Deciphering Pancharatnam's discovery of geometric phase

TL;DR

This paper clarifies Pancharatnam's original work on the geometric phase, explaining its historical context, correcting common misinterpretations, and connecting it to modern developments in the field.

Contribution

It provides a detailed, accessible analysis of Pancharatnam's original derivation, highlighting its differences from Berry's work and clarifying its significance in geometric phase research.

Findings

Clarifies Pancharatnam's original derivation of geometric phase

Highlights differences between Pancharatnam's and Berry's approaches

Connects historical work to recent developments in geometric phase

Abstract

While Pancharatnam discovered the geometric phase in 1956, his work was not widely recognized until its endorsement by Berry in 1987, after which it received wide appreciation. However, because Pancharatnam's paper is unusually difficult to follow, his work has often been misinterpreted as referring to an evolution of states of polarization, just as Berry's work focused on a cycle of states, even though this consideration does not appear in Pancharatnam's work. We walk the reader through Pancharatnam's original derivation and show how Pancharatnam's approach connects to recent work in geometric phase. It is our hope to make this widely cited classic paper more accessible and better understood.