When we think of computers, we imagine machines that process zeros and ones. Quantum computers do something very different: they work with tiny particles that can be in several states at once. It sounds like science fiction, but there are already laboratories and companies building these machines today.
From bit to qubit
A classical computer uses bits, which can only be worth 0 or 1. A quantum computer uses qubits, which take advantage of a strange property of physics called superposition: they can be 0, 1 or both at the same time. It is as if a spinning coin in the air were neither heads nor tails, but both at once.
That ability allows a quantum computer to explore many possibilities in parallel. For some specific problems, it can solve in minutes what would take a classical supercomputer thousands of years.
The problem of extreme cold
There is a big challenge: qubits are very fragile. Any vibration or change in temperature spoils them. That is why quantum computers are cooled down to almost absolute zero, about 273 degrees below zero, inside golden chambers that look like giant lamps.
At that extreme cold, materials behave in a special way and allow those particles to be controlled without their quantum state being lost. It is one of the most difficult pieces of engineering that exists today.
What are they really for?
Not all problems benefit from quantum computing. They are especially useful for tasks such as simulating molecules and designing new medicines, optimising routes and logistics systems, or improving data encryption. They are precisely the problems where there are many possible combinations and the best one has to be found.
Experts insist that they will not replace the computers we use every day. They will be complementary tools, specialised in problems that are impossible to solve today.
A future under construction
Quantum computing is still in its early stages. Today’s machines make mistakes frequently and are difficult to scale, that is, to build with more qubits. But progress is coming at a good pace and several large technology companies are competing to be the first to achieve a truly useful machine.
Most likely, before we see a quantum computer at home, we will see it working in laboratories and research centres, solving problems that today seem impossible. A silent revolution that is already underway.
