Coherent ultrafast measurement of time-bin encoded photons

TL;DR

This paper presents a novel ultrafast measurement technique for time-bin encoded photons using nonlinear interactions, enabling high-fidelity projective measurements with picosecond resolution, advancing quantum communication capabilities.

Contribution

Introduces a nonlinear interaction method for ultrafast, high-resolution projective measurements of time-bin encoded photons, surpassing previous detector limitations.

Findings

Successfully performed tomographically complete measurements

Achieved high fidelity violating CHSH-Bell inequality

Demonstrated picosecond-scale resolution in quantum measurements

Abstract

Time-bin encoding is a robust form of optical quantum information, especially for transmission in optical fibers. To read out 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 CHSH-Bell inequality by more than 6 standard deviations.