Experimental high-dimensional entanglement certification and quantum steering with time-energy measurements

TL;DR

This paper demonstrates a new method for certifying high-dimensional entanglement and quantum steering in time-energy measurements, even after significant dispersion, advancing scalable quantum communication.

Contribution

It introduces an experimental scheme for certifying high-dimensional entanglement and steering in telecom photons, resilient to fiber dispersion, enabling scalable quantum networks.

Findings

Certified 24-dimensional entanglement and 9-dimensional steering.

Maintained 21-dimensional entanglement after fiber dispersion equivalent to 600 km.

Proved 7-dimensional entanglement semi-device independently.

Abstract

High-dimensional entanglement provides unique ways of transcending the limitations of current approaches in quantum information processing, quantum communications based on qubits. The generation of time-frequency qudit states offer significantly increased quantum capacities while keeping the number of photons constant, but pose significant challenges regarding the possible measurements for certification of entanglement. Here, we develop a new scheme and experimentally demonstrate the certification of 24-dimensional entanglement and a 9-dimensional quantum steering. We then subject our photon-pairs to dispersion conditions equivalent to the transmission through 600-km of fiber and still certify 21-dimensional entanglement. Furthermore, we use a steering inequality to prove 7-dimensional entanglement in a semi-device independent manner, proving that large chromatic dispersion is not an obstacle in distributing and certifying high-dimensional entanglement and quantum steering. Our approach, leveraging intrinsic large-alphabet nature of telecom-band photons, enables scalable, commercially viable, and field-deployable entangled and steerable quantum sources, providing a pathway towards fully scalable quantum information processer and high-dimensional quantum communication networks.