arXiv subjects

M. R. Isherwood

Publications and source records attributed to M. R. Isherwood.

3 recordsLinked to original sources

arXiv2003

Chaotic filtering of moving atoms in pulsed optical lattices

We propose a mechanism for a velocity-selective device, which exploits the fundamental phenomenon of dynamical localization. It would allow packets of cold atoms travelling through a pulsed optical lattice in one direction to pass undisturbed, while dispersing atoms travelling in the opposite direction. This mechanism is based on a chaotic diffusion process, with a momentum-dependent diffusion coefficient. We analyse this classical effect, and we show that it is enhanced by dynamical localization.

nlin.CD↗

arXiv2002

A chaotic 'turnstile' for atoms in periodic potentials

Using a new type of chaotic ratchet generated by pulsed standing waves of light, we propose a mechanism which would allow packets of atoms travelling through a pulsed optical lattice in one direction to pass almost undisturbed, while strongly heating atoms drifting through in the opposite direction. An analytical formula for the diffusive energy growth is derived and shown to give good agreement with numerical calculations.

physics.atom-ph↗

arXiv2002

Cold atoms in optical lattices :a Hamiltonian ratchet

We investigate a new type of quantum ratchet which may be realised by cold atoms in a double-well optical lattice which is pulsed with unequal periods. The classical dynamics is chaotic and we find the classical diffusion rate $D$ is asymmetric in momentum up to a finite time $t_r$. The quantum behaviour produces a corresponding asymmetry in the momentum distribution which is 'frozen-in' by Dynamical Localisation provided the break-time $t^* > t_r$. We conclude that the cold atom ratchets require $Db/ \hbar \sim 1$ where b is a small deviation from period-one pulses.

physics.atom-ph↗