Good news! Pardon, it is not the very latest research (first published July 2023). It appears this research goes beyond quantum communication!
Caveat: I am not an expert on quantum computing etc., but I sense this could be some important research.
"Scientists can now efficiently produce nearly perfect entangled photon pairs from quantum dot sources.
Entangled photons are particles of light that remain connected, even across large distances, and experiments on this topic were recognized by the 2022 Nobel Prize in Physics. Combining entanglement with quantum dots, a technology recognized with the Nobel Prize in Chemistry in 2023, the IQC research team aimed to optimize the process for creating entangled photons, which have a wide variety of applications, including secure communications.
“ The combination of a high degree of entanglement and high efficiency is needed for exciting applications such as quantum key distribution or quantum repeaters, which are envisioned to extend the distance of secure quantum communication to a global scale, or link remote quantum computers,” ... “Previous experiments only measured either near-perfect entanglement or high efficiency, but we're the first to achieve both requirements with a quantum dot.”
By embedding semiconductor quantum dots into a nanowire, the researchers created a source that creates near-perfect entangled photons 65 times more efficiently than previous work. This new source ... can be excited with lasers to generate entangled pairs on command. The researchers then used high resolution single photon detectors provided by Single Quantum in The Netherlands to boost the degree of entanglement.
“Historically, quantum dot systems were plagued with a problem called fine structure splitting, which causes an entangled state to oscillate over time. This meant that measurements taken with a slow detection system would prevent the entanglement from being measured,” ... “We overcame this by combining our quantum dots with a very fast and precise detection system. We can basically take a time stamp of what the entangled state looks like at each point during the oscillations, and that's where we have the perfect entanglement.” ..."
From the abstract (I understand only 2% of what they are saying here):
"An on-demand source of bright entangled photon pairs is desirable for quantum key distribution (QKD) and quantum repeaters. The leading candidate to generate such pairs is based on spontaneous parametric down-conversion (SPDC) in non-linear crystals. However, its pair extraction efficiency is limited to 0.1% when operating at near-unity fidelity due to multiphoton emission at high brightness. Quantum dots in photonic nanostructures can in principle overcome this limit, but the devices with high entanglement fidelity (99%) have low pair extraction efficiency (0.01%). Here, we show a measured peak entanglement fidelity of 97.5% ± 0.8% and pair extraction efficiency of 0.65% from an InAsP quantum dot in an InP photonic nanowire waveguide. We show that the generated oscillating two-photon Bell state can establish a secure key for peer-to-peer QKD. Using our time-resolved QKD scheme alleviates the need to remove the quantum dot energy splitting of the intermediate exciton states in the biexciton-exciton cascade."
The world is one step closer to secure quantum communication on a global scale (original press release) University of Waterloo researchers combine Nobel prize winning concepts to achieve scientific breakthrough
The entangled photon source, an indium-based quantum dot embedded in a semiconductor nanowire (left), and a visualization of how the entangled photons are efficiently extracted from the nanowire.
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