Does provable absence of barren plateaus imply classical simulability?

A large amount of effort has recently been put into understanding the barren plateau phenomenon. In this perspective article, we face the increasingly loud elephant in the room and ask a question that has been hinted at by many but not explicitly addressed: Can the structure that allows one to avoid barren plateaus also be leveraged to efficiently simulate the loss classically? We collect evidence-on a case-by-case basis-that many commonly used models whose loss landscapes avoid barren plateaus can also admit classical simulation, provided that one can collect some classical data from quantum devices during an initial data acquisition phase. This follows from the observation that barren plateaus result from a…

• UD
  U.S. Department of Energy
• CI
  California Institute of Technology
• CU
  Chulalongkorn University
• CN
  Consejo Nacional de Investigaciones Científicas y Técnicas
• NR
  National Research Council of Thailand
• OO
  Office of Science
• WB
  Walter Burke Institute for Theoretical Physics
• EA
  Engineering and Physical Sciences Research Council

  Award: EP/T517665/1
• NP
  National Physical Laboratory
• AS
  Advanced Scientific Computing Research
• LD
  Laboratory Directed Research and Development

  Awards: 20230527ECR, 20230049DR
• LA
  Los Alamos National Laboratory

  Awards: 20230049DR, 20230527ECR