Collective energy gap of preformed Cooper pairs in disordered superconductors.

In most superconductors, the transition to the superconducting state is driven by the binding of electrons into Cooper pairs [1]. The condensation of these pairs into a single, phase coherent, quantum state takes place at the same time as their formation at the transition temperature, . A different scenario occurs in some disordered, amorphous, superconductors: Instead of a pairing-driven transition, in-coherent Cooper pairs first pre-form above , causing the opening of a pseudogap, and then, at , condense into the phase coherent superconducting state [2-11].

Negative Magnetoresistance in Amorphous Indium Oxide Wires.

We study magneto-transport properties of several amorphous Indium oxide nanowires of different widths. The wires show superconducting transition at zero magnetic field, but, there exist a finite resistance at the lowest temperature. The R(T) broadening was explained by available phase slip models.

Single-slit electron diffraction with Aharonov-Bohm phase: Feynman's thought experiment with quantum point contacts.

In a "thought experiment," now a classic in physics pedagogy, Feynman visualizes Young's double-slit interference experiment with electrons in magnetic field. He shows that the addition of an Aharonov-Bohm phase is equivalent to shifting the zero-field wave interference pattern by an angle expected from the Lorentz force calculation for classical particles. We have performed this experiment with one slit, instead of two, where ballistic electrons within two-dimensional electron gas diffract through a small orifice formed by a quantum point contact (QPC).

Dripping faucet dynamics is determined by synchronization of drop oscillations and detachment.

A dripping faucet is an example of an everyday system that exhibits surprisingly rich dynamics ranging from periodic to chaotic. Using a simple capacitive device, we experimentally demonstrate that the dynamics is determined by the degree of synchronization between two temporally disparate processes: the time at which a drop attains a critical mass and an oscillatory process that accompanies the formation of a drop. We present a full experimental phase-space reconstruction of the ensuing dynamics.