The quantum arms race continues to grow exponentially. The biggest quantum computers double every six months, but how do we know if they're accurate?

Researchers Samuele Ferracin, Theodoros Kapourniotis, and Dr. Animesh Datta of the University of Warwick have developed a protocol that allows a quantum computer to control its responses to difficult problems. In other words, it permits to quantify the effects of noise on the outputs of quantum computers. Noise is a variable that influences the hardware state of a quantum machine but is outside the user's control, such as temperature fluctuations. This can affect the accuracy of the results of any system.

The test produces two percentages of analysis that allow determining if their machines are working properly to improve their performance: a crucial first step in establishing the usefulness of quantum computing in the future.

Dr. Animesh Datta from the University of Warwick Department of Physics said: "A quantum computer is only useful if it does two things: first, that it solves a difficult problem; the second, which I think is less appreciated, is that it solves the hard problem correctly. If it solves it incorrectly, we had no way of finding out. So what our paper provides is a way of deciding how close the outcome of a computation is to being correct."

The alternative method using quantum computers allows performing a series of already known calculations and therefore establishing the accuracy of the results. Based on this, researchers can define a statistical limit on how far the quantum computer can be from the correct answer in the difficult problem we want it to answer, known as the target calculation. The procedure is analogous to what programmers use to check the status of large programs in classical computers, with small functions whose outputs are known as a priori. If the program responds correctly to these, then they can be sure that the whole program is correct.

Lead author Samuele Ferracin has said: "We have spent the last few years thinking about new methods to check the answers of quantum computers and proposing them to experimentalists. The first methods turned out to be too demanding for the existing quantum computers, which can only implement 'small' computations and perform restricted tasks. With our latest work, we have successfully developed a method that suits existing quantum computers and encompasses all their main limitations. We are now collaborating with experimentalists to understand how it performs on a real machine."

Quantum computing uses particular properties of quantum physics, working in a completely different way than current digital technology. Taking advantage of the behavior of quantum systems, a radical form of processing allows data to be analyzed in all those states at the same time, giving it an enormous advantage over classical calculus. Some types of problems, such as those found in a code violation and in chemistry, are particularly suitable for exploiting this property.

The quantum arms race continues to grow exponentially. The biggest quantum computers double every six months, reaching certain supremacy. Testing, programming, packaging to improve the chips are some of the challenges that the next engineers will see Quantum supremacy refers to a milestone in the development of quantum computers, in which a quantum computer first and foremost performs a function that would require an unreasonably large amount of time using a classic computer.