Heat and information are related. In the 1960s, physicist Rolf Landauer discovered a surprising link: deleting information, like erasing data from a device, always produces heat. This idea, called the Landauer principle, shows that removing information requires energy and increases entropy, a measure of disorder in a system.
Researchers at TU Wien recently tested this idea in quantum systems. They confirmed that when a quantum system loses information, it exchanges energy and entropy with its surroundings. This finding supports Landauer’s principle and matters for quantum computers, which use quantum physics to process information. Deleting data in these systems has energy costs, setting limits on how efficiently they can work.
Quantum interactions and information loss
In physics, some systems are deterministic and reversible, meaning their future and past states can be predicted. For example, knowing a planet’s position and speed lets scientists calculate its path backward or forward. No information is lost in these systems. Quantum systems can also be reversible, but only until they interact with their environment. When a quantum particle is measured, it connects with a measuring device, transferring information. This changes the particle’s state in a way that cannot be undone, causing information to leak into the environment.
To study this, scientists at TU Wien used clouds of ultracold rubidium atoms, cooled to nearly absolute zero and held on a special chip. They let two atom clouds spread and overlap, then split the system into a quantum part and an environment part. By measuring how the clouds interfered with each other, they saw how information moved from the quantum system to the environment, increasing entropy and releasing energy. This complex experiment confirmed Landauer’s principle in a many-particle quantum system. The results deepen our understanding of how information and energy are connected, offering insights into quantum technologies and the fundamental rules of quantum physics.
This research is published in Nature Physics.