An adaptive Bayesian quantum algorithm for phase estimation
- URL: http://arxiv.org/abs/2303.01517v1
- Date: Thu, 2 Mar 2023 19:00:01 GMT
- Title: An adaptive Bayesian quantum algorithm for phase estimation
- Authors: Joseph G. Smith, Crispin H. W. Barnes, David R. M. Arvidsson-Shukur
- Abstract summary: We present a coherence-based phase-estimation algorithm which can achieve the optimal quadratic scaling in the mean absolute error and the mean squared error.
In the presence of noise, our algorithm produces errors that approach the theoretical lower bound.
- Score: 0.0
- License: http://creativecommons.org/licenses/by/4.0/
- Abstract: Quantum-phase-estimation algorithms are critical subroutines in many
applications for quantum computers and in quantum-metrology protocols. These
algorithms estimate the unknown strength of a unitary evolution. By using
coherence or entanglement to sample the unitary $N_{\mathrm{tot}}$ times, the
variance of the estimates can scale as $O(1/{N^2_{\mathrm{tot}}})$, compared to
the best ``classical'' strategy with $O(1/{N_{\mathrm{tot}}})$. The original
algorithm for quantum phase estimation cannot be implemented on near-term
hardware as it requires large-scale entangled probes and fault-tolerant quantum
computing. Therefore, alternative algorithms have been introduced that rely on
coherence and statistical inference. These algorithms produce quantum-boosted
phase estimates without inter-probe entanglement. This family of
phase-estimation algorithms have, until now, never exhibited the possibility of
achieving optimal scaling $O(1/{N^2_{\mathrm{tot}}})$. Moreover, previous works
have not considered the effect of noise on these algorithms. Here, we present a
coherence-based phase-estimation algorithm which can achieve the optimal
quadratic scaling in the mean absolute error and the mean squared error. In the
presence of noise, our algorithm produces errors that approach the theoretical
lower bound. The optimality of our algorithm stems from its adaptive nature:
Each step is determined, iteratively, using a Bayesian protocol that analyses
the results of previous steps.
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