Phase estimation ยท Algorithms
Quantum phase estimation
Theorem statement
Given access to the controlled version of an $n$-qubit unitary $U$
and its eigenstate $\ket{\psi}$ such that
$U\ket{\psi}=e^{2\pi i\theta}\ket{\psi}$,
for every integer $n_a\geq1$, there exists a quantum algorithm
that estimates $\theta$ modulo $1$ up to precision $2^{-n_a}$
and failure probability at most $1-4/\pi^2$,
using at most $n_a$ ancilla qubits,
$2^{n_a}-1$ queries to controlled-$U$,
$n_a(n_a-1)+3\lfloor n_a/2\rfloor$ CNOT gates,
and $n_a(3n_a+1)/2$ single-qubit gates.
Sources
- Quantum Algorithms Revisited
Richard Cleve, Artur Ekert, Chiara Macchiavello, Michele Mosca, 1998
Lean context
- Lean declaration
QuantumAlg.QuantumPhaseEstimation.main
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