Universality of anomalous tunneling for Nambu–Goldstone modes

Establish whether anomalous tunneling—the near-perfect low-energy transmission of collective excitations through a barrier—occurs universally for Nambu–Goldstone modes associated with the spontaneous breaking of continuous symmetries in quantum many-body systems.

Background

Anomalous tunneling refers to the counterintuitive phenomenon in Bose–Einstein condensates where low-energy Bogoliubov phonon excitations transmit through a repulsive barrier with high probability, approaching perfect transmission at zero energy. This behavior differs from single-particle tunneling and has been linked to superfluidity.

Beyond Bose–Einstein condensates, there is a broader theoretical interest in whether anomalous tunneling is a universal feature of Nambu–Goldstone modes arising from spontaneous symmetry breaking. Establishing or refuting this universality would clarify the generality of anomalous tunneling across systems with continuous symmetry breaking and deepen understanding of collective excitations.