# Robust architecture for programmable universal unitaries

## TL;DR

This paper introduces a robust, error-insensitive method for decomposing large unitary matrices using multi-channel blocks, enabling flexible and scalable quantum and classical information processing.

## Contribution

It presents a novel decomposition approach based on multi-channel blocks that is universal and resilient to fabrication errors, unlike traditional planar mesh schemes.

## Key findings

- Scheme is universal even with random block matrices
- Placement of variable elements is arbitrary
- Enhanced robustness to fabrication errors

## Abstract

The decomposition of large unitary matrices into smaller ones is important, because it provides ways to realization of classical and quantum information processing schemes. Today, most of the methods use planar meshes of tunable two-channel blocks, however, the schemes turn out to be sensitive to fabrication errors. We study a novel decomposition method based on multi-channel blocks. We have shown that the scheme is universal even when the block`s transfer matrices are chosen at random, making it virtually insensitive to errors. Moreover, the placement of the variable elements can be arbitrary, so that the scheme is not bound to specific topologies. Our method can be beneficial for large-scale implementations of unitary transformations by techniques, which are not of wide proliferation today or yet to be developed.