Work

Measurement with indefinite causal order and the Sagnac interferometer

Year: 2024

Type: article

Abstract: It has been shown that measurements involving indefinite causal order can be superior to those in which a sequence of operations occurs in a specified order. In optics, such measurements are realized naturally in a Sagnac interferometer. We show that such an arrangement can measure the solid angle (on the Poincaré sphere) enclosed by a sequence of unitary transformations of the polarization. This is the Pancharatnam-Berry phase. Extension from the classical or single-photon treatment to a fully quantized treatment allows the analysis of the interferometer for arbitrary quantum states of light.This article is part of the theme issue 'The quantum theory of light'.

Source: Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences

DOI: 10.1098/rsta.2024.0447

Authors: S. M. Barnett, S. Croke, S. Franke-Arnold

Institution: University of Glasgow

Language: English

Topic: Quantum Mechanics and Applications

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Funder: Engineering and Physical Sciences Research Council

Awards: G6808631030, Indefinite causal order as a resource for quantum technology