Getting ready for quantum computers

One of the MIT’s best-known physicists, Seth Lloyd, has used a musical analogy to explain quantum computers. “A classical computation is like a solo voice — one line of pure tones succeeding each other,” he writes. “A quantum computation is like a symphony — many lines of tones interfering with one another.” Quantum computers are certainly music to the ears of scientists who predict that they will eventually be able to solve incredibly complex computational problems much faster than any technology we have today.

“The reality of quantum computing is probably 10 to 15 years away, yet it merits our attention now,” says Dr. Seungyun Lee of the joint committee on information technology (JTC1) set up by the international standardization bodies IEC and ISO.

“The excitement in the industry for this new paradigm of computer hardware is understandable, given the promise of far greater computational power with whole new multidimensional capabilities.”

Benefits, but also risks

Computers currently store data using bits. They have two states — either on or off — represented as a 1 or a 0. Quantum computing replaces binary bits with qubits that have more states which are changing continuously. Qubits can be on, off or somewhere in between all at the same time. This state is called “superposition” and enables qubit-based computers to carry out far more calculations much faster. When qubits become ‘entangled’ they share all the possible combinations of the quantum states of the individual qubits, substantially boosting computational power in the process.

Quantum computing is bit like parallel processing on amphetamines. Today's computers work faster by splitting a computation into parts, which are executed simultaneously on different processors attached to the same machine. As another MIT professor, Max Tegmark, points out in his book Life 3.0, "The ultimate parallel computer is a quantum computer." Tegmark goes on to quote the Oxford academic, David Deutsch, who takes things one step further by claiming that "quantum computing shares information with huge numbers of versions of themselves throughout the multiverse" in order to solve problems faster in our Universe.

While Deutsch's ideas remain controversial, what experts do agree on is that the technology is likely to bring massive benefits, such as accelerating medical research, making advances in artificial intelligence and perhaps even finding answers to climate change. That's the good news. The problem is that the technology also poses a huge risk for some of our most sensitive data. Quantum computers will be powerful enough to crack the encryption codes that currently protect all our sensitive data, from mobile banking to medical records. The science of cryptography is at the heart of cyber security.

Protecting critical infrastructure

Mobile phone calls, messaging and online banking all rely on complex mathematical algorithms to scramble information in order to protect it from malicious hackers, spies and cyber criminals. It is no exaggeration to say that there would be no confidentiality or security online without encryption and that many of the operations we take for granted today would no longer be feasible. Faced with increasing cyber attacks against critical infrastructure — including but not limited to power utilities, transport networks, factories and the health care industry — encryption is evolving to meet the threat.

The most prevalent system nowadays is public key encryption. It works by giving users two keys: a public key, shared with everyone, as well as a private key. The keys are large numbers that form part of an intricate mathematical algorithm that scrambles a user’s messages. The sender encrypts a message by using the receiver’s public key in order that only the intended recipient can unlock it with her or his private key. Even though the public key is freely available, the numbers involved are sufficiently large to make it very difficult to reverse the encryption process with only the public key.

The power of quantum cryptography

As computers become more powerful, however, and in the face of rogue states with the technology resources to pose a more serious threat, cryptographers are turning away from mathematics and looking to physics — specifically the laws of quantum mechanics — to achieve greater security. Wikipedia defines quantum cryptography as “the science of exploiting quantum mechanical properties to perform cryptographic tasks.”

That is because quantum cryptography is based on the behaviour of quantum particles, which are smaller units than molecules. For example, an encryption system called quantum key distribution (QKD) encodes messages using the properties of light particles.

The only way for hackers to unlock the key is to measure the particles, but the very act of measuring changes the behaviour of the particles, causing errors that trigger security alerts. In this way, the system makes it impossible for hackers to hide the fact that they have seen the data.

The threat is so great that scientists are urging organizations to start looking at and adopting quantum encryption systems. Quantum computers may not be available for another decade, but quantum cryptography has already been available for a few years.

A version of this post originally appeared on Medium