Quantum evaporation may occur in a variety of systems such as superfluids, Bose-Einstein condensates, and gravitational black holes (Hawking radiation). However, to date all predictions are based on semiclassical models, e.g., the Einstein equations and classical space-time metric for a black hole and only the fluctuations are quantized. Here we use a fully quantized dynamical equation, the quantum nonlinear Schrödinger equation, to study the evolution of quantum solitons. As a result of quantum fluctuations in the center-of-mass position, the expectation value of the quantum soliton width increases and concomitantly evaporates through the emission of frequency-entangled photon pairs. The frequency of this emission decreases as the soliton evaporates due to the soliton spreading. In the final phase, the soliton mean field collapses irreversibly into a state with zero mean amplitude. These results may provide insight to quantum evaporation in other systems where a full quantum description is still to be developed and highlights that even classically stable systems may also be subject to quantum evaporation.

• Received 26 October 2017

DOI:https://doi.org/10.1103/PhysRevA.98.043859