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Growth of the Wang-Casati-Prosen counter in an integrable billiards

by Z. Hwang, C. A. Marx, J. Seaward, S. Jitomirskaya, M. Olshanii

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Submission summary

Authors (as registered SciPost users): Maxim Olshanii
Submission information
Preprint Link: scipost_202108_00061v2  (pdf)
Date accepted: 2022-08-01
Date submitted: 2022-06-24 05:34
Submitted by: Olshanii, Maxim
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
Specialties:
  • Mathematical Physics
Approaches: Theoretical, Computational

Abstract

This work is motivated by an article by Wang, Casati, and Prosen [Phys.~Rev.~E vol.~89, 042918 (2014)] devoted to a study of ergodicity in two-dimensional irrational right-triangular billiards. Numerical results presented there suggest that these billiards are generally not ergodic. However, they become ergodic when the billiard angle is equal to $\pi/2$ times a Liouvillian irrational, a class of numbers with properties lying in between irrational and rational. In particular, Wang et al.\ study a special integer counter that reflects the irrational contribution to the velocity orientation; they conjecture that this counter is localized in the generic case, but grows in the Liouvillian case.% We propose a generalization of the Wang-Casati-Prosen counter: this generalization allows to include rational billiards into consideration. We show that in the case of a $\ang{45} \!\! : \!\ang{45} \!\! : \! \ang{90}$ billiard, the counter grows indefinitely, consistent with the Liouvillian scenario suggested by Wang et al.

Author comments upon resubmission

We thank the Referee 2 for s/his help with improving the accessibility of our manuscript. According to s/his suggestion we
(a) completely changed the order of presentation; (b) expanded the introduction by a factor of two; (c) clearly presented the position of our system of interest on the integrable->rational->Liouvillian->generic axis for right-triangular billiards. We want to express our wholehearted thank you: our manuscript improved visibly. Hoping for an affirmative answer.

Published as SciPost Phys. 14, 017 (2023)

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