arXiv:2304.01190 · IEEE Journal of Quantum Electronics
Entangled Photon Pair Source Demonstrator Using the Quantum Instrumentation Control Kit System
S. Xie, Leandro Stefanazzi, Christina W. Wang, Cristián Peña, Raju Valivarthi, Lautaro Narváez, Gustavo I. Cancelo, Keshav Kapoor, Boris A. Korzh, Matthew D. Shaw, Panagiotis Spentzouris, M. Spiropulu
We report the first demonstration of using the Quantum Instrumentation and Control Kit (QICK) system on RFSoC-FPGA technology to drive the electro-optic intensity modulator that generate time-bin entangled photon pairs and to detect the photon signals. With the QICK system, we achieve high levels of performance metrics including coincidence-to-accidental ratio exceeding 150, and entanglement visibility exceeding 95%, consistent with performance metrics achieved using conventional waveform generators. We also demonstrate simultaneous detector readout using the digitization functional of QICK, achieving internal system synchronization time resolution of 3.2 ps. The work reported in this paper represents an explicit demonstration of the feasibility for replacing commercial waveform generators and time taggers with RFSoC-FPGA technology in the operation of a quantum network, representing a cost reduction of more than an order of magnitude.
We report the first demonstration of using the Quantum Instrumentation and Control Kit (QICK) system on RFSoC-FPGA technology to drive the electro-optic intensity modulator that generate time-bin entangled photon pairs and to detect the photon signals. With the QICK system, we achieve high levels of performance metrics including coincidence-to-accidental ratio exceeding 150, and entanglement visibility exceeding 95%, consistent with performance metrics achieved using conventional waveform generators. We also demonstrate simultaneous detector readout using the digitization functional of QICK, achieving internal system synchronization time resolution of 3.2 ps. The work reported in this paper represents an explicit demonstration of the feasibility for replacing commercial waveform generators and time taggers with RFSoC-FPGA technology in the operation of a quantum network, representing a cost reduction of more than an order of magnitude.
Scalable quantum networks require quantum interfaces that coherently connect stationary matter qubits with flying photonic qubits. In solid-state defect platforms, such interfaces require coordinated optical excitation, microwave spin control, photon detection, and feedback with nanosecond-level timing, while conventional instrument-based control systems become increasingly difficult to scale as experimental protocols grow in complexity. Here we present an open-source FPGA control architecture for solid-state spin–photon interface experiments. Built on the Quantum Instrumentation Control Kit (QICK), the platform extends the existing FPGA overlay by integrating a programmable multi-channel single-photon counter, enabling photon-count–centric experiment execution while preserving compatibility with the QICK software ecosystem. This architecture integrates time-gated single-photon detection with synchronized RF, microwave, and digital control within a unified hardware environment. Using single nitrogen-vacancy (NV) centers in diamond, we experimentally validate the platform through microwave spin manipulation, resonant optical control, automated measurement routines, and time-bin–encoded spin–photon correlation protocols relevant to quantum networking. These results establish an extensible and experimentally validated control framework for solid-state spin–photon interfaces, with clear potential to accelerate the development of scalable quantum-network nodes.
The QICK (Quantum Instrumentation Control Kit), first introduced in 2022, is a standalone open source control system for quantum information science. Since then, QICK has been migrated to new hardware platforms, expanded its functionality for applications with different types of qubits (superconducting, atomic, ion-trapped, and spin defects), as well as quantum sensors, and quantum networks. QICK is a highly optimized control kit, with a library of functions that can be used for more than one application. In particular, the software and firmware are customized to minimize latency and maximize control performance and throughput. In this white paper, we describe hardware details and performance of the QICK Box. The QICK Box features up to 16 outputs, up to 8 inputs, and 8 20-bit DC biases. Modular output and input daughtercards give the choice of signal chains optimized for fast DC-coupled signals or RF signals up to 10 GHz. Power levels, step attenuation, and bandpass filtering are controlled by software. We demonstrate the system's performance through single-shot readout measurements of a six-transmon device at the Quantum Underground Instrumentation Experimental Testbed (QUIET) at Fermilab, achieving (91.7 +/- 0.4)% readout fidelity limited by T1 decay during the readout. The single shot readout signal-to-noise ratio (SNR) is 4.4 +/- 0.1 without a quantum amplifier, confirming that the QICK Box is suitable for high-fidelity quantum control and measurement applications. Advances in firmware and software will be described in a separate paper.
This thesis presents the development of a superconducting qubit control and readout system based on FPGA technology, with a focus on the design of a pulse sequencer and the integration of frequency-multiplexed control. The system leverages the Quantum Instrumentation Control Kit (QICK), an open-source Xilinx RFSoC-based platform capable of direct digital synthesis and acquisition of microwave signals up to 10 GHz. The QICK firmware was extended to support the simultaneous generation and readout of multiple frequency-multiplexed tones, enabling the control and measurement of several qubits coupled to a shared feedline. This approach optimizes the number of controllable qubits relative to the available ADC and DAC resources on the RFSoC 4x2 board. Furthermore, this work includes the development of Qubase, a Python-based pulse sequencer that allows users to easily define and execute complex sequences of control and measurement pulses through the QICK Python interface. The resulting architecture is both flexible and scalable, providing a foundation for efficient multi-qubit experiments and enabling advanced techniques such as quantum error correction and real-time feedback.
Entangled photon pairs are created by a system consisting of a 1064 nm pump diode laser that is fiber coupled to a high generation rate photon pair source. The source is a dual element periodically poled potassium titanyl phosphate (KTP) waveguide that up-converts 1064 nm photons to single 532 nm photons in the first stage. In the second stage, the green photons are down converted to energy entangled photon pairs at 800 nm and 1600 nm. The output photon pairs are guided by fiber to sorting optics where they are separated and sent into high-efficiency photon detectors. In particular, the 1600 nm photons are detected by a superconducting nanowire with efficiency over 60% and dead time less than 50 ns. Detector output electrical signals are sent to a time tagger with bin resolution as narrow as 25 ps for coincidence counting. The ultimate goal of this setup is to demonstrate a singlesource, high efficiency, high data rate, quantum communication system to enable Earth-space quantum networks. Of particular interest is a source of entangled photons that is amenable to utilization in aircraft and spacecraft under rigorous flight and environmental conditions. Test results that characterize the entangled photon pair creation and detection capabilities of our system will be presented.
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.
The operation of long-distance quantum networks requires photons to be synchronized and must account for length variations of quantum channels. We demonstrate a 200 MHz clock-rate fiber optic-based telecommunication C-band quantum network using off-the-shelf components combined with custom-made electronics. The network is backed by a scalable and fully automated synchronization system with ps-scale timing resolution. Synchronization of the photons is achieved by distributing O-band-wavelength laser pulses between network nodes. Specifically, we distribute photon pairs between three nodes, and measure a reduction of coincidence-to-accidental ratio from 77 to only 42 when the synchronization system is enabled, which permits high-fidelity qubit transmission. Our demonstration sheds light on the role of noise in quantum communication and represents a key step in realizing deployed co-existing classical-quantum networks.