1. Google reported a task taking 200 seconds that it estimated would need 10,000 years classically. IBM argued it could be done classically in about 2.5 days. What is the best interpretation?○ Google's experiment was flawed and the result was withdrawn○ Both were defensible, because an advantage claim depends on the best known classical method, and IBM demonstrated a better one○ IBM's objection was commercial and had no technical basis○ The episode showed that quantum computers offer no advantage at all
2. What was the task Sycamore performed in that experiment?○ Factoring a large number used in encryption○ Simulating a pharmaceutical molecule○ Random circuit sampling, chosen because it is classically hard and of no practical use○ Optimising a logistics network
3. What is dequantisation?○ The loss of a quantum state through interaction with the environment○ The discovery of a classical algorithm that matches a result previously thought to require a quantum computer○ The process of converting quantum output into classical bits○ A method for reducing the number of qubits an algorithm needs
4. What is an amplitude?○ The physical energy level of a qubit○ A number associated with a measurement outcome, whose square gives that outcome's probability○ The number of operations a qubit can undergo before decohering○ The strength of the signal used to control a qubit
5. What is the crucial difference between amplitudes and ordinary probabilities?○ Amplitudes are always larger than probabilities○ Amplitudes can be negative, so contributions can cancel, whereas probabilities only ever add○ Amplitudes are measured directly while probabilities are inferred○ Amplitudes apply to multiple qubits while probabilities apply to one
6. Describing n qubits requires 2 to the power n amplitudes. Which conclusions follow? Select all that apply.☐ Simulating quantum systems on classical computers becomes infeasible quickly☐ The machine performs 2 to the n calculations simultaneously and can return the best one☐ The information is not directly readable, because measurement returns a single outcome☐ Quantum algorithms must be designed so the desired answer survives measurement
7. What happens when you measure a system of 300 qubits?○ You obtain all the amplitudes describing the system○ You obtain 300 classical bits, chosen according to the amplitudes, and the remaining information is destroyed○ You obtain the answer with the highest amplitude○ You obtain a compressed representation of the full state
8. Why is the list of known quantum algorithms with significant speedups so short?○ Because the field has received relatively little research funding○ Because current hardware cannot run most known algorithms○ Because an algorithm must exploit mathematical structure to cancel wrong answers, and most problems lack that structure○ Because most quantum algorithms remain classified
9. Which are consequences of the no-cloning theorem? Select all that apply.☐ Classical majority-vote error correction cannot be used on quantum states☐ Intermediate states cannot be inspected without destroying them, so debugging is statistical☐ An eavesdropper cannot copy a qubit in transit undetected☐ Quantum computers cannot store classical data
10. Why are quantum computers not expected to solve NP-complete problems efficiently?○ Because such problems require more qubits than can physically be built○ Because unstructured search offers no structure for cancelling wrong answers, and the best possible result is a quadratic speedup that does not tame exponential growth○ Because NP-complete problems are undecidable○ Because classical computers already solve them efficiently