Black Holes Decohere Quantum Superpositions
Speaker
Date
Time
Place
Cosmology Hall (Room 7S1)
Abstract
We show that if a massive body is put in a quantum superposition of spatially separated states, the mere presence of a black hole in the vicinity of the body will eventually destroy the coherence of the superposition. This occurs because, in effect, the gravitational field of the body radiates soft gravitons into the black hole, allowing the black hole to harvest "which path'' information about the superposition. A similar effect occurs for quantum superpositions of electrically charged bodies. The effect is very closely related to the memory effect and infrared divergences at null infinity.
Biography
Robert M. Wald is an American theoretical physicist known for his seminal contributions to general relativity, black hole thermodynamics, and quantum field theory in curved spacetime. A student of John Wheeler at Princeton, he has spent most of his career at the University of Chicago. Wald formulated the first law of black hole mechanics and introduced the "Wald entropy" formula, now central to theories of quantum gravity. He is a member of the American Academy of Arts and Sciences and a recipient of the Einstein Prize of the American Physical Society for his work on the foundations of gravitational physics.