Purity Swapping in the Jaynes-Cummings Model: Obtaining Perfect Interference Patterns from Totally Unpolarized Qubits

TL;DR

This paper demonstrates that in the Jaynes-Cummings model, purity can be swapped between a qubit and a quantum system through non-unitary interactions, enabling perfect interference patterns even from unpolarized sources.

Contribution

It introduces the concept of purity swapping in the Jaynes-Cummings model and shows how it can produce perfect interference from unpolarized qubits, with implications for quantum state control.

Findings

Purity swapping occurs in the Jaynes-Cummings model.

Perfect interference patterns are achievable from unpolarized sources.

The Gea-Banacloche attractor is robust against purity degradation.

Abstract

We show the existence of dynamical purity swapping phenomena in the Jaynes-Cummings model. Moreover we show that purity swapping between a qubit and a generic quantum system is possible, provided they are coupled via non-unitary matrix elements interaction. We particularize to the case of a quantum optical Ramsey interferometer. We show that using purity swapping, a perfect interference pattern can be obtained at the output port of the interferometer even if we start from totally unpolarized sources. This feature is shown to be associated with the phenomena of recreation of the state vector at half of the revival time. In fact, we show that the Gea-Banacloche attractor is robust against degradation of the purity of the qubit input state. We also show that the Tsallis entropy T2 is a useful entanglement monotone allowing one to relate directly entanglement with purity exchange in interacting systems. We conjecture an Araki-Lieb type inequality for T2 that bounds the maximum interchange of purity between interacting systems.