| Autor: |
Smith, JG, Barnes, CHW, Arvidsson-Shukur, DRM |
| Přispěvatelé: |
Arvidsson-Shukur, DRM [0000-0002-0185-0352], Apollo - University of Cambridge Repository |
| Rok vydání: |
2022 |
| Předmět: |
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| Popis: |
Given Ntot applications of a unitary operation, parametrized by an unknown phase, a phase-estimation protocol on a large-scale fault-tolerant quantum system can reduce the standard deviation of an estimate of the phase from scaling as O[1/Ntot] to scaling as O[1/Ntot]. Owing to the limited resources available to near-term quantum devices, protocols that do not entangle probes have been developed. Their mean absolute error scales as O[log(Ntot)/Ntot]. Here, we propose a two-step protocol for near-term phase estimation, with an improved error scaling. Our protocol's first step produces several low-standard-deviation estimates of θ, within θ's parameter range. The second step iteratively homes in on one of these estimates. Our protocol achieves a mean-absolute-error scaling of O[log(logNtot)/Ntot] and a root-mean-square-error scaling of O[logNtot/Ntot]. Furthermore, we demonstrate a reduction in the constant scaling factor and the required circuit depths. This allows our protocol to outperform the asymptotically optimal quantum-phase-estimation algorithm for realistic values of Ntot. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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