The quantum century

In 1925, the field of physics was shaken up. Erwin Schrödinger and Werner Heisenberg, working independently, formulated the equations that describe the behavior of matter at the subatomic scale: at the smallest scale of reality, nothing is certain until it is measured; particles exist in multiple states simultaneously, and two objects separated by kilometers can share an instantaneous fate. Einstein was not entirely pleased with this new dimension.

A century later, we live surrounded by the fruits of that breakthrough. Applications like the transistor—which powers the phone in your pocket—the laser—which reads barcodes at the supermarket—the atomic clock—which coordinates GPS—all are the result of applied quantum physics. The first quantum revolution.

Now we have begun other. He This year's Turing Award —the most prestigious award in computer science—, awarded for the first time to scientists in the quantum world, is an unmistakable sign. Charles Bennett, an IBM physicist, and Gilles Brassard, a computer scientist at the University of Montreal, received the prize for founding quantum information science. Their collaboration began in 1979 in Puerto Rico, when Bennett approached Brassard at the hotel pool where they were staying during a conference to propose the following idea: using the laws of quantum mechanics to create money that was impossible to counterfeit.

In 1984, they both published the BB84 protocolThe first quantum cryptography system: a secret key transmitted in photons of light that is automatically destroyed if anyone tries to intercept it. In 1993, they went further and described quantum teleportation: the transfer of information between entangled particles, wherever they may be. This is not science fiction, but a real and fundamental property of the particles that make up the universe.

Today, these ideas have left the laboratories. Engineers at the University of Pennsylvania have transmitted quantum signals through Verizon's commercial fiber optic network. New York State has invested $300 million in a quantum hub at Stony Brook. China already operates a 2,000-kilometer quantum communication network between Beijing and Shanghai. The quantum internet—where privacy will depend not on difficult mathematical problems, but on the laws of physics—is being built right now.

And quantum entanglement turns out to be even deeper than it seemed. Researchers like Jonathan Oppenheim use quantum information theory to investigate one of the greatest mysteries in physics: the information paradox of black holes. When one The black hole evaporates; where does the information go? Of all that it swallowed? Entanglement could be the answer. The same mechanism that protects our communications could explain the fate of matter at the edge of the universe.