How much quantum computing capability do you actually need before it becomes useful for real problems?

[Scott98]

Quantum computers exist but can't solve anything practical yet. What's the threshold where quantum suddenly becomes useful? 100 qubits? 1000?

[Sega26]

Threshold depends on problem. Some problems might be useful with 1000-10000 logical qubits. Others need millions. Not single number

[QuantumKnight]

Drug discovery is frequently cited useful application. Simulating molecular behavior. Might need 10000 logical qubits. Currently can't even make 100 stable physical qubits

[Delulu]

Optimization problems come earlier. Maybe 1000-5000 logical qubits find better solutions than classical. Financial optimization machine learning tasks

[HitmanMarcus94]

The error correction overhead is killer. 1000 physical qubits becomes maybe 10 logical qubits after error correction. Need millions of physical qubits for thousands of logical

[Brandon18]

Some near-term applications need fewer qubits. Materials science simulation might work with 1000 logical qubits. That's still probably 5+ years away

[SharpFox]

The threshold might be higher than researchers hope. If overhead is worse than models predict useful quantum computers might need tens of millions of qubits

[MJF]

Early wins will be niche applications. Specific problems where quantum has real advantage. Not replacing classical computers broadly

[Oscar_75]

Financial modeling optimization scheduling might be first industries to get quantum advantage. Insurance actuarial calculations require massive search

[William56]

Some think practical quantum is still 20 years out. Others say 5 years. Uncertainty is real. Hard to predict when moving through phase transitions

[QuantumLeap96]

This is why near-term quantum and far-term quantum are different fields. Near-term is what current hardware can do. Far-term is solving real business problems. Gap is huge