Quantum Darwinism, Thermodynamics, and Quantum Benchmarking

The world in which we live is at its foundation quantum, though it appears to follow the rules of classical physics in our everyday experience. Quantum Darwinism provides a mechanism for an apparently classical reality to emerge from an underlying quantum model, built from a small list of assumptions and requirements. In this talk, we will discuss some of the deep connections between Quantum Darwinism and thermodynamics or statistical mechanics. In particular, we will focus on the consequences of non-classical measurement statistics and how quasiprobability distributions build a bridge between the study of emergent classicality and quantum thermodynamics.

One highly-relevant use case for these results is in benchmarking and understanding the behavior of current NISQ-era quantum computers. We present results obtained by simulating the dynamics of a simple qubit model known to exhibit Quantum Darwinism using devices made available by IonQ and IBM. Our goal is to study the sensitivity of these machines to small amounts of non-classicality by explicitly breaking Quantum Darwinism in the simulated system and subsequently checking how the various quasiprobability distributions for different measurement choices change to reflect this. This allows us to study the quantum-to-classical transition in the simulated system in its natural quantum habitat, with the caveat that the noise present in the device will limit how precisely the transition can be observed. This provides a natural benchmark for quantum computers: how precisely can they probe the transition between classical and quantum? There are a large variety of approaches to this question beyond what we present, and in the future such tests will be more than benchmarks and will provide a path to study both Quantum Darwinism and quantum thermodynamics directly on quantum computers.