Differential equations are essential and popular in science and engineering. Learning-based methods including neural operators, have emerged as a promising paradigm. We explore its quantum counterpart, and propose QuanONet – a quantum neural operator which has not been well studied in literature compared with their counterparts in other machine learning areas. We design a novel architecture as a hardware-efficient ansatz, in the era of noisy intermediate-scale quantum (NISQ). Its circuit is pure quantum. By lying its ground on the operator approximation theorem for its quantum counterpart, QuanONet in theory can fit various differential equation operators. We also propose its modified version TF-QuanONet with ability to adaptively fit the dominant frequency of the problem. The real-device empirical results on problems including anti-derivative operators, Diffusion-reaction Systems demonstrate that QuanONet outperforms peer quantum methods when their model sizes are set akin to QuanONet.

We rethink the basic operations, i.e., inner product and matrix multiplication used in neural networks. A quantum-inspired alternative is proposed, utilizing the power of high-dimensional Hilbert space by devising a high-order form of tensor product. We re-parameterize the original (low-order) vectors/matrices into an expressive high-order form, without incurring extra model parameters, and the extra computational overhead is negligible (e.g., about 2%). As an in-place transparent atomic operation, we show its use in the key components in Transformers: token embeddings, attentions (query, key, value) and the MLP. Due to its inherent compatibility to vanilla multiplicative operations, we propose C2Q-SFT, i.e., classic-to-quantum (C2Q) protocol for supervised fine-tuning (SFT): it continues to train a given model by transparently replacing the standard operations with ours. As shown by our experiments, it shows advantages for both training from scratch and fine-tuning on downstream tasks across scales of LLMs. C2Q-SFT consistently outperforms standard SFT, with relative improvements on MMLU (+0.56%) and GSM8k (+0.61%). It sheds light on the innovation of operations in networks, orthogonal to the efforts on new architecture, position encoding, and training algorithms, etc. See project page at: https://github.com/Thinklab-SJTU/LLM/QI-LLM.