Quantum Noise Theory of Exceptional Point Sensors

Understand

Distinct from closed quantum systems, non-Hermitian system can have exceptional points (EPs) where both eigenvalues and eigenvectors coalesce.

• Recently, it has been proposed and demonstrated that EPs can enhance the performance of sensors in terms of amplification of detected signal.
• Meanwhile, the noise might also be amplified at EPs and it is not obvious whether exceptional points will still improve the performance of sensors when both signal and noise are amplified.
• We develop quantum noise theory to systematically calculate the signal and noise associated with the EP sensors.