Clarice Cudischevitch

Imagine lock-tight email that prevents your information from being copied by hackers. This is an increasingly achievable reality thanks to the progress being made in a field of physics that, until recently, did not even exist: quantum information. Rafael Chaves, a researcher from the International Institute of Physics of Natal, Rio Grande do Norte, and a Serrapilheira grantee, seeks to discover the possibilities and limitations of this new field.

Rafael Chaves

“Quantum information cannot be copied unless the spy breaks the very laws of physics,” Chaves explains. Quantum theory was developed just over 100 years ago to explain the paradoxical behavior of microscopic systems and is at the core of the so-called Information Age. “It provides the basic rules that govern the world of electrons, photons and atoms. It opened the door to the most varied inventions, namely semiconductors, devices without which modern-day computers would not exist.”

Chaves says that although computers use quantum devices, the way they process information is completely non-quantum, similar to that of a mechanical computer. In his research Chaves aims to understand the implications of making information processing quantum. One such implication is precisely the fact that unlike traditional information, quantum information processing would make it impossible to copy information. “This phenomenon could be used in what is called quantum cryptography, an extremely secure means of communication where a spy cannot access your information.”

Artistic rendering of the so-called instrumentality test. Credit: Rafael Chaves/Ella Maru Studio

Another important property that the physicist points out is entanglement, a correlation between quantum particles so strong that they still act upon each other, even at great distances, as if they were, in some cases, a single unit of information. “Entanglement is at the heart of several discoveries. There are quantum computers, theoretically much faster than the computers commonly available today, that can reduce the time it takes to carry out certain calculations from years to minutes.”

Chaves’s research focuses on several aspects that are complementary. From a more fundamental point of view, his group applies the mathematical theory of causality, machine learning and artificial intelligence to understand the limits of classical physics and how quantum effects force science to reevaluate basic concepts of cause and effect. From the perspective of application, the group uses the incompatibility between the quantum effects and our intuition about causality to develop new protocols for information processing, primarily in the context of communication and cryptography.

Chaves developed an interest in this field as an adolescent when he entered a technical program on industrial computing and was fascinated by the potential of electronic devices. “I soon realized that I had to go beyond simply learning how to use a computer; I wanted to understand how the complex components of this machine worked at their most basic level. Naturally, I headed in the direction of physics, and computing and quantum information turned out to be the best choice to satisfy my interest in both science and technology.” Now he considers himself to be a “hacker of physics.”

A new science

Quantum information got the spotlight starting in the twenty-first century, especially because of its interdisciplinarity and the progress made in recent years. “There are already devices on the market using quantum cryptography and, with the launch of a Chinese satellite that can distribute entanglement over long distances, it is just a matter of years before we see the first stage of the so-called quantum internet, where communication will be completely secure,” stresses Chaves.

Quantum computers are a plan for a not-so-distant future, but there are already some very rudimentary versions out there for which technology companies and research groups are seeking applications. “The government of China, for example, has a project where very difficult optimization problems like reducing automobile traffic could become more efficient by using these quantum—albeit rudimentary—devices.”

That said, Chaves points out that despite the huge potential of quantum information, we should be realistic. “All we have are predictions, applications that may not be confirmed and several new discoveries that we cannot even imagine. This is what basic science is all about.” Chaves, who is also a surfer, says he is a rebel. “I believe in critical and self-built knowledge; that mathematical rigor is constricted if there is no creativity and that interdisciplinarity is essential for carrying out cutting-edge science in the twenty-first century.”