🤖 AI Summary
This work addresses the challenge of effectively training and deploying quantum neural networks under the stringent power and area constraints imposed by cryogenic control electronics, particularly low-resolution digital-to-analog converters (DACs). The study is the first to identify the gradient deadlock phenomenon that arises under low-precision quantization and introduces a temperature-controlled stochastic parameter update mechanism to mitigate this issue. The proposed method enables efficient training with DAC resolutions as low as 4–10 bits, overcoming conventional quantization bottlenecks. Remarkably, it achieves near full-precision baseline accuracy during 6-bit inference and even surpasses high-precision benchmarks when trained with only 4-bit resolution, substantially reducing hardware power consumption and area overhead.
📝 Abstract
Scaling quantum computers requires tight integration of cryogenic control electronics with quantum processors, where Digital-to-Analog Converters (DACs) face severe power and area constraints. We investigate quantum neural network (QNN) training and inference under finite DAC resolution constraints, evaluating two QNN architectures across four diverse datasets (MNIST, Fashion-MNIST, Iris, Breast Cancer). Pre-trained QNNs achieve accuracy nearly indistinguishable from infinite-precision baselines when deployed on quantum systems with 6-bit DAC control electronics, exhibiting characteristic elbow curves with diminishing returns beyond 3-5 bits depending on the dataset. However, training QNNs directly under quantization constraints reveals gradient deadlock below 12-bit resolution, where parameter updates fall below quantization step sizes, preventing training entirely. We introduce temperature-controlled stochastic quantization that overcomes this limitation through probabilistic parameter updates, enabling successful training at 4-10 bit resolutions. Remarkably, stochastic quantization not only matches but frequently exceeds infinite-precision baseline performance across both architectures and all datasets. Our findings demonstrate that low-resolution control electronics (4-10 bits) need not compromise QML performance while enabling substantial power and area reduction in cryogenic control systems, presenting significant implications for practical quantum hardware scaling and hardware-software co-design of QML systems.