In Qiskit, there's no getting around quantum circuits. They are the central and most powerful element you will be working with. Master quantum circuits in Qiskit, and you will master everything.
by Frank ZickertSeptember 19, 2025
The QuantumCircuit class is the foundation of Qiskit is an open-source Python framework for programming and simulating quantum computers. It lets users create quantum circuits, run them on real quantum hardware or simulators, and analyze the results. Essentially, it bridges high-level quantum algorithms with low-level hardware execution. Learn more about Qiskit. Every algorithm, experiment, or hardware run begins with a circuit, which is a structured sequence of quantum and classical operations applied to A qubit is the basic unit of quantum information, representing a superposition of 0 and 1 states. Learn more about Quantum Bit.
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You use a QuantumCircuit both as a design tool and as a transport format. It lets you specify computations, compile and transform them, and then pass them to simulators or A quantum computer is typically a large, highly controlled system kept at near-absolute-zero temperatures to preserve quantum behavior. It contains a processor with qubits—often made from superconducting circuits, trapped ions, or photons—manipulated by microwaves, lasers, or magnetic fields. Surrounding systems handle cooling, error correction, and control electronics to maintain quantum coherence and read out results. Learn more about Quantum Computer. Without it, there would be no consistent way to express logic, perform optimizations, or adapt to hardware constraints.
To work effectively, you need to understand how to build, manipulate, and execute QuantumCircuit objects. Mastery gives you precise control over program flow, gate selection, and the mapping of abstract ideas onto real processors. Once you gain this control, the rest of theQiskit is an open-source Python framework for programming and simulating quantum computers. It lets users create quantum circuits, run them on real quantum hardware or simulators, and analyze the results. Essentially, it bridges high-level quantum algorithms with low-level hardware execution. Learn more about Qiskit stack including In quantum computing, **transpilation** is the process of converting a high-level quantum circuit (written for an ideal model) into an optimized version that can run on a specific quantum device. It adjusts the circuit to match the device’s available gate set, connectivity, and error characteristics. The goal is to preserve the computation’s logic while minimizing errors and resource use. Learn more about Transpilation, Execution in quantum computing is the process of running a quantum circuit on qubits to perform a computation. It involves applying a sequence of quantum gates (unitary operations) followed by measurement, which collapses the qubits’ superpositions into classical outcomes. Because quantum states are probabilistic, repeated executions (shots) are used to estimate the result distribution accurately. Learn more about Execution, and Analysis becomes more transparent and effective.
For very small circuits, you can use the plain method where qubits are only identified by their positions.
