Ground state preparation of random all-to-all Hamiltonians using ADAPT-VQE

Gupta S, Sambasivam B, Economou SE, Barnes E, Kemper AF, Jha R
arXiv:2606.18339
arXiv
funding
DE-SCSC0025430, DE-SC0025384

Abstract

The ground state of random Hamiltonians with all-to-all interactions such as the quantum Sherrington-Kirkpatrick (SK) model and the Sachdev-Ye-Kitaev (SYK) model follow volume-law entanglement and are expected to be hard to model using tensor networks. In recent years, some progress has been made to push the limit of classical methods using neural quantum states. However, it remains an open question whether there exist quantum algorithms that could offer a quantum advantage over the state-of-the-art classical methods in simulating random Hamiltonians. In this work, we show that one such algorithm, TETRIS-ADAPT-VQE, can construct accurate ground states with high fidelity for dense and sparse SYK models containing up to N=20 Majorana fermion (with >= 99.3% fidelity) and for the quantum SK model with up to L=18 sites (with >= 99.9998% fidelity). We find that while the preparation of ground states is efficient (in terms of operator pool size and circuit depth) for the SK model, it is not efficient for either dense or moderately sparse SYK models.