A. Chaturvedi (UG ): Quantum prescriptions are more distinct than they are distinguishable
Channel: Centrum Fizyki Teoretycznej PAN
Date: 09/04/2021

Anubhav Chaturvedi  (University of Gdańsk) 
Quantum prescriptions are more distinct than they are distinguishable.
In what way do quantum prescriptions for physical entities fundamentally deviate from that of classical theories? Such a question necessitates formal notions of classicality and the ontological framework provides a vital ground for such notions. Based on an intuitive generalization of the principle of `the identity of indiscernibles', we introduce such a notion of classicality, called bounded ontological distinctness. Formulated as a principle, bounded ontological distinctness equates the distinguishability of a set of operational physical entities to the distinctness of their ontological counterparts. Employing three instances of two-dimensional quantum preparations, we demonstrate the violation of bounded ontological distinctness or excess ontological distinctness of quantum preparations. Moreover, our methodology enables the inference of tight lower bounds on the extent of excess ontological distinctness of quantum preparations. Similarly, we demonstrate excess ontological distinctness of quantum transformations, using three two-dimensional unitary transformations. However, to demonstrate excess ontological distinctness of quantum measurements, an additional assumption such as outcome determinism or bounded ontological distinctness of preparations is required. Unlike other well-known ontological principles, the operational prerequisite for the experimental demonstration of excess ontological distinctness, i.e. the distinguishability of physical entities is inherently experimentally robust. Furthermore, we show that quantum violations of other well-known ontological principles implicate quantum excess ontological distinctness. Finally, to showcase operational vitality, we introduce two distinct classes of communication tasks powered by excess ontological distinctness.
CTP Quantum Information Days (online), 22-24 February 2021.
Center for Theoretical Physics PAS (Warsaw, Poland)