QUANTUM computing sounds so high-tech, it must surely be a product of the 21st century.
Actually, it had its origins in 1981 when famed physicist Richard Feynman introduced the concept in a lecture, where he argued that the best way to simulate real-world phenomena that have a quantum-mechanical basis is to have a machine that follows quantum-mechanical rules. That was the genesis for the quantum computing concept.
You could say we have come a long way since then. Yet, quantum computing is still at its infancy stage. Many top organisations like IBM, Google and even Nasa are working on it but we’re still decades away from quantum computing being available to the masses.
Something of a breakthrough happened recently though, with Google having achieved “quantum supremacy” over traditional computers. To better understand what that means, we first need to look at the differences between quantum computers and traditional computers.
In a typical computer, inputs and outputs are sequenced in terms of 1’s and 0’s (these are called binary digits or “bits”).
Bits are useful in computing because they are easy to implement, with switches that are either in the “on” or “off” position.
Quantum computers use concepts from quantum physics, and as with quantum physics, quantum computing can be quite challenging to grasp.
One key difference with traditional computing is that it uses quantum bits (or qubits). While a bit takes on either 1 or 0, a qubit utilises the complex mathematics of quantum mechanics so it can occupy a quantum state of both 1 and 0 at the same time. This is referred to as “superposition”.
For the non-physicists among us, this may be a bit difficult to picture but to use a spherical analogy, a classical computing bit can be at either of the two poles of the sphere whereas a qubit can be at any point on the sphere.
The significance of this is that it enables a quantum computer to process a multitude of inputs simultaneously.
For example, a 10-qubit quantum computer can process 1,024 possible inputs at once (instead of analysing them one at a time).
Another key principle of quantum physics that apply to quantum computing is “entanglement”, which is even harder to grasp.
In simplistic terms, entanglement allows particles to be manipulated despite the distance between them, so that anything that happens to one particle will be reflected in the other.
If superposition and entanglement sound like daunting concepts, just know that these two principles are what allow quantum computers to be able to solve very complex problems in much quicker time than traditional computers.
Now on to “quantum supremacy”. This is a term for the point when a quantum computer is able to perform a calculation that a traditional computer wouldn’t be able to do in any reasonable amount of time.
Apparently, this has happened. Last month, it was reported that a Google paper on quantum supremacy briefly appeared on the website of Nasa’s Ames Research Centre in California. It was taken down shortly afterwards, which means it obviously wasn’t meant for publication yet. Still, enough people had downloaded it that it’s circulating on the Internet.
Apparently, Google’s quantum computer was able to solve a very specific complex calculation — i.e. proving the randomness of numbers produced by a random number generator — in just three minutes and 20 seconds. That same calculation would have taken the world’s fastest super-computer, IBM’s Summit, about 10,000 years to do.
Note that Summit has a peak performance of 200 petaflops, or 200,000 trillion calculations per second.
Yet when the same calculation challenge was given to both the Google Quantum computer and Summit, the result was 200 seconds versus (a projected) 10,000 years, respectively.
It must be said though that the specific complex calculation that Google’s quantum computer solved so quickly was a contrived problem that has few practical uses.
In short, the impressive task it performed was designed specifically to demonstrate quantum supremacy, and nothing more. Still, it was a significant milestone and a proof of concept of the potential of quantum computing.
In Google’s paper, the team that worked on it writes that their achievement “provides an experimental realisation of quantum supremacy on a computational task and heralds the advent of a much-anticipated computing paradigm”.
They added: “To our knowledge, this experiment marks the first computation that can only be performed on a quantum processor”.
So, when can we expect a general-purpose quantum computer that the masses can use?
Answer: Not anytime soon.
The general consensus among industry observers is that a general-purpose quantum computer is literally decades away, with some saying as long as 30 years before we can see quantum computers being commonplace.
The Google quantum computer had all of 53 qubits. Observers say a usable general-purpose quantum computer would have to have millions of qubits for it to be of any use. (Technically speaking, such a computer would need just thousands of error-free qubits, but to achieve that, it would need to have millions of “noisy” qubits that are not error free.)
Building a quantum computer is nothing like building a conventional computer. They must be kept in vacuum chambers containing fewer particles than what you would find in outer space. And they need to be kept in refrigerating units colder (near absolute zero) than anything that occurs naturally in the universe.
The refrigerant gas used, helium-3, is actually a nuclear research by-product, which by definition makes it very rare. You also need special cables to transmit microwave signals to control the qubits. Currently, these are made by just one company — a Japanese firm called Coax Co.
Of course, in the future it might be possible for researchers to find ways to build quantum computers that don’t need such extremely cold conditions. And perhaps more firms will eventually take to manufacturing those special cables.
Like all things technological, time will make it more common and cheaper. The natural question then is, what will we need quantum computers for?
We could make some predictions — and some industry folks have — but if the history of the traditional computer is anything to go by, making such predictions is a fool’s errand.
When traditional computers were first introduced in the 1950s, they were big, clunky things used for complex math calculations such as those needed for making the hydrogen bomb.
The general view then was that only the military and other big and serious organisations would have a need for computers.
No one could have envisioned that 70 years on, we would be using computers to buy things online, pick up new skills via online learning or connecting with each other via social media.
Broadly speaking, industry observers think quantum computing could be useful in areas as diverse as weather forecasting, traffic forecasting, medicine, chemistry, cryptography and so on.
But at the end of the day, we really don’t know how such powerful computing would be used, say 50, 60 or 70 years from now, when quantum computers are the industry standard.
It’s literally beyond our imagination. But no doubt people will find interesting ways to make the most of it. That’s how it always is with technology.
Oon Yeoh is a consultant with experiences in print, online and mobile media. Reach him at [email protected].