Observing the ambiguity of simplicity via quantum simulations of an Ising spin chain. (arXiv:1711.03661v1 [quant-ph])

The modelling of stochastic processes is ubiquitous throughout the natural
and social sciences. An ideal model produces the correct statistical output
without any unnecessary complexity. This minimal-complexity criterion is
important conceptually, entailing the least number of causes of effects
(Occam's razor), and practically, entailing the least stored information in the
simulation. Here, we experimentally compare classical and quantum information
encodings in simulating an Ising spin chain, showing that quantum encodings
perform better and redefine our understanding of what is complex. We
experimentally observe a recently conjectured effect, the ambiguity of
simplicity. Specifically, we simulate Ising chains at different temperatures, A
and B, such that classical encodings require fewer resources to model A than B,
while quantum encodings are simpler for B than A. This challenges the
perspective that relative complexity is contained solely in the configuration
of the system being modelled. Our error-tolerant techniques account for
inevitable imperfections in realising quantum simulators, thus providing the
technological milestone needed to simulate increasingly complex stochastic
processes.

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