D. Rogovin

Fluctuation phenomena in tunnel junctions

Abstract A general theory of electrodynamic fluctuations in tunnel junctions is developed. Using standard many-body techniques we determine the quasiparticle, pair, and quasiparticle-pair current power spectra and show that these current fluctuations are simply related to the associated pieces of the junction I ( V ) characteristic. In addition a theory of the Josephson radiation linewidth is presented.

Superconductivity and macroscopic quantum phenomena

Abstract The unique coherence properties displayed by superconductors has often lead to the observation that the entire system behaves like a single quantum particle of mass 2m and charge 2e. In this paper we establish the conditions under which this macroscopic quantum assertion is valid within the framework of the microscopic theory of superconductivity.

Does the ''two-level-atom'' picture of a Josephson junction have a theoretical foundation in BCS

Abstract Yes, except that the rigorous equations are nonlocal and involve the internal pair coordinates.

The Josephson junction as a macroscopic radiating atom

Abstract We investigate the electrodynamic properties of a Josephson junction emitting coherent radiation and establish that it can be regarded as a two-level atom within the framework of the microscopic theory of superconductivity.

Coherent transient effects in Josephson junctions

Abstract We examine the transient behavior of a Josephson junction from a particular initial state. It is demonstrated that the junction displays a new type of cooperative behavior that should be experimentally observable.

Superconductivity and Quantum Optics

In these lectures we will be describing the applications of quantum optical techniques to superconducting tunnel junctions. This work has been motivated, in part, by the close analogy between the quantum mechanics of BCS electron pairs in a superconducting tunnel junction and the quantum mechanics of two-level systems.1 Since two-level systems are a mainstay of quantum optics, it is natural that we begin considering problems such as coherent transients in superconducting junctions (a classic two-level system) from a quantum optical point of view. Two such problems, supperradiance and Rabi flopping effects in Josephson devices will be discussed. Some of the coherent transient effects we will see are different from those observed in the normal two-level atom problem, but there are also many similarities.

Pair transfer in the absence of phase coherence

Abstract In his thesis, Josephson asserts that pair transfer accompanied by spontaneous photon emission does not demand the existence of a definite phase relationship between the two superconductors. In this letter we demonstrate the validity of this statement.

The role of the cooperation number in superconducting systems

Abstract The role of the cooperation number in superconducting systems is examined. It is demonstrated that coherence in both bulk superconductors, as well as the a.c. Josephson–Fiske effect, arises from the fact that these systems are in states in which the cooperation number is large and not from the existence a of well-defined phase.