Quantum operations with indefinite direction of time: the quantum time flip
Seminar author:Giulio Chiribella
Event date and time:05/20/2021 10:00:am
Event location:https://us02web.zoom.us/j/83095734619?pwd=MG5VN1pPVjNUbVM5S1dZVm1nbC9TQT09
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The standard operational framework of quantum theory is time-asymmetric. This asymmetry reflects the capabilities of ordinary agents, who are able to deterministically pre-select the states of quantum systems, but not to deterministically post-select the outcomes of quantum measurements. However, the fundamental dynamics of quantum particles is time-symmetric, and is compatible with a broader class of operations where pre-selections and post-selections are combined in general ways that do not presuppose a definite direction of time. In this talk I introduce a framework for quantum operations with indefinite time direction, providing an example, called the quantum time flip, where an unknown, time-symmetric process is accessed in a coherent superposition of two alternative time directions. In certain information-theoretic tasks, a hypothetical agent with access to the quantum flip can in principle outperform all agents who operate in a definite time direction.
Related paper: G. Chiribella and Z. Liu, The quantum time flip, https://arxiv.org/abs/2012.038