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
Quantum eraser experiment whole, it cannot be locally carried by each photon on its own. This experiment demonstrates the phenomenon of microscopic non-locality. Quantum eraser experiment In quantum mechanics, the quantum eraser experiment is an interferometer experiment that demonstrates several fundamental aspects of quantum mechanics, including quantum entanglement and complementarity. The double-slit quantum eraser experiment described in this article has three stages: A key result is that it does not matter whether the eraser procedure is done before or after the photons arrive at the detection screen. Quantum erasure technology can be used to increase the resolution of advanced microscopes. The quantum eraser