Exceptional Point Enhances Sensitivity of Optomechanical Mass Sensors

Abstract

We propose an efficient optomechanical mass sensor operating at exceptional points (EPs), nonhermitian degeneracies where eigenvalues of a system and their corresponding eigenvectors simultaneously coalesce. The benchmark system consists of two optomechanical cavities (OMCs) that are mechanically coupled, where we engineer mechanical gain (loss) by driving the cavity with a blue (red) detuned laser. The system features EP at the gain and loss balance, where any perturbation induces a frequency splitting that scales as the square-root of the perturbation strength, resulting in a giant sensitivity factor enhancement compared to the conventional optomechanical sensors. For non-degenerated mechanical resonators, quadratic optomechanical coupling is used to tune the mismatch frequency in order to get closer to the EP, extending the efficiency of our sensing scheme to mismatched resonators. This work paves the way towards new levels of sensitivity for optomechanical sensors, which could find applications in many other fields including nanoparticles detection, precision measurement, and quantum metrology. arXiv:1903.02542v2 [cond-mat.mes-hall]

Observation of anti-parity-time-symmetry, phase transitions and exceptional points in an optical fibre

“…The sensitivity of parameter estimation near EPs has been extensively studied in recent years in numerous non-Hermitian physical platforms, exploring their fundamental and practical limitations. Some works have shown that the larger response to small-scale variations near the EP can give rise to improved sensors [57][58][59][60][61] . Others have however pointed out that the enhanced response may be accompanied by an elevated noise level, affecting the signal-tonoise ratio of the measurement [62][63][64] .…”

Self-organized synchronization of mechanically coupled resonators based on optomechanics gain-loss balance

“…In such a system, the frequency of the driven mechanical system yieldsω 1 = ω 1 − g ck α * α, which can be tuned through the driving field (see Appendix B). This frequency control is useful to bring closer the frequencies of the nondegenerated mechanical resonators involved in our system, even at the vicinity of an EP [29]. This can be seen by comparing Fig.…”

“…eff . This leads to a well-known exceptional point (EP) at J = γ eff 4 , which can be used for mass sensing [29] and it also marks the threshold of phonon lasing where the mechanical resonators exhibit self-sustained limit cycle oscillations [26].…”

Coupling of Integrated Waveguide and Optomechanic Cavity for Microwave Phonon Excitation in Si Nanobeams

“…Such cavities have been designed in phoxonic (or OM) crystals that exhibit simultaneous photonic and phononic band gaps [13][14][15]. Current research trends on OM structures include topics such as radiation-pressure cavity cooling [16,17], quantum coherent optomechanics [1,18], coherent amplification/cooling of Surface Acoustic Waves (SAWs) in optomechanical microcavities [6,[19][20][21][22][23][24], and high resolution sensing, in particular of biomolecules [25][26][27]. The basic phonon circuits which are typically taken into consideration are resonant mechanical cavities, as promising building blocks of more complex devices, including filters, couplers, and mechanical sources/detectors.…”