Optical Phase Measurement Using Entangled Photons

Tomohisa Nagata, Ryo Okamoto, Jeremy L. O’Brien +2 more

Precision measurements are important across all fields of science. In particular, optical phase measurements can be used to measure distance, position, displacement, acceleration, and optical path length. Quantum entanglement enables higher precision than would otherwise be possible. We demonstrated an optical phase measurement with an entangled four-photon interference visibility greater than the threshold to beat the standard quantum limit-the limit attainable without entanglement. These results open the way for new high-precision measurement applications.

Guo‐Yong Xiang, Brendon L. Higgins, Dominic William Berry +2 more

Paul A. Knott, Jacob Dunningham

Austin T. Green, Jérémy R. Rouxel, Vladimir Chernyak +1 more

Entangled photons can encode more information than classical light, enabling quantum-enhanced optical measurements. We formulate optical rotatory dispersion (ORD) spectroscopy as a quantum metrology phase-estimation problem using photons entangled in their orbital angular momentum (OAM). While polarization-entangled photons have previously been shown to improve the precision of ORD measurements, we extend this approach by exploiting the higher-dimensional entanglement available through photon OAM. We show how the optical activity of a medium can be imprinted on the interference patterns of OAM-entangled photons measured by coincidence detection. The attainable precision of this setup, quantified by the Fisher information, exceeds that of the classical detection scheme. Our analysis shows that the metrological performance is controlled by the symmetry of the entangled state, the OAM index through the Gouy phase accumulated in the detection geometry, and the pixel resolution of the detectors. Beyond chiroptical spectroscopy, our results provide a general strategy for the broader task of phase estimation with entangled structured light.

Li-Zheng Liu, Yu-Zhe Zhang, Zheng-Da Li +8 more

Giora Peniakov, Zu-En Su, Amir Beck +3 more

In principle, the use of entangled photons provides enhanced precision in optical phase measurements. This precision significantly surpasses the classical shot-noise limit, and thereby has many possible applications in science and technology. In practice, however, entangled multiphoton states have been generated so far using various intrinsically probabilistic and unscalable processes, thereby counteracting the advantages that the entangled photon states might have. The authors overcome these limitations here by using a quantum knitting machine, based on a single semiconductor quantum dot, to generate a polarization-entangled multiphoton state in a deterministic manner. The multiphoton state is then used to demonstrate super-sensitive optical phase measurement. The results pave the way for realizing genuine quantum enhanced optical measurements in the very near future.