(Fig.1) The present error-prone quantum computers are unable to give right answers, so physicists tried to hide their errors into random meaningless numbers as fake supremacy.
Despite extremely long years of researches and exaggerated news, quantum computers are still useless with No practical use.
This website's (in 2023 ) first part says
"Enormous amounts of money have been invested into quantum computing, but so far it has Not surpassed conventional computers."
It means the so-called "quantum supremacy" or "quantum advantage over classical computer" appearing on the media so far is fake, Not faster than a conventional classical computer (= because if quantum computers were really faster or supreme, they should have already replaced the current ordinary computers, which did Not happen ).
This 2nd-paragraph says
"IBM readily admits that nobody has yet demonstrated quantum advantage"
Today's quantum computers have only less than 100 qubits (= each qubit can take only 0 or 1 state ), which are still Not computers nor able to calculate anything.
Practical quantum computer for achieving true quantum advantage or supremacy is said to need more than millions of qubits. Google quantum computer had a far smaller number of qubits (= just 53 qubits = just 53 bitstring ) that can Not achieve true quantum supremacy.
This 4th-paragraph says
"For a quantum computer to be practical, millions of qubits must be accommodated on a single chip. The most advanced quantum computers today have only a few hundred qubits, meaning they can only perform calculations that are already possible (and often more efficient) on conventional (= classical ) computers" ← No quantum advantage in today's quantum computers with only small numbers of qubits.
(Fig.N) Today's (fake) quantum supremacy claims are based on unfounded assumption of (fictional) quantum parallel worlds involved in giving random (meaningless) numbers
What the Google quantum computer (= still Not a computer ) did was just output random useless numbers (= just output random 53 bitstring ).
This 2nd-paragraph says
"The calculation has almost No practical use—it spits out a string of random numbers.... Useful quantum machines are many years away"
This 8th-paragraph says
"Nothing useful in any practical sense — in fact, it is randomly generated, a random quantum circuit"
↑ Of course, ordinary classical computers can more easily and rapidly output larger random numbers, so No quantum computer's supremacy from the beginning.
But today's unrealistic quantum mechanics says the quantum computer could output random (meaningless) numbers through (unseen, unfounded) multiple quantum superposition (= a dead and alive cat ) states or parallel worlds that cannot be emulated by a classical computer using only single world ( this 6-7th paragraphs ).
↑ No evidence of quantum superposition nor parallel worlds, because they can observe only one state in one single world, when measuring the qubit states ( this 5th-paragraph, this 5th-paragraph ).
↑ They baselessly claim Google 53-qubit quantum computer got random (meaningless) numbers through (unseen) 253 different parallel world (= superposition ) states (= one qubit takes 0 and 1 × 53 qubits ) while 53 qubits were randomly flipped ( this 5th-paragraph, this 4th-paragraph ).
This 7th paragraph says
"For classical computers, it is much more difficult to compute the outcome (= just random numbers ) of these operations because it requires computing the probability of being in any one of the 2^53 possible states, where the 53 comes from the number of qubits"
This 8th paragraph say
"Sycamore's aim was to randomly produce strings of 1's and 0's, one digit for each qubit, producing 253 bit strings"
↑ There is No evidence that quantum superpostion (= an unreal, unseen dead and alive cat state ) or parallel worlds really happened in quantum computers outputting random numbers, so No evidence of quantum supremacy.
(Fig.Q) A superconducting (= transmon) qubit is just a classical circuit where two different electric currents represent 0 and 1 bit states.
Google quantum computer used a (classical) superconducting circuit's electric current state as a qubit 0 or 1 (or classically-mixing currents treated as illusory superposition ) state that can be manipulated by (classical) microwave ( this p.2-right ).
Despite No evidence, they say these 53 qubits flipped randomly by microwave created (imaginary) quantum superposition or 253 parallel world states until one random number was measured.
An ordinary classical computer was unfairly forced to imitate the unseen unfounded sueprposition of 253 parallel worlds, and could outperform the Google quantum computer after all.
So there is No quantum supremacy not only from the beginning but also officially ( this 4th-paragraph ).
Today's quantum computers are too error-prone to give right answers, which means there was No quantum supremacy nor advantage over classical computers from the beginning, because an ordinary classical computer can always give right errorless numbers.
↑ If today's error-prone quantum computers cannot give right answers, it is impossible to prove quantum computers actually utilize (unseen) quantum superposition or parallel world states to get right final answers.
This 2nd-last-paragraph says
"The Google computer also lacks the ability to correct errors"
So some physicists tried to make the error-prone quantum computers output random meaningless numbers into which a lot of errors are hidden for claiming fake quantum supremacy.
↑ Because random meaningless numbers remain random, no matter how many errors they contain.
The estimated error rate of Google 53-qubit quantum computer outputting random numbers after about 20 cycles of randomly flipping qubits was 99.8%, which means fidelity (= 1 - error rate ) was just 0.2% ( this p.8, this p.3-right, this p.16 ).
This p.3(or p.2)-1st-paragraph says
"Google's recent quantum supremacy experiment estimated that their fidelity
was merely ∼0.2% (i.e., the experiment was ∼~99.8% noise = 99.8% error rate )" ← Google quantum computer just output errors.
This 9th-paragraph says
"Google's computations on Sycamore were Not very precise, achieving a fidelity of just 0.2 percent"
(Fig.E) Today's quantum computers are too error-prone to give right answers. so No true quantum supremacy.
The recent Google's 67 qubits and Quantinuum's 56 qubits outputting random meaningless numbers contained impractically many errors of 99.9% and 65% high error rates.
↑ These error rates are just optimistic guess (= actual error rates were probably much higher ), becaue it is impossible to know true error rates from random meaningless numbers.
↑ Today's error-prone quantum computers unable to give right answers are far from quantum supremacy or advantage over errorless classical computers.
This 6~11th paragraphs say
"The point where quantum computers overtake classical ones is known as "quantum supremacy, but achieving this milestone in a practical way would need a quantum computer with millions of qubits. The largest machine today has only about 1,000 qubit (= so today's Google, Quantinuum's less than 100 qubits can Not achieve true quantum supremacy )"
"The team tested the fidelity of H2-1's output using what's known as the linear cross entropy benchmark (XEB = fidelity )"
"They registered an XEB result of approximately 0.002 (= fidelity = 1- error rate ) with the 53 superconducting qubits built into Sycamore (= Google 53-qubit quantum computer's error rate was 99.8% )."
"Quantinuum scientists — achieved an XEB score of approximately 0.35 (= fidelity ). This means the H2 quantum computer can produce results without producing an error 35% of the time (= 65% error rate ). "
↑ It means the random meaningless numbers of Google supremacy experiment was just the result of errors, Not of quantum mechanical calculations based on (unseen) quantum superposition, so No evidence of quantum supremacy.
(Fig.2) (fake) Quantum advantage needs the unfounded assumption that a photon can split into multiple photons by (fictional) quantum superposition or parallel worlds. Ordinary classical light wave can also split, so No quantum advantage.
The overhyped claim that Chinese and Canadian Xanadu's photon quantum computers might have showed quantum advantage over ordinary classical computers is false, based on wrong assumption.
First of all, photons or weak classical lights are too easily lost, so photon's quantum computers can never become reality, let alone showing advantage.
Actually this fake photon quantum computer's advantage experiments detecting photons (= weak lights ) randomly (= called gaussian boson sampling = GBS ) without any computation nor error correction is useless, of No practical application ( this 3rd-last-paragraph, this p.6-cons, this-last-paragraph ).
This 8th-paragraph-caveats says
"the problems they are solving are experiments – the results are, for lack of a better word, useless."
The last paragraph of this site says
"neither Jiuzhang (= Chinese photon quantum computer ) nor Google’s superconductor-based prototype can be applied to real-world problems" ← useless ( this last-paragraph ).
↑ The fact that we still do Not use these (useless) quantum computers in our daily life means these quantum advantage and supremacy are fake.
This p.2-left-1st-paragraph says
"Boson sampling,.. These sampling
problems also lie at the basis of the random circuit sampling
protocol, which would lead to the first experimental
claim of a quantum computational advantage. However,
in a game of constantly shifting goal posts, this claim has
already been challenged" ← Quantum advantage turned out to be false and illusion.
In these fake quantum advantage experiments, physicists just sent multiple photons (= or weak lights ) into multiple beam splitters, and detected the output photons at multiple photodetectors randomly with No meaningful computation.
This 3rd-paragraph says
"The problem consists of sampling from the output distribution of detection events generated when many single photons are concurrently injected into a randomly chosen network of linear optical components (= beamsplitters ). "
(Fig.C) A classical indivisible photon can take only one path to be detected by photodetector, while a quantum photon can take multiple paths simultaneously, which is quantum advantage ?
They falsely treated classical light wave as a fictional individible photon ball (in Galton's board ) that cannot split at a beam splitter.
↑ So they say this fictional indivisible classical light wave or photon ball cannot imitate a quantum photon that can split into two paths at a beam splitter ( this p.32-Figure 1.9 ) by utilizing (fictional) quantum superposition or parallel universes, which means quantum advantage ( this 3~4th-paragrpahs ) ! ← nonsense.
This 7th-paragraph says
"Photons are first sent into a network of channels. There, each photon encounters a series of beam splitters, each of which sends the photon down two paths simultaneously, in what's called a quantum superposition ( this scenario )"
This 4th-paragraph says
"However, while these distinguishable classical balls (= indivisible classical photons ) take familiar, distinct paths down the board, rolling either left or right off of each peg they encounter, the ( divisible quantum ) photons in some sense collectively take all possible paths (= superposition or prallel worlds ) through their network...
Surprisingly, the interference of these paths makes it hard for a classical computer to predict"
There is No such thing as a classical individible light or photon ball in Galton board.
Real classical light wave can split into two paths at each beam splitter realistically (= without using fictional quantum superposition or parallel worlds ).
As a result, the quantum advantage based on false assumption of the indivisible classical photon is illusion, and quantum computers are useless, Not faster.
When two photons (= two lights ) enter a beam splitter simultaneously, these two photons or lights may exit the beam splitter on the same side, as if they appear to stick to each other ( this-16th-paragraph, this 3rd-paragraph ), which is called Hong-Ou-Mandel (= HOM ) effect ( this 5th-paragraph, this 2nd-paragraph ) allegedly involving quantum superposition.
↑ This Hong-Ou-Mandel effect can be naturally explained by interference of classical light wave at beam splitter + constructively-interfering light's amplitude surpassing photodetector's detection threshold ( this p.5 this p.6~ ) where constructive (or destructive ) light interference occurs in one (or the other ) exit path (= like two lights stick ).
So the assupmtion of a quantum photon (= divisible by fictional quantum superposition ) is unnecessary, replaceable by ordinary (realistically-divisible) classical light wave, and No quantum advantage.
(Fig.P) Illusory photon's quantum computer's advantage is based on useless tasks called "boson sampling" just detecting random lights or photons with No actual speed-up.
They assumeed (fictional) classical light or a photon that is indivisible at a beam splitter needed extremely much time to calculate the probabilities of many paths through which an (fictional) individible classical photon ball has to pass for imitating a divisible quantum photon that can go through multiple paths simultanaously by using superposition or parallel worlds.
They estimated this classical photon calculation's time might increase proportional to 2100 where 100 is photon's number ( this-3rd-last-paragrapg ) used in this experiment.
↑ This extremely-time-consuming calculation of summing all probabilities of many paths which a classical photon has to take to imitate quantum photon's superposition is expressed as "permanent ( this-lower, this p.5-6, this p.19-23 )"
If we replace the indivisible classical photon ball by the divisible classical light wave, this quantum advantage disappears.
↑ There is No such thing as an individible classical photon ball or a quantum photon divisible by (unseen) superposition.
Only dividible classical light wave exists in this world, so No quantum advantage from the beginning.
Even when a classical method was unfairly forced to conduct this extremely-time-consuming calculation of many light paths based on the fictional indivisible classical photon imitating quantum photon's superposition or parallel worlds, the classical computer could outperform the photon quantum computer after all ( this 2nd-paragraph ).
This-lower conclusion says
"introduced a classical algorithm that accurately simulated Gaussian boson sampling, outperforming some quantum experiments. This work questioned the claimed quantum advantage" ← officially, No quantum advantage.
So there is No quantum advantage after all.
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