Trapped Particles

I. V. Krasnov

Abstract The quasiclassical kinetic theory of optical forces has been applied to describe the kinetics of accumulation, deep trapping and cooling of particles in a bichromatic dark trap (BDT), which is placed into a reservoir with a thermal gas at room temperature containing an admixture of resonant atoms. BDT (proposed in our previous works, Krasnov 2016 Laser Phys. 26 105 501, 2017 27 085 501) is a multiple-optical-beam dark trap, in which rectified gradient forces in a bichromatic light field are used to manipulate the particles. The purpose of the present study is to investigate the possibility of direct BDT loading from the equilibrium gas mixture which will result in trapping and cooling of a sufficiently great amount of atoms by BDT. We derived a reduced Fokker-Planck equation in the energy space (for the Wigner particle distribution function) including the collision term. This equation takes into account the optical trapping force, its quantum fluctuations, particle loss from the trap and weakly-dissipative nature of BDT. Its asymptotic solution allows one to describe the particle kinetics and obtain explicit formulas for the main characteristics of BDT (particle capture rate into BDT, temperature and number of the trapped particles). Ultimately, we demonstrate the high efficiency of the particle accumulation in BDT. In particular, the concentration of the trapped particles (with the temperature at least by four orders of magnitude lower than the room temperature) has been shown to be able to exceed the concentration of the ‘hot’ untrapped particles by several dozens of times, and it has been demonstrated that the accumulation efficiency can reach the values of the order of 10 3 .

Miguel Orszag

Jonas Larson, Th. K. Mavrogordatos

Kissangou, Roxen, Wilby, Marius Romuald Kamsap, Mike Delon Mboumba +2 more

We describe and use a macroscopic linear quadrupolar trap to explore the trapping and equilibrium properties of charged particles. These devices, when operated to trap atomic ions, are at the core of ion based quantum computer and optical atomic clock. To illustrate the characteristics of few particle trapping, and observe different force balance on a charged particle, a macroscopic linear trap, operating at room condition, is trapping micrometer-sized particles. Compared to atomic or molecular ions, their mass can not be neglected and requires an extra voltage for gravity force compensation. We show how this compensation can be demonstrated experimentally and that the choice of hollow-core glass spheres has the advantage of a good reproducibility of the experiments, that allows one to deduce with good precision the charge-to-mass ratio of the trapped particle.

Miguel Orszag

Kissangou, Roxen, Wilby, Marius Romuald Kamsap, Mike Delon Mboumba +2 more

We describe and use a macroscopic linear quadrupolar trap to explore the trapping and equilibrium properties of charged particles. These devices, when operated to trap atomic ions, are at the core of ion based quantum computer and optical atomic clock. To illustrate the characteristics of few particle trapping, and observe different force balance on a charged particle, a macroscopic linear trap, operating at room condition, is trapping micrometer-sized particles. Compared to atomic or molecular ions, their mass can not be neglected and requires an extra voltage for gravity force compensation. We show how this compensation can be demonstrated experimentally and that the choice of hollow-core glass spheres has the advantage of a good reproducibility of the experiments, that allows one to deduce with good precision the charge-to-mass ratio of the trapped particle.