What could the NSA do with a quantum computer?

After many false starts it’s a research field that is just now coming of age - when harnessed, particles can perform staggeringly powerful computation.

The news that the US National Security Agency has been spying on public emails, phone calls and internet chat logs provokes an obvious question: just how much data can the NSA cope with? That depends on whether it has a working quantum computer.

A report leaked to the Guardian suggests that the NSA can get three billion pieces of information a month from computer records alone. Much has been made of how it would take ridiculous amounts of computer time to analyse it all. But that is exactly why the NSA, GCHQ and almost every other security agency in the world have spent the past two decades with one eye on a select group of physicists who could soon make the supercomputers of today look like children’s toys.

A standard “classical” computer stores information as a series of zeroes and ones on the microchips of its circuitry. A 0 is represented by the absence of electrical charge on a component called a capacitor. The presence of charges gives a 1. By moving the charges around between components in welldefined ways, you can represent any number you want and perform any computation.

The quantum computer uses a single atom or electron, rather than a bulky electrical charge, as the 0 or 1. In fact, the particle can be 0 and 1 at the same time. In certain conditions, atoms and subatomic particles can be in two places at once, or spin clockwise and anticlockwise at the same time. That means you can use a single atom to represent two binary digits.

Then there’s entanglement, another phenomenon of the subatomic world. This allows you to link many of the doubleheaded particles to create a string of binary digits that can simultaneously represent a huge array of numbers. A string of just 250 particles is enough to encode, simultaneously, more numbers than there are atoms in the known universe. Put those particles together in the form of a computer, and they can perform a staggeringly powerful computation on all these possible numbers at once.

So far, researchers have identified two applications for quantum computing. The first is a kind of reverse multiplication known as factorisation. This allows you to discover which numbers multiply each other to create any given number. It sounds trivial, but if the bigger number is big enough, no normal computer can do this in a reasonable time. The difficulty of factorisation is the mainstay of all data security, from military intelligence to financial transactions. So, a quantum computer is a game-changer.

The second application seems even more esoteric at first glance. It is a reverse telephonebook search: given a number, it can do the equivalent of finding a name, and much more quickly than any machine we have now. It is a way of sifting through unsorted data efficiently – just what the NSA needs.

And after many false starts it’s a research field that is just now coming of age. The first working, commercial quantum computer was created by DWave Systems, a firm based in Vancouver, Canada. Its first sale, in May 2011, was to the defence company Lockheed Martin, which has links with the NSA.

A major investor in D-Wave is In-Q-Tel, the business arm of the CIA, which “delivers innovative technology solutions in support of the missions of the US intelligence community”. IQT believes its customers can benefit from the promise of quantum computing because the intelligence world faces “many complex problems that tax classical computing”, according to Robert Ames, an IQT vice-president. He made that statement in September last year. Now we know just what he meant.

A new NSA data centre in Bluffdale, Utah. Photograph: Getty Images

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 24 June 2013 issue of the New Statesman, Mr Scotland

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Scientists have finally said it: alcohol causes cancer

Enough of "linked" and "attributable": a new paper concludes that alcohol directly causes seven types of cancer.

I don't blame you if you switch off completely at the words "causes cancer". If you pay attention to certain publications, everything from sunbeds, to fish, to not getting enough sun, can all cause cancer. But this time, it's worth listening.

The journal Addiction has published a paper that makes a simple, yet startling, claim: 

"Evidence can support the judgement that alcohol causes cancer of the oropharynx [part of the throat], larynx, oesophagus, liver, colon, rectum and [female] breast"

So what's especially significant about this? 

First, scientists, unlike journalists, are very wary of the word "causes". It's hard to ever prove that one action directly led to another, rather than that both happened to occur within the same scenario. And yet Jennie Connor, author of the paper and professor in the Preventive and Social Medicine department at the University of Otago, New Zealand, has taken the leap.

Second, alcohol not only causes cancer of one kind – the evidence supports the claim that it causes cancer at seven different sites in our bodies. There was weaker evidence that it may also cause skin, prostate and pancreatic cancer, while the link between mouth cancers and alcohol consumption was the strongest. 

What did we know about alcohol and cancer before?

Many, many studies have "linked" cancer to alcohol, or argued that some cases may be "attributable" to alcohol consumption. 

This paper loooks back over a decade's worth of research into alcohol and cancer, and Connor concludes that all this evidence, taken together, proves that alcohol "increases the incidence of [cancer] in the population".

However, as Connor notes in her paper, "alcohol’s causal role is perceived to be more complex than tobacco's", partly because we still don't know exactly how alcohol causes cancer at these sites. Yet she argues that the evidence alone is enough to prove the cause, even if we don't know exactly how the "biologial mechanisms" work. 

Does this mean that drinking = cancer, then?

No. A causal link doesn't mean one thing always leads to the other. Also, cancer in these seven sites was shown to have what's called a "dose-response" relationship, which means the more you drink, the more you increase your chances of cancer.

On the bright side, scientists have also found that if you stop drinking altogether, you can reduce your chances back down again.

Are moderate drinkers off the hook?

Nope. Rather devastatingly, Connor notes that moderate drinkers bear a "considerable" portion of the cancer risk, and that targeting only heavy drinkers with alcohol risk reduction campaigns would have "limited" impact. 

What does this mean for public health? 

This is the tricky bit. In the paper, Connor points out that, given what we know about lung cancer and tobacco, the general advice is simply not to smoke. Now, a strong link proven over years of research may suggest the same about drinking, an activity society views as a bit risky but generally harmless.

Yet in 2012, it's estimated that alcohol-attributable cancers killed half a million people, which made up 5.8 per cent of cancer deaths worldwide. As we better understand the links between the two, it's possible that this proportion may turn out to be a lot higher. 

As she was doing the research, Connor commented:

"We've grown up with thinking cancer is very mysterious, we don't know what causes it and it's frightening, so to think that something as ordinary as drinking is associated with cancer I think is quite difficult."

What do we do now?

Drink less. The one semi-silver lining in the study is that the quantity of alcohol you consume has a real bearing on your risk of developing these cancers. 

On a wider scale, it looks like we need to recalibrate society's perspective on drinking. Drug campaigners have long pointed out that alcohol, while legal, is one of the most toxic and harmful drugs available  an argument that this study will bolster.

In January, England's chief medical officer Sally Davies introduced some of the strictest guidelines on alcohol consumption in the world, and later shocked a parliamentary hearing by saying that drinking could cause breast cancer.

"I would like people to take their choice knowing the issues," she told the hearing, "And do as I do when I reach for my glass of wine and think... do I want to raise my risk of breast cancer?"

Now, it's beginning to look like she was ahead of the curve. 

Barbara Speed is a technology and digital culture writer at the New Statesman and a staff writer at CityMetric.