Question: Quantum Internet! Recently hearing that Los Alamos National Laboratories have been able to run quantum Networks for the past two years, I’m intrigued, what are your views on quantum Internet? Is it possible? Can you outline the main benefits?

Chris Mansell answered on 23 Jun 2013:

The quantum Internet seems like a technology that could become successful in the next few years. There are already a few companies selling products (e.g. id Quantique, MagiQ Technologies, QuintessenceLabs, SeQureNet) but I think they get a lot of funding from governments and wouldn’t be profitable otherwise.

The quantum Internet would have two main advantages: (1) information sent across it would be extremely secure; and (2) it would help enhance the power of quantum computers.

The key to understanding advantage (1) is knowing that quantum systems (in this case, particles of light known as photons) get changed in the process of measuring them. With a bit of cleverness, you can detect whether the photons have been messed with and in this way, detect the prescience of anyone trying to listen in on what you’re saying.

You could ask: once someone has taken some of the photons and measured them, can’t they change the back to how they would have been before? The answer is no, they couldn’t. Couldn’t they make copies of the photons and measure those ones instead? They couldn’t do this either (because quantum mechanics doesn’t allow information encoded in quantum systems to be copied). All sorts of sneaky possibilities have been considered and none of them work..

Ordinary methods of keeping information on the Internet (e.g. bank details when you do online shopping) seem to work fine. However, the modern financial system relies on these methods so it is best for them to be as secure as possible. Even with all the tests in the quantum Internet, who knows if it will actually be more secure? Well, you don’t need to worry. I’ve heard that the current plan is to have two layers of security: the ordinary layer and the quantum layer. To steal any information, one would have to break through both layers of security.

Advantage (2) is quite cool. If quantum computers become better and then start getting sold, companies and people will want them to be as powerful as possible. If two people know what they are doing, they can share their computing power with each other, and thus have a combined, more powerful computer. This could also happen with a quantum computers but only if there is a quantum Internet connection between the two people.