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Zenith Grant Awardee

Aephraim Steinberg

University of Toronto

Project Title

Quantum and classical agents and their ability to clone and erase information

Project Summary

Quantum mechanics makes measurement central to the understanding of reality, and has taught us that every observation must disturb the system we observe. Nevertheless, our understanding of conscious agents typically relies on fundamentally classical notions of measurement. (This even despite much speculation about whether quantum phenomena play a role in consciousness). Classical observations of a quantum system irreversibly disturb it, but their results can for instance be copied with ease. Quantum measurements are different: they cannot be “cloned,” but on the other hand, they may in some cases be undone (“erased”). We will study, theoretically and experimentally, what measurements with varying degrees of “quantumness” enable agents to accomplish. This is a first step towards elucidating the implications of such quantum agents, and in particular whether it is even possible to observe the world “quantumly” and still maintain a sense of independence and an objective view of reality. 

Technical Abstract

Agency is usually conceived of semi-classically, agents relying only on classical information obtained via von Neumann-type interactions. Such agents retain the abilities to replicate the information or erase it. The disadvantage of this type of measurement is incomplete knowledge about the system, for example learning only about one component of the spin. In principle, one could consider quantum agents who can interact with the world in an arbitrary way and obtain a more general description of another quantum system. It could even store complete information about the system in a quantum memory – but in this limit, all information in the system is destroyed, and the information is not replicatable.  We are proposing to study the interplay between an agent’s ability to replicate information and erase (or undo) a measurement in more general scenarios.   Through this study we hope to further understand the implications of the degree to which an agent’s interaction with the world are quantum-mechanical. The project will involve a theoretical study of the interplay between quantum erasure and quantum cloning followed by an experimental study of the behaviour of quantum agents with varying-strength interactions.

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