gatebased

Gate-based quantum computing, also called the circuit model, is a paradigm in which computation is performed by applying a sequence of quantum logic gates to a register of qubits, followed by measurement. It is the most widely studied model of quantum computation and forms the basis for many quantum algorithms.

In gate-based computation, the information is encoded in qubits represented by two-level quantum systems. Computation proceeds by applying unitary operations (gates) such as single-qubit gates (Hadamard H, phase S, T) and two-qubit gates (CNOT, CZ). A quantum circuit is a sequence of such gates; after the final layer, measurement yields classical outcomes. A set of gates is universal if any unitary can be approximated to arbitrary accuracy; common universal gate sets include {H, T, CNOT} or {CNOT, arbitrary single-qubit rotations}.

Implementations face challenges such as decoherence, noise, and error accumulation. Practical gate-based quantum computing relies on quantum error correction and fault-tolerant architectures, with thresholds defining the necessary error rates. Quantum compilers translate high-level algorithms into gate sequences optimized for a given hardware.

Gate-based quantum computing has been used to design and demonstrate algorithms such as Shor’s factoring and Grover’s search, typically via small-scale experiments. It is contrasted with other models such as measurement-based (one-way) quantum computing and adiabatic/quantum annealing approaches.

Outside physics, the term gate-based may appear in other domains, for example in gate-based authentication or access-control contexts, but in technical literature it most commonly refers to the circuit model of quantum computation.