Indexed on: 11 Nov '16Published on: 11 Nov '16Published in: arXiv - Quantum Physics
Quantum information processing (QIP) promises to improve the security of our communications as well as to solve some algorithms with exponential complexity in polynomial time. Biphotons have been demonstrated as one of the most promising platforms for real implementations of QIP systems. In particular, time-bin entangled photons have been used for implementations of quantum gates which require highly stable interferometers. On the other hand, frequency-bin entanglement has been proposed to avoid the use of interferometers and the complexity of their stabilization, which potentially makes the implementation of quantum gates highly scalable. Through Fourier transform pulse shaping and electro-optic modulation, there has been a wide range of experiments that show control of entangled photons in the frequency domain. In addition, biphoton frequency combs (BFC) have also been generated using bulk optics and frequency filtering of broadband continuous biphoton spectra. However, on-chip entangled photon pair generation provides a suitable platform because of its reduced cost and compatibility with semiconductor foundries. Here, we begin exploring the time-frequency signatures of on-chip biphoton frequency combs. For the first time, we demonstrate nonlocal dispersion cancellation, a foundational concept in time-energy entanglement, with a chip-generated BFC, suggesting the potential for large-alphabet quantum key distribution. Also, we examine the multifrequency nature of our photon-pair source in a time entanglement measurement scheme. Taking advantage of multiple frequencies from the BFC results in a modulation of the interference pattern, which simultaneously proves time-entanglement for all frequencies. These BFCs potentially offer a new path towards high-dimensional frequency-bin entanglement for highly scalable quantum computing.