A correlator for constructing the second-order autocorrelation function g(2)(τ) implemented on a field-programmable gate array (FPGA) is presented. The device is intended for high-precision recording of time intervals between photons emitted by single emitters. Using an FPGA made it possible to achieve a temporal resolution of 185 ps and real-time event processing. Experimental data confirming the achievement of photon antibunching with g(2)(0) < 0.5, which is typical for single quantum emitters, are demonstrated. The device can be used for analyzing photon correlations in tasks of quantum optics and when working with single quantum emitters.
A correlator for constructing the second-order autocorrelation function g(2)(τ) implemented on a field-programmable gate array (FPGA) is presented. The device is intended for high-precision recording of time intervals between photons emitted by single emitters. Using an FPGA made it possible to achieve a temporal resolution of 185 ps and real-time event processing. Experimental data confirming the achievement of photon antibunching with g(2)(0) < 0.5, which is typical for single quantum emitters, are demonstrated. The device can be used for analyzing photon correlations in tasks of quantum optics and when working with single quantum emitters.
Abstract This paper presents a correlator for constructing the second-order autocorrelation function g(2)(τ), implemented on a field-programmable gate array (FPGA). The device is designed for high-precision recording of time intervals between photons detected from single emitters. The use of an FPGA makes it possible to achieve a time resolution of 185 ps and real-time event processing. Experimental data confirming the achievement of photon antibunching with g(2)(0) < 0.5, characteristic of single quantum emitters, are demonstrated. The device can be used to analyze photon correlations in quantum optics problems and when working with single quantum emitters.
Several quantum setups, such as quantum key distribution networks[1] and quantum simulators (e.g. boson sampling), by their design rely on single photon sources (SPSs). These quantum setups were demonstrated to operate in optical frequency domain. However, following the steady advances in circuit quantum electrodynamics, a proposal has been made recently[2] to demonstrate boson sampling with microwave photons. This in turn requires the development of reliable microwave SPS. It’s one of the most important characteristics are the first-order and the second-order correlation functions g1 and g2. The measurement technique of g1 and g2 is significantly different from that in the optical domain [3],[4] because of the current unavailability of microwave single-photon detectors. In particular, due to high levels of noise present in the system a substantial amount of statistics in needed to be acquired. This work presents a platform for measurement of g1 and g2 that processes the incoming data in real time, maximizing the efficiency of data acquisition. The use of field-programmable gate array (FPGA) electronics, common in similar experiments[3] but complex in programming, is avoided; instead, the calculations are performed on a standard desktop computer. The platform is used to perform the measurements of the first-order and the second-order correlation functions of the microwave SPS.
The detection of temporally coincident signals plays an important role in different technological applications for metrology and communication, and particularly, in the area of quantum optics. In this sense, the simultaneous detection of two or more photons allows one to take advantage of the non-classical features of light that manifest themselves in certain types of correlations that cannot be described classically. We present here the development of programmable modules, by using FPGA technology, which are part of the coincident pulse detection and counting system. Our implementation, in a development board from Xilinx, allows to determine when two or more pulses overlap within a temporal window, with a configurable width in the range of 1 and 255 ns to compensate for possible path differences. We obtained the photodetection statistics result of the single and coincident pulse measurements and compared them with that predicted by a theoretical analysis. In addition, we have emulated the signals corresponding to different photon sources through a beam splitter, and obtained the photodetection statistics from which we determine, for each case, the second order correlation function g(2)(τ).
Precise time synchronization is a fundamental challenge in distributed quantum systems, with direct implications for secure communication, sensing, and next-generation network technologies. In this study, we present a Field Programmable Gate Array (FPGA)-based implementation of a Time-Correlated Entangled Photons (TCEP) source-based synchronization system, achievingsub-nanosecondaccuracy with timing jitter consistently below 200 ps for a distance up to 20 km. The system leverages the strong temporal correlations inherent in entangled photon pairs to compute synchronization offsets between spatially separated nodes. The design features a modular architecture with optimized kernels for temporal correlation, data aggregation, and normalization, enabling efficient resource utilization and high-throughput performance. Experimental validation demonstrates the FPGA's ability to process photon timestamp data and compute cross-correlation functions significantly faster than traditional CPU-based approaches, achieving execution times in the millisecond range even for large datasets. Our FPGA implementation achieved a consistent$\sim$800 times speedup over CPU, with performance largely unaffected by channel length. Resource utilization analysis highlights the scalability of the design, with the fully integrated system operating at a clock frequency of 397.5 MHz while maintaining efficient use of logic elements, registers, and memory blocks. This hardware-efficient approach provides the timing backbone for next-generation technologies, facilitating advancements in ultra-reliable low-latency communication, distributed quantum computing, quantum-enhanced sensing, navigation, and lays a foundation for forthcoming 6G networks and the quantum internet.
Coincidence counters play the role of gating events from the background noise in almost every quantum photonics setup. Precise multi-channel and high count-rate coincidence counting tools have become desirable due to an increase in the complexity of quantum photonics experiments. However, timing analyzers are struggling to meet these needs. We are proposing a Field Programmable Gate Array (FPGA) based coincidence counting system which provides 8 operational channels with 8.9 ps root mean square (RMS) resolution (with a bin width of 7.7 ps) and a count-rate of 320 million counts per second (MCPS) (with 40 MCPS per channel). We have successfully tested our design in different quantum photonics scenarios such as the detection of two-photon interference and pseudo-photon-number resolving detection of a coherent state of light where it has shown its capability of working beyond the saturation of detectors. Also, we have introduced a Dual Data Rate Registration TDC, which improved the linearity of the time tagging operation by using both clock edges without increasing the dead-time or using the space excessively. 1.2 LSB in max DNL error, 1.8 LSB in max INL error, 10 ps in FWHM and 3.2 ps in RMS resolution improvements were achieved.
The second-order correlation function of light g(2)(τ) constitutes a pivotal tool to quantify the quantum behavior of an emitter and in turn its potential for quantum information applications. The experimentally accessible time resolution of g(2)(τ) is usually limited by the jitter of available single-photon detectors. Here, we present a versatile technique allowing g(2)(τ) to be measured from a large variety of light signals with a time resolution given by the pulse length of a mode-locked laser. The technique is based on frequency upconversion in a nonlinear waveguide, and we analyze its properties and limitations by modeling the pulse propagation and the frequency conversion process. We measure g(2)(τ) from various signals including light from a quantum emitter—a confined exciton-polariton structure—revealing its quantum signatures at a scale of a few picoseconds and demonstrating the capability of the technique.