What is a quantum computer?

While everyday life doesn’t show us much quantum effects, quantum physics rule every particle at the atomic level. Quantum physics and particularly the superposition principle, allow particles to be in different places at the same time until a signal interferes with them. Manipulating quantum systems is very difficult as the simple act of observing the particles cancels its superposed proprieties.

Still, this same “superposition principle” would make a quantum computer infinitely more powerful than any classical computer. While a classical computer manipulates “bits” that can take the value 0 or 1, a quantum computer would use the superposition principle to manipulate “qubits”, particles that can exist as 1 and 0 at the same time.

This may sound ideal but a single atom or even only heat can interfere with such “qubits”, randomly settling its value to 1 or 0 but not to 1 AND 0 anymore, thus making it a classical bit. It seems worth it to overcome this challenge as quantum computers would unleash huge computing power. This was highlighted in 1994, when mathematician Peter Shor found a quantum algorithm which had the potential to crack any credit cards.

The promise of quantum computing: Computing power and security

Today’s security systems, from credit cards to authentication tools, rely on our inability to factorize efficiently a large number into primes, even with the most powerful algorithm ever created for classical computers. All our credit cards are vulnerable because any computer has the capability to crack the encryption protocol but it would take a classical computer hundreds of years. With the quantum algorithm Shor designed to factorize large numbers, it would be infinitely easier and faster.

Even if theoretically such quantum computers should dominate classical ones, making one seems so hard that some researchers remain skeptical about its feasibility. But Google seems to take the bet as they teamed up with NASA last year to acquire D-WAVE, a quantum computer company. Funny thing is even D-WAVE unclear on how to use its quantum computer, according to Wired. Although the quantum computer was built, its architecture was only designed to solve optimization problems, such as finding the shortest road from A to B, preventing it from running Shor’s algorithm.


But the real question is whether it is faster than classical computers.

After lots of experiments that seemed to confirm its supremacy over classical computers, running up to 35,500 times faster, Google and NASA researchers raced D-WAVE against the most powerful classical algorithms ever made. This last experiment showed that D-WAVE was not as fast as the best classical algorithm on average. In the end, Google and NASA got mixed results as D-WAVE showed “some quantum behavior but not leveraging it efficiently”. Yet.

Still, the fact that D-WAVE already competes with state-of-the-art algorithms is encouraging. It remains the product of a 10-year-old small startup that faced “the best algorithm ever developed by a team of the top scientists in the world” according to Geordie Rose, founder of D-WAVE.

Although quantum computing could wipe out most of our modern security systems thanks to the “superposition principle”, it also has the capability of building a virtually foolproof security technology. Quantum computing is only at its beginning, and most of what it can achieve is not yet understood by scientists. Today, the likes of Google and NASA see the enormous computing power available with quantum computing, but the extent of this power is yet to be discovered.