Research Topic: Quantum Devices in Atom Optics

Atom diode and its applications

We have proposed an atom diode [1, 2], i.e., a one-dimensional laser device that lets the ground state atom pass in one direction but not in the opposite direction. The first version of the device is based on a three-level atom where we achieved the "diodic" behavior by combining a STIRAP transfer [3], an additional state-selective mirror potential that reflects only ground-state atoms and a quenching laser [1,4]:

Using numerical simulations we have proved that the device shows the claimed "diodic" behavior in a range of ultra-cold velocities. Moreover, we have presented a diode for a two-level atom based on two state-selective mirror potentials, a pumping laser and a quenching laser [2]:

Raizen et. al. [5, 6] have independently proposed such an "atom diode" or one-way barrier. They have also presented a method for cooling an ensemble of atoms by moving a one-way barrier through the trap [6]:

The diode sweeps slowly through the potential and captures the atoms near their classical turning points. If the diode catches the atom, the atom will undergo an irreversible process which involves the scattering of a spontaneous photon. Then the moving diode, which becomes a hard wall for the captured atom, transports it to the bottom of the potential without increasing its kinetic energy. (A similar process occurs by moving down a racket slowly with a tennis ball at rest on it.) Thus the particles are cooled by an atom diode that is slowly swept through the cloud. This cooling method has the advantage that no atoms are lost during the process in contrast to evaporative cooling. At present and during the whole project, we collaborate with M. G. Raizen [4], who is currently working on the experimental implementation.

Our research goal is to propose, improve, extend, and apply the previously found Atom diode. The device has been examined up to now mainly by using a one-dimensional approximation for the atomic motion. But if the atom is excited by a laser there is a momentum transfer in the laser direction which is totally neglected in the one-dimensional description. Therefore it is very important to examine the atom diode in three dimensions and determine the working parameter ranges. In addition, we expect also to find new effects which do not exist in the simple one-dimensional approximation. Using a two-dimension optical lattice [7] (being "open" in the remaining third dimension) many parallel wave guides can be realized. Due to this increasing importance of atoms in waveguides, it is very important to know how the different operations and devices work with confined atoms and to built control devices even for many-particle states. We will also look at applications of the atom diode. In the first instance, we will examine in detail the cooling method based on the atom diode which has been described up to now only in a simplified and classical way. On the other hand, we will try to find other interesting application of the diode.

[1] A. Ruschhaupt and J.G. Muga, "Atom diode: a laser device for a unidirectional transmission of ground-state atoms", Physical Review A 70 (2004) 061604(R).
[2] A. Ruschhaupt and J.G. Muga, "Adiabatic interpretation of a two-level atom diode, a laser device for unidirectional transmission of ground-state atoms", Physical Review A 73 (2006) 013608.
[3] K. Bergmann, H. Theuer, and B.W. Shore, Rev. Mod. Phys. 70 (1998) 1003.
[4] A. Ruschhaupt, J. G. Muga, and M. G. Raizen, "Improvement by laser quenching of an atom diode: a one-way barrier for ultra-cold atoms", Journal of Physics B: At. Mol. Opt. Phys. 39 (2006) L133-L138.
[5] M. G. Raizen, A. M. Dudarev, Qian Niu, and N. J. Fisch, Phys. Rev. Lett. 94 (2005) 053003.
[6] A. M. Dudarev, M. Marder, Qian Niu, N. J. Fisch, and M. G. Raizen, Europhys. Lett. 70 (2005) 761.
[7] I. Bloch, J. Phys. B: At. Mol. Opt. Phys. 38 (2005) S629.

Last modified: Wed, 13 Oct 2010

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Edited by Andreas Ruschhaupt