Using quantum theory to simplify input–output processes

• Main Authors: Thompson, Jayne, Garner, Andrew J. P., Vedral, Vlatko, Gu, Mile
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2018
• Subjects: Quantum Mechanics; Information Theory and Computation
• Online Access: https://hdl.handle.net/10356/86645; http://hdl.handle.net/10220/45332
• Institution: Nanyang Technological University

All natural things process and transform information. They receive environmental information as input, and transform it into appropriate output responses. Much of science is dedicated to building models of such systems—algorithmic abstractions of their input–output behavior that allow us to simulate how such systems can behave in the future, conditioned on what has transpired in the past. Here, we show that classical models cannot avoid inefficiency—storing past information that is unnecessary for correct future simulation. We construct quantum models that mitigate this waste, whenever it is physically possible to do so. This suggests that the complexity of general input–output processes depends fundamentally on what sort of information theory we use to describe them.