Tag archives: quantum physics
By Tushna Commissariat at the APS March Meeting in Denver
It has been another exceedingly busy day the APS March Meeting – there were sessions on the SQUID’s many applications, robotic clams, global health physics and the spread of epidemics, and even some toys based on physics principles. Here’s another quick round-up of the fascinating talks.
On SQUID row
It’s the 50th birthday of the superconducting quantum interference device or SQUID – a very sensitive magnetometer that accurately measures extremely subtle magnetic fields – this year, and there were sessions this morning to discuss its impact to date as well as possible future applications. Kent Irwin from Stanford University discussed how superconducting photon detectors that are used in a host of astronomical and cosmological observations are being amplified using SQUIDs. Such SQUID-boosted sensors are being used to make more accurate measurements of the cosmic microwave background (CMB) – to look at its power as well as certain polarizations modes it exhibits. As certain experiments look for signs of gravitational waves in in the CMB polarization, this could be particularly helpful.
By Tushna Commissariat
If you like piña coladas and quantum mechanics, then we hope you are currently on the two-week “Bright Horizons 19” Southeast Asia cruise, as on board is physicist and writer Sean Carroll. He will be giving multiple lectures over the next 15 days on everything from the Higgs boson to dark matter and other fundamentals of quantum mechanics. Also floating along with Carroll are other lecturers who will cover topics from natural history to genetics to military strategy. If, like us, you are stuck at home, you can take a look at Carroll’s slides on his blog, maybe have a cocktail while you are at it.
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.
By Matin Durrani
I don’t know if they’re going to be dubbed “Alice” and “Bob”, but those names seem fairly appropriate for the two new figures – one male, one female – that make up the latest artwork from the German-born quantum-physicist-turned sculptor Julian Voss-Andreae.
Set to be installed at a new physics and nanotechnology building at the University of Minnesota in Minneapolis-St Paul, the work is officially titled Spannungsfeld – a German term that literally means “tension field” and which implies, according to Voss-Andreae, a “dynamic tension, often between polar opposites, that permeates everything in its vicinity”.
By Tushna Comissariat
Would you know exactly where to run and shelter in the event of nuclear fallout in your city? Would it be best to stay where you are or move, and for how long should you stay inside before venturing out into your post-apocalyptic world? If these questions have plagued your mind, you can now turn to a new model developed by Michael Dillon, an atmospheric scientist at the Lawrence Livermore National Laboratory in California, US. Dillon’s practical model outlines simple ideas and suggestions that the average person – without advanced equipment and know-how – could apply in the event of a low-level nuclear attack, which is the most plausible type likely to take place in today’s political climate. You can read all about about the model on both the io9 website and in Science magazine, and then map out your perfect route.
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.
By Margaret Harris
This is the second in a series of blog posts about “Lateral Thoughts”, Physics World’s long-running humour column. You can read the first one here.
The Lateral Thoughts column of humorous, off-beat or otherwise “lateral” essays has been part of Physics World ever since the magazine was launched in October 1988. In my previous post about the column’s history, I described some ways that Lateral Thoughts have changed since the early days (tl;dr version: loads of sexism, side order of class conflict). But in my trawl through the archive, I’ve also discovered that some things haven’t changed very much at all over the past quarter-century.
By Matin Durrani and Tushna Commissariat
If you’re in the tiny minority of people whose job title says “particle physicist”, chances are you’ll have been to CERN at least once in your career to help build a detector, analyse some collision data or muse in the cafeteria over supersymmetry (or the apparent lack of it so far). But for the rest of the world, going to the Geneva lab is simply not on the agenda, which is one reason why the Science Museum in London has this week unveiled a big new exhibition devoted to CERN’s Large Hadron Collider. Entitled simply Collider, the exhibition “blends theatre, video and sound art with real artefacts from CERN” that will, say organizers, “recreate a visit to the famous particle-physics laboratory”.
By Matin Durrani
Well, despite all the excitement of last month’s special 25th-anniversary issue of Physics World, there’s been no let-up for us – we’ve been busy beavering away on the next issue of your favourite physics magazine, which is now ready for you to read in print, via our apps or online.
If you’re a member of the Institute of Physics (IOP), you can access the entire new issue free via the digital version of the magazine or by downloading the Physics World app onto your iPhone or iPad or Android device, available from the App Store and Google Play, respectively.
Our cover story this month is about a strange series of experiments, carried out by Yves Couder and Emmanuel Fort at Paris Diderot University, examining the behaviour of oil droplets vibrating on the surface of an oil bath. The droplets are classical in nature but also seem to show much of what would be expected of a quantum system, including interference patterns. So is this coincidence or not? Jon Cartwright investigates.
By Hamish Johnston
QKD is a popular quantum-cryptography technique that is already being used commercially. It allows two parties, usually called Alice and Bob, to exchange an encryption key, secure in the knowledge that the key will not have been read by an eavesdropper (Eve). This guarantee is possible because the key is transmitted in terms of quantum bits (qubits) of information, which if intercepted and read are changed irrevocably, thus revealing the actions of Eve.
QKD cannot be cracked if it is implemented using equipment that behaves exactly as expected. Qubits are normally transmitted as single photons, for example, and therefore Alice and Bob must be equipped with single-photon detectors. The problem is that these detectors are not perfect and by simply shining a bright laser at a detector, Eve can trick it into thinking that it has detected a single photon even though that photon has been read by her.
While physicists have come up with several ways of thwarting such attacks, these tend to complicate the QKD process so as to make it impractical. Now, two independent teams of physicists have demonstrated aspects of a new scheme called measurement device independent QKD (MDI-QKD) that seems to close the loophole.