Few-Photon Scattering in Dispersive Waveguides with Multiple Qubits

TL;DR

This paper extends a numerical simulation method to multiple qubits in waveguides, analyzes photon scattering and bound states, and applies the findings to quantum gate fidelity, aiding the study of complex quantum systems.

Contribution

It introduces an extension of the Krylov-subspace simulation technique to multiple qubits and explores bound states and gate fidelity in waveguide QED systems.

Findings

Derived expressions for bound states in the continuum (BIC)

Analyzed photon scattering in multi-qubit systems

Assessed gate fidelity using BIC excitation

Abstract

We extend the Krylov-subspace based time-dependent numerical simulation technique for a qubit interacting with photons in a waveguide to the multiple qubit case. We analyze photon scattering from two qubits analytically and derive expressions for the bound states in the continuum (BIC). We show how the BIC can be excited. We use the BIC in a recent Pauli-Z gate proposal involving decoherence free subspaces and obtain the gate fidelity as a function of the gate parameters. The techniques presented in the paper are useful for investigating the time evolution of quantum gates and other many-body systems with multiple quenches in the Hamiltonian.