High-dimensional quantum information processing promises capabilities beyond the current state of the art, but addressing individual information-carrying modes presents a significant experimental challenge. Here we demonstrate effective high-dimensional operations in the time-frequency domain of non-classical light. We generate heralded photons with tailored temporal-mode structures through ultrafast pulse shaping of a parametric downconversion pump. We then implement a quantum pulse gate, enabled by dispersion-engineered sum-frequency generation, to project onto programmable temporal modes, reconstructing the quantum state in seven dimensions. We also manipulate the time-frequency structure by selectively removing temporal modes, explicitly demonstrating the effectiveness of engineered nonlinear processes for mode-selective manipulation of quantum states.
@article{arxiv.1607.03001,
title = {Tomography and Purification of the Temporal-Mode Structure of Quantum Light},
author = {Vahid Ansari and John M. Donohue and Markus Allgaier and Linda Sansoni and Benjamin Brecht and Jonathan Roslund and Nicolas Treps and Georg Harder and Christine Silberhorn},
journal= {arXiv preprint arXiv:1607.03001},
year = {2018}
}