Macroscopic Quantum Coherence in a Magnetic Nanoparticle Above the   Surface of a Superconductor
  We study macroscopic quantum tunneling of the magnetic moment in a single-domain particle placed above the surface of a superconductor. Such a setup allows one to manipulate the height of the energy barrier, preserving the degeneracy of the ground state. The tunneling amplitude and the effect of the dissipation in the superconductor are computed. 
Eugene M. Chudnovsky (Lehman College, CUNY), Jonathan R. Friedman   (SUNY - Stony Brook)