1. Dr. Yu and colleagues present a table-top experiment using maximally path-entangled quantum states of light in an interferometer with an area of 715 meter squared, sensitive enough to measure the rotation rate of Earth. A rotatable setup and an active area switching technique allow us to control the coupling of Earth's rotation to an entangled pair of single photons. The achieved sensitivity of 5 μrad/s constitutes the highest rotation resolution ever achieved with optical quantum interferometers, surpassing previous work by three orders of magnitude. To the best of our knowledge, this is the largest quantum-optical Sagnac interferometer in the world, surpassing previous state-of-the-art rotation sensors employing two-particle entanglement. This measurement represents a significant milestone in the development of larger-scale quantum interferometers. Our result demonstrates the feasibility of extending the utilization of maximally entangled quantum states to large-scale interferometers. Further improvements to our methodology will enable measurements of general-relativistic effects on entangled photons opening the way to further enhance the precision of fundamental measurements to explore the interplay between quantum mechanics and general relativity along with searches for new physics.
2. For the first time, Dr. Yu proposes an experiment that uses single photon detection interferometry to search for axions and axion-like particles in the galactic halo. It is shown that photon counting with a dark rate of 6E-6 Hz can improve the quantum sensitivity of axion interferometry by a factor of 50 compared to the quantum-enhanced heterodyne readout for 5-m long optical resonators. The proposed experimental method has the potential to be scaled up to kilometer-long facilities, enabling the detection or setting of constraints on the axion-photon coupling coefficient of 1E-17 - 1E-16 GeV-1 for axion masses ranging from 0.1 to 1 neV, achieving an unprecedented sensitivity of axion detection.
