A Four-Channel GPS-Referenced Pulse Time Stamper with Sub-10 ns Granularity for Photon Correlation Measurements

We report the design and implementation of a four-channel pulse time-stamping system optimized for high-precision photon counting and correlation experiments in atomic, molecular, and optical physics. The instrument achieves sub-10 ns timing granularity with Cortex-M7 microcontrollers by performing rising edge input capture from a 150 MHz system clock, and accepts sensor output logic pulses with levels ranging from 3.3V to 12V. All four input channels are independently monitored by separate microcontrollers to facilitate simultaneous capture and data storage, and all four controllers reference the same GPS-derived 1 pulse-per-second (1 PPS) signal to correct for any drift in the separate internal clocks. This architecture provides absolute timing referenced to UTC while preserving precise relative timing correlations among detector channels. Event times are recorded for offline analysis, allowing reconstruction of photon arrival statistics over extended acquisition periods. The system is particularly well suited for measurements of photon correlation functions, including bunching and anti-bunching phenomena, as well as other time-resolved quantum optical experiments requiring long-term stability and absolute time referencing. By combining high sensitivity, multi-channel capability, and GPS synchronization in a compact architecture, this instrument provides a flexible and cost-effective platform for precision timing applications in AMO physics.