- #1

liechmaster

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as title says i have two questions about qrover's algorithm, first one is more general i guess:

1. in the most of articles i have read about this algorithm the measure wasn't well explained,problem is that authors wrote "now we measure first n qubits"

when we are using n+1 ( one is as control qubit in oracles transformation)

my question is.. how we can measure only n qubits? what about that control qubit? i know it is not important one but i guess we can't just throw it out...

2. i am not sure if i well understand the shift phase , i mean the step when our solution qubit |x> changes its state to -|x>

is all about that in the oracle transformation? when we got gubit register |z> ( made from state |00..0> by H x H ... x H gates) and single qubit in state |1> and then we apply the H gate on it? and on that n+1 qubits we apply simple black box and in result : (-1)^f(z)|z>*[(|0>-|1>)/sqrt(2)] ( where f(x)=1 for solution and 0 for others)

is is all about changing the phase on solution qubit?

i hope my text is readable enough ; ) ( maybe little chaotic)

looking forward for replays.