Data acquisition system for fast multichannel coincidence photon counting

In this paper we present the data acquisition (DAQ) system for a multichannel coincidence photon counter where this DAQ is optimized for a small coincidence window, high speed data retrieving without reduction and parallel data processing. For single photon detection we use Avalanche Photodiodes (APD) which are practical tools for detection in quantum optics and photonics quantum information experiments. However they introduce noise into the measurements originating from their dark count detection and after pulsing. One way to limit this contribution is to decrease the time window in which the coincidence detection measurement is performed. We have developed this DAQ based entirely on a standard Field Programmable Gate Array (FPGA) where the width of the coincidence time window is in the sub-nanosecond range. The same unit is also responsible for sending the result to the User Interface (UI). The communication between the UI and the FPGA platform is through a single link Peripheral Component Interconnect Express (PCIe) by means of streaming DMA. Our DAQ is developed for Xilinx Spartan-6 devices but other devices are also supported. A Linux driver with all necessary functionality to communicate with the DAQ as well as the UI is also developed. The use of our unit can be extended for other detection counting physical systems.