Chapter 03 / Concept 11 of 48

Basis and computational encoding

Encode discrete bit strings as computational basis states, useful for combinatorial and binary inputs.

Input / assumptions→ Quantum or learning model→ Measurement / inference→ Validation

Core idea

Encode discrete bit strings as computational basis states, useful for combinatorial and binary inputs. The central design question is what information the representation retains, which operations are physically implementable, and how prediction quality and total resource cost are measured. In QML, a mathematical formulation must be paired with an explicit data-access model and a reproducible evaluation protocol.

$$b\mapsto|b_1b_2\cdots b_n\rangle$$

Worked example

Encode binary feature vector (1,0,1) as $|101\rangle$.

How to study or implement it

Start with a minimal analytic case that can be checked by hand. Build a noiseless simulation, inspect intermediate states or predictions, and then repeat with finite sampling. Compare against a suitable classical reference using the same dataset, preprocessing, and evaluation split. Record circuit depth, qubit count, optimization steps, and measurement budget.

Interpretation and limitations

A basis encoding does not itself create smooth similarity between nearby samples. When evaluating experimental claims, separate theoretical asymptotic statements from measured end-to-end performance. Include preprocessing, state preparation, parameter tuning and output extraction in the comparison.

Further exploration

See the chapter overview, interactive lab, guided learning path, and curated sources.

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