Google Research

Quantum Chemistry Calculations on a Trapped-Ion Quantum Simulator

  • Cornelius Hempel
  • Christine Maier
  • Jhonathan Romero
  • Jarrod McClean
  • Thomas Monz
  • Heng Shen
  • Petar Jurcevic
  • Ben Lanyon
  • Peter J. Love
  • Ryan Babbush
  • Alán Aspuru-Guzik
  • Rainer Blatt
  • Christian Roos
Physical Review X, vol. 8 (2018), pp. 031022


Quantum-classical hybrid algorithms are emerging as promising candidates for near-term practical applications of quantum information processors in a wide variety of fields ranging from chemistry to physics and materials science. We report on the experimental implementation of such an algorithm to solve a quantum chemistry problem, using a digital quantum simulator based on trapped ions. Specifically, we implement the variational quantum eigensolver algorithm to calculate the molecular ground-state energies of two simple molecules and experimentally demonstrate and compare different encoding methods using up to four qubits. Furthermore, we discuss the impact of measurement noise as well as mitigation strategies and indicate the potential for adaptive implementations focused on reaching chemical accuracy, which may serve as a cross-platform benchmark for multiqubit quantum simulators.

Learn more about how we do research

We maintain a portfolio of research projects, providing individuals and teams the freedom to emphasize specific types of work