The concept of a coherent exciton state is formulated. It is shown that for this state the macroscopic wave function may be introduced which satisfies a nonlinear equation of the type familiar in the phenomenological theory of a superfluid liquid. The corresponding nondissipative flux is the flux of energy. For excitons interacting with an electromagnetic field, a coupled system of Maxwell equations and Ginzburg—Pitaevskii (phenomenological theory of Bose liquid) type equations is obtained.

Keywords: excitons, coherent state of excitons, macroscopic wave function, phenomenological theory of superfluid liqui, Bose-liquid equations, Ginzburg—Pitaevskii equations PACS: 03.75.Kk, 67.10.−j, 71.35.−y (all) DOI: 10.3367/UFNe.2017.10.038227 URL: https://ufn.ru/en/articles/2017/11/f/ 000424395100006 2-s2.0-85042141426 2017PhyU...60.1180K Citation: Keldysh L V "Coherent states of excitons" Phys. Usp. 60 1180–1186 (2017) BibTexBibNote ® (generic)BibNote ® (RIS)MedlineRefWorks Received: 12th, July 2017, accepted: 18th, October 2017 Оригинал: Келдыш Л В «Когерентные состояния экситонов» УФН 187 1273–1279 (2017); DOI: 10.3367/UFNr.2017.10.038227