1 Controllable Magnet Molecular Qubits Based on Endohedral Fullerenes Jie Li, Lei Gu and Ruqian Wu* Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA. Well-protected magnetization, tunable quantum states and long coherence time are desired for developing magnetic molecules as qubits quantum information processing and storage. Based on the first-principles calculations and dynamic simulations, we demonstrate that endohedral fullerene molecule Ir@C 28 has stable magnetization, huge magnetic anisotropy energy (> 30 meV per molecule) and bias-tunable structural phases. In particular, qubits based on Ir@C 28 may have coherence times up to several ࢓ࡿ at high temperature (~100K) after full consideration of spin-vibration couplings. These results suggest a new strategy of using endohedral fullerene as qubits for technological breakthroughs. * E-mail: wur@uci.edu.