The superconducting quasicharge qubit.

The non-dissipative nonlinearity of Josephson junctions converts macroscopic superconducting circuits into artificial atoms, enabling some of the best-controlled qubits today. Three fundamental types of superconducting qubit are known, each reflecting a distinct behaviour of quantum fluctuations in a Cooper pair condensate: single-charge tunnelling (charge qubit), single-flux tunnelling (flux qubit) and phase oscillations (phase qubit or transmon). Yet, the dual nature of charge and flux suggests that circuit atoms must come in pairs.

Infrared spectroscopy of molecular submonolayers on surfaces by infrared scanning tunneling microscopy: tetramantane on Au111.

We have developed a new scanning-tunneling-microscopy-based spectroscopy technique to characterize infrared (IR) absorption of submonolayers of molecules on conducting crystals. The technique employs a scanning tunneling microscope as a precise detector to measure the expansion of a molecule-decorated crystal that is irradiated by IR light from a tunable laser source. Using this technique, we obtain the IR absorption spectra of [121]tetramantane and [123]tetramantane on Au(111).

Single-molecule-resolved structural changes induced by temperature and light in surface-bound organometallic molecules designed for energy storage.

We have used scanning tunneling microscopy, Auger electron spectroscopy, and density functional theory calculations to investigate thermal and photoinduced structural transitions in (fulvalene)tetracarbonyldiruthenium molecules (designed for light energy storage) on a Au(111) surface. We find that both the parent complex and the photoisomer exhibit striking thermally induced structural phase changes on Au(111), which we attribute to the loss of carbonyl ligands from the organometallic molecules. Density functional theory calculations support this conclusion.