简介:ByA.PeresandA.Stern'sopinionsacomputationalprocessevolvesalongacycliclogicorbitdefinedbyacomputation.A.Sternthoughtthatifwecoulddesignsuchacircuit,itsoperationscanbeextendedtoincludingnonconservativebehaviorassociatedwiththeexternalperturbationsorinternalquantumerrors.A.PeresdidnotdiscusshowtomakeφM-1=φo.A.Sternproposedonlyanecessaryconditionforaconservationofastateofaquantumcircuit.Inthispaperwepresentanecessaryandsufficientconditionforauniversalconservationofastateofaquantumcircuit.Wealsofindalloperatorswhichcanallowtheconservation.