简介:WeprovideanewexpressionofthequantumFisherinformation(QFI)forageneralsystem.Utilizingthisexpression,theQFIforanon-fullrankdensitymatrixisonlydeterminedbyitssupport.Thisexpressioncanbringconvenienceforaninfinite-dimensionaldensitymatrixwithafinitesupport.Besides,amatrixrepresentationoftheQFIisalsogiven.