How to train your quantum dragon

Quantum transport in nanoscale devices provides a stringent benchmark for next-generation computing, communication, and sensing devices, as well as improved energy management and novel functionalities in fields like molecular electronics and quantum computing. We present the first quantum-computer implementation of non-equilibrium Green’s functions (NEGF) to study quantum dragon nanodevices: tight-binding systems that maintain perfect and nearly perfect transmission T(E)≈1. The transport problem is reformulated as a linear system solved with a highly optimized Variational Quantum Linear Solver (VQLS)[1]. Moreover, an exact SVD-based ansatz with minimal parameters for 2- and 6-site dragons is employed as a fixed-structure variational quantum circuit. To accelerate expectation-value estimation, stitched Hadamard-test layouts exploit parallelism and reduce compilation overhead. For 2- and 6-site nanodevices, we confirm T(E)=1 for all propagating energies E in the attached leads, and recover quadratic suppression under weak disorder, consistent with the dragon paradigm[2]. These results establish a pathway for condensed-matter and nuclear physicists to leverage quantum hardware for first-principles transport simulations.

1-C. Bravo-Prieto et al., Quantum, 7, 1188 (2023).

2-M. A. Novotny et al., Chaos, Solitons & Fractals, vol. 199(P3) (2025).