Seminar

Pointer states of a system interacting with an environment are defined to be the most resilient states of the system under decoherence caused by the environment. For a fixed system-environment interaction, these states form a basis into which all the other states of the system will decohere eventually. On the other hand, coherent states have been traditionally regarded as the states “closest to the classical” and in fact, for quantum Brownian motion, these states are indeed the approximate pointer states selected by the environment. However, we show that the physics of open systems, in general, singles out different states than coherent states as the most stable states under decoherence. We thus open a new, physically-motivated, problem of finding the most robust states, i.e, the approximate pointer states for generic open quantum systems. These states generalize the widely-used notion of pointer states, responsible for the emergence of classical properties of the everyday world.