Dynamical mean field theory (DMFT) is a state-of-the-art method to compute systems of strongly correlated electrons. In this theory, one partitions the system into an effective impurity describing the strongly interacting local orbitals, and a bath that models the orbitals of neighbouring atoms and is coupled to the impurity. Its applications have mainly been directed to condensed matter systems, although it is increasingly being adopted for the study of chemical systems like reactions in metalloproteins or surface adsorption phenomena. Solving the effective problem of an interacting impurity coupled to a bath scales exponentially with system size on conventional computers, and for this reason the high computational cost required for accurate solutions limits DMFT to small systems. An exponential speedup is expected on quantum computers, but the algorithms proposed so far are based on real time evolution of the wavefunction, which requires very low noise levels in the quantum hardware, and thus it is not feasible on the current generation of noisy intermediate scale quantum computers. Here we present a quantum algorithm to perform DMFT calculations on currently available quantum computers, and demonstrate it on two quantum hardware platforms. This approach uses the variational quantum eigensolver (VQE) method for ground and excited states to obtain the needed quantities as part of an exact diagonalization impurity solver. VQE has demonstrated its capability to mitigate noise in electronic structure calculations of small molecules on NISQ hardware. We present the algorithm for a two site DMFT system, which we benchmark using simulations on conventional computers as well as experiments on superconducting and trapped ion qubits, demonstrating that this method is suitable for running DMFT calculations on currently available quantum hardware.

Noise-resilient dynamical mean field theory algorithm and experimental realization on quantum computers

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.