Authors
Dominic W Berry, Craig Gidney, Mario Motta, Jarrod R McClean, Ryan Babbush
Publication date
2019/12/2
Journal
Quantum
Volume
3
Pages
208
Publisher
Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften
Description
Recent work has dramatically reduced the gate complexity required to quantum simulate chemistry by using linear combinations of unitaries based methods to exploit structure in the plane wave basis Coulomb operator. Here, we show that one can achieve similar scaling even for arbitrary basis sets (which can be hundreds of times more compact than plane waves) by using qubitized quantum walks in a fashion that takes advantage of structure in the Coulomb operator, either by directly exploiting sparseness, or via a low rank tensor factorization. We provide circuits for several variants of our algorithm (which all improve over the scaling of prior methods) including one with T complexity, where is number of orbitals and is the 1-norm of the chemistry Hamiltonian. We deploy our algorithms to simulate the FeMoco molecule (relevant to Nitrogen fixation) and obtain circuits requiring about seven hundred times less surface code spacetime volume than prior quantum algorithms for this system, despite us using a larger and more accurate active space.
Total citations
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