Quantum mechanics

Gyroscope

Engineering

Cosmology

Scale factor (cosmology)

Optical fiber

Eigenvalues and eigenvectors

Computer science

Rotation (mathematics)

Ring laser gyroscope

Metric expansion of space

Dark energy

Physics

Brillouin zone

Optics

Fibre optic gyroscope

Electronic engineering

Resonator

Artificial intelligence

Sensitivity (control systems)

Brillouin scattering

Sagnac effect

Hermitian matrix

Dissipative system

Nature

Exceptional points (EPs) are special spectral degeneracies of non-Hermitian Hamiltonians that govern the dynamics of open systems. At an EP, two or more eigenvalues, and the corresponding eigenstates, coalesce1–3. Recently, it was predicted that operation of an optical gyroscope near an EP results in improved response to rotations4,5. However, the performance of such a system has not been examined experimentally. Here we introduce a precisely controllable physical system for the study of non-Hermitian physics and nonlinear optics in high-quality-factor microresonators. Because this system dissipatively couples counter-propagating lightwaves within the resonator, it also functions as a sensitive gyroscope for the measurement of rotations. We use our system to investigate the predicted EP-enhanced Sagnac effect4,5 and observe a four-fold increase in the Sagnac scale factor by directly measuring rotations applied to the resonator. The level of enhancement can be controlled by adjusting the system bias relative to the EP, and modelling results confirm the observed enhancement. Moreover, we characterize the sensitivity of the gyroscope near the EP. Besides verifying EP physics, this work is important for the understanding of optical gyroscopes. precisely controllable integrated optical gyroscope based on stimulated Brillouin scattering is used to study non-Hermitian physics, revealing a four-fold enhancement of the Sagnac scale factor near exceptional points.

Observation of the exceptional-point-enhanced Sagnac effect