Soliton-Bound States in the Magnetic Gap

Valery I. Rupasov, Mahi R. Singh

A system of polaritons interacting with a two-level atom placed within a frequency dispersive medium is proven to be integrable and diagonalized exactly by the Bethe ansatz method, despite a nonlocal effective polariton-polariton coupling. Its spectrum consists of bound many-polariton complexes (quantum solitons) and exhibits unusual features due to the existence of the polaritonic gap. Only solitons containing an even number of polaritons (``even'' solitons) propagate within the gap, while an ``odd'' soliton is pinned to the atom and forms a many-polariton--atom bound state.

Erik Schwartz Sørensen, Ian K. Affleck, David Augier +1 more

Ze Cheng, Gershon Kurizki

Sajeev John, Rupasov, V I

We study quantum effects of light propagation through an extended absorbing system of two-level atoms placed within a frequency gap medium (FGM). Apart from ordinary solitons and single particle impurity band states, the many-particle spectrum of the system contains massive pairs of confined gap excitations and their bound complexes - gap solitons. In addition, ``composite'' solitons are predicted as bound states of ordinary and gap solitons. Quantum gap and composite solitons propagate without dissipation, and should be associated with self-induced transparency pulses in a FGM.

B.V. Samsonov

Röhrs, Rene

In this thesis, we investigate polarised solitary waves, known as magnetic solitons and dark-antidark solitons, in binary (two-component) Bose-Einstein condensates in the miscible phase. These solitons have been recently realised in experiments and are predicted to form bound states. We calculate the interaction potentials between magnetic solitons with the same and opposite polarisation, uncovering the mechanisms underlying bound state formation. By considering two superimposed counter-propagating magnetic solitons with opposite polarisation, we analytically calculate the dissociation energy of the bound states and find good agreement with full numerical simulations. Furthermore, we show that the oscillation period of bound states depends on the maximum soliton separation. We subsequently extend these results to dark-antidark solitons. For binary dipolar Bose- Einstein condensates, we derive the dispersion relation of elementary excitations and find that, in the presence of a spin-roton, spin-density modulations form around dark-antidark solitons. These modulations lead to additional local maxima and minima in the inter-soliton potentials, enabling the formation of additional bound state regions. Additionally, we compare the collision characteristics of magnetic solitons in non-dipolar systems with dark-antidark solitons in dipolar–nondipolar condensate mixtures and explore the collisions between bound states in the non-dipolar case.