50 IBM A1000-136 Practice Questions: Question Bank 2025

A developer is new to quantum computing and asks what a qubit measurement returns. Which statement is correct?

You are evaluating whether a circuit has produced entanglement. Which result is the strongest indicator that two qubits are entangled?

A user wants to execute the same quantum circuit many times to estimate outcome probabilities on IBM Quantum hardware. What is the standard way to do this?

A team wants to understand why their circuit results differ between an ideal simulation and real hardware. Which factor most directly explains the difference?

A developer uses Qiskit and sees that their circuit cannot run on a chosen backend due to unsupported two-qubit connections. What is the best next step?

A researcher wants to run VQE to estimate a molecule’s ground-state energy. Which pairing is most appropriate for VQE?

A team is debugging a circuit that produces unexpected results on hardware. They suspect readout (measurement) error. Which technique is most directly aimed at reducing measurement bias in reported results?

A developer notices their transpiled circuit has many SWAP gates, increasing error. What is a best-practice approach to reduce SWAP overhead?

You run a circuit on hardware and obtain a distribution that differs from the ideal simulator. You suspect the main issue is decoherence due to long circuit duration. Which change most directly targets this issue while preserving the algorithm’s intent?

A student says, "If I apply a Hadamard gate to one qubit and then a CNOT with that qubit as control, the two-qubit state is always entangled." Under which condition is this statement correct?

A team new to quantum computing is comparing classical bits with qubits. Which statement best describes a qubit before measurement?

In IBM Quantum, a developer wants to execute the same circuit many times to estimate measurement probabilities. What is the purpose of specifying the number of "shots"?

A developer is reviewing a 2-qubit circuit that applies H on qubit 0 followed by CNOT with control qubit 0 and target qubit 1. Starting from |00⟩, what state does this circuit ideally prepare?

A user runs a circuit on a real IBM Quantum backend and observes results that deviate from an ideal simulator. They want a practical next step to quantify how much error is coming from readout (measurement) rather than gates. What should they do?

A circuit must run on a backend with limited qubit connectivity. Which action is the transpiler most likely to take to satisfy the hardware coupling constraints?

A team is using Qiskit Runtime primitives for iterative experimentation. They want reduced latency by minimizing repeated job submission overhead while still retrieving expectation values for a parameterized circuit. Which approach best fits this goal?

A developer expects two qubits to be entangled, but measurement results show each qubit is approximately 50/50 independently and the joint distribution looks uncorrelated. Which mistake most plausibly causes this outcome?

A data science team wants to use Grover’s algorithm. They propose applying it to a problem with no efficiently implementable oracle. What is the best guidance?

A researcher uses a noise model in simulation and gets results close to hardware, but after transpiling for the real backend the results get worse. Which factor most likely explains the degradation?

A team is building a variational algorithm and wants to estimate the expectation value of a Hamiltonian that is a sum of Pauli terms (e.g., ZI + XX + YY). On real hardware, what is the best-practice strategy to measure these terms?

A new team member says, “Because a qubit can be in superposition, it stores both 0 and 1 and therefore reading it gives both values at once.” Which statement best corrects this misunderstanding?

You are prototyping a circuit and want a quick way to visualize gate placement and qubit lines before running anything. Which IBM Quantum tool is most appropriate?

A researcher runs a Bell-state circuit and expects roughly 50/50 results for 00 and 11. On hardware they also see non-trivial counts for 01 and 10. Which explanation is most accurate at a foundational level?

A team is comparing two transpiled circuits for the same algorithm. One has fewer two-qubit gates but requires routing across distant qubits on the chosen device. Which metric typically correlates most with improved success probability on NISQ devices?

You want to run a parameter sweep for a variational algorithm using IBM Quantum. Which approach is most aligned with best practice to reduce queuing and overhead while iterating many times?

A developer maps a circuit onto a backend but gets unexpectedly high depth after transpilation. They suspect the issue is poor qubit placement relative to device connectivity. What is the most direct action to address this?

A team is evaluating whether Grover’s algorithm will provide an immediate speedup for searching a small unsorted list on today’s noisy hardware. Which statement is most accurate?

A circuit includes mid-circuit measurements intended to classically control a subsequent gate (feed-forward). The results are inconsistent on a backend that does not support dynamic circuit features. What is the best resolution?

You are asked to explain why measuring one qubit of an entangled pair can affect predicted outcomes of the other, yet cannot be used for faster-than-light communication. Which explanation is correct?

A user runs a circuit with 3 qubits but only measures 2 of them. The resulting counts show bitstrings of length 2. They expected 3-bit strings and think the backend dropped a qubit. What is the best explanation?

A new team member says, "If I measure one qubit from an entangled pair, the other qubit instantly becomes a specific value." Which clarification is most accurate in the context of quantum computing fundamentals?

A developer runs a quantum circuit on a real device and gets results that differ from their simulator results. They want to quickly determine whether noise is the likely cause without changing the circuit. What is the best practice approach in IBM Quantum tools?

A scientist is building a variational algorithm (e.g., VQE/QAOA) workflow. They want to minimize total runtime and queue time on hardware while still improving parameters. Which strategy is most appropriate?

You create a Bell state using H on qubit 0 followed by CX(0,1). When you measure both qubits in the Z basis, what pattern should you expect (ignoring noise)?

A user wants to choose a hardware backend for a 2-qubit circuit that includes a CX gate. Which backend attribute is MOST directly relevant to ensure the circuit can be executed with minimal additional SWAP operations?

A project uses Grover’s search. The team expects an exponential speedup over classical search for any problem size. Which statement best reflects the actual performance expectation?

A developer is troubleshooting unexpectedly low fidelity results after transpilation. The transpiled circuit shows a large increase in depth due to inserted SWAP gates. What is the most likely root cause?

A team wants to represent a classical optimization problem as an Ising Hamiltonian for use with QAOA. Which high-level step is required before running the quantum circuit?

A user runs a circuit that includes mid-circuit measurement and a classically controlled operation (apply X if measurement result is 1). The circuit behaves correctly on a simulator but fails on a chosen hardware backend. What is the MOST likely explanation?

A researcher wants to estimate the expectation value of an observable for a parameterized circuit (as used in VQE). They notice high variance in their estimate and limited hardware time. Which approach is generally most effective to reduce estimator error without changing the problem definition?

A student is reviewing measurement results from a single-qubit circuit. The simulator returns 50% probability for measuring |0⟩ and 50% for measuring |1⟩. Which qubit state is most consistent with this outcome when measured in the computational (Z) basis?

You want to create a Bell pair in Qiskit using two qubits initialized to |00⟩. Which sequence of gates is the standard approach?

A developer is preparing to run circuits on IBM hardware and needs access to both real devices and managed simulators through IBM Quantum. Which IBM service is typically used as the entry point for these resources?

A researcher wants to compare ideal (noise-free) results with hardware-like noisy results for the same circuit to understand error impact before consuming real-device queue time. What is the most appropriate approach in the IBM tooling ecosystem?

A team is implementing a variational algorithm (e.g., VQE) and observes high variance in estimated expectation values. They want to reduce statistical error without changing the ansatz. Which action most directly addresses this?

A developer transpiles a circuit for a specific IBM Quantum backend and sees many SWAP gates inserted, significantly increasing depth. What is the most likely cause?

A user runs a circuit with 1024 shots and gets counts that do not sum to 1024. What is the best initial troubleshooting step?

A data scientist wants to use Grover’s algorithm to search an unstructured space. Which component must be provided or built to apply Grover’s search to a specific problem?

A team applies measurement error mitigation and observes probabilities slightly below 0 or above 1 after mitigation. What is the most accurate interpretation and recommended handling?

A circuit uses mid-circuit measurements to classically control later quantum operations. On some backends, the run fails or the behavior differs from simulation. What is the most likely reason and best practice?