Pattern Atlas

Extended Quantum Computing Patterns

Basis Change

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© https://arxiv.org/abs/2601.06281

Intent

Transform a quantum state from one basis to another so that the next operation can be performed in a more suitable representation.

Context

An algorithm contains an operation that is easier to express or apply in a basis different from the current one.

Forces

The transformation adds gates and may need to be reversed later. Approximate transformations can reduce circuit depth at the cost of accuracy.

Solution

Apply a unitary transformation that maps the state to the required basis. Examples include the quantum Fourier transform, the Hadamard transform, and quantum discrete cosine or sine transforms.

Result

The state is represented in a basis suited to the next part of the computation.

Examples

Quantum Fourier transform, inverse quantum Fourier transform, Hadamard transform, quantum DCT, and quantum DST.

Related Patterns

Uniform Superposition; Quantum Phase Estimation (QPE)

Known Uses

QFT implementations in Qiskit, PennyLane, and Classiq, and the DCT and DST routines provided by Classiq.