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arXiv · 1908.09836

Variational Quantum Algorithm for Non-equilibrium Steady States

Nobuyuki Yoshioka·Yuya O. Nakagawa·Kosuke Mitarai·Keisuke Fujii
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Abstract

We propose a quantum-classical hybrid algorithm to simulate the non-equilibrium steady state of an open quantum many-body system, named the dissipative-system Variational Quantum Eigensolver (dVQE). To employ the variational optimization technique for a unitary quantum circuit, we map a mixed state into a pure state with a doubled number of qubits and design the unitary quantum circuit to fulfill the requirements for a density matrix. This allows us to define a cost function that consists of the time evolution generator of the quantum master equation. Evaluation of physical observables is, in turn, carried out by a quantum circuit with the original number of qubits. We demonstrate our dVQE scheme by both numerical simulation on a classical computer and actual quantum simulation that makes use of the device provided in Rigetti Quantum Cloud Service.

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Nobuyuki Yoshioka, Yuya O. Nakagawa, Kosuke Mitarai, Keisuke Fujii. 2019-08-26. Variational Quantum Algorithm for Non-equilibrium Steady States. https://doi.org/10.1103/physrevresearch.2.043289

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