ABSTRACT
We report on the first results from a new microwave cavity search for dark matter axions with masses above 20 µeV. We exclude axion models with two-photon coupling g_{aγγ}â³2×10^{-14} GeV^{-1} over the range 23.55
ABSTRACT
We present measurements of a topological property, the Chern number (C_{1}), of a closed manifold in the space of two-level system Hamiltonians, where the two-level system is formed from a superconducting qubit. We manipulate the parameters of the Hamiltonian of the superconducting qubit along paths in the manifold and extract C_{1} from the nonadiabatic response of the qubit. By adjusting the manifold such that a degeneracy in the Hamiltonian passes from inside to outside the manifold, we observe a topological transition C_{1}=1â0. Our measurement of C_{1} is quantized to within 2% on either side of the transition.