Theory of variational quantum simulation

Understand

The variational method is a versatile tool for classical simulation of a variety of quantum systems.

• Great efforts have recently been devoted to its extension to quantum computing for efficiently solving static many-body problems and simulating real and imaginary time dynamics.
• In this work, we first review the conventional variational principles, including the Rayleigh-Ritz method for solving static problems, and the Dirac and Frenkel variational principle, the McLachlan's variational principle, and the time-dependent variational principle, for simulating real time dynamics.
• We focus on the simulation of dynamics and discuss the connections of the three variational principles.