SKM 2021 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 13: Quantum Computing (joint session TT/DY)
TT 13.6: Vortrag
Mittwoch, 29. September 2021, 12:30–12:45, H7
Adaptive variational NISQ quantum algorithms for dynamics and excited states preparation — Yongxin Yao1,2, Niladri Gomes1,2, Feng Zhang1,2, Cai-Zhuang Wang1,2, Kai-Ming Ho1,2, Thomas Iadecola1,2, and •Peter P. Orth1,2 — 1Ames Laboratory, Ames, Iowa, USA — 2Iowa State University, Ames, Iowa, USA
Simulating quantum dynamics of interacting many-body systems is one of the main potential applications of quantum computing, since the growth of entanglement makes such simulations exponentially hard on classical devices. The shallow circuit requirement of current QPUs limits algorithms based on Trotter product formulas to simulate early time dynamics. Here, we present an adaptive approach to construct a variational wave function ansatz for accurate quantum dynamics simulations based on McLachlan’s variational principle [1]. The key idea is to dynamically expand the variational ansatz along the time-evolution path such that the McLachlan distance, which is a measure of the simulation accuracy, remains below a set threshold. We apply this adaptive variational quantum dynamics simulation approach (non)integrable quantum spin models and find the circuits to contain up to two orders of magnitude fewer CNOT gates than those obtained from first-order Trotter expansion. We also present results on development of an adaptive VQE-X algorithm for preparation of highly excited states in many-body models [2].
[1] Yao et al., PRX Quantum 2, 030307 (2021)
[2] Zhang et al., arXiv:2104.12636 (2021)