Ground state cooling, quantum state engineering and study of decoherence of ions in Paul traps

• Published in: Journal of modern optics Vol. 47; no. 14-15; pp. 2573 - 2582
• Main Authors: Schmidt-Kaler, F., Roos, Ch, Nägerl, H. C., Rohde, H., Gulde, S., Mundt, A., Lederbauer, M., Thalhammer, G., Zeiger, Th, Barton, P., Hornekaer, L., Reymond, G., Leibfried, D., Eschner, J., Blatt, R.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: London Taylor & Francis Group 01.11.2000; Taylor & Francis
• Subjects: Atomic and molecular physics; Atomic properties and interactions with photons; Classical and quantum physics: mechanics and fields; Exact sciences and technology; Optical cooling of atoms; trapping; Photon interactions with atoms; Physics; Quantum information; Ground states; Quantum optics; Laser cooling; Quantum decoherence; Experimental study; Positive ions; Calcium 40; Ion trap; Atomic ions; Information processing; Excitation spectrum; Quantum information; Quantum gate; Calcium ions
• ISSN: 0950-0340; 1362-3044
• DOI: 10.1080/09500340008232182

We investigate single ions of 40 Ca + in Paul traps for quantum information processing. Superpositions of the S ½ electronic ground state and the metastable D 5/2; state are used to implement a qubit. Laser light on the S ½ ↔ D 5/2 transition is used for the manipulation of the ion's quantum state. We apply sideband cooling to the ion and reach the ground state of vibration with up to 99.9% probability. Starting from this Fock state (n = 0), we demonstrate coherent quantum state manipulation. A large number of Rabi oscillations and a ms-coherence time is observed. Motional heating is measured to be as low as one vibrational quantum in 190ms. We also report on ground state cooling of two ions.