Quantum processing through a manifold of dark states

摘要

We propose a scalable network, in which all quantum operations can be executed through external controls.Nodes of this network are high-finesse electromagnetic cavities, each coupled to a single three-level atom. Thenodes are connected by optical fibers. Each atom is addressed by a control laser, which along with the cavityfield drives atomic transitions. The network can be in the form of arrays of iN/i-cavities connected by iN/isubB/sub fibersin one to three dimensions. We find that under certain conditions, the system possesses two kinds of degeneratedark states. The first kind are iN /istates corresponding to atomic excitations at each node and these are ourlogical states for quantum processing. The second kind are iN/isubB/sub states on pairs of sites connected by a fibre. Bymanipulating intensities and phases of control lasers on the cavities, one can pass adiabatically among these darkstates due to their degeneracy. This network operates as a iN/i-level quantum system in which one can generatecomputationally useful states by protocols of external controls. We obtain numerical results for small chains andsquare lattices to demonstrate some quantum operations like the transport of states across the array, generationof superposed states and phase-flipping in a network. We also discuss effects of dissipation and limitations ofthe model.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.