Lecture 018

// QUESTION: what is unknown 2d plane?

Quantum Phase Estimation

Although Q.P.E. is about complex unitrary eigenvectors and values. This is not what we study today.

Some Motivation

Some Motivation

In Grover, we can:

\theta-estimation algorithm measures angles between |start\rangle and U^k|start\rangle for various k, it does not require us to know the 2-d plane. // QUESTION: what?// But we need to be able to measure in a basis containing |start\rangle

Given an unknown |start\rangle, how to you use it to do measurement against |start\rangle multiple times?

Hadamard Test

def measureAgainstMysteryStart(U, |Start>)
  Make T
  H on T
  If T then U on |Start>
  H on T
  Measure T
  return |Start>


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