move the T-complexity formula to GateCounts

Author: anurudhp

qualtran/cirq_interop/t_complexity_protocol.py

@@ -20,7 +20,7 @@
 
 from qualtran import Bloq, Controlled, DecomposeNotImplementedError, DecomposeTypeError
 from qualtran.resource_counting import SympySymbolAllocator
-from qualtran.symbolics import ceil, log2, SymbolicFloat, SymbolicInt
+from qualtran.symbolics import ceil, SymbolicFloat, SymbolicInt
 
 from .decompose_protocol import _decompose_once_considering_known_decomposition
 
@@ -38,7 +38,9 @@ class TComplexity:
 
     @staticmethod
     def rotation_cost(eps: SymbolicFloat) -> SymbolicFloat:
-        return ceil(1.149 * log2(1.0 / eps) + 9.2)
+        from qualtran.resource_counting import GateCounts
+
+        return GateCounts.rotation_t_cost(eps)
 
     def t_incl_rotations(self, eps: float = 1e-11) -> SymbolicInt:
         """Return the total number of T gates after compiling rotations"""

qualtran/resource_counting/_bloq_counts.py

@@ -20,6 +20,8 @@
 import numpy as np
 from attrs import field, frozen
 
+from qualtran.symbolics import ceil, log2, SymbolicFloat
+
 from ._call_graph import get_bloq_callee_counts
 from ._costing import CostKey
 from .classify_bloqs import bloq_is_clifford, bloq_is_rotation
@@ -236,6 +238,16 @@ def _keep(key, value) -> bool:
 
         return {k: v for k, v in d.items() if _keep(k, v)}
 
+    @staticmethod
+    def rotation_t_cost(eps: SymbolicFloat) -> SymbolicFloat:
+        """T-cost of a single Z rotation with precision `eps`.
+
+        References:
+            [Efficient synthesis of universal Repeat-Until-Success circuits](https://arxiv.org/abs/1404.5320)
+            Bocharov et. al. 2014. Page 4, Paragraph "Simulation Results."
+        """
+        return ceil(1.149 * log2(1.0 / eps) + 9.2)
+
     @property
     def rotation_to_t(self) -> int:
         """Total number of T Gates for the rotations."""