IBM A1000-099: Assessment: Foundations of Quantum Computing Practice Exam 2025: Latest Questions

A researcher explains that measuring a qubit in a superposition yields a single classical outcome and changes the qubit’s state. Which statement best describes what happens after a measurement in the computational basis?

You are building a circuit that should create the Bell state (|00⟩ + |11⟩)/√2 from the initial state |00⟩. Which gate sequence accomplishes this?

A team wants to run a quantum circuit multiple times to estimate measurement probabilities. In IBM Quantum terminology, what is the primary purpose of increasing the number of shots?

A developer is comparing classical bits and qubits for an internal training session. Which statement is accurate at a foundational level?

You simulate a 3-qubit circuit and obtain a statevector. What does the amplitude associated with basis state |101⟩ represent?

A circuit returns nearly uniform measurement counts even though a clear bias is expected. The team suspects unintended extra measurements. In a typical quantum workflow, which issue most directly explains why adding intermediate measurements can change later results?

A business wants to explore quantum approaches for a combinatorial optimization problem (e.g., selecting a best portfolio under constraints). Which pairing of algorithm family and problem type is most appropriate at a foundational level?

A team needs to choose between running a circuit on a simulator or on real quantum hardware. They want repeatable, noise-free results for debugging logic and verifying ideal amplitudes. What is the recommended approach?

A developer composes a circuit with only H, X, and CNOT gates (no measurements until the end). They claim it can generate any single-qubit rotation needed for an algorithm. What is the key limitation of this claim?

A user runs Grover’s algorithm for a single marked item in a search space of size N. They repeatedly apply the Grover iteration far more than √N times and see the success probability drop. What best explains this behavior?

In a 1-qubit experiment, a developer measures the same prepared state many times and wants to estimate outcome probabilities. What is the most appropriate interpretation of the results?

A student applies a Hadamard gate (H) to |0⟩ and then immediately measures in the computational (Z) basis. What result should they expect in an ideal simulator?

A developer runs the same circuit on real hardware with 4000 shots and gets slightly different counts each time, even though the circuit is unchanged. Which is the most likely explanation?

You need to create a Bell state starting from |00⟩. Which gate sequence achieves this in an ideal circuit model?

A team wants to estimate the expectation value ⟨Z⟩ of a single-qubit state using repeated measurements in the Z basis. If they observe counts: 0 occurs 900 times and 1 occurs 100 times (1000 shots total), what is the best estimate of ⟨Z⟩?

A circuit contains two consecutive X gates on the same qubit with no operations in between. As a best practice when optimizing circuits for execution on noisy hardware, what should be done?

A user runs a circuit on an IBM Quantum backend and receives an error indicating the circuit is not compatible with the backend’s basis gates. What is the most appropriate next step?

A product team is evaluating whether a near-term quantum approach is suitable. Which problem is most aligned with typical NISQ-era applications?

A researcher prepares the 2-qubit state (|00⟩ + |11⟩)/√2 and measures both qubits in the computational basis many times. Which observation best indicates entanglement rather than just classical correlation from a mixture?

A developer attempts to implement Grover’s algorithm for a small search space. Their circuit uses an oracle plus a diffusion operator, but the measured success probability is low on real hardware. Which action is most likely to improve results without changing the algorithm’s goal?

A researcher runs a circuit multiple times on a quantum device and gets different bitstrings across runs, even though the circuit is identical each time. Which statement best explains this behavior?

You need to verify whether two qubits in a circuit are entangled at a given point in time. Which approach is most appropriate on real hardware using IBM Quantum tools?

A developer is troubleshooting why a circuit produces a high error rate when executed on a real QPU. The circuit uses many two-qubit gates between non-adjacent qubits. What is the most effective best practice to reduce errors?

You are asked to explain why Grover’s algorithm is often described as providing a quadratic speedup. For a search space of size N, what is the expected number of oracle queries for Grover’s algorithm (ideal case, single marked item)?

A team runs a circuit on both a statevector simulator and a real IBM Quantum backend. The simulator’s results match the expected distribution, but hardware results are noticeably biased. Which explanation best accounts for this discrepancy, and what is a practical mitigation?