Approximate quantum state reconstruction without a quantum channel

TL;DR

This paper presents a method for optimal quantum state reconstruction across multiple users without quantum channels, using measure-broadcast-prepare schemes that achieve the highest possible fidelity.

Contribution

It introduces a universal, physically realizable measurement and reconstruction scheme for distributing quantum states to many users with optimal fidelity.

Findings

Achieves universal upper bound fidelity in quantum state reconstruction

Works for arbitrary many identical pure states in general dimensions

Provides practical measurement bases for cloud-based quantum state distribution

Abstract

We investigate the optimal quantum state reconstruction from cloud to many spatially separated users by measure-broadcast-prepare scheme without the availability of quantum channel. The quantum state equally distributed from cloud to arbitrary number of users is generated at each port by ensemble of known quantum states with assistance of classical information of measurement outcomes by broadcasting. The obtained quantum state for each user is optimal in the sense that the fidelity universally achieves the upper bound. We present the universal quantum state distribution by providing physical realizable measurement bases in the cloud as well as the reconstruction method for each user. The quantum state reconstruction scheme works for arbitrary many identical pure input states in general dimensional system.