Measurement of complex scattering matrix in a nano-cavity array for boundary scattering tomography

TL;DR

This paper demonstrates an on-chip homodyne measurement setup to reconstruct the boundary scattering matrix of a silicon photonic cavity array, advancing boundary scattering tomography for quantum simulation.

Contribution

It introduces a novel on-chip homodyne measurement method for boundary scattering matrix reconstruction in silicon photonic cavity arrays.

Findings

Successfully reconstructed the edge scattering matrix of a 3x3 cavity array.

Demonstrated boundary measurement technique without bulk access or additional scatterers.

Enabled potential for scalable Hamiltonian tomography in photonic quantum simulators.

Abstract

On-chip silicon photonic coupled cavity arrays (CCA) are a promising platform for quantum simulators, with access to high Quality (Q) factor resonators, tunability, and foundry compatibility. Furthermore, scalable two-dimensional (2D) silicon photonic CCAs allow for simulation of rich physical phenomena via Hamiltonian engineering. However, complete reconstruction of the Hamiltonian is limited by access to cavities in the bulk, with current approaches relying on imaging scattered light from bulk resonators. These approaches often require additional scatterers to be built in, limiting scalability, while also being hampered by imaging technology in the near-infrared range. Instead of these approaches, Hamiltonian tomography algorithms that require homodyne boundary measurements have been demonstrated in literature, however measurements of complex scattering measurements along a CCA boundary have not been shown. Here, we experimentally demonstrate an on-chip homodyne measurement setup along a single boundary of a $3\times 3$ silicon photonic racetrack resonator array and reconstruct the system's edge scattering matrix.