Schrödinger's cat regard the "alive and dead" cat superposition as quite real. Intended as a critique of the Copenhagen interpretation (the prevailing orthodoxy in 1935), the Schrödinger's cat thought experiment remains a defining touchstone for modern interpretations of quantum mechanics. Physicists often use the way each interpretation deals with Schrödinger's cat as a way of illustrating and comparing the particular features, strengths, and weaknesses of each interpretation. Schrödinger wrote: Schrödinger's famous thought experiment poses the question, ""when" does a quantum system stop existing as a superposition of states and become one or the other?" (More technically, when does the actual quantum state
Unitary transformation (quantum mechanics) qubit is driven simultaneously at two frequencies, formula_65 and formula_66, for which formula_67. formula_68 In addition, there are many fourth-order terms coupling the modes, but most of them can be neglected. In this experiment, two such terms which will become important are formula_69. (H.c. is shorthand for the Hermitian conjugate.) We can apply a displacement transformation, formula_70, to mode formula_64<nowiki>. For Unitary transformation (quantum mechanics) In quantum mechanics, the Schrödinger equation describes how a system changes with time. It does this by relating changes in the state of system to the energy in the system (given by an operator called