The heralded amplification for the single-photon multi-mode W state of the time-bin qubit

TL;DR

This paper proposes a simple, linear-optics-based amplification protocol to enhance the fidelity of single-photon multi-mode W states of time-bin qubits, which is practical for current quantum information applications.

Contribution

It introduces an efficient, experimentally feasible amplification method for protecting time-bin qubit W states using only linear optical elements and minimal auxiliary photons.

Findings

Fidelity of W states can be increased with transmission t<0.5

Protocol is simple, economical, and compatible with current technology

Contains encoded time-bin information perfectly

Abstract

We put forward an effective amplification protocol for protecting the single-photon multi-mode W state of the time-bin qubit. The protocol only relies on linear optical elements, such as the $50:50$ beam splitters, variable beam splitters with the transmission of $t$ and the polarizing beam splitters. Only one pair of the single-photon multi-mode W state and some auxiliary single photons are required, and the fidelity of the single-photon multi-mode W state can be increased under $t<\frac{1}{2}$. The encoded time-bin information can be perfectly contained. Our protocol is quite simple and economical, and it can be realized under current experimental condition. Based on above features, it may be useful in current and future quantum information processing.