Tiny quantum sensor breaks noise limits, could boost MRI, space tech

Researchers at the Niels Bohr Institute (NBI) at the University of Copenhagen have developed a novel tunable quantum sensing system that significantly improves measurement accuracy by overcoming noise limits inherent in conventional optical sensors. This tabletop device leverages large-scale entanglement by pairing a multi-photon light state with a large atomic spin ensemble, enabling frequency-dependent squeezing of light. This approach reduces quantum noise across a broad frequency range by dynamically adjusting the phase and amplitude of light, which traditional systems cannot achieve without large-scale infrastructure. The innovation addresses both back-action noise—disturbances caused by the measurement process—and detection noise, enhancing sensor sensitivity beyond the standard quantum limit. Unlike previous frequency-dependent squeezing applications that require extensive optical resonators (around 300 meters long), the NBI team’s compact system achieves similar performance on a tabletop scale. Potential applications include improved detection of time variations, acceleration, and magnetic fields, with significant implications for biomedical imaging such as enhancing MRI resolution for earlier neurological disorder diagnosis, as well