Bound state in the continuum

A bound state in the continuum (BIC, BSC) is an eigenstate of some particular quantum system with the following properties: Energy lies in the continuous spectrum of propagating modes of the surrounding space; The state does not interact with any of the states of the continuum (it cannot emit and cannot be excited by any wave that came from the infinity); Energy is real and Q factor is infinite, if there is no absorption in the system. BICs are observed in electronic, photonic, acoustic systems, and are a general phenomenon exhibited by systems in which wave physics applies.

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