Simultaneous cooling of axial vibrational modes in a linear ion trap (16 pages)

K. Ravi

Christof Wunderlich, Giovanna Morigi, Dirk Reiß

In order to use a collection of trapped ions for experiments where a well-defined preparation of vibrational states is necessary, all vibrational modes have to be cooled to ensure precise and repeatable manipulation of the ions quantum states. A method for simultaneous sideband cooling of all axial vibrational modes is proposed. By application of a magnetic field gradient the absorption spectrum of each ion is modified such that sideband resonances of different vibrational modes coincide. The ion string is then irradiated with monochromatic electromagnetic radiation, in the optical or microwave regime, for sideband excitation. This cooling scheme is investigated in detailed numerical studies. Its application for initializing ion strings for quantum information processing is extensively discussed.

L. A. Akopyan, Ilia V. Zalivako, Kirill Lakhmanskiy +2 more

Ions in radio-frequency traps are widely used in various fields of applied and fundamental physics, such as metrology and quantum computing. One of the important tasks required for modern experiments is deep cooling of ion crystals. The results of simulations of an increase in the efficiency of deep cooling of linear ion crystals by the method of electromagnetically induced transparency (EIT cooling) by imposing an optical lattice on the radio-frequency trap have been reported. It has been shown that this method makes it possible to narrow the frequency range occupied by various vibrational modes of ions and to increase their axial frequencies of motion without violating the linear configuration of the crystal. Thus, for a crystal of eight ions in a Paul trap with secular frequencies ω z = 2 π × 100 kHz and ω r = 2 π × 650 kHz, the application of an optical lattice allows the reduction of the frequency range occupied by vibrational modes by a factor of 2. The dependence of the optimal power of the optical lattice for narrowing the vibrational spectrum on the number of particles in the trap and its parameters has been investigated.

Juha Javanainen

Almut Beige

René Rugango, J E Goeders, T H Dixon +5 more

We demonstrate sympathetic sideband cooling of a 40 CaH + molecular ion co-trapped with a 40 Ca + atomic ion in a linear Paul trap. Both axial modes of the two-ion chain are simultaneously cooled to near the ground state of motion. The center of mass mode is cooled to an average quanta of harmonic motion , corresponding to a temperature of . The breathing mode is cooled to , corresponding to a temperature of .