Entanglement-Assisted Entanglement Purification

The efficient generation of high-fidelity entangled states is the key element for long-distance quantum communication, quantum computation, and other quantum technologies, and at the same time the most resource-consuming part in many schemes. We present a class of entanglement-assisted entanglement purification protocols that can generate high-fidelity entanglement from noisy, finite-size ensembles with improved yield and fidelity as compared to previous approaches. The scheme utilizes high-dimensional auxiliary entanglement to perform entangling nonlocal measurements and determine the number and positions of errors in an ensemble in a controlled and efficient way, without disturbing the entanglement of good pairs. Our protocols can deal with arbitrary errors, but are best suited for few errors, and work particularly well for decay noise. Our methods are applicable to moderately sized ensembles, as will be important for near term quantum devices.

Automated summary

The efficient generation of high-fidelity entangled states is crucial for various quantum technologies, and the proposed entanglement-assisted entanglement purification protocols in this work provide an improved method for achieving this. By utilizing high-dimensional auxiliary entanglement, the protocols can generate high-fidelity entanglement from noisy, finite-size ensembles with minimal disturbance to good pairs. The methods are particularly effective for dealing with few errors and decay noise, and are suitable for moderately sized ensembles, which will be important for upcoming quantum devices.