  We study the quantum remnant of a scalar field protected by the uncertainty
principle. The quantum remnant that survived the later stage of evolution of
the universe may provide dark energy and dark matter depending on the
potential. Though the quantum remnant shares some useful property of complex
scalar field (spintessence) dark energy model, % However although it avoids the
formation of Q-ball, quantum fluctuations are still unstable to the linear
perturbations for $V \sim \phi^q$ with $q<1$ as in the spintessence model.
