How do we create a Quantum Internet?

Introduction and quantum computing

Is life analogue or digital? We live in a digital age, so the answer might seem obvious. Think again. Reality is not digital – it's quantum. Modern computers are only digital because the analogue subatomic world is too complex to understand.

Cue the quantum computer, where ones and zeros coexist as quantum bits – or qubits – and where packets of data are replaced by encoded light cables of myriad quantum states simultaneously. Quantum computers are magnitudes more powerful than present machines, and that can only mean one thing: a quantum internet.

NASA wants to use quantum computing for calculating space missions

What is quantum computing?

Get ready for some subatomic awesomeness. Classical digital computers use transistors to process information in various sequences of 0s and 1s. Transistors are merely switches that switch on or off to produce a 0 or a 1, thus producing binary computer language. More transistors means more processing power, with the Intel Broadwell-EP Xeon – at 7.2 billion transistors – the current market leader.

Quantum computers use the laws of quantum mechanics to offer endless possibilities thanks to the fact that tiny particles such as electrons and photons can be in multiple states – not just one and zero, but both at the same time. This is called superposition. So instead of on or off 'bits' of classical computing, we get qubits, which can be 0, or 1, or both simultaneously.

100 million times faster

Extrapolate how many more calculations a quantum computer is capable of simultaneously and you get this stunning result: a 500 qubit computer could perform more calculations in a single step than there are atoms in the observable universe. Dealing in qubits essentially means that a quantum computer can operate 100 million times faster than traditional computers, solving a problem in a split-second that would take a regular digital computer thousands, if not millions, of years to calculate.

"A lot of computationally intensive processes such as genome modelling, drug research and weather forecasting will benefit enormously where lots of small and simultaneous computations are required," says Andersen Cheng, CEO of cybersecurity startup Post-Quantum. "It will also enable many financial modelling and trading analytics to be supercharged for financial gains."

So it's no surprise that even though quantum computing is still firmly in the research phase, one company now sells them.

D-Wave is already selling quantum computers

On sale now: quantum computers

D-Wave Systems, based in Canada, is the first quantum computer manufacturer. There are four of its latest D-Wave 2X systems in existence: at the company's facility in Burnaby, British Columbia, at the USC-Lockheed Martin Quantum Computing Centre in Los Angeles, at NASA's Ames Research Centre in Mountain View, California, and at the US Energy Department's Los Alamos National Laboratory in New Mexico (though the latter is still under construction).

Probably the most famous is the one held by NASA, which is a collaboration between NASA's Quantum Artificial Intelligence Laboratory (QuAIL) and Google. This D-Wave 2X – like the others – is a 1,098-qubit quantum computer. Shielded to 50,000 times less than Earth's magnetic field in a vacuum facility, the D-Wave 2X is cryogenically cooled to minus 460 degrees Fahrenheit, about 180 times colder than interstellar space. Quantum computers need to be cold – absolute zero, to be precise – and shielded from any electromagnetic interference.

D-Wave has created the first 1,000-qubit computer

A quantum cloud

The other major quantum computing surge is coming from IBM, which has developed the world's first quantum computing platform at the IBM T.J. Watson Research Center in New York. It's been accessible since May on the IBM Cloud.

Although it 'only' has a five-qubit quantum processor, the aim is to increase the compute power to 50 qubits, the point where IBM thinks it will outperform all of the current top 500 supercomputers put together.

"Quantum computing is becoming a reality and it will extend computation far beyond what is imaginable with today's computers," says Arvind Krishna, senior vice president and director at IBM Research. "This moment represents the birth of quantum cloud computing."

Top Image: IBM's five-qubit processor (Image Credit: IBM)

Quantum data and cryptography

How would a quantum internet work?

Simple – you create a quantum network to link up quantum computers, and make them available in the cloud. Quantum networks use photons – single light particles – to transmit information between quantum nodes.

"A quantum network would basically work similarly to a classical fibre network, but instead of using strong optical signals, the signal is carried by a single photon," explains Dr Matthias Keller, Senior Lecturer in Atomic, Molecular and Optical Physics at the University of Sussex in the UK.

Transferring quantum data

Encoding information into single photons has its drawbacks because quantum states are very fragile. If just one photon is lost, all quantum data is lost. The main issue is the interface between the qubit and the photon – the information and its mode of transport – which is what Keller's research team is working on.

By trapping atomic ions as qubits in optical cavities – which have two mirrors – and exciting them with laser ions, the ions only transmit light in the direction of the mirrors. "We use this 'Purcell effect' to transfer the quantum information from the ion to the photon," says Keller. "Due to the finite transmission of the mirrors, the photon leaks out and can be coupled into optical fibres for transmission," he adds.

That's to get the data ready to send. The receiver reverses the process to extract it. "It's currently the most successful system for quantum computing," says Keller.

IBM has built a quantum computer which anyone can access and use via the cloud

What is quantum cryptography?

Although quantum computers are expected to complement the regular internet for some time, with such advanced computers in the wild, classical encryption techniques used by conventional computers (usually calculations based on sets of prime numbers) will become next to useless. They'll be unravelled in seconds.

"Quantum computers will be able to crack the most commonly used encryption protocol today, which will make the internet as we know it, totally unusable," says Cheng, whose company Post-Quantum develops cryptographic algorithms that are thought to be secure against an attack by a quantum computer. In a post-quantum world, criminals and hackers won't bother with phishing and device weakening to gain access to systems and data.

Brute force

"They could openly transport a bulldozer to your front door and start brute forcing your door lock," says Cheng, employing an analogy about barefaced computer hacking. "Putting more locks on the door will not help and there is nothing you can do about it … it will destroy the trust that we have in current communication channels and data repositories."

Cheng insists we need quantum safe identity authentication as part of any future internet, so we know who we're communicating with as well as whether the communication channel itself is safe. "We will also need to ensure non-repudiation of any transactions agreed by the two parties," he adds. "Unless you have a post-quantum secure and immutable record keeping process in place, you will still have a trust issue even if you have addressed the encryption issue."

A photo of the infrastructure which is required for an ion-photon interface

Will we see a quantum internet?

Yes, but don't expect regular computers to disappear. "Most likely, a future quantum network implementation would be a hybrid network consisting of classical and quantum channels," says Keller. Due to their size and cost, quantum computers will typically operate in the cloud – that's the most efficient way – but it's likely that we will all be able to connect via the normal internet to these machines for specific reasons. To make massive calculations, yes, but also to make secure transactions or send information securely.

Only those who have a refrigerator that reaches absolute zero can contemplate an era of quantum computing at home, but quantum computing does look set to become part of the cloud, and a portion of the internet accessible by all will become quantum in nature.

After treading water for several decades and leaning heavily on Moore's Law, the tech industry is finally coming round to embracing the quantum reality, but it comes with a cryptographic kicker – the internet will need to be completely reinvented.