Tag archives: quantum computers
By Hamish Johnston at the BQIT:16 conference in Bristol
Today I have made the short trip from the office to the University of Bristol, which is hosting the BQIT:16 conference on quantum information. I had been looking forward to the “Industry Perspective” session, which was headlined by Steve Adachi of the US defence supplier Lockheed Martin. Several years ago the firm was the first commercial buyer of what some consider to be the world’s first commercial quantum computer – a device made by Canada’s D-Wave Systems – and I wanted to know what Lockheed Martin was doing with it.
To say that D-Wave and its products are controversial is an understatement. Indeed, I wouldn’t be surprised if some delegates to this conference are brought to fisticuffs over D-Wave’s quantum annealing protocols later this evening in Bristol’s cider pubs.
By Matin Durrani
The April 2016 issue of Physics World magazine is ready and waiting for you to access via our app for mobile and desktop.
Our cover story this month is about Rydberg atoms – those super-sized atoms that are one of the hot topics in condensed-matter physics – and in particular how they could be used to create quantum computers.
You can also find out how virtual-reality tools could help you to learn about the science of optics and learn more about a new research centre at the National Autonomous University of Mexico that’s bringing a fresh approach to the science of complexity.
If you’re a member of the Institute of Physics (IOP), you can now enjoy immediate access to the new issue with the digital edition of the magazine in your web browser or on any iOS or Android mobile device (just download the Physics World app from the App Store or Google Play). If you’re not yet in the IOP, you can join as an IOPimember for just £15, €20 or $25 a year to get full access to Physics World digital.
By Tushna Commissariat in New York City, US
Although the APS March meeting finished last Friday and I am now in New York visiting a few more labs and physicists in the city (more on that later), I am still playing catch-up, thanks to the vast number of interesting talks at the conference. One of the most interesting sessions of last week, and a pretty popular one at that, was based on “20 years of quantum error correction” and I went along to the opening talk by physicist John Preskill of the California Institute of Technology. I had the chance to catch up with Preskill after his talk and we discussed just why he thinks that we are not too far away from a true quantum revolution.
Just in case you haven’t come across the subject already, quantum error correction is the science of protecting quantum information (or qubits) from errors that would occur as the information is influenced by the environment and other sorts of quantum noise, causing it to “decohere” and lose its quantum state. Although it may seem premature that scientists have been working on this problem for nearly two decades when an actual quantum computer has yet to be built, we know that we must account for such errors if our quantum computers are ever to succeed. It will be essential if we want to achieve fault-tolerant quantum computation that can deal with all sorts of noise within the system, as well as faults in the hardware (such as a faulty gate) or even a measurement.
Over the past 20 years, theoretical work in the field has made scientists confident that quantum computing of the future will be scalable. Preskill says that “it’s exciting because the experimentalists are taking it quite seriously now”, while initially the interest was mainly theoretical. Previously, scientists would artificially create the noise in the quantum systems that they would correct but now actual quantum computations can be fixed. Indeed, Preskill says that one of the key things that has really moved quantum error correction along in the past few years is the concentrated improvement of the hardware used, i.e. better gates with multiple qubits being processed simultaneously.
By Hamish Johnston
This morning I was speaking to quantum-entanglement expert Jian-Wei Pan, who shares the Physics World Breakthrough of the Year 2015 award for his work on quantum teleportation. Pan briefly mentioned research reported earlier this week by John Martinis, Hartmut Neven and colleagues at Google Research whereby a D-Wave 2X quantum computer was used to perform a computational task 100 million times faster than a classical algorithm.
This is a remarkable result, but does it mean that D-Wave’s controversial processors actually work as quantum computers? Some quantum-computing experts are urging caution in how the research is interpreted.
By Hamish Johnston
Has D-Wave Systems built the world’s first commercial quantum computer? The Canada-based company says it has but some physicists in the quantum-information community beg to differ. Putting aside heady questions like “Does it work?”, I think everyone agrees that the Tardis-sized black boxes that house D-Wave’s processors look great. But what exactly is inside?
By Tushna Commissariat
It’s been nearly two weeks since I spent three intense and interesting days in Sweden bundled into a classroom with other journalists and scientists to polish up our knowledge of all things quantum. Since attending the NORDITA science-writing workshop, I have spent a lot of time thinking about one of the main themes of the meeting: “What is the best way to communicate quantum physics to the public?”
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
“Reality is a concept you can apply to your cats,” says Rainer Kaltenbaek to a room full of journalists and physicists, “so long as you don’t talk to Schrödinger.” Indeed, he warns us to not bother applying reality to anything that exists at the quantum level as we will just end up disappointed.
I am in Stockholm at a workshop for science writers being hosted at the Nordic Institute for Theoretical Physics (NORDITA) and the idea of completely forgetting “reality” is one of the many interesting things I have been pondering. Over the past two days we have discussed Bell’s loopholes, using your bathtub as an analogue laboratory to study black (and white) holes and learned about problems that even the best quantum computers (if they could be built) will not be able to solve.
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 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.