# Universal tool for single-photon circuits: quantum router design

## TL;DR

This paper introduces a universal approach using non-Hermitian Hamiltonians to design and analyze single-photon quantum circuits, exemplified by a novel six-port quantum router with tunable photon routing capabilities.

## Contribution

The paper presents a new method employing non-Hermitian Hamiltonians for designing and analyzing single-photon circuits, demonstrated through an analytically described six-port quantum router.

## Key findings

- Analytical expressions for photon transmission and reflection coefficients.
- Tunable photon detection probabilities via interference effects.
- Validation of the non-Hermitian approach for quantum circuit design.

## Abstract

We demonstrate that the non-Hermitian Hamiltonian approach can be used as a universal tool to design and describe a performance of single photon quantum electrodynamical circuits(cQED). As an example of the validity of this method, we calculate a novel six port quantum router, constructed from 4 qubits and 3 open waveguides. We have got analytical expressions, which describe the transmission and reflection coefficients of a single photon in general form taking into account the non-uniform qubit's parameters. We show that, due to naturally derived interferences, it is possible to tune the probability of photon detection in different ports in-situ.