Published26 March 2020at11:53, updated on16 June 2020at17:38

With its debut almost 80 years ago, ENIAC (Electronic Numerical Integrator And Computer) kick-started a technological race that is ongoing to date. It was the first purely electronic computational machine, a room-sized invention capable of running calculations at a speed and volume that dwarfed anything humans had been able to accomplish before.

Since then, computer manufacturers have been pushing the frontiers of engineering to achieve exponentially more powerful computing while reducing hardware size. Intel co-founder Gordon Moore famously predicted that the continuous shrinking of transistors would allow computer chips to double their processing power every two years. The forecast became known as Moore’s Law, and it has guided the semiconductor industry for over half a century. But things are changing.

It turns out you can only squeeze so much out of a single technological development. With time, chip components have become so small that their innovation and manufacturing are becoming prohibitively costly and slow. Just the research needed to stick to Moore’s Law costs silicon chip producers 18 times more than it did in 1971, according to economists at Stanford and MIT.

As a result, we must put the focus on developing a technological successor that allows us to keep up with our current pace of progress – enter quantum computing.

**Quantum vs traditional computers**

Traditional computing is based on the accumulated interactions of basic units of information: bits. These can hold two possible values, either 1 or 0 – hence the binary denomination.

However, quantum computers operate by leveraging quantum mechanics and information theory (i.e. the properties of atoms, of matter itself). The basic unit of information in quantum information theory is called a qubit. It can hold the value of 1 and 0, but also of everything in between – all at the same time. This property, called quantum superposition, describes the uncertainty of a particle’s state until this is measured, and it is best explained by using the example of Schrodinger’s cat.

In this classic problem of logic, Schrodinger puts a cat in a closed box with a deadly poison. While the box remains closed, it is impossible to tell if the cat has taken the poison and is therefore dead, or if the poison lays untouched and the cat is still alive. The cat being dead or alive represents the 1 or 0 in a qubit. But here it’s where it gets tricky.

Since we can’t really say whether the cat is still alive or dead, quantum mechanics tells us that the cat is both alive (1) and dead (0) – and everything in between at the same time. That is, of course, until we open the box and see what happened. In this example, opening the box would be equivalent to measuring the state or value of a qubit.

Down to the practical level – and beyond giving some of us a mild headache – what all of this essentially means is that quantum computers can perform some calculations incredibly faster than traditional ones. And that is because they offer a completely different approach to mathematical problems.

Let’s say we find ourselves in the middle of a labyrinth and need to find the way out as quickly as possible. Whereas a traditional computer would try the various possible routes one at a time, a quantum computer can try all the paths at once. This allows these machines to be way better than traditional computers at solving certain types of problems, like factoring large numbers or cracking a code.

The triumph of quantum computers over traditional ones is what is known as quantum supremacy. Such a milestone will be reached when a quantum computer can beat the most advanced supercomputer at the planet at a particular task or benchmark test.

Google claimed to have achieved quantum supremacy last year. Although many have cast a shadow of doubt over that claim, it gives us a good idea of what this technology can achieve and will achieve soon enough – the company’s quantum computer allegedly took 200 seconds to perform a task that would take IBM’s *Summit *(the world’s fastest supercomputer) 10,000 years to complete.

**What lies ahead for quantum computing**

So, when will I be able to buy a quantum computer? Well, it is highly unlikely that you’ll be carrying around a quantum laptop in the year 2050 – or any time after that for that fact. And that’s not only because of technical limitations (which of course are plenty), but also because you will not need to.

On the hardware side of things, the biggest limiting factor is the high instability of quantum states. Maintain qubits stable and superposed requires cooling them at temperatures near absolute zero. In plain language: to have a controllable and accurate quantum computer, you need, as of today, a huge refrigerating apparatus.

As for their potential applications — quantum computers cannot only be extremely advantageous in certain fields and problems of today; they also open the doors to a new realm of capabilities that we are not even able to imagine at this point. However, all these applications will probably have nothing to do with the everyday tasks reserved for personal computers and smartphones.

The true power of quantum computing, at least in theory, resides in their power to make endless calculations possible in a reasonable amount of time. There are already many algorithms designed to exploit these capabilities, promising great leaps forward in areas like data analysis, cryptography and artificial intelligence. Additionally, there are other quantum properties, like entanglement, which we are barely starting to study – we will be discussing them in a future article.

Only time will tell which paths are viable. The clock is ticking, and it’s a quantum one.

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