International Symposium on Highly Efficient Accelerators and Reconfigurable Technologies (HEART)
Quantized NN Workflow for Low-Latency Multi-Qubit State Discrimination on FPGA
Pradeep Kumar Gautam, Shantharam Kalipatnapu, H Shankaranarayanan, Ujjawal Singhal, Benjamin Lienhard, Vibhor Singh, Chetan Singh Thakur
Abstract
Measuring a qubit state is a fundamental but error-prone task in quantum computing. As the number of qubits increases, scalable readout demands multiplexed qubit measurement, which often suffers from crosstalk and other nonidealities. The conventional approach of qubit state detection often struggles with scalability and noise resilience. Neural network (NN)-based discriminators have emerged as a promising alternative, offering superior performance for inferring qubit states from multiplexed signals. However, their deployment on hardware platforms like Field programmable gate arrays (FPGA) is hindered by computation complexity, resource constraints, and latency. In this work, we present an end-to-end methodology for designing and deploying quantized NN-based multi-qubit state discriminators on FPGAs. We demonstrate that implementing a fully connected neural network accelerator for multi-qubit readout is advantageous, balancing computational complexity with low latency requirements without significant loss in accuracy. We significantly reduce the FPGA footprint and latency of the neural network by employing quantization-aware training (QAT) to quantize weights, activations, and inputs, and leveraging automated mapping flows for efficient, hardware-aware design-space exploration and optimization. The hardware accelerator performs frequency-multiplexed readout of five superconducting qubits in 26.7 ns, on a radio frequency system on chip (RFSoC) ZCU111 FPGA. These modules can be implemented and integrated into existing FPGA based quantum control and readout platforms, making them ready for experimental deployment.