Improved quantum computing algorithm to find ground states of correlated quantum models

Quantum computing algorithm data charts
Top: As imaginary time 𝜏 increases, the energy error decreases beyond chemical accuracy. The circuit depth, given by the number of Controlled NOT (CNOT) gates, grows initially and then saturates. Bottom: the adaptive ansatz is automatically constructed by choosing generators from an operator pool.
Scientific Achievement

A new variational quantum algorithm improves the preparation of quantum many-body ground states by automatically building efficient quantum circuits.

Significance and Impact

This efficient method enables determination of ground state properties of molecules and materials using current noisy intermediate-scale quantum computing technology.

Research Details
  • The flexible algorithm builds quantum circuits adaptively for a given model by minimizing the distance to the exact evolution along an imaginary time path 
  • The method avoids complex high-dimensional parameter optimization and exhibits a favorable scaling of the circuit depth with system size. 
  • Obtained ground state energies of various molecules with better than chemical accuracy (<1 kcal/mol). 

N. Gomes, A. Mukherjee, F. Zhang, T. Iadecola, C.-Z. Wang, K.-M. Ho, P. P. Orth, and Y.-X. Yao, "Adaptive Variational Quantum Imaginary Time Evolution Approach for Ground State Preparation," Adv. Quantum Technol. 2100114 (2021).