Quantum simulation of excited states from parallel contracted quantum eigensolvers

Abstract

Computing excited-state properties of molecules and solids is considered one of the most important near-term applications of quantum computers. While many of the current excited-state quantum algorithms differ in circuit architecture, specific exploitation of quantum advantage, or result quality, one common feature is their rooting in the Schrödinger equation. However, through contracting (or projecting) the eigenvalue equation, more efficient strategies can be designed for near-term quantum devices. Here we demonstrate that when combined with the Rayleigh-Ritz variational principle for mixed quantum states, the ground-state contracted quantum eigensolver (CQE) can be generalized to compute any number of quantum eigenstates simultaneously. We introduce two excited-state (anti-Hermitian) CQEs that perform the excited-state calculation while inheriting many of the remarkable features of the original ground-state version of the algorithm, such as its scalability. To showcase our approach, we study several model and chemical Hamiltonians and investigate the performance of different implementations.

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Cited by in corpus (7)

• Exact Ansatz of Fermion-Boson Systems for a Quantum Device
• Ground and Excited States from Ensemble Variational Principles
• Characterizing conical intersections of nucleobases on quantum computers
• Subspace-Search Quantum Imaginary Time Evolution for Excited State Computations
• Equation-of-motion internally contracted multireference unitary coupled-cluster theory
• Transformation-free generation of a quasi-diabatic representation from the state-average orbital-optimized variational quantum eigensolver
• Correlated Purification for Restoring $N$-Representability in Quantum Simulation