We have a new paper Coherent Ultrafast Measurement of Time-Bin Encoded Photons by John Donohue, Megan Agnew, Jonathan Lavoie, and Kevin Resch which has just been published in Physical Review Letters. The paper was chosen as an Editors Suggestion and reviewed in the article It’s a Good Time for Time-Bin Qubits by Todd Pittman (University of Maryland) in Physics.
Abstract: Time-bin encoding is a robust form of optical quantum information, especially for transmission in optical fibers. To readout the information, the separation of the time bins must be larger than the detector time resolution, typically on the order of nanoseconds for photon counters. In the present work, we demonstrate a technique using a nonlinear interaction between chirped entangled time-bin photons and shaped laser pulses to perform projective measurements on arbitrary time-bin states with picosecond-scale separations. We demonstrate a tomographically complete set of time-bin qubit projective measurements and show the fidelity of operations is sufficiently high to violate the Clauser-Horne-Shimony-Holt-Bell inequality by more than 6 standard deviations.