Adaptive variational quantum computing approaches for response function calculations

Adaptive variational quantum circuit for single-particle Green’s function measurement. The adaptive variational quantum imaginary time evolution algorithm is used to generate the ground state circuit. The variational degrees of freedom are further utilized in subsequent adaptive variational real-time state propagation after the application of an ancilla-controlled multi-qubit Pauli gate to maximally compress the circuit.

Scientific Achievement

Accurate simulations of Green’s functions and nonlinear susceptibilities for electron and spin systems are achieved with highly compressed circuits.

Significance and Impact

This enables simulations of response functions crucial to interpret experimental results and predict materials properties using near-term quantum processors.

Research Details

  • Development of an adaptive variational quantum algorithm to accurately measure single-particle Green’s functions and nonlinear susceptibilities along the real-time axis.
  • Benchmark calculations for fermionic models, molecules, and spin systems.
  • Demonstration of substantially shallower circuits obtained from adaptive algorithms as compared with other available approaches in the literature.

M. Mootz, T. Iadecola, and Y.-X. Yao, Adaptive Variational Quantum Computing Approaches for Green’s Functions and Nonlinear Susceptibilities, J. Chem. Theory Comput., 2024, 20, 8689−8710. https://doi.org/10.1021/acs.jctc.4c00874