Avoiding barren plateaus using classical shadows

Understand

Variational quantum algorithms are promising algorithms for achieving quantum advantage on near-term devices.

• The quantum hardware is used to implement a variational wave function and measure observables, whereas the classical computer is used to store and update the variational parameters.
• The optimization landscape of expressive variational ans\"atze is however dominated by large regions in parameter space, known as barren plateaus, with vanishing gradients which prevents efficient optimization.
• In this work we propose a general algorithm to avoid barren plateaus in the initialization and throughout the optimization.