Ion-qubit quantum computers are useless forever, cannot be scaled up.

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Quantum computers are useless forever
Oxford ionics useless hyped computer

Ion-qubit quantum computers are hopeless, cannot be scaled up to 100 qubits, which fall far short of millions of qubits required for a (illusory) practical quantum computer.

(Fig.1)  Quantum computer companies (= IonQ, Quantinuum.. ) need to spread overhyped fake news to get investment money and hide their deadend impractical quantum computers.

An ion's energy states used as a qubit.

Ion qubits use each unstable ion's two energy states as a qubit's 0 or 1 bit state.

Ion-qubit quantum computers using each ion's two energy states as one qubit's 0 or 1 bit values (= controlled by laser light ) are useless forever, contrary to hypes.

Ion qubits are useless, Not computers.

Even the largest ion-qubit quantum computer has only 98 error-prone qubits which are far from a practical quantum computer needing millions of qubits.

Ion qubits unstably trapped in electromagnetic field used in IonQ ( this-2nd-paragraph = only 36 qubits = one qubit takes only 0 or 1 value = still Not a computer ) and Quantinuum with only 98 qubits can never to scaled up to more than 200 qubits, let alone to millions of qubits required for a (illusory) practical quantum computer ( this-4th-paragraph ).

Ion qubits cannot be scaled up to practical level.

A practical quantum computer needs millions of qubits which are impossible to realize forever.

This or this-summary says  -- Unscalable ion qubits
"IONQ's trapped Ion qubits technology is Not scalable enough for Quantum Supremacy ( this-introduction-1st-paragraph )."

This or this-12~14-paragraphs say  -- Ion qubits useless forever
"Trapped-ion qubit computers also have a scalability problem. Each chip can contain at most a few tens of ions without the interactions among them becoming too complex to control. Reaching millions of qubits will require moving ions between modules, a feat scientists have yet to reliably achieve."

Ion qubits must be shuttled, taking too much time

Ion qubits are too slow to be practical ( this-p.11-Table.1 ).

This-9th-paragraph says  -- Impractical ion qubits
"but it is Not clear how scalable these (ion qubit) devices are... In QCCD (= used in Quantinuum ) the trapped ion qubits are shuffled between different processing zones using dynamic electric fields. This may seem cumbersome"

This-p.3-right-2nd-paragraph (2025) says 6nbsp;-- Too slow ion qubits
"Although QCCD enables flexible qubit connectivity, several scalability challenges remain. First, as physical shuttling of ion qubits is required, the overall transportation time increases with system size"

The 9th, 11th paragraphs of this (2025) say  -- Error-prone qubits
"they could not only prepare two magic states (= some qubit state mixing 0 and 1 bit states with some probabilities ) from just eight physical qubits (= just 8 bitstring, still Not a computer ), but also perform a two-qubit non-Clifford gate with a logical error rate of about one mistake per 5,000 operations (= still impractically bad error rate far higher than the practically-required error rate of 10^-15,  this-p.7-Table II )"

"Our simulations (= just simulation, still unrealized ) suggest we can use roughly 40 physical qubits (= still far from millions of qubits required for a practical quantum computer ) to create one very high-fidelity magic-state qubit (= still one reliable qubit 0 or 1 has Not been realized )"

Quantum computers are useless, too error-prone.

Quantinuum's error-prone ion qubits unable to correct errors just discarded undesirable results illegitimately.

↑ This Quantinuum's paper ↓

p.4-Fig.5 says  -- Illegitimate post-selection
" the magic states are prepared using pre-selection... post-selection"

p.5-left-IV says  -- Too high error rate
"Quantinuum H2-1 trapped-ion quantum processor.., and 56 qubits (= too small numbers of qubits, still Not a quantum computer ) total"

"the average acceptance rate across all single-copy experiments is 82.58% (= 20% results were discarded as errors )"
"The acceptance rate is 65.73% and 3 logical |−1⟩ state (= 35% results were discarded as errors )"

↑ So this Quantinuum research just discarded erroneous results by the illegitimate pre-selection (= repeat and reset until success qubits' results were obtained = very time-consuming ) and post-selection (= erroneous results were discarded without error correction ), so only 65 ~ 80% results were accepted ( this-p.6 ).

No quantum computer error correction

Ion qubits discarding erroneous results post-selectively are impractical forever.

↑ So the actual error rates were 35 ~ 20 % in just less than 56 ion qubits, which is completely impractical.

This Quantinuum's p.2-right-3rd-paragraph says  -- Illegitimate trick
"Upon failure to verify the preparation a logical |0⟩ state, the qubits can be conditionally reset and the fault-tolerant preparation can be re-attempted in a repeat-until-success fashion or pre-selected upon verification (= primitive, time-consuming method without error correction )"

This Quantinuum's p.1-right-last-paragraph says  -- Post-selection cheating
" When an uncorrectable state is detected, our fault-tolerance procedure rejects the trial. This postselection"

↑ So contrary to the overhyped fault-tolerant quantum computer news, they just illegitimately discarded erroneous results (= pre- and post-selection ) without quantum error correction in just less than 56 ion qubits (= unable to be scaled up ).

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