(Fig.1) The allegedly fault-tolerant topological quantum computer with fictional quasiparticle qubits with fractional charge is just fiction.
Overhyped media repeatedly says "(illusory) topological quantum computer based on (fictional) Majorana or anyon quasiparticles could be robust or fault-tolerant."
↑ But there is No evidence of robust nor fault-tolerant topological quantum computers.
First of all, Majorana quasiparticle (or anyon quasiparticle, this introduction-4-5th-paragraphs ) is a fictional particle that does Not exist.
So even one single Majorana qubit has Not been realized ( this 1st-paragraph ).
It is far from millions of qubits required for practical quantum computer.
These fictional Majorana or anyon quasiparticles needed for the still non-existent topological quantum computer are said to have fractional charges unrealistically split from an indivisible electron ( this p.1-figure, this p.29 ).
This 7th-paragraph says
"the motion of electrons and holes can synchronize to behave as a single quasiparticle, in which fragments of the electron appear as if they are physically separated (= impossible, this p.2-2nd-paragraph ). These quasiparticles are sometimes dubbed anyons"
Furthermore, the alleged mechanism of this topologically-protected robust quantum computer based on imaginary (non-existent) braids is so unrealistic that it will never be realized.
(Fig.2) Topological quantum computer full of imaginary concepts such as quasiparticles and unseen braids will never be realized.
They baselessly claim that the (fictional) Majorana or anyon quasiparticles can twist around each other by the unseen (illusory) braids (= nonphysical ), which virtual worldlines ( this Figure 1 ) would be hard to untie, so "robust" without showing what this 'magical braid' is made of. ← nonsense.
This 10~11th paragraphs insist
"The researchers (unscientifically) liken these qubits to a knot on a shoestring, so that how the knot is tied indicates the information stored"
".. To be clear, No one is tying physical knots in a nanowire (- No physical knots ) — but you can mathematically visualize the timeline of these quasiparticles as you swap their positions as knots or braids. These knots are known as topologically protected states; hence, the proposed quantum computers built with Majorana fermions are known as topological quantum computers."
This 3rd-paragraph says
"The anyons the researchers believe they have created are Not true particles.. Instead anyons are (fictitious) quasiparticles that exist only inside a material."
This p.3-middle-lower says
"a topological quantum
computer does not seem much like a
computer at all. It works its calculations
on braided strings—but Not physical
strings in the conventional sense (= unreal braids )."
This 3rd-last paragraph says
"The word entanglement suggests that the states of the particles are physically interwoven, braided, or overlapped,.. In actuality, the particles have No physical connection or communication line (= topological braid is illusion )."
This p.1-left says
"Braiding two anyons (= fictitious fractional-charge quasiparticle ) physically by moving one around
the other in real space is theoretically straightforward
but challenging to implement experimentally (= due to lack of reality )."
↑ So neither Majorana quasiparticle nor braid is real ( this p.3-middle-lower ). ← No topological robust quantum computer.
The fictional Majorana quasiparticle itself is impossible to detect or see.
The fictitious fractional-charge anyon or Majorana quasiparticles were said to indirectly appear in some special composite materials as the form of characteristic electric conductance ( this middle = so illusory Majorana quasiparticle means just some electric conductance with zero energy, No real particle, this p.1-intro, this middle-Looking for Majoranas in nanowires ) or quantum Hall effect under some electromagnetic fields.
↑ So physicists just observed some special electric conductance (= anyon quasiparticle itself is unobservable ) and falsely claimed they might have detected the sign of (non-existent) fractional-charge anyon quasiparticles, which is Not a legitimate science.
This 12th-paragraph says
"When the scientists varied the voltage to their devices, they detected a sudden peak in their electrical conductance . They claimed this electrical signal (= Not fictitious quasiparticle itself ) was evidence of discrete, quantized levels of conductance, a hallmark of Majorana (quasi-)particles"
Actually, Nature journal retracted the dubious research paper of the alleged first discovery of anyon or Majorana quasiparticle by Microsoft.
↑ It is impossible to prove the existence of (imaginary) Majorana quasiparticle just by measuring vague electric conductance.
(Fig.3) Fictional topological quantum computer with imaginary quasiparticles could be simulated by 27 trapped ions ? ← useless, error-prone, far from fault-tolerant.
Recently, many media outlets simultaneously reported that the UK-based company Quantinuum and Harvard, Caltech team might have finally created (fictional) quasiparticles called non-abelian anyon with (unreal) fractional-charges that could remember their pasts and potentially enable fault-tolerant robust quantum computer.
↑ Unfortunately, None of these claims are real.
This "Remember the past" means the imaginary braid or knots (= whose knot forms may remain or be 'remembered' ) allegedly created by fictional quasiparticle topological qubits. ← But even one quasiparticle qubit has Not been realized, so No evidence of such quasiparticles remembering the past.
↑ The 3rd, 5th, 10th paragraphs of another news about this same research say
"Vishwanath's team used a powerful machine called a quantum processor to make, a brand-new phase of matter called non-Abelian topological order (= useless concept irrelevant to real world )... the team demonstrated synthesis and control of exotic particles called non-Abelian anyons (= fictional quasiparticle )"
"Non-Abelian anyons, known to physicists as quasi-particles, are only mathematically possible.. The qualifier "quasi" refers to the fact that they are Not exactly particles" ← Anyon or Majorana quasiparticles are Not real particles.
" Quantinuum's newest H2 processor,.. 27 trapped ions." ← Just 27 ion qubits (= one qubit can take only 0 or 1 state ) are far from a practical computer that will need millions of qubits.
Google also conducted the similar research about (fictional) non-Abelian anyon quasiparticles using only 25 superconducting qubits ( this p.7-left-1st-paragraph ) that is still Not a practical computer at all.
↑ Quantinuum and Google tried to express (fictional) anyon quasiparticles by using conventional (= irrelevant ) ion or superconducting qubits, which could Not make real (fault-tolerant) topological quantum computers nor anyon quasiparticle.
The point is neither Quantinuum nor Google achieved real fault-tolerant topological quantum computer with (fictional) anyon quasiparticles, hence, these researches are still useless.
The 7th paragraphs of this or this site say
"Physicist.. has despaired of the hype and says it's clear to him that neither Quantinuum nor Google has created a topological qubit. It does not take quantum computing to the next level. While Google and Quantinuum demonstrated that their hardware can exhibit several hallmark features of a topological qubit, the components are too fragile to fulfill their intended role in quantum computing" ← useless
The 11th and last paragraphs of this or this site say
"Quantinuum machine does Not truly create nonabelions, but merely simulates some of their properties (= quasiparticle qubit has Not been realized after all, this-9th-paragraph, this 2nd-last-paragraph )"
"it is still unclear how efficient his team’s nonabelions will turn out to be." ← still No evidence of robust nor fault-tolerant quantum computer
The 3rd-last paragraph of this or this says
"because these anyon states are made from conventional, error-prone qubits, No one yet knows whether they can be made stable enough to truly act as topologically protected qubits" ← still error-prone, Not a robust topological quantum computer.
This Quantinuum's 27-ion-qubits showed very bad error rate of 35% (= global fidelity was 0.65 ) and the fidelity per qubit was 0.984 (= so each qubit's error rate was 1 - 0.984 = 0.016 = 1.6% ), which is far worse than practically-required error rate of 10-15 ( this 5th-paragraph ).
The error rate of Google's superconducting qubits was also too bad to be a practical computer ( this p.7-left-1st-paragaph showed each two-qubit-gate error rate was 7.3 × 10-3 = 0.73%, which is impractical, too ).
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