Driven – Dissipative Dynamics of a Gas of Ultracold Atoms in a Harmonic Trap Array Interacting with a Background Bose – Einstein Condensate

Roland Cristopher Caballar^1*

¹Department of Mathematics and Physics, College of Science, University of Santo Tomas, City of Manila, Metro Manila, Philippines

* Presenter:Roland Cristopher Caballar, email:rfcaballar@ust.edu.ph

We consider a gas of N ultracold atoms trapped in a series of harmonic oscillator potentials adjacent to each other. Each of these harmonic oscillator potentials contains a number of these ultracold atoms, which are initially in the ground state. These atoms are then excited to a higher energy level by multiple Raman lasers. This ensemble of excited ultracold atoms trapped in a series of adjacent harmonic oscillator potentials is then immersed in a Bose – Einstein condensate (BEC), where the number of atoms in the condensate is much greater than the number of trapped ultracold atoms. The BEC then acts as a reservoir of Bogoliubov excitations emitted by the excited trapped ultracold atoms, allowing them to return to their original energy levels. By continuously exciting and de-exciting this ensemble of trapped ultracold atoms via this driven – dissipative method, it is shown that the gas of ultracold atoms will, over time, achieve a steady state whereby the expectation value of the number of atoms in each trap approaches a constant value. However, for a given number of atoms trapped in each oscillator potential, the steady state can be achieved only for a particular set of parameters governing the system, such as the Rabi frequency and detuning of the Raman lasers coupling the energy levels of the atoms, as well as the frequency of the harmonic traps. One possible application of this system is in preparing an ensemble of quantum states with a fixed number of particles in one particular energy level, such as Bose – Einstein condensates and ultracold atom sources for use in atom interferometry and time – of – flight experiments.

Keywords: Ultracold atoms, Open quantum systems, Dissipative quantum state preparation