Quantum backaction evasion with reservoir engineering

Jin Yang, Sibo Fang, Chengsong Zhao +2 more

Mazyar Mirrahimi, Zaki Leghtas, Uri Vool

Yohei Nishino, James W. Gardner, Yanbei Chen +1 more

We propose a back-action evading scheme for a free mass that combines reservoir engineering with velocity measurement. The underlying principle follows the double-pass-type speed meter, which measures the mirror's velocity using a nonreciprocal interaction. In our method, the nonreciprocal coupling is realized through reservoir engineering, following the recipe proposed in [Phys. Rev. X 5, 021025]. We show that reservoir engineering can reproduce the double-pass speed meter with optimal feedforward, using only reciprocal interactions. The resulting force sensitivity surpasses the standard quantum limit, providing an alternative route to quantum back-action evasion in cavity optomechanical systems.

Guang-Zheng Ye, Ye Liu, Wan-Jun Su +2 more

Quantum noises impose limits on both backaction cooling and displacement measurements in macroscopic resonators. Here, we demonstrate that for dissipative optomechanical systems in the deeply unresolved sideband regime, squeezed-vacuum engineering of Fano interference enables broadband, tunable suppression of backaction noise and complete evasion of backaction heating, along with destructive noise correlations in the measurement spectrum. This leads to ground-state cooling over a cavity-linewidth scale for both blue- and red-detuned drives, as well as substandard quantum limit position sensitivity both at and away from mechanical resonance. Our Letter establishes squeezed-reservoir engineering as a powerful platform for exploring nonclassical correlations, quantum sensing, and information processing via noise-interference control.

Claudio Conti