Tag archives: quantum theory
By Matin Durrani
Happy New Year from all the team at Physics World!
To get things off to a cracking start, check out the January issue of Physics World magazine, which has a wonderful feature by Patrick Hayden and Robert Myers about how the study of “qubits” – quantum bits of information – could be key to uniting quantum theory and general relativity. The issue is now live in the Physics World app for mobile and desktop, and you can also read the article on physicsworld.com from tomorrow.
Elsewhere in the new issue, you can discover how physicists have waded into the debate over whether magnetic fields can control neurons and enjoy a great feature on why some birds don’t kick out intruder cuckoo eggs.
You can also find out just why so many physicists are worried about Donald Trump’s imminent inauguration as US president.
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.
By Matin Durrani
This year marks the 50th anniversary of the publication of a now-famous paper in the journal Physics by the Northern Irish physicist John Bell, in which he proved that making a measurement on one particle could instantaneously affect another particle – even if it’s a long way off.
As our regular columnist Robert P Crease writes in the November issue of Physics World magazine, that kind of instantaneous effect, which proved the concept of entanglement, was not something that Bell was originally keen on. In fact, Bell had actually set out to prove the opposite – that it was possible, using “hidden variables”, to have a theory of physics that could keep things nice and “local”, and so avoid what Einstein had dubbed “spooky action at a distance”.
But Bell reversed his thinking. “I made a phase transition in my mind,” he told Crease shortly before his death in 1990 aged 62.
Yesterday (4 November) marked the 50th anniversary of the day that Bell’s paper arrived at the journal’s offices and today (5 November) sees the opening of an exhibtion at the Naughton Gallery on the campus of Queen’s University Belfast, from which Bell graduated with a first-class degree in mathematical physics in 1949.
Entitled “Action at a distance”, the exhibition runs until 30 November and promises to “explore Bell’s life and the artistic response to his legacy by artists from across the world”. There is also an accompanying series of lectures from Andrew Whitaker, Maire O’Neill, Mauro Paternostro, Artur Ekert and Anton Zeilinger.
By Tushna Commissariat
I’ve left sunny Stockholm and I’m back at the office in blustery Bristol, but I still have a few good quantum tales to tell from the science-writers’ workshop at NORDITA last week. On Thursday, the main speaker of the day was Raymond Laflamme, who is the current director of the Institute for Quantum Computing at the University of Waterloo in Canada. Laflamme – who kick-started his career working on cosmology at the University of Cambridge in the UK as a student of Stephen Hawking – studies quantum decoherence and how to protect quantum systems from it by applying quantum error-correction codes, as well as using nuclear magnetic resonance (NMR) to develop a scalable method of controlling quantum systems.
By Tushna Commissariat in Stockholm, Sweden
Google the word “quantum” and take a look at what comes up.
In addition to the obvious news articles about the latest developments in the field and the Wikipedia entries on quantum mechanics, you’ll undoubtedly come across a heap of other, seemingly random, stories.
I found, for example, a David Bowie song being compared to a quantum wavefunction (by none other than British science popularizer Brian Cox), as well as a new cruise ship being named Quantum of the Seas. Then there’s the usual jumble of pseudo-scientific “wellness” therapies that misguidedly adopt the word in a strange attempt to give their treatments some sort of credibility.
So while it seems that everyone is talking about quantum something or other, how much do we really understand this notoriously difficult subject? More to the point, how much do science journalists, like me, really know about the subject? I write stories about quantum mechanics from time to time for Physics World and the subject can, I assure you, be fiendish and quite mind-bending.
By Hamish Johnston in Canada’s Quantum Valley
“We have entered the quantum world and we can control it” is how Raymond Laflamme characterizes the current quantum renaissance that is sweeping across many fields of physics. Laflamme is director of the Institute for Quantum Computing (IQC) at Canada’s University of Waterloo and he began his career at the University of Cambridge as a student of Stephen Hawking, working on cosmology.
By Hamish Johnston in Canada’s Quantum Valley
“There’s no place like this in the world,” said Vadim Makarov (above) as we walked up to his lab at the Institute for Quantum Computing (IQC) at Canada’s University of Waterloo. What’s unique about the place, according to Makarov and others I spoke to in Waterloo, is that it brings together a diverse group of researchers (physicists, computer scientists, mathematicians, engineers, etc) in one place to develop quantum-information technology.
By Louise Mayor
Yesterday I had an exciting trip out of the office.
Earlier this week, one of Physics World’s freelance writers, Jon Cartwright, told how me he’d been invited to the Bristol University theory department’s weekly seminar. Felix Flicker, a 2nd-year PhD student who organizes these events, had seen Jon’s article “The life of psi” in this month’s Physics World, which discusses a theorem published in Nature Physics. The theorem is interesting because if its assumptions hold, it rules out one of the four interpretations of quantum mechanics and leaves us with three.
I wanted in on the seminar action!
Last year when I was planning the Physics World special issue on quantum frontiers (which was out in March and is still available as a free PDF download), I had approached Jon to ask whether he’d like to tackle a quantum topic, and he let me know he was interested in covering the paper by Matthew Pusey, Jonathan Barrett and Terry Rudolph. Jon had seen the story reported elsewhere but had found these accounts were light on the details and didn’t get to the bottom of the science. I liked the idea and Jon went ahead. Once the story arrived in my inbox I was hooked! I found it to be one of those stories that covers some tricky concepts but if you let yourself become immersed in the story and think through what’s being explained, is very rewarding.
By James Dacey
In the May issue of Physics World, science writer Jon Cartwright explores some of the most profound questions about the nature of reality. His feature, “The life of psi”, engages with an apparently simple question: what are quantum wavefunctions? Of course, like many of the most interesting questions in physics, the answer to the question is far from elementary. In fact, it is a question that goes right to the heart of quantum mechanics and philosophy, and one that has puzzled some of the greatest minds for the best part of a century.
By Hamish Johnston
The string theorist Alexander Polyakov has won the 2013 Fundamental Physics Prize. The $3m prize is awarded by Milner Foundation, which is funded by the Russian entrepreneur Yuri Milner and was inaugurated last year.