arXiv subjects

Vikash Ranjan

Publications and source records attributed to Vikash Ranjan.

2 recordsLinked to original sources

arXiv2005

Stability of Bloch Oscillations in two coupled Bose-Einstein condensates

We investigate analytically, the stability of Bloch waves at the boundary of the first Brillouin zone in two coupled Bose-Einstein condensates confined in an optical lattice. Contrary to the single component case, we find here two critical density regimes which determine the stability of the Bloch waves. Breakdown of Bloch oscillations appear when n1/n2 Nc2, here Nc1 and Nc2 are some critical values of n1/n2. There is an intermediate regime between Nc1 and Nc2 where the Bloch oscillations are stable and the condensates behave like single particles.

cond-mat.stat-mech↗

arXiv2005

Quantum Theory of a Bose-Einstein Condensate out of Equilibrium

We consider the interaction between a single-mode quantized perturbing external field and a Bose-Einstein condensate (BEC) out of equilibrium. The usual Rabi type oscillations between the ground and the excited state of the coherent topological modes are observed with a Rabi frequency modified by the two-body atomic interactions. Taking into account the granular structure of the external perturbing field reveals the well know phenomena of collapse and revival of the Rabi oscillations. In particular we find that atomic interactions reduce the Rabi frequency and also affect the collapse and revival sequence.

cond-mat.stat-mech↗