April 6 - Quantum Decoherence
Elise Crull, History and Philosophy of Science, University of Notre Dame
Since the advent of quantum mechanics, the question of how a world comprised entirely of quantum systems can exhibit classical behavior (or fail to exhibit frequent quantum behavior) has puzzled physicists and philosophers alike. How do we explain the transition from one regime to the other?
The answer, it is now widely claimed, is decoherence. Quantum systems unavoidably interact with their environments and thereby become entangled with them. This system-environment entanglement results in decoherence—the delocalization of the system's (previously coherent) phase relations leading to approximate localization of the system in a basis that is stable with respect to the environment. In other words: upon interaction with an environment, a system's "quantum-ness" is leaked rapidly into that environment. As a result, we don't observe quantum behavior on a macro-scale, though we should expect to.
In this talk, I present the basics of decoherence and explore some of its fascinating consequences, including whether or not it truly solves the puzzle of the quantum-to-classical transition.