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Hybrid approach

As explained in Building Quantum Software with Python

A hybrid algorithm combines classical and quantum computation in a single procedure, typically using classical processing to guide repeated quantum computations.

Combines classical processing with quantum computation in one procedure. Classical logic prepares circuits, selects iteration counts, evaluates measured outcomes, checks stopping conditions, and updates the next quantum run. section 11.0 section 11.1

A typical hybrid optimization loop:

  • Prepare a quantum state with a circuit and run a chosen number of Grover iterations. section 11.1
  • Measure the circuit and process the outcome classically to determine whether it is good. section 11.1
  • Update circuit parameters or the search threshold, then repeat until progress or a stopping condition ends the search. section 11.3.3

Grover adaptive search

For f(k) = k² − 5 with 0 ≤ k < 4, a circuit encodes the polynomial, an oracle marks desired outcomes, and Grover iterations amplify them. Classical processing examines measurements and controls subsequent iterations. The same pattern supports a knapsack optimizer: measured selections are converted into value and weight, then the minimum value and circuit parameters are adjusted. section 11.1 section 11.3.3

Figure 11.2 A flow diagram of Grover adaptive search
figure

Use the flow diagram to trace the feedback loop from quantum execution through classical evaluation and back to the next iteration. section 11.1

How Building Quantum Software with Python covers it

How deep it goes
Defines the feedback loop and demonstrates outcome processing, parameter updates, iteration schedules, and stopping conditions.
Examples
Uses polynomial search for k² − 5 and a knapsack workflow with measured selections, values, weights, thresholds, and iteration logs.
What it assumes
Assumes familiarity with quantum circuits, Grover iterations, oracle-marked outcomes, and classical optimization state.
What you can do after
Apply it via grover_optimizer by supplying circuit construction, outcome processing, progress checks, parameter updates, and stopping logic.
How it connects
Connects Grover's algorithm, quantum oracles, Grover adaptive search, quantum optimization, and the knapsack problem.

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This explainer was generated by Manning's knowledge graph from the text of Building Quantum Software with Python. The section links point to the parts of the book it draws on.