Quantum key distribution, information, encryption, internet, network are all useless forever.

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fake quantum supremacy

Quantum computers potentially factoring large numbers for cracking the cryptosystem by Shor algorithm are impossible and unrealized forever.

[ Quantum computers are useless, unable to factor huge numbers using (fictional) superposition or parallel-world simultaneous calculations based on Shor algorithm. ]

(Fig.1) The largest numbers factored so far by (still-useless) quantum computers is only 21 = 3 × 7 using fake (slower) Shor algorithm based on a single-world calculation (= the current useless quantum computers cannot utilize quantum superposition or unseen parallel worlds for dream-like simultaneous calculations, contrary to the media-hype )

The current encryption system and keys such as RSA are based on two prime numbers or semi-primes, which are said to be cracked by (still-unrealized) quantum computers which may implement multiple simultaneous calculations of Shor's algorithm at once using (fictional) superposition = a dead-and-alive cat states or parallel worlds ( this p.4 ).

The point is all the current quantum computers are unable to correct errors, so they can Not calculate any meaningful values nor give right answers.  ← Useful factoring by quantum computers or executing Shor algorithm is impossible (forever).

So far, the largest numbers factored by the (still-useless) quantum computers are only 21 = 3 × 7 and 15 = 3 × 5 ( this 6th-paragraph,  this 3rd-paragraph,  this 4~5th-paragraphs ) using the fake modified version of Shor's algorithm (= called "semi-classical or Kitaev's (fake) Shor's algorithm" this 9,  this 2-3rd paragraphs,  this p.6 ) which can carry out only one task at once using only one single world (= implement one task, reset, and recycle each quantum bit or qubit,  this 14th-paragraph,  this p.2 6th-paragraph,Fig.1.B-D  this Figure.3,4,6,7 ) instead of implementing the dreamlike simultaneous quantum calculations which are required for faster factoring in true Shor's algorithm.

So the so-called post-quantum cryptography anticipating such an illusory quantum computers' threat or speed-up is completely meaningless ( this 4th-last~ 2nd-last paragraph,  this 4~5th-paragraphs ).

Actually such dubious post-quantum encryption keys were easily cracked even by ordinary laptops or classical computers.  ← The post-quantum encryption is useless, meaningless and just a waste of time.

As shown in the upper figure, when we try to factor 15 = 3 × 5 using Shor's algorithm, we first choose an arbitrary number (= for example, choosing "2" here ).

And then, we conduct multiple calculations like 21 divided by 15 gives the remainder of 2 (= 21 mod 15 = 2 ), 22 divided by 15 gives the remainder of 4, 23 divided by 15 gives the remainder of 8, 24 divided by 15 gives the remainder of 1,.. and find the period number (= 4, in this case ) which means the number of terms periodically giving and repeating the same remainders ( this p.7-12,  this p.96 ).

↑ These simultaneous calculations giving multiple different remainders in Shor's algorithm need to be done by using (still-unrealized) quantum computers's fictional superposition ( this Step.6,  this p.9,  this p.2-last-paragraph ) or parallel worlds ( this last-paragraph,  this 19-20th paragraphs,  this last-paragraph ) in order to factor large numbers faster and break the current encryption key system ( this 10th-paragraph ).

↑ In order to unrealistically carry out these multiple different simultaneous calculations for factoring large numbers using Shor algorithm on the same common quantum bits or qubits, not only qubits but also the external devices emitting microwave pulses for manipulating qubits have to be unrealistically split into multiple different parallel worlds ( = one microwave pulse must split into multiple microwave pulses existing in different parallel worlds to simultaneously calculate different parallel-world numbers by manipulating qubits existing in different parallel worlds ), which is impossible also in the original quantum mechanical rule.

Using the period "4" allegedly found by performing multiple (parallel-world) calculations, we can obtain two prime numbers (= 24/2 - 1 = 3, and 24/2 + 1 = 5 ) composing 15 = 3 × 5 ( this p.13-14 ).

↑ Contrary to the media-hype baselessly saying like "Quantum computers will be exponentially faster", the current useless quantum computers can Not carry out these simultaneous quantum mechanical calculations (= giving multiple different remainders using different parallel worlds simultaneously by Shor algorithm is impossible in the current useless quantum computers ), instead, they can only do one single simple task using fake slower Shor's algorithm needing the help of traditional classical computer or algorithm ( this p.3-first-paragraph,p.23-2(b) ).

It means thinking about the post-quantum encryption prepared for the fictional quantum computers' power of simultaneous calculations using imaginary parallel worlds is nonsense, and just a waste of time and money.

Factoring by optimization in (fake) quantum annealers instead of using true (quantum parallel-world) Shor's algorithm is Not faster, hence unable to crack RSA encryption.

(Fig.1') Fake quantum computers = annealing machines cannot factor arbitrary unknown numbers, because they have to find and set the already-known solutions of only some particular factoring as the lowest (= optimal ) energy beforehand.

Some physicists claimed to have factored some particular large numbers using optimization (= adiabatic ) method (= instead of Shor's algorithm ) run by (fake) quantum computers called "quantum annealers" with far smaller numbers of qubits than originally required for factoring by true Shor's algorithm ( this 3rd-paragraph,  this p.6 ).

The point is these quantum annealers such as D-Wave and Harvard's (fake) quantum simulators for solving optimization problems are Not real quantum computers, hence, quantum annealer's optimization methods were proved to be slower than the ordinary classical computers ( this You can't necessarily do ).

This 5th-paragraph says
"Unlike with general-purpose quantum computers, it hasn't been mathematically demonstrated that quantum annealers can consistently outperform traditional computers."

In order to factorize numbers by this optimization methods, first, physicists have to artificially encode the true solutions as the lowest-energy (equilibrium) states instead of actually performing factoring.  ← This is trick.  Physicists already have to know the solutions of factoring beforehand to encode the solutions as the minimum energies.

↑ If the right solution is not known beforehand, the annealing machine would just randomly move back and forth between an infinite number of wrong solutions (or local minima ) without being pulled down toward the right solution encoded as the lowest energy state.

So physicists can factor only some artificially-chosen particular numbers (= this optimization or energy minimization methods cannot factor any arbitrary numbers, so useless and Not faster,  this 5-7th paragraphs ) whose factored solutions or prime numbers can be encoded in even a small number of quantum bits or qubits.

Whether quantum or classical (= actually, No boundaries between them.  Physicists often unfairly chose very time-consuming methods as "(fake) classical methods" to hype the (fictional) quantum speed-up ), all things in the nature gradually evolve into the lowest energy state (= solution ? ), which means the optimization by annealing can Not prove the quantum mechanical speed-up ( this 5-7th paragraphs ).

The recent Chinese research also used this ( Not faster) optimization method in only 10 qubits (= only 10 bitstring ) for factoring only one particular number (= 261980999226229 ) using Schnorr's algorithm instead of true Shor's algorithm .  ← Actually this Chinese team's research used "hybrid computers" where most of complicated calculations were done by the ordinary classical computers, and the 10-qubit quantum computer's part (= still Not a comptuer ) allegedly did some optimization procedure of finding some lowest energy ( this p.1-2,Fig.1 ) related to factoring.

In the optimization or annealing method, after physicists artificially encode the (factored) solutions as the lowest energy (= ground ) state (= by artificially adjusting qubits' interaction strengths or the artificially-created Hamiltonian energy's coefficients,  this Fig.2, p.16-17 ), all they can do is just wait and see the system automatically evolving into the lowest energy or optimal state (= this is set to be the "solution" in advance,  this p.2 ) without performing any meaningful calculations.

↑ Not only in quantum mechanics but also in classical mechanics, all things in the world gradually evolve and settle down to the lowest energy (= equilibrium) states, so the optimization method can Not prove the quantum computer's supremacy.

↑ They often deliberately chose very time-consuming methods of finding the minimum energies only for the ordinary classical computers (= so, unfair comparison, this 6-7th paragraphs ), and wrongly claimed the (fake) quantum computers (= annealing machines ) could solve some (optimization) problembs much faster than the classical (super-)computers !

As a result, all these dubious quantum computers are useless, unable to factor large numbers or crack the current encryption (forever), because these quantum computers are still Not computers or calculators at all.

 

Quantum information or quantum key encoded in a fragile photon or weak light cannot be distributed more than several hundred kilometers.  ← Quantum network is unusable for actual internet.

[ Photons or weak light used as quantum key or information carriers easily get lost and drastically decrease to less than 1/10000 after traveling only 200 km optical fiber. ]

(Fig.2) Quantum information or key encoded in a photon or weak light's polarization (= ex. horizontal = 0, vertical = 1 polarization ) or phase is easily lost and significantly diminished to the impractical photon's number level over only 200 km = sending such a fragile quantum information over long distance is impossible forever.

In quantum encryption, physicists try to encode the quantum key information in a fragile photon or weak light's polarization in vain, for example, the horizontally polarized (= H ) light is treated as the photon's qubit 0 state, vertically-polarized (= V ) light is treated as the photon's qubit 1 state ( this p.12,  this p.2-Fig,1 ).

Basically, each quantum information should unrealistically consist of multiple (unseen) parallel worlds or quantum superposition (= a dead-and-alive cat ) state mixing horizontally (= H ) and vertically (= V ) polarized lights or photons existing simultaneously (= which is just classically mixed weak polarized lights, Not fantasy quantum superposition, actually ) until the measurement of it.

The problem is these (fictitious) photons or weak lights used as the quantum information carriers easily get lost and diminished, which makes the quantum cryptography or quantum internet technology impractical forever.

This 2nd paragraph says
" A major obstacle is posed by the fact that most photons are scattered or absorbed before getting to the receiver. In a standard optical fiber, a photon’s chances of survival are 10% after 50 km and fall to only 0.01% after 200 km ( this 4th-paragraph,  this p.34,  this p.6-Fig.4,  this p.3-Fig.2 ). This is devastating considering that standard optical repeaters can’t faithfully regenerate a quantum signal, and quantum repeaters are still beyond today’s technological reach."

This significant photon loss is why quantum information encoded in such fragile photons or weak lights cannot be sent over long distance = the longest distance of quantum key distribution even in the latest 2022 is less than 400 km ( this figure ).

As shown in this p.5-Fig.5-(b), two photon count rate drastically decreases from 105 counts per sec (= Hz ) to only 10-3 counts after traveling 400km optical fiber.

Furthermore, in order to detect and distinguish such a elusive single photon or very weak light from other irrelevant background light, the optical fibers and photodetectors must be always cooled down to almost absolute zero to exclude dark photon counts caused by unspecific thermal fluctuation or background light (= background dark photon counts can Not be excluded completely ), which operation cost would be far more than the practical level ( this 9th-paragraph ).

No matter how low the temperature becomes, it is impossible to avoid the contamination by irrelevant background lights, photons or thermal noises detected as (fake) photons (= dark count ) or incorrect quantum key information by the photodetectors which detection efficiency is often less than 50 % ( this p.1-introduction, this p.2,  this p.4 ), and the photodetector cannot determine the precise number of photons arriving ( this p.46-1st-paragraph,  this p.2-footnote ).

↑ It means a photon is just a fictional and artificially-created particle or weak laser light detected as "electrons' current" ejected by the incident weak (classical) light in the photodetectors where physicists can freely change the photons' count rate or detection efficiency by adjusting the detection voltage ( this p.4-last ).  ← a fictitious photon = detection voltage or threshold of photodetector.

Unlike the ordinary practical (= classical ) internet or optical communication which can easily copy and amplify the diminished light pulses after traveling some distance, the quantum information or photon's polarization is Not allowed to be measured or amplified, because the measurement of the photon or light's polarization is supposed to destroy the quantum mechanical information's superposition states which must be kept in 'uncertain' states in unseen parallel-worlds ( this quantum beam splitter,  this 3-6th-paragraphs,  this p.29 ).

This 4th paragraph says
"In QKD, two distant users (we’ll call them Alice and Bob) exchange quantum objects (= ex. photon's polarization qubits) through a quantum channel. With the proper protocol in place, quantum theory ensures that any attempt at eavesdropping on the channel results in a modification of the qubits, which will be detected by Alice and Bob. Therefore, QKD offers a secure way to exchange cryptographic keys. However, because qubits cannot be amplified, there are physical limitations on the distances between links. Most commercially available systems have a range of around 100km."

So contrary to the media-hype, commercialization of quantum network or key distribution is far from reality ( this p.8-left,  this p.2-abstract,  this p.3-3rd-paragraph ).

This 5th-paragraph says
"quantum networking is still in its infancy. The creation and manipulation of qubits are challenging tasks that require precise control and extreme environmental conditions. Moreover, maintaining the entanglement of qubits over long distances, a prerequisite for a global quantum network, is a significant technical hurdle yet to be overcome."

The alleged first commercial quantum network is just "trial (= still far from practical network )" just between two points inside one city

In order to extend the distance of distributing quantum information, the quantum repeaters ( this p.1-introduction ), which allegedly send quantum information without measuring fragile photon's state, are needed, but the practical repeaters are impossible forever (= due to the current quantum information theory's irreparable flaws ) despite the long-time research ( this p.4-fist-paragraph ).

This "2.Extended quantum network section" says
"Sending information halfway around the world is much harder with quantum networks than with classical networks. In classical networks, amplifiers placed periodically along the line reemit signals, splitting a marathon into a relay race. Quantum networks can’t use amplifiers, though, because reading and reemitting qubits would disrupt their (meaningless) entanglement, ruining the transmission..."

"..Some people have demonstrated designs that would in principle be a quantum repeater, but there aren't any deployed in a real network.. Right now, researchers are largely focusing on developing metropolitan-scale networks, which are small enough to avoid needing quantum repeaters."

This 3rd-paragraph says
"But building a quantum network is No easy task. Such networks often work by transmitting single photons that are entangled; .. Unfortunately, the signal from a single photon is easily lost over long distances. Carriers of quantum information can also lose their quantum nature in a process known as decoherence."

Ther are various versions of quantum information or key distribution methods, none of which are practical.

In the "trusted node (relay) quantum key distribution method (which is one of classical key distribution methods )", quantum information or key (= light polarization ) is measured in the ordinary classical way (= destroying quantumm information ) at some middle points, and this light or photons with the measured polarization is copied, created and amplified again (= in the classical way ), relayed, and sent to the next receiver or middle points, so it cannot extend the substantial distance of sending quantum information in the quantum mechanical way ( this p.2-B,  this 4th-paragraph ).

The distance of the twin-field quantum key distribution is Not the single distance of quantum information traveling, but twice the true distance of sending quantum key over which two photons or lights are sent to the middle point ( this 6th-paragraph,  this p.3-Fig.2 ).  ← So "830-km fiber by twin-field quantum key distribution" means less than 415 km distribution

Satellites are said to send photons or lights over 1000 km, because the outer space contains much less atmospheric molecules absorbing and scattering lights or photons than the optical fibers on the ground.

But of course, almost all photons or quantum key information emitted from a distant satellite also easily get lost and disappear at the ground station after traveling 1000 km.

And the distribution of fragile weak quantum information and photons from a satellite cannot avoid irrelevant background lights emitted from stars or cities, which are detected as false photons.  ← So distribution of quantum information using satellites can be basically conducted only in the dark night and in the places distant from the city's light, which is also impractical forever.

Quantum key distribution from satellites is also unrealistic and impractical.

[ Photons or lights emitted from distant satellites also easily get lost and significantly decrease, so it's impossible to distinguish a single photon or weak light originating from the satellite and other irrelevant background lights or thermal noises detected as false photons. ]

(Fig.3) Quantum entanglement or teleportation is a meainingless useless concept.

Sending quantum information encoded in a fragile photon or weak light's polarization through optical fibers has been unrealistic and impractical despite long time researches on quantum network which is one of fake science fields stopping our real scientific progress ( forever ) by making the world's reseachers waste their time only for illusory useless concepts such as superluminal entanglement and destroy their future careers.

Satellites orbiting in the outer space are said to send photons or lights through the vacuum or lower-density atmosphere, hence, decrease the photons' loss than the optical fibers on the ground.

But even the quantum network or quantum key distribution (= QKD ) by those satellites are also useless and impractical forever due to the significant photons' loss by the atmosphere ( this p.3 ) and a lot of irrelevant background light noise outside ( this p.1-introduction ).

This 2nd-paragraph~ says
"QKD (= quantum key distribution ) schemes have been demonstrated on distances of a few hundreds of kilometers—sufficient to cover communications networks between cities. But increasing their range, eventually to the global scale, is a formidable challenge.."

"..A key barrier to long-distance quantum communications is related to the losses—from absorption and scattering—incurred by light traveling along optical fibers or through the atmosphere. While in classical communications optical amplifiers can be used as repeaters that compensate for such losses, the amplification of individual photons corrupts their quantum information. Researchers are investigating various quantum repeater technologies that could overcome this limitation, but quantum repeaters will not soon be ready to support intercontinental quantum communications. The only viable, near-term approach is offered by the free-space optical channel, linking low-Earth-orbit satellites to Earth. The advantage of this approach is that the photons’ transmission path—except for the lower ∼10 km of the atmosphere—is virtually in a vacuum, with negligible absorption and scattering."

"..Transmitting light from a satellite to Earth, however, has other challenges. For example, the satellite’s telescopes and those on the ground must continuously stay pointed at one another to optimize signal transmission. This pointing can be complicated by atmospheric conditions that randomly deflect and distort the light beams. In addition, the satellite and ground station need to synchronize their clocks to identify signal photons based on arrival times."

This 10th-paragraph says
"Although losses (= of photons sent from satellites ) are much smaller than with a comparable fiber connection, the absorption and diffraction processes still lead to a signal with interruptions. Generation of photons at megahertz rates (= 106 photons per second ) at the source usually leads to a quantum signal at the receiver in the order of a few hertz (= significantly decrease to only a few photons per second ) or less.".

↑ It means the photons' number (= photons' click rate in a detector = megaherz = 106/sec ) or light intensity emitted from the satellite significantly decreases to only a few hertz = a few photons' detection/sec in the ground stations which are about 1000 km apart from the satellite. which large loss of quantum information encoded in fragile photons cannot be used for the practical quantum internet or practical real-time communication.

Spooky action or superluminal quantum entanglement is a meaningless and useless concept.

Chinese team is said to have conducted the experiment showing the so-called quantum entanglement (= faster than light spooky link or science fiction ? ) using a satellite and photons (= just attenuated classical light is called "(fictitious) photon" ).

First of all, quantum entanglement or teleportaion is a meaningless and useless concept sending No real information, to say nothing of sending information faster than light ( this 2nd-last paragraph ).

They made the satellite send 5.9 million pairs of photons or light pulses per second (= 5,9 MHz = which is just estimation from the light intensity instead of actually counting fictitious photons ) to two distant ground stations (= distance between the satellite and ground stations is 500 ~ 1600 km,  this p.4-2nd-3rd-paragraphs, p.10-1st & last-paragraphs ).

↑ These two photons or lights were prepared to have the mutually-orthogonal polarizations which means when one light or photon has horizontal H (or vertical V ) polarization, the other light of photon has vertical (or horizontal ) polarization, which is expressed as the superposition of HV and (= or ) VH polarization states of a pair of two photons.

When one ground station measured one of photons' pair as horizontally-polarized, this measurement immediately (= by faster-than-light entanglement action !? ) determines the other photon sent to the other distant ground station as vertically-polarized ( this 3rd-paragraph,  this 3rd-paragraph ).

↑ As you see, this meaningless quantum entanglement is just the "measurement" of some state (= ex. polarizations ) of a pair of photons or lights, Not an act of sending some real information or communication ( this middle,  this 1-5th paragraphs ).

The Chinese satellite sent 5.9 million of photons or lights's pairs per second and two ground stations could detect only 1.1 photon or light pair per second (= 1.1 Hz,  this 7th-paragraph ), which faint detected satellite's light is easily hidden in other irrelevant background light (= ~ 2000 false photon counts per second from background light were detected in each ground station's photodetector, they say ) such as (stars and Moon) light ( this p.5-last-p.6 ).

As a result, all the current quantum information technology such as quantum key distribution, network and internet using fragile (fictitious) photons though optical fibers and satellites are completely useless and impractical ( except for this ), wasting time and money in meaningless experiments going nowhere, forever.

Quantum cryptography or network system of detecting eavesdropper destroying a photon or weak light can be explained by classical mechanism.  Quantum mechanics is meaningless, unnecessary.

[ Eavesdropper destroying a photon or weak light can be detected, so quantum key information is secure ?  ← This has nothing to do with quantum mechanics.  "Classical weak light" is also destroyed by eavesdropper, and it can be detected. ]

(Fig.4) Creating a single (fictitious) photon at the designated time is impossible.  ← a photon is just an attenuated light (= photon's number is just a rough estimation from classical light intensity ). Most of photons get lost and those lost photons can be stolen by eavesdropper unnoticed.

It is repeatedly said that quantum network, encryption, information and quantum key encoded in a photon or weak light's polarization are "ultra-secure" without showing any convincing evidences (= because there is still No practical quantum network to test it ).

Physicists vaguely argue that quantum mechanical "no-cloning theorem" prohibits quantum photon's information from being copied by eavesdropper who would leave indelible traces behind which can be easily detected as a proof of eavesdropping ( this 1st-paragraph,  this 10th-paragraph,  this p.1-2 ).

↑ This (baseless) logic of the so-called secure quantum information technology can be easily explained by the ordinary classical light wave, because a very weak light wave, which corresponds to a photon, is also fragile and easily destroyed by eavesdropper's measurement (= by seeing the destroyed weak light or fictitious photon, eavesdropper can be easily detected ).  ← Classical weak fragile light can also make very "secure internet (= eavesdropper can be detected by seeing the destroyed weak light )" according to their illogical quantum information logic.

Furthermore, the very weak classical light misteken for the fictitious photon cannot be copied (= it's impossible to copy and create exactly the same new weak light at the same time as when the eavesdropper measures and destroys it., which time lag can be easily detected as the sign of eavesdropping ).

So quantum mechanics is completely unnecessary (= classical weak light can replace the fictitious photon ), and just preventing our real scientific development.

In the mainstream quantum cryptography such as BB84, Alice is supposed to randomly send multiple horizontally (= 0 ) or vertically (= 1 ) polarized lights or photons as quantum key information to the receiver Bob who must randomly choose the polarization filters with vertical-horizontal-angle-basis or +45o/-45o-angle-basis for detecting and distinguishing photons which can be naturally explained by the weak classical light wave that was detected by a photodetector, only when the light intensity after passing polarizing filter exceeds some detection threshold, hence, the fictional quantum photon or superluminal entanglement is unnecessary for any technologies such as (still-impractical) quantum information, key distribution or internet.

In optical fibers, instead of using photon or light's polarization, they often try to encode the key information in the different wave phases of the very weak light wave pulse (= or fictitious photon ) like a bit 0 = early-arrival light, 1 = late-arrival-light ( this p.2,  this p.3 ), which is also just classical light wave theory Not needing illusory quantum mechanics or a photon.

Their quantum key distribution, information and quantum internet based on the fictitious fragile photon (= just very weak light ) are unstable and impractical forever.

As I said, almost all of photons or weak light easily get lost, the receiver can get only a small fraction of the sent photons or weak light as quantum key, and many other irrelevant background light and thermal fluctuation can be easily mixed with such a small amount of remaining quantum key photons or light, and detected as false photons at the receiver's photodetector.

To distinguish true sent photons or quantum key photons from other irrelevant background light or false photons, the sender Alice and the receiver Bob have to record the exact times (= a few nanosecond window,  this p.6-1st-paragraph ) when they send or receive photons for checking whether the detected photons are really the true quantum key photons or not, and these recorded times must be communicated and shared with each other using the ordinary classical communication methods.

Then, they can use only an extremely small number of the remaining photons or weak lights which were sent at the times designated by the sender and receiver as the true quantum key information.

But sending those fragile photons or weak lights as quantum key is highly impractical.

Only 79426 photons or light pulses out of 12.8 million photons sent can be detected as quantum key at the receiver's photodetector after those photons travel only 1.45 km ( this p.3-secure key generation ).
↑ Photons and lights sent by Alice significantly decrease to only 1/100 of the original photons or light at the receiver Bob.

Furthermore, there is No such thing as a photon particle.
Physicists often use just the attenuated laser light wave as (fictitious) photons' source ( this p.1-2nd-paragraph ), so it's impossible to create and send a single photon at the designated time on demand ( this p.6-last,  this p.3-2nd-paragraph ).

↑ The number of (fictitious) photons contained in each sent light pulse is uncertain and random ranging from multiple photons to zero photons ( this 1.motivation-2nd-paragraph,  this p.2-4th-paragraph ).  ← This means there is No such thing as a photon.  A (fictitious) photon is artificially defined as a "click" of photodetectors.

Eavesdropper can easily steal the (quantum) information of those randomly-changing photons unnoticed, because most of those photons or lights get lost regardless of eavesdropper measuring or destroying photons, which is called "photon-number splitting (=PNS) attack ( this p.22-24,  this p.3,  this p.3-left )".

This p.15-last-paragraph says
"Ideally a QKD system would use a true single photon source, which never generates more than one photon in each output pulse. However, as these are Not yet available commercially, an attenuated laser diode is often used instead. The pulses from an attenuated laser can of course contain more than one photon. For these, the same information is redundantly encoded on all the photons in the pulse, thus creating the conditions for Eve to attack the system through a photon-number-splitting attack."

Physicists claim that if they mix the decoy photons or decoy light pulses with the quantum key photons, and check the loss of the decoy photons (= allegedly destroyed by eavesdropper ), they can know whether this photon's information is stolen by eavesdropper or not ( this p.8 ).

↑ But this logic of detecting eavesdroppers is wrong, because most of both quantum key and decoy photons easily get lost irrelevant to the eavesdropper, hence it's impossible to detect eavesdropper by cheking and roughly estimating the number of the lost photons ( this p.3 ).

And this quantum encryption principle based on decoy photons or quantum no-cloning theorem does Not need the quantum mechanics at all.

Weak classical light wave can be also used as decoy light, and even if eavesdroppers measure and destroy the weak light, and try to create and copy the destroyed weak light, it causes the detectable "time lag", which means eavesdroppers cannot create the same weak light instantly, hence, this time lag can be easily detected as a sign of eavesdropper.

Diminished quantum fragile photon's information cannot be amplified or copied.  → Quantum repeater allegedly sending photons over long distance is needed but it's impractical forever.

[ Quantum repeater allegedly copying quantum photon's superposition (= multiple-polarization) state without measuring or destroying it is useless forever.  ← Long-distance quantum network and key distribution are impossible forever. ]

(Fig.5) Quantum repeater allegedly using (meaningless) entanglement and telerpotation is just "simultaneous measurement" of photons or light's polarizations instead of sending some real quantum information.  ← Impractical forever

In the ordinary (classical) network or internet, when the light signal decreases after traveling some distance, it is measured, copied and amplified, which makes it possible to transmit the light signal or information over any long distance.  = useful and practical (classical) network or communication method.

On the other hand, quantum information encoded as a fragile photon or light's (uncertain and superposition) polarization states (= called photon's qubit ) can Not be measured, copied or amplified ( this 2nd-paragraph ), because the measurement and determination of the photon or light's polarization state is supposed to destroy quantum (meaningless) superposition or information ( this p.1-left,  this 1st-paragraph,  this p.11 ).

This stupid inconvenient (artificial) quantum mechanical rule makes the so-called quantum network and key distribution over long distance impractical and impossible forever.

In order to send such an inconvenient quantum information, which is Not allowed to be measured or copied, the quantum repeater is said to be necessary.

This 2-3rd paragraphs says
"photons decay exponentially as they propagate, limiting the maximum communication distances to about 100 kilometers. In classical networks, this problem is solved by using repeaters consisting of photon amplifiers. However, these are not practical in a quantum internet because amplification degrades quantum entanglement. Hence quantum repeaters are needed.."

"..Such repeaters, like their classical counterparts, divide long communication lines into shorter ones by inserting repeater “nodes.” Entanglement is first established between adjacent nodes using, for example, entangled photon-pair sources... The entanglement can then be extended to nonadjacent nodes, and so on, by entanglement swapping or teleportation, until long distances can be covered. Finally, the quantum information is teleported. In this way the quantum signal is transmitted without exponential degradation and without being amplified."

But despite the long time researches across the world, the practical quantum repeaters remain unrealized (= forever,  this 2.  this 3-5th-paragraphs,  this p.1-left ), where our basic science stops progressing stuck in the harmful and meaningless quantum mechanical information theory and unrealistic quantum computers.

Quantum repeater's teleportation means just the mesurement of a pair of two (entangled) photons or lights with some polarization, which is unable to send real useful information.

Still-impractical quantum repeater is said to have potential to magically send fragile quantum information such as photons' polarizations over long distance even without directly copying or amplifying it using (fictional superluminal) entanglement and teleportation ( this last-paragraph,  this p.6-8,  this p.3-Fig.1 ).

First, each light source (= such as BBO crystal or laser's classical polarized light ) of S1 and S2 emits two (entangled) photons or lights with the opposite polarizations, which means, for example, when one photon-1 (or light-1) is measured to have horizontal H (or vertical V ) polarization, this "measurement" instantaneously (= faster-than-light entanglement ? No ! ) determines that the other photon-2 or light-2 have vertical (or horizontal) polarization ( this 2nd-paragraph,  this 3rd-paragraph,  this 2nd-paragraph ).

↑ So quantum entanglement is just the "measurement" of some states such as polarizations of two photons or lights without sending any real informations or communication, hence, entanglement is an unphysical, useless and meaningless concept.

The point is we only know these two entangled photons or lights emitted from each light source have the opposite polarizations (= when the photon-1 is horizontal H polarization, the photon-2 is vertical V polarization.  When the photon-3 is vertical V, the photon-4 is horizontal, as shown in the upper figure ), and we don't know which of these two photons has vertical or horizontal polarizations ( = When the photon-1 is vertical, the photon-2 is horizontal, whether photon-1 is horizontal or vertical is unknown ), until the measurement of polarizations using the polarization beam splitters and photodetectors.

One photon (= 2 ) of a pair of photons emitted from the light source S1, and one photon (= 3 ) of a pair of photons emitted from the light source S2 are sent to the middle detectors-b, and we suppose these middle detectors-b measure the polarizations of these two photons sent from S1 and S2 as the same vertical-vertical polarizations (= VV ) or horizontal-horizontal polarizations (= HH ) using polarizing beam splitters (= PBS or BS ) and multiple photodetectors, which measurement is called the Bell state measurement (= BSM ).

↑ As shown in the upper figure, when the middle detectors-b measure two sent photons-2 and 3 having the same parallel polarizations (= the case-1 where both photons-2 and 3 have vertical polarizations VV, or the case-2 where both photons-2 and 3 have horizontal polarization HH, which case of 1 (= VV) or 2 (= HH) is true is unknown ), it means the other photons-1 and 4 sent to the "sender" and the "receiver" also have the same light polarizations, becase each photons' pair emitted from S1 or S2 is prepared to have the opposite or orthogonal polarizations.

For example, in the case-1, two photons-2 and 3 sent to the middle detectors-b have the same vertical (= V ) and vertical polarizations, which means two photons-1 (= sent to the sender ) and 4 (= sent to the receiver ) have the same horizontal (= H ) and horizontal polarizations, as shown in the upper figure.

↑ Quantum mechanics ridiculously claims this mere measurement of polarizations of two photons-2 and 3 at the middle photodetectors-b (= called Bell state measurement of BSM ) can "teleport" the photon-1's polarization (= ex. H or horizontal ) of the sender to the polarization of the photon-4 (= with the same horizontal H ) sent to the receiver ( this 3rd-paragraph, ).

This quantum repeater's (fictitious) teleportation, which is just the "measurement" of photons' polarizaions instead of sending real information ( this 3rd-paragraph ), is called "entanglement swapping ( This middle-figure-can you repeat ?  this how quantum repeaters work,  this p.4-Fig.1,   this Figure.6 )".

Whether the sender's photon-1's polarization is the same as the receiver's photon-4's polarization is unknown to the receiver, until the the photons' polarization measurement results (= VV or HH ) at the middle photodetectors-b are sent to the receiver using the ordinary classical mechanical channel.

↑ This means quantum teleportation (or entanglement) can Not send any meaningful information, if it does Not use ordinary classical communication methods ( this 8 ), which is why I repeatedly said quantum teleportation and (fictitiously superluminal) entanglement are just the meaningless and useless concepts.

↑ If the middle detectors-b measure two photons-2 and 3 to have the opposite polarizations (= HV or VH ), which means the sender's photon-1 and the receiver's photon-4 also have the opposite polarizations, hence, the receiver has to change his photon-4's polarization from vertical (= V ) to horizontal (= H ) or H → V to complete 'teleportation' of the same photon's polarization from the photon-1 to photon-4, after the receiver obtains this measurement result at the middle detectors-b through the ordinary classical communication ( this p.3-11 ).

As you see, this quantum teleportation is just the measurement of a pair of photons or lights' polarizations at detectors and sending this measurement result to the receiver using the ordinary classical mechanical communication methods (= of course, Not faster than light ), which has nothing to do with quantum mechanics or teleporting some objects like StarTrek-like fiction.

This p.5-upper-Fig says
"Quantum teleportation relies on Alice, the sender, and Bob, the receiver, sharing a pair of entangled particles A and B. Alice has a particle that is in an unknown quantum state X. Alice performs a Bell-state measurement on particles A and X, producing one of four possible outcomes. She tells Bob about the result by ordinary (= classical ) means. Depending on Alice’s result, Bob leaves his particle unaltered (1) or rotates it (2, 3, 4). Either way it ends up a replica of particle X ( this p.3,  this p.2 )"

Quantum teleportation, entanglement swapping is the method of (useless) repeater sending quantum information ?

Each light source (= S1 and S2 ) is set to emit a pair of (entangled) photons or lights with the opposite polarizations.
After the (Bell-state) measurement (= BSM ) of photons' polarizations at the middle photodetectors-b, the sender and receiver can have the (entangled) photons with the same polarizations through the (meaningless) teleportation, which is also called "entanglement swapping" used in the quantum repeater where the so-called quantum information or photons' polarizations are sent only by the ordinary classical communication channels (= there are No quantum mechanical ways of sending real information,  this p.13 ).

All the quantum mechanical concepts such as entanglement swapping, teleportation and repeater are unable to directly send or amplify the fragile quantum information or photon's polarization ( this 5th-paragraph ), instead, they just make other multiple light sources emit multiple photons or lights, and measure their light polatizations at photodetectors simultaneously (= bell state measurement or BSM ).

The most difficult problem which makes this repeater impractical forever is that they have to be able to measure all these four photons-1,2,3,4 emitted from two light sources (= of course, much more than four photons are needed for connecting more than two light sources over longer distance ) exactly at the same time (= this is much more impossible when they have to measure much more photons over longer distance ) to distinguish these (entangled) correlated photons from other irrelevant background photons or lights.

↑ The simultaneous (Bell state) measurement of a pair of photons is the only method of connecting two repeaters and relaying quantum information.  ← But connecting and measuring two elusive photons exactly at the same time at the same point (= coincidence detection at multiple photodetectors ) is extremely difficult.

In the actual entanglement swapping experiment, when 76 million photons or light pulses per second (= 76 MHz ) are sent, only 25 ~ 150 four-coincidence photons per 4000 seconds can be detected (= fourfold coincidence photon counts,  this p.3-left-upper, and Fig.3 ).

In another quantum repeater experiemnt sending photons over 5m optical fibers, the number of photons significantly decreases = the single photon count = 1.5 × 105/sec → the two-photon coincidence count rate = 1.25 × 104/sec → four-photons (= sender, receiver, the middle BSM two detectors ) or fourfold coincidence count rate = only 410 photons per hours ( this p.19-3rd-paragraph, p.22-2nd-paragraph ) !

As a result, it is impossible and unrealistic to send quantum information or key such as photons over long distance by relaying and connecting each two photons' pair through the rare coincidence measurements of photons' polarizations, using any (usless) quantum technologies like (fictitious) entanglement, teleportation and repeaters due to the significant photons' loss.

Sending quantum information or key using (fictitious) quantum entanglement, teleportation, repeaters and memories over long distance is impossible and impractical forever.

[ Relaying and sending quantum information or keys need the almost-impossible "coincidence measurements" of many elusive photons or weak lights. ]

(Fig.6) Chance of sending the correct quantum key information or photons to the distant places is significantly diminished like 1/100 (= decreasing rate in each repeater or BSM = Bell state coincidence measurement of a pair of photons ) × 1/100 × 1/100 . = 0 over long distance  = Practical quantum internet or key distribution is impossible forever.

As I said, quantum information and fragile photons can neither be measured, copied nor ampified, because the measurement of the quantum (photon) state destroys the quantum information or imaginary superposition state.

So in order to send such an inconvenient quantum information or photons over long distance (= longer than 200km ), the quantum repeater is said to be needed, but the practical repeaters are unrealized (forever).

Because quantum repeaters are Not allowed to directly measure and amplify the attenunated quantum information or photons ( this 3~19th paragraphs ).

Instead, quantum network, internet and key distribution have to rely on very unreliable and unpredictable methods based on the rare coincidence detection of a pair of two photons by the photodetectors in each point connecting different repeaters and optical fiber's segments.

Due to this fragile unreliable quantum state, practical quantum network, internet and cryptography are impossible to realize (forever) despite decades of researches across the world.

This 3rd paragraph says
"However, the journey from theory to practice is often fraught with challenges, and QKD (= quantum key distribution ) is no exception. While the theoretical foundations of QKD are well-established, the practical implementation of this technology is still in its nascent stages. The main hurdle lies in the transmission of quantum particles (= fragile photons or weak light ) over long distances without loss or alteration."

This 1~2nd paragraphs say
"Quantum networking – like quantum computing - holds tantalizing promise.. Obviously, we’re Not there yet."

Even the current latest unstable quantum repeaters can send such fragile photons or weak light encoding information over only 50 km = very short distance ( due to severe photon loss ), which falls far short of distance required for practical quantum internet or network.

↑ This dubious quantum repeater showed almost No advantage about rates of transmitting photons ( This 5th-last~6th-last paragraphs )  ← completely useless and impractical.

In order to send and relay quantum information (= ex. photon or light's polarization ) using the quantum repeaters, first, each of two light sources S1 and S2 in the upper figure must emit a pair of (entangled) photons or lights with the opposite polarizations (= when one photon has horizontal H polarization, the other photon has vertical V polarization, which photon of these two entangled photons has horizontal or vertical polarization is unknown and uncertain ).

And the photon-2 (= V2 in the upper figure ) from S1 light source and the photon-3 (= V3 ) must reach the middle detectors-b exactly at the same time (= this condition is too strict and extremely difficult like colliding two elusive small photons at the same point ! ) and their polarizations must be measured by the so-called Bell-state measurement (= BSM ).

↑ The chance of two photons from two different light sources S1 and S2 hitting the middle photodetectors-b coincidentally and being measured by them is very slim, approximately 1/100 in the laboratory-scale distance.

This p.25-lower says
"The current EDR (= entanglement distribution rate ) is primarily limited by the probabilistic generation of entangled photon pairs through the SPDC process. The production probability of entangled photon-pair is approximately 0.012 for a single pump pulse (including 50% photon loss in the post-selection of two-photon entanglement). The four-photon generation probability is therefore 1.44 × 10-4 (= 0.012 × 0.012 ) .."

In order to connect all these four photons emitted from the light sources S1 and S2, and distinguish them from many irrelevant background noise photons, this system has to be able to detect all these four photons-1,2,3,4 exactly at the same time (= four photons or fourfold coincidence detection ) at the different detectors-a,b,c as shown in the upper figure.

↑ If all these four photons cannot be detected at the same time, it means detectors have detected other irrelevant photons or background light with wrong polarizations or long quantum keys, so sending and relaying the correct quantum (key) information fail.

Furthermore, the photon-4 (= H4 ) from the light source S2 and the photon-5 (= H5 ) from the different distant light source S3 must also be detected at the same time as all other distant photons-1,2,3 to connect and relay all these photons, which multiple coincidence photons' detections with extremely low probability drastically decreases the chance of connecting and relaying quantum information encoded in photons' polarizations.

↑ The chance of successfully sending quantum (key) information over long distance connecting multiple repeaters based on such uncertain and rare coincidence detections of multiple elusive photons significantly decreases like 1/100 (= one coincidence detection rate at one middle detectors ) × 1/100 × 1/100 × 1/100 .. = 0.

↑ This extremely low coincidence detection efficiency of multiple (entangled) photons' pairs at multiple detectors and repeaters is one of major reasons why sending quantum information by the quantum network, internet or quantum key distribution over long distance is impossible forever.

↑ Actually fourfold (= four photons ) and threefold (= three photons ) coincidence count rates become much. much smaller than one or two-photon coincidence count rates ( this p.4-Fig.5,  this p.5 ).

In this paper (p.2-left-lower, and Figure.2), the fourfold (= four photon ) coincidence count rate (= only 80 photon counts per 80 hours ) drastically decreases from the ordinary two (entangled) photon count rate (= 104 per second ).

Basically, different detectors in different positions are prepared at different times, so the photon-4 and the photon-5 in the upper figure must be transiently stored in the quantum memories-c,d until the middle photodetectors become ready ( this p.5-1st-paragraph ).

This Fig.6 says
" Quantum repeaters can extend the range of a quantum network by replacing a long fiber-optic link, where entangled photons are likely to be lost, with a series of shorter links. Each shorter link can attempt to distribute entanglement between repeaters multiple times, while successfully transmitted entanglement is stored in quantum memories.."

In these quantum memories, quantum information or photons are transiently absorbed and stored as atomic or ion's excited energy state inside the memory ( this p.2-first ).

For the quantum memories to re-emit the stored photons, they have to apply other read-out laser light pulses to stimulate the re-emission of the stored photons.  ← This laser light pulses for re-emission become the background light noise or dark counts of false photons ( this 7-10 paragraphs ).

Quantum memories must be cooled down to almost absolute zero like other photodetectors and optical fibers, which cost too much, and make the quantum information technology unfeasible ( this 2nd-last to last paragraphs ).

Basically the current quantum memories cannot store the photons long enough ( this p.2-2nd-paragraph ), and the number of photons after re-emitted from memories drastically decreases, which just makes the situation much worse.

This abstract says the (memory) storage efficiency is only 12 %

As shown in this paper p.22-2nd-paragraph, the fourfold (= four photons ) counting rate drastically decreases from 410 counts per hour before the memory storage to only 1.27 counts per hour after stored photons are re-emitted from the momories.  ← completely useless.

Quantum key distribution and quantum internet are just hyped pseudo-science.

The 1st, 4th, 7th, 8th, 10th, last paragraphs of this hyped news say

"Researchers.. have demonstrated that advanced quantum-based cybersecurity can be realized in a deployed fiber link (= wrong.  Researchers just sent fragile weak light wave or photons over only 5km short distance with No tests of cybersecurity = still No practical use )."

"The signal traveled across ORNL's fiber-optic network encoded in continuous variables that described the properties of light particles, or photons, in amplitude and phase (= utilizing wave amplitude and phase means a photon is just a weak classical light wave, Not a particle )"

"Quantum key distribution is a cryptographic protocol where two parties can generate a secure key that only they know,.. In this experiment, this is done by using lasers to generate weak optical pulses (= just laser light wave, Not a photon particle ) between two points, usually referred to as Alice and Bob."

"When the receiving party measures a pulse, measurements can reveal whether an eavesdropper intercepted and corrupted the message (= this quantum cryptography or cybersecurity mechanism can be explained by weak classical light wave whose destruction tells us whether the light is eavesdropped on or not, which does Not need a fictional quantum photon,  this-1st-paragraph )"

"Excess noise erodes the rate of the key that can be distributed. Too much noise,.. (= quantum key using weak light is vulnerable to noise )"

"Future efforts will (= just speculation, practical quantum key distribution is still unrealized ) focus on reproducing the experiment's results under a wider range of network scenarios."

Success rate of sending weak light or quantum information is only less than 5%, which is useless.

↑ This research tried to send weak light pulses (= Not a photon particle ) to a detector at a distance of 5km, and only 5 % of those sent lights whose phases were used as information arrived at the detector (= most of lights or photons were lost and unrecoverable ), which is impractical as internet or network.

This research paper ( this ↓ )

p.1-left-3rd-paragraph says "A major technical challenge in CV-QKD (= Continuous-variable quantum key distribution ) detection is carrier phase recovery: to reliably decode the information encoded on field quadratures"  ← quantum key distribution is still useless with a lot of challenges

p.3-right-1st-paragraph says "generate 12 ns-wide pulses at a 1 MHz repetition rate (= 106 light pulses per second were sent ). These pulses pass through polarization-maintaining optical fiber"
p.5  Weak light or photons were sent through the 5km optical fiber.
p.5-left-1st-paragraph says The symbol rate for the system is 50 kSymbols/s (= out of 1 MHz ), 5% of the rep-rate (= only 5% light pulses were successfully sent ), which cannot send important information reliably

↑ Just sending light or information over the short 5km lost 95% of them (= unrecoverable ), so stably sending secure quantum information over practically-long distance is just a pipe dream ( this p.6-Fig.4 ).

Quantum key distribution, internet and cryptography are hopeless.

Contrary to the hypes, all the quantum information technologies such as quantum key distribution, internet, network, cryptography are already deadend with No progress or No hope of utility.

Quantum internet has to rely on very weak light or photon whose wave phase or polarization is used as information, and quantum mechanical stupid rule forbids researchers from copying and amplifying the weak light 's information ( this 2nd-paragraph ).

As a result, it is impossible to send the very weak light or quantum information over long distance required for practical internet ( this-lower challenge of quantum network,  this p.1-left ).

This 2nd, 5-6th paragraphs say
"First, the quantum internet relies on the transmission of single photons that cannot be amplified or split. Without amplification, these signals diminish within 100 km or less of their source. Therefore, optical loss and noise present much bigger problems for the quantum world."

"storing photons is still a big challenge"
"the biggest challenges involve the emission of single photons and their transport over long distances."  ← still impractical quantum internet.

Quantum repeater unable to amplify the light information just sends two weak lights with the same (or perpendicular ) polarization (= which they call entanglement that means classical lights with some correlated polarizations unrelated to quantum mechanics ) to two distant places and detects them simultaneously (= No quantum mechanical superluminal link ).

↑ Success rate of detecting these two weak lights simultaneously is only 0.00092 (= 9.2 × 10-4 ) over only 50 km distance (= which means almost all weak lights or photons are lost even using quantum repeaters which cannot solve the issue of fragile photons in quantum internet,  this-5~6th-paragraphs,  this p.3-left ).

So like useless overhyped quantum computers, quantum internet (= still far from actual internet ) and key distribution are also impractical pseudo-science just wasting researchers' time and taxpayers' money.

Quantum communication is impossible forever, contrary to hypes.

The 3rd, 6-7th, last paragraphs of this hyped news say

"Entangled photons are particles of light that remain connected, even across large distances, and the 2022 Nobel Prize in Physics recognized experiments on this topic.. the IQC research team aimed (= meaning "still unrealized" ) to optimize the process for creating entangled photons, which have a wide variety of applications, including secure communications (= false, entanglement is useless )."

"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 (= still impractically-low efficiency even in this latest research, though )."

"This new source.. can be excited with lasers to generate entangled pairs on command (= false, efficiency of creating these correlated lights or illusory entanglement is still extremely low, Not on command ). The researchers then used high-resolution single photon detectors (= a fictitious photon itself is undetectable, they just detect electrons excited by light )"

"Using their new quantum dot entanglement source, the researchers simulated a secure communications method known as quantum key distribution (= just simulation, Not experimental realization ), proving that the quantum dot source holds significant promise in the future (= just speculation, still useless ) of secure quantum communications."

↑ This research just let quantum dot (= artificial atom ) emit two (classical) lights (= or photons ) with the same polarization (= HH ), which they called entanglement using fictitious exciton quasiparticle ( this p.2-Fig.1 ), and detected them simultaneously with impractical low efficiency that prevents precise communication.  No quantum mechanical prediction nor practical application.

99% of photons or quantum information were lost, so quantum communication or internet is impossible.

This research paper ↓

p.1-left says "Developing a bright, deterministic source of entangled photon pairs for applications in photonic quantum information.. has been a long-standing scientific and technological challenge"  ← It means quantum information, entanglement are still useless, illusion.
p.1-right-2nd-paragraph says "quantum key distribution (QKD) protocol allows all photon pairs emitted from the biexciton-exciton (= fictional quasiparticle ) cascade to generate a secure key,. To estimate the potential key rates"  ← this research just simulated or estimated QKD, No experimental realization.

p.5-right-Tomography apparatus says "apparatus was used to maintain the nanowire sample at 4.5K (= impractically-low temperature )"
p.6-left-source efficiency says " The total optical efficiency after the 70:30 beamsplitter to the SPAD (= single photon avalanche diodes ) detector after the spectrometer was estimated to be 2.41 ± 0.07% (= only 2.41% photons or lights were left, all other 98% photons or information were lost )"
"pair extraction efficiency at the first lens of 0.65 ± 0.02%"

↑ "Extraction efficency" is the proportion of photons generated in the quantum dots that escape from the device ( this-middle ), which was just 0.65% ( this p.2-lower-p.3 ), which means almost all photons or lights (= 99.35% ) having information as light polarization were lost when they escaped from quantum dots ( = photon-pair source efficiency is very low, only 0.0037, this p.17-5th-paragraph ).

Quantum entanglement is useless, helpless for massive photon loss in the current impractical quantum communication.

Quantum entanglement means just simultaneous measurement of two (classical) lights or photons' polarizations (= ex. when one light has horizontal polarization, the other light always has horizontal polarization, = HH ), which can neither send real information nor secure communication, as seen in still-impractical quantum key distribution.

Quantum information carried by (fictional) photons or weak light's polarization easily gets lost ( this 7th-paragraph,   ).
The successful rate of sending and detecting (allegedly-entangled) photon pair over only 50km is extremely-low, only 0.00092 or 9.2 × 10-4 ( this 6th-paragraph,  this p.6-Fig.4 ), which means the successful rate of sending photons or quantum information over longer distance is hopeless, much much lower (= 0.00092 × 0.00092 ×.. ).

↑ Practical internet or communication needs 100% successful rate of sending information, so quantum communication trying to use fragile photons or weak light at extremenly low temperature (= 4K ) and extremely high photon information loss rate is completely useless.

Nobel prize is often used as a political tool to justify and enable impractical science to get taxpayers' money as research funds, as seen in unrealistic entanglement, (parallel-world) quantum computers and harmful vaccines.

 

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