Indexed on: 07 Jul '17Published on: 07 Jul '17Published in: arXiv - Quantum Physics
The frequency degree of freedom in photonic quantum states offers a promising platform for scalable and robust Quantum Information Processing (QIP), and can easily be extended to higher dimensions to simplify the implementation of quantum circuits as well as to improve the robustness of quantum communications. In this regard, quantum frequency combs from chip-scale integrated sources are good candidates for frequency domain QIP due to their low cost, material scalability and compatibility with semiconductor foundries. However, to use these quantum combs for frequency domain QIP, a demonstration of entanglement in the frequency basis, showing that the entangled photons are in a coherent superposition of multiple frequency bins, is required. We present a verification of high-dimensional frequency-bin entanglement of an on-chip quantum frequency comb with 40 mode pairs, through a two-photon interference measurement that is based on electro-optic phase modulation. Our demonstrations are an important step in establishing integrated optical microresonators as a source for high-dimensional frequency-bin encoded quantum computing, as well as dense quantum key distribution.