🌐中文EnglishEspañolItalianoPortuguêsРусский한국어中文日本語EntityQ2496679· pop 9· linked from 108 articles关联函数matrix element computed by inserting a product of operators between two states in quantum field theoryAvailable in 9 languagesEspañol日本語РусскийPortuguêsItalianoCatalanUkrainian한국어Connectionspath integralEntityvacuum stateEntityCategoriesCovariance and correlationQuantum field theory