28/06/2023

Folha: Quantum computing and IBM's advances

Reproduction of Marcelo Viana's column in Folha de S. Paulo.

Quantum computers utilize tiny units, called qubits, that take advantage of the bizarre behavior of subatomic matter, described by quantum mechanics , to perform calculations at extraordinary speeds, beyond the reach of any conventional computer.

In an article published in the journal Nature on June 14, an IBM team used quantum computing to solve a problem in physics known as the Ising model, named after the German physicist Ernst Ising (1900-1998).

This is a system made up of tiny magnets that interact according to the laws of electromagnetism. In theory, it is possible to calculate how the magnets evolve over time under the effect of these interactions. But, if the number of magnets is relatively large, on the order of a hundred, say, the calculation is too complex even for the fastest conventional supercomputers that exist.

The big news is that the IBM team has reportedly found a method to mitigate the effects of this "noise" caused by the interactions of qubits with their surrounding environment. Interestingly, the way they did this was by introducing additional noise, which makes the calculation results even less reliable!

The point is that, by varying the size and type of noise appropriately, they can identify its effects on the calculation and "subtract" them from the result. In practice, they ran the program 600,000 times, which took about ten minutes: although each of the responses obtained is unreliable in itself, from the set of them a correct solution for the Ising model is obtained.

To read the full text, visit the newspaper's website.