aim was to bring together academic and industry leaders “in quantum physics and engineering to identify the next generation of quantum technologies for translational development”. As Knight said during his opening speech, the time has come to “balance the massive leaps that the science has made with actual practical technology”.

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Scientists battle celebrities, a quantum ‘unconference’ and space travel, past and future

 

By Tushna Commissariat

Its been a strange week for scientists and celebrities popping up together on the world stage – what with rapper B.o.B and Neil deGrasse Tyson’s very public face-off about the former’s conspiracy theory claims of the Earth being flat  – but it didn’t end there. In a celebrity trio that is even more surprising, physicist Stephen Hawking has come together with Hollywood actor Paul Rudd, (most recently starring in the film Ant-Man) in a video narrated by Keanu Reeves. Earlier this week, Caltech’s Institute for Quantum Information and Matter hosted the event One Entangled Evening: a Celebration of Richard Feynman’s Legacy. As a promo of sorts for the event – which had special appearances by Rudd, Reeves, Hawking, Bill Gates and even Yuri Milner, apart from actual quantum physicists such as John Preskill and Dave Wineland – they filmed the above video with Rudd and Hawking battling each other at a game of quantum chess. You will have to watch the video to see who wins.

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Quantum cats, physicists and stamp collecting, extraterrestrial building work

Calculating cat: Schrö makes her way through a quantum computer (Courtesy: IQC)

Calculating cat: Schrö makes her way through a quantum computer. (Courtesy: IQC)

By Hamish Johnston

The Internet loves cats and our readers love quantum mechanics so a new mobile app called Quantum Cats just has to be the lead item in this week’s Red Folder. Created by physicists at the Institute for Quantum Computing and researchers at the University of Waterloo Games Institute, the app immerses the user in the adventures of four cats: Classy, who obeys classical physics; Digger, who is a master of quantum tunnelling; Schrö, (above) who is a superposition of quantum states; and Fuzzy, who embodies the uncertainty principle. It’s available on Google Play and the App Store, so have a go and tell us what you think.

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A journal for brief ideas, Heisenberg’s mirror, space-mission stickers and more

Mission accomplished: these graphics were created by Ariel Waldman and Lisa Ballard. (Courtesy: spaceprobe.es)

Mission accomplished: these graphics were created by Ariel Waldman and Lisa Ballard. (Courtesy: spaceprob.es)

By Hamish Johnston

Dr Heisenberg’s Magic Mirror of Uncertainty” is the name of a series of photographs taken in 1999 by the American photographer Duane Michals. The picture over at that link is lovely, but I don’t really see the connection to quantum mechanics. I suspect my artist friends would accuse me of being a scientific literalist, which doesn’t bother me one bit.

More to my liking are the graphics pictured above, which have been created by Ariel Waldman and Lisa Ballard. The pair run a website called spaceprob.es, which “catalogues the active human-made machines that freckle our solar system and dot our galaxy”. Here is their page on Voyager 2, which is packed with facts about the mission’s instruments and many accomplishments. These and other illustrations of space missions can be bought as stickers and posters – the perfect gift for the space enthusiast in your life.

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Entangled and stringy videos, a new chat show about the heavens, Hawking and Newton hit the Oregon Trail and more

By Hamish Johnston

This week’s Red Folder begins with a pair of videos that attempt to explain some of the most difficult concepts in physics. First up is a video featuring physicist and filmmaker Derek Muller, who does a lovely job of explaining quantum entanglement with the help of a few cardboard cut-outs and a couple of spinning avatars (see above).

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Quantum kung fu

This article first appeared in the “Lateral Thoughts” section of the July 2014 issue of Physics World

By Felix Flicker

Felix Flicker

Practising the “plate trick”. (Courtesy: Paul Blakemore)

If someone puts you in an armlock, what should you do? If you happen to be a martial artist well-practised in the art of joint manipulation, or chin na, you will know the answer already: there is one simple move that will allow you to turn the tables on your aggressor, leaving them on the wrong end of a throw. However, if your skill set tends more toward manipulating mathematical symbols, there is still hope, for the answer is also closely tied to theoretical physics.

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‘Anomalous weak values’ are nonclassical, and here is the proof

The weak value of an observable A can be nonsensical

The weak value of an observable A can be nonsensical.

By Hamish Johnston

Last month we reported on a quirky paper in Physical Review Letters entitled “How the result of a single coin toss can turn out to be 100 heads” by Christopher Ferrie of the University of New Mexico and Joshua Combes of the Perimeter Institute for Theoretical Physics in Waterloo, Canada.

The paper addresses “anomalous weak values” in quantum mechanics, a phenomenon that was first identified in 1988 by Yakir Aharonov, Lev Vaidman and colleagues at Tel Aviv University. A weak value is the result of a weak measurement on a quantum system. This is done by making repeated gentle measurements on the quantum states of identical particles. The result of each measurement only has a tiny correlation to the quantum state of the particle so the wave function of the particle does not collapse into that state. However, by making the measurement on many particles, a weak value providing useful information about the state can be obtained.

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