Information is physical, even in quantum systems, study suggests

Information may seem ethereal, given how easily we forget phone numbers and birthdays. But scientists say it is physical, and if a new study is correct, that goes for quantum systems, too.

Although pages of text or strings of bits seem easily erased with the press of a button, the act of destroying information has tangible physical impact, according to a principle proposed in 1961 by physicist Rolf Landauer. Deleting information is associated with an increase in entropy, or disorder, resulting in the release of a certain amount of heat for each erased bit. Even the most efficient computer would still output heat when irreversibly scrubbing out data.

This principle has been verified experimentally for systems that follow the familiar laws of classical physics. But the picture has remained fuzzy for quantum mechanical systems, in which particles can be in multiple states at once and their fates may be linked through the spooky process of quantum entanglement.