Yaroslav M. Blanter

Recent Advances in Studies of Current Noise

This is a brief review of recent activities in the field of current noise intended for newcomers. We first briefly discuss main properties of shot noise in nanostructures, and then turn to recent developments, concentrating on issues related to experimental progress: non-symmetrized cumulants and quantum noise; counting statistics; super-Poissonian noise; current noise and interferometry

Resonant coupling of a SQUID to a mechanical resonator

We analyze the properties of a mechanical resonator embedded into a quantum SQUID and analyze under which conditions it is possible to realize a resonant coupling between the SQUID and the resonator. We find, within the present technology, how it is possible to tune the system into the regime where the plasma frequency of the SQUID matches the resonator frequency and maximizes the corresponding coupling. In these conditions the doubly degenerate quantum level of the system is split by the coupling between the SQUID and the resonator.

Dynamics of a SQUID ratchet coupled to a nanomechanical resonator

We propose a position detection scheme for a nanoelectromechanical resonator based on the ratchet effect. This scheme has an advantage of being a dc measurement. We consider a threejunction SQUID where a part of the superconducting loop can perform mechanical motion. The response of the ratchet to a dc current is sensitive to the position of the resonator and the effect can be further enhanced by biasing the SQUID with an ac current. We discuss the feasibility of the proposed scheme in existing experimental setups.

Electromotive interference in a mechanically oscillating superconductor: Generalized Josephson relations and self-sustained oscillations of a torsional SQUID

We consider the superconducting phase in a moving superconductor and show that it depends on the displacement flux. Generalized constitutive relations between the phase of a superconducting interference device (SQUID) and the position of the oscillating loop are then established. In particular, we show that the Josephson current and voltage depend on both the SQUID position and velocity. The two proposed relativistic corrections to the Josephson relations come from the macroscopic displacement of a quantum condensate according to the (non-inertial) Galilean covariance of the Schrodinger equation, and the kinematic displacement of the quasi-classical interfering path. In particular, we propose an alternative demonstration for the London rotating superconductor effect (also known as the London momentum) using the covariance properties of the Schrodinger equation. As an illustration, we show how these electromotive effects can induce self-sustained oscillations of a torsional SQUID, when the entire loop oscillates due to an applied dc-current.