Our paper “Ultrafast measurement of energy-time entanglement with an optical Kerr shutter” by Andrew Cameron, Kate Fenwick, Sandra L. Cheng, Sacha Schwarz, Benjamin MacLellan, Philip Bustard, Duncan England, Benjamin Sussman, and Kevin Resch was published in Physical Review A. This work is a collaborative effort between the University of Waterloo and the National Research Council of Canada.
Abstract: The energy-time degree of freedom has emerged as a promising avenue for photonic quantum technologies due to its intrinsic robustness against decoherence; however, the timescales associated with energy-time entangled photons make for difficult measurement and manipulation. We implement two optical Kerr gates, in short (35 mm) pieces of single-mode fiber, to achieve ultrafast measurement of the time correlations of energy-time entangled photon pairs, with resolutions of 320 ± 30 fs and 290 ± 30 fs for signal and idler photons, respectively. These measurements, in addition to joint spectral measurements of the photon-pair state, are used to verify entanglement by means of the violation of a time-bandwidth inequality. Without the need for an interferometric setup or frequency conversion, the optical Kerr shutter is a valuable addition to the ultrafast quantum optics control and metrology toolbox.
