Quantum feedback cooling of a mechanical oscillator using variational measurements: Tweaking Heisenberg's microscope

Hojat Habibi*, Emil Zeuthen, Majid Ghanaatshoar, Klemens Hammerer

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

13 Citations (Scopus)

Abstract

We revisit the problem of preparing a mechanical oscillator in the vicinity of its quantummechanical ground state by means of feedback cooling based on continuous optical detection of the oscillator position. In the parameter regime relevant to ground-state cooling, the optical backaction and imprecision noise set the bottleneck of achievable cooling and must be carefully balanced. This can be achieved by adapting the phase of the local oscillator in the homodyne detection realizing a so-called variational measurement. The trade-off between accurate position measurement and minimal disturbance can be understood in terms of Heisenbergs microscope and becomes particularly relevant when the measurement and feedback processes happen to be fast within the quantum coherence time of the system to be cooled. This corresponds to the regime of large quantum cooperativity Cq ≳ 1, which was achieved in recent experiments on feedback cooling. Our method provides a simple path to further pushing the limits of current state-of-the-art experiments in quantum optomechanics.

Original languageEnglish
Article number084004
JournalJournal of Optics
Volume18
Issue number8
Number of pages12
ISSN0972-8821
DOIs
Publication statusPublished - 1 Aug 2016
Externally publishedYes

Keywords

  • feedback cooling
  • Heisenberg's microscope
  • quantum optomechanics
  • variational measurements

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