Arrays of Cooper Pair Boxes Coupled to a Superconducting Reservoir: `Superradiance' and `Revival.'

TL;DR

This paper models arrays of Cooper Pair Boxes coupled to a superconducting reservoir, demonstrating quantum optical phenomena like superradiance and revival, and suggesting experimental feasibility with current superconducting technologies.

Contribution

It introduces a simplified spin model to study superradiance, revival, and entanglement revival in superconducting systems, bridging quantum optics and condensed matter physics.

Findings

Superradiance-like emission observed in the model.

Revival phenomena analogous to quantum optical systems.

Potential for experimental observation with current superconducting technology.

Abstract

We consider an array of Cooper Pair Boxes, each of which is coupled to a superconducting reservoir by a capacitive tunnel junction. We discuss two effects that probe not just the quantum nature of the islands, but also of the superconducting reservoir coupled to them. These are analogues to the well-known quantum optical effects `superradiance,' and `revival.' When revival is extended to multiple systems, we find that `entanglement revival' can also be observed. In order to study the above effects, we utilise a highly simplified model for these systems in which all the single-electron energy eigenvalues are set to be the same (the strong coupling limit), as are the charging energies of the Cooper Pair Boxes, allowing the whole system to be represented by two large coupled quantum spins. Although this simplification is drastic, the model retains the main features necessary to capture the phenomena of interest. Given the progress in superconducting box experiments over recent years, it is possible that experiments to investigate both of these interesting quantum coherent phenomena could be performed in the forseeable future.