| """Resource-level QIR to Fibonacci braid backend."""
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|
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| from __future__ import annotations
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|
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| from dataclasses import dataclass
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| from typing import Iterable, List
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|
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| from qlambda.compiler import QIRInstruction
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|
|
|
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| @dataclass(frozen=True)
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| class BraidOp:
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| sigma: int
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| forward: bool = True
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|
|
|
|
| class TopologicalBraidBackend:
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| """Compile QIR gate names to Fibonacci braid words.
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|
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| This is a resource-level backend. It emits braid-word schedules for
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| accounting and falsification tests; it is not a matrix-equivalence proof.
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| """
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|
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| H_BRAID = (BraidOp(0), BraidOp(1), BraidOp(0), BraidOp(1), BraidOp(0))
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| X_BRAID = (BraidOp(0), BraidOp(0))
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| S_BRAID = (BraidOp(0), BraidOp(0))
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| CNOT_BRAID = (BraidOp(2), BraidOp(1), BraidOp(0), BraidOp(1), BraidOp(2))
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| CCX_BRAID = (
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| BraidOp(4), BraidOp(5), BraidOp(4), BraidOp(5), BraidOp(4),
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| BraidOp(2), BraidOp(3), BraidOp(4), BraidOp(2), BraidOp(3), BraidOp(4),
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| BraidOp(4), BraidOp(5), BraidOp(4), BraidOp(5), BraidOp(4),
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| )
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|
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| def __init__(self, sk_t_length: int = 300):
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| self.sk_t_length = sk_t_length
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|
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| def compile(self, qir: Iterable[QIRInstruction]) -> List[BraidOp]:
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| braids: List[BraidOp] = []
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| for inst in qir:
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| braids.extend(self.compile_gate(inst))
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| return braids
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|
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| def compile_gate(self, inst: QIRInstruction) -> List[BraidOp]:
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| gate = inst.gate.upper()
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| if gate == "X":
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| return list(self.X_BRAID)
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| if gate == "H":
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| return list(self.H_BRAID)
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| if gate == "S":
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| return list(self.S_BRAID)
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| if gate in {"T", "TDG"}:
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| forward = gate == "T"
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| return [BraidOp(0, forward=forward) for _ in range(self.sk_t_length)]
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| if gate == "CX":
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| return list(self.CNOT_BRAID)
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| if gate == "CCX":
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| return list(self.CCX_BRAID)
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| if gate in {"ROTR", "SHR", "BARRIER"}:
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| return []
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| if gate.endswith("_DAGGER"):
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| base = QIRInstruction(gate[:-7], inst.controls, inst.targets, inst.params)
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| return [BraidOp(op.sigma, not op.forward) for op in reversed(self.compile_gate(base))]
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| raise NotImplementedError(f"Gate {inst.gate!r} has no topological braid mapping")
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|
|
