Noise self-cancelling metrology using twisted light

Noise fundamentally limits the ultimate optical precision. Here, we unveil a real-time noise self-cancelling metrology by exploiting the unique spiral phase of light possessing orbital angular momentum (OAM). With a compact twisted interferometer and a novel measurement scheme exploiting an ensemble of N phase-orthogonal single-pixel intensity pairs on petals of the daisy flower-like interference pattern, we cancel various noises (intensity noise, interferometer noise, and detector noise) by three orders of magnitude, enabling detection of a weak input signal, in excellent agreement with our theoretical analysis. Remarkably, our approach allows detection of an aperiodic, non-repetitive dynamic event masked by 100x larger noise background faithfully with picoscale resolution, which is otherwise undetectable. Because no upper limit on the quantum numbers of OAM state exists, in principle, the noise cancellation scales up indefinitely. These results open promising ways to enhance precision metrology, secure communication, and develop analogous ideas for twisted acoustic waves, electron beams, and matter waves.