Efficient continuous-wave noise spectroscopy beyond weak coupling

Kyle Willick, Daniel K. Park, Jonathan Baugh

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


The optimization of quantum control for physical qubits relies on accurate noise characterization. Probing the spectral density S(ω) of semiclassical phase noise using a spin interacting with a continuous-wave (CW) resonant excitation field has recently gained attention. CW noise spectroscopy protocols have been based on the generalized Bloch equations (GBE) or the filter function formalism, assuming weak coupling to a Markovian bath. However, this standard protocol can substantially underestimate S(ω) at low frequencies when the CW pulse amplitude becomes comparable to S(ω). Here we derive the coherence decay function more generally by extending it to higher orders in the noise strength and discarding the Markov approximation. Numerical simulations show that this provides a more accurate description of the spin dynamics compared to a simple exponential decay, especially on short timescales. Exploiting these results, we devise a protocol that uses an experiment at a single CW pulse amplitude to extend the spectral range over which S(ω) can be reliably determined to ω=0.

Original languageEnglish
Article number013414
JournalPhysical Review A
Issue number1
Publication statusPublished - 2018 Jul 18

Bibliographical note

Publisher Copyright:
© 2018 American Physical Society.

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics


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