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Quantum internet is useless forever.
Quantum teleportation is meaningless
(Fig.1) Fragile quantum information (= weak light or photons ) is too easily lost to send over long distance.
Quantum internet or network is impractical forever, because fragile quantum information (= weak light or photons ) is too easily lost.
This-middle-What is it so much more difficult to build a quantum internet ? says
"Photons (= weak light = quantum information ) are lost on their way through the optical cable. In a normal network signals can be easily amplified using repeaters which add more photons to the light pulses. But in the quantum internet if a single photon gets lost, all of the information transmitted is irretrievably destroyed. This kind of loss is the biggest problem when building a functional network."
This-middle-Poor results (4/16/2025) says
"Designing the network architecture of a quantum network is challenging. The no-cloning theorem might be a reliable safeguard against copies, but it also eliminates the possibility of signal duplication and amplification. The overall effect is that quantum networks are prone to information loss and limited ranges of only a few miles."
↑ So the quantum mechanical stupid (= no-cloning ) rule unreasonably forbids fragile quantum information (= weak light or photon ) from being copied or amplified (= No useful repeaters ), which makes it impossible to send information over long distance.
After researchers barely sent fragile quantum information over 404km with too low efficiency (= sent only 0.00032 photons per second, this-p.6-2nd-last-paragraph = useless slow internet ) in 2016, even recent researches could send photons over only 25km ~ 254km. ← regressing.
The 5th-last, 2nd-last paragraphs of this hyped news (8/28/2025) say
"Our network has just one server and one node (= Not internet ), connecting two buildings, with about a kilometer of fiber-optic cable" ← Even the latest quantum internet could barely send fragile information (= weak light ) over only 1km, useless.
"Overcoming this challenge will (= still unrealized ) require new devices"
The 2nd-last paragraph of even this overhyped news also admits
"Further research will still be needed to successfully repeat quantum signals over long distances (= still too short distance to be practical)"
(Fig.2) ↓ Extremely low efficiency of impractical quantum internet and memory.
The 1st, 7th, last paragraphs of this hyped news (7/21/2025) say
"Quantum teleportation... could be central to the realization of a so-called "quantum internet, a version of the internet that enables the safe and instant transmission of quantum information" ← wrong, quantum teleportation can send only classical information.
"These include an Input state preparation; an EPR-source to generate entangled photon pairs (= just two classical lights ) from an integrated photonic chip, a Bell-state measurement and a quantum memory based on erbium ion ensembles."
"As part of their next studies, the researchers plan to (= still unrealized ) focus on improving the performance of the erbium ion-based solid-state memory.. they would like to extend its storage times and improve the efficiency (= because still bad efficiency ) with which it stores quantum information."
↑ This research paper ↓
p.1-right-1st-paragraph says "we send the idler photon to Alice, who performs the joint Bell-state measurement (BSM) on both idler and input photons obtained from attenuated laser"
"Thirdly, the signal photon is sent to the 167Er3+ ions quantum memory,... stored for more than 2 µs (= Er3+ ion stored the input photon as excited-energy state for only very short 2μs, which is an impractical memory )"
p.4-left-1st-paragraph says "The overall storage efficiency is about 1.1% ( this-p.2-Efficienty )." ← So this quantum memory (= Er3+ ions ) lost 99.9% stored light energy (= quantum information ), completely useless.
↑ This-p.2-right-last says "The memory efficiency is defined as the ratio of the energy of the retrieved signal to the input signal" ← Only 1.1% of the input light signal was retrieved (= 99.9% of light information was lost )
This-research paper-p.7-Fig.S1 and p.10-Fig.S5 shows Three-fold coincidences are just 2.5 per 300s.
↑ It means the rate of 3 detectors detecting 3 photons (= lights ) simultaneously ( this-p.12-Figure.5, ) is just 2.5 times per 300 seconds due to massive photon loss.
↑ Detecting 3 photons only 2.5 times per 300 seconds is too slow and completely impractical as (quantum) internet or communication, contrary to hypes.
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