CQT Talk by Huang Zixin, Macquarie University
Title: Sub-wavelength quantumimaging and hypothesis testing for astronomy
Date/Time: 17-Aug, 02:00PM
Venue: Level 3 Seminar Room
Abstract: The resolution limit of standard imaging techniques is expressed by theRayleigh criterion, which states that two point-like sources are difficult toresolve if their transverse separation is smaller than the Rayleigh length.While the criterion is useful in the case of direct detection imaging, othermeasurement techniques may not be subject to this limitation. Estimatingthe angular separation between two sources is a challenging task for directimaging, especially when their angular separation is smaller than or comparableto the Rayleigh limit. In addition, if one is tasked with first discriminatingwhether there are one or two sources, then detecting the faint emission of asecondary source in the proximity of a much brighter one is in itself a severechallenge for direct imaging. Using quantum state discrimination and quantum imaging techniques, we show thatone can significantly reduce the probability of error for detecting thepresence of a weak secondary source, especially when the two sources have smallangular separations. If the weak source has intensity ε≪1 relative to the bright source, we find that theerror exponent can be improved by a factor of 1/ε. We also find linear-opticalmeasurements that are optimal in this regime [1]. We apply these techniques toLIDAR [2] as well as exoplanet detection. We then experimentally demonstrate clear sub-Rayleigh scaling for quantum statediscrimination of singular versus binary sources, and we approach the quantumCramer-Rao bound for estimating the angular separation of two sources withequal brightness. Most importantly, the two tasks can be achieved with a singlemeasurement setup: all the above tasks can be performed with a simpleinterferometer [3]. [1] Z Huang, C Lupo, Phys. Rev. Lett. 127, 130502 (2021); Editor's Selectionand Featured in Physics. [2] U Zanforlin, C Lupo, P Connolly, P Kok, G Buller, and Z Huang, accepted inNat. Comm. (2022); arXiv:2202.09406
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