ffect ed . ▁Another ▁way ▁is ▁to ▁apply ▁the ▁gate ▁to ▁its ▁target ▁only ▁if ▁another ▁part ▁of ▁the ▁memory ▁is ▁in ▁a ▁desired ▁state . ▁These ▁two ▁choices ▁can ▁be ▁illustrated ▁using ▁another ▁example . ▁The ▁possible ▁states ▁of ▁a ▁two - qu bit ▁quantum ▁memory ▁are ▁ ▁The ▁C NOT ▁gate ▁can ▁then ▁be ▁represented ▁using ▁the ▁following ▁matrix : ▁ ▁As ▁a ▁mathematical ▁consequence ▁of ▁this ▁definition , ▁, ▁, ▁, ▁and ▁. ▁In ▁other ▁words , ▁the ▁C NOT ▁applies ▁a ▁NOT ▁gate ▁( ▁from ▁before ) ▁to ▁the ▁second ▁qu bit ▁if ▁and ▁only ▁if ▁the ▁first ▁qu bit ▁is ▁in ▁the ▁state ▁. ▁If ▁the ▁first ▁qu bit ▁is ▁, ▁nothing ▁is ▁done ▁to ▁either ▁qu bit . ▁ ▁In ▁summary , ▁a ▁quantum ▁computation ▁can ▁be ▁described ▁as ▁a ▁network ▁of ▁quantum ▁logic ▁gates ▁and ▁measurements . ▁Any ▁measurement ▁can ▁be ▁de ferred ▁to ▁the ▁end ▁of ▁a ▁quantum ▁computation , ▁though ▁this ▁de fer ment ▁may ▁come ▁at ▁a ▁computational ▁cost . ▁Because ▁of ▁this ▁possibility ▁of ▁de fer ring ▁a ▁measurement , ▁most ▁quantum ▁circ uits ▁dep ict ▁a ▁network ▁consisting ▁only ▁of ▁quantum ▁logic ▁gates ▁and ▁no ▁measurements . ▁More ▁information ▁can ▁be ▁found ▁in ▁the ▁following ▁articles : ▁universal ▁quantum ▁computer , ▁Sh or ' s ▁algorithm , ▁Gro ver ' s ▁algorithm , ▁Deutsch – J oz sa ▁algorithm , ▁amplitude ▁ampl ification , ▁quantum ▁Fourier ▁transform , ▁quantum ▁gate , ▁quantum ▁ad i ab atic ▁algorithm ▁and ▁quantum ▁error ▁correction