When two condensates are placed in a double potential well and the phase and population differences are such that the system is in equilibrium, the population difference will remain fixed. A naïve conclusion is that there is no tunneling at all, and the bosons are truly "trapped" on one side of the junction. However, macroscopic quantum self-trapping does not rule out quantum tunneling — rather, only the possibility of observing tunneling is ruled out. In the event that a particle tunnels through the barrier, another particle tunnels in the opposite direction. Because the identity of individual particles is lost in that case, no tunneling can be observed, and the system is considered to remain at rest.