rung: 3
name: "Transfer Test Rung"
description: "Keep only the strongest principles from the first two rungs and test them across multiple backend targets."
objective: "Measure which [[4,2,2]] heuristics transfer across backend families rather than overfitting a single noise profile."

bootstrap_incumbent:
  seed_style: ry_rz
  encoder_style: cx_chain
  verification: z_only
  postselection: z_only
  ancilla_strategy: reused_single
  optimization_level: 3
  layout_method: sabre
  routing_method: sabre
  approximation_degree: 1.0
  target_backend: fake_sherbrooke
  noise_backend: fake_sherbrooke
  shots: 768
  repeats: 3
  notes: "Transfer-focused incumbent."

search_space:
  max_challengers_per_step: 6
  dimensions:
    target_backend: [fake_sherbrooke, fake_brisbane, fake_kyoto]
    noise_backend: [fake_sherbrooke, fake_brisbane, fake_kyoto]
    seed_style: [ry_rz, h_p]
    verification: [z_only, both]
    postselection: [z_only, all_measured]
    ancilla_strategy: [reused_single, dedicated_pair]

tier_policy:
  cheap_margin: 0.001
  confirmation_margin: 0.0
  cheap_shots: 768
  expensive_shots: 1536
  cheap_repeats: 3
  expensive_repeats: 1
  promote_top_k: 2
  enable_hardware: false
  confirm_incumbent_on_hardware: true
  hardware_budget: 1

score:
  name: weighted_acceptance_cost
  base_cost: 1.0
  cheap_quality:
    noisy_fidelity: 0.20
    logical_witness: 0.30
    codespace_rate: 0.20
    stability_score: 0.20
    spectator_alignment: 0.10
  expensive_quality:
    logical_witness: 0.50
    codespace_rate: 0.15
    stability_score: 0.25
    spectator_alignment: 0.10
  cost_weights:
    two_qubit_count: 0.05
    depth: 0.01
    shot_count: 0.00025
    runtime_estimate: 0.02
    queue_cost_proxy: 0.40

step_budget: 3
patience: 2

transfer_backends:
  - fake_sherbrooke
  - fake_brisbane
  - fake_kyoto

hardware:
  backend_name:
  channel:
  instance:
  token_env_var: QISKIT_IBM_TOKEN