Wigner's friend and continuous time evolution of the state of a closed system and the probabilistic, discontinuous collapse of the state of a system upon measurement. Wigner's friend is therefore directly linked to the measurement problem in quantum mechanics with its famous Schrödinger's cat paradox. The thought experiment posits a friend of Wigner in a laboratory and lets him perform a quantum measurement on a physical system (this could be a spin system or also Schrödinger's cat). This system is assumed to be in a superposition of two distinct states, say, state 0 and state 1 (or "dead" and "alive", in the
Supersymmetric quantum mechanics Supersymmetric quantum mechanics In theoretical physics, supersymmetric quantum mechanics is an area of research where mathematical concepts from high-energy physics are applied to the field of quantum mechanics. Understanding the consequences of supersymmetry has proven mathematically daunting, and it has likewise been difficult to develop theories that could account for symmetry breaking, "i.e.", the lack of observed partner particles of equal mass. To make progress on these problems, physicists developed "supersymmetric quantum mechanics", an application of the supersymmetry (SUSY) superalgebra to quantum mechanics as opposed to quantum field theory. It was hoped that studying SUSY's consequences in this simpler setting