Quantum entanglementMeaning of entanglementParadoxHidden variables theoryViolations of Bell's inequalityOther types of experimentsMystery of timeSource for the arrow of timeNon-locality and entanglementQuantum mechanical frameworkPure statesEnsemblesReduced density matricesTwo applications that use themEntropyEntanglement measuresQuantum field theoryApplicationsEntangled statesMethods of creating entanglementTesting a system for entanglementNaturally entangled systems