Technology for Co-existence of Traditional Data and Quantum Information Over Long Distances

c. Technology for Co-existence of Traditional Data and Quantum Information Over Long Distances In order to most efficiently use resources including optical fiber, there is a need to have quantum states propagate along the same fiber that simultaneously carries traditional data traffic. The presence of traditional data signals can cause various noise and interference effects including Raman scattering and four-wave mixing. Since quantum signals are sensitive to background light levels of <<1 photon, these unwanted effects can seriously limit the amount of optical power that can be launched into the fiber and thereby limit the data rate that can be transmitted. One mitigation technique is to use a classical data wavelength that is much longer than the quantum wavelength. However, there is also the desire to have as low a loss at the quantum wavelength as possible, which is typically near 1550 nm. This project will study means to allow quantum and classical data to co-propagate over long distances. Any suitable designs including the use or optimization of Raman amplifiers, wavelength engineering, polarization control, modulation format, or any other technique can be considered provided it does not assume time-synchronization between all the channels which is seen as overly constrictive. A metric of the maximum data rate possible over 100 km of fiber propagation to maintain a ratio of quantum signal to classical noise of >10 is one way to assess the overall performance. Questions Contact: John Boger, john.boger@science.doe.gov