Design and Development of Flexible and Low-Cost Coincidence Counting Unit

A flexible and low-cost Coincidence Counting Unit (CCU) with customizable features that are software selectable is designed and developed for the use in various experiments of quantum information and quantum metrology. A digital logic-based implementation approach using Field Programmable Gate Array is followed with specific emphasis on reducing the time for coincidence events of photons and making it easily scalable. In this paper, an 8-channel CCU with software configurable features such as coincidence window selection (in increment of 0.54 ns) and 8-fold coincidences (up to 4 sets) at a time has been implemented.