Interferometry and higher-dimensional phase measurements using directionally unbiased linear optics

TL;DR

This paper introduces interferometers built from Grover multiports that enable advanced phase measurements, including simultaneous multi-axis rotation sensing, surpassing traditional beam-splitter-based systems.

Contribution

It demonstrates novel interferometer configurations using Grover multiports, enabling multi-parameter phase measurements and higher-dimensional rotation sensing.

Findings

Interferometers with Grover multiports exhibit unique interference features.

They can interpolate between HOM and anti-HOM behaviors.

They enable simultaneous three-axis rotation measurements.

Abstract

Grover multiports are higher-dimensional generalizations of beam splitters, in which input to any one of the four ports has equal probability of exiting at any of the same four ports, including the input port. In this paper, we demonstrate that interferometers built from such multiports have novel features. For example, when combined with two-photon input and coincidence measurements, it is shown that such interferometers have capabilities beyond those of standard beam-splitter-based interferometers, such as easily controlled interpolation between Hong-Ou-Mandel (HOM) and anti-HOM behavior. Further, it is shown that the Grover-based analog of the Mach-Zehnder interferometer can make three separate phase measurements simultaneously. By arranging the transmission lines between the two multiports to lie in different planes, the same interferometer acts as a higher-dimensional Sagnac interferometer, allowing rotation rates about three different axes to be measured with a single device.