What is Fault tolerant quantum computer?

• A. A device that can withstand any classical fault
• B. A type of random circuit sampling
• C. A measure of entanglement
• D. A future quantum machine designed to run long calculations without collapsing from errors

Answer: (D)

Fault-tolerant quantum computing is about keeping quantum computations accurate even in the presence of noise and imperfect operations. To do this, the system uses quantum error correction codes that encode a logical qubit into many physical qubits, along with fault-tolerant gate designs and regular syndrome measurements to detect and correct errors as computations progress. The goal is to prevent errors from accumulating and causing the result to become unreliable, enabling long computations to run reliably.

That’s why describing it as a future quantum machine designed to run long calculations without collapsing from errors is the best fit: it captures the idea of maintaining correctness over extended computations despite the noisy quantum environment. It’s not simply about withstanding a classical fault, not about a random circuit sampling task, and not about a measure of entanglement.