Remove TSqrt2 and use Tz instead.

Author: codrut3

qualtran/rotation_synthesis/matrix/_clifford_t_repr.py

@@ -13,7 +13,7 @@
 #  limitations under the License.
 
 import math
-from typing import cast, Mapping, Optional
+from typing import cast, Mapping, Optional, Union
 
 import cirq
 import numpy as np
@@ -103,27 +103,28 @@ def _matsumoto_amano_sequence(matrix: _su2_ct.SU2CliffordT) -> tuple[str, ...]:
         if np.all(parity[:, i] == 0):
             parity[:, [i, 2]] = parity[:, [2, i]]
             break
-    gates : tuple[str, ...] = ()
+    gates: tuple[str, ...] = ()
+    new: Union[_su2_ct.SU2CliffordT, None]
     if np.array_equal(parity, np.array([[1, 1, 0], [1, 1, 0], [0, 0, 0]])):
         # Leftmost syllabe is T
-        new = _su2_ct.TSqrt2.adjoint() @ matrix
+        new = _su2_ct.Tz.adjoint() @ matrix
         gates = ('T',)
     elif np.array_equal(parity, np.array([[0, 0, 0], [1, 1, 0], [1, 1, 0]])):
         # Leftmost syllabe is HT
         new = _su2_ct.HSqrt2.adjoint() @ matrix
-        new = _su2_ct.TSqrt2.adjoint() @ new
+        new = _su2_ct.Tz.adjoint() @ new
         gates = ('T', 'H')
     elif np.array_equal(parity, np.array([[1, 1, 0], [0, 0, 0], [1, 1, 0]])):
         # Leftmost syllabe is SHT
         new = _su2_ct.SSqrt2.adjoint() @ matrix
         new = _su2_ct.HSqrt2.adjoint() @ new
-        new = _su2_ct.TSqrt2.adjoint() @ new
+        new = _su2_ct.Tz.adjoint() @ new
         gates = ('T', 'H', 'S')
     else:
         raise ValueError(f'Unexpected parity matrix:\n{parity}')
     new = new.scale_down()
     if new is None or not new.is_valid():
-        raise ValueError(f'Invalid SU2CliffordT matrix\n{new.matrix}')
+        raise ValueError('Invalid SU2CliffordT matrix')
     seq = _matsumoto_amano_sequence(new)
     return seq + gates
 

qualtran/rotation_synthesis/matrix/_su2_ct.py

@@ -347,14 +347,6 @@ def _key_map():
     * SU2CliffordT(np.array([[_zw.One, _zw.Zero], [_zw.Zero, _zw.J]]), ("S",))
 )
 
-# T gate scaled by sqrt(2) * (1 + w^*) to make its determinant = 2(2+sqrt(2))
-# TSqrt2 is equal to Tz below
-TSqrt2 = (
-    _zw.SQRT_2
-    * (1 + _zw.Omega.conj())
-    * SU2CliffordT(np.array([[_zw.One, _zw.Zero], [_zw.Zero, _zw.Omega]]), ("T",))
-)
-
 # Paulis
 ISqrt2: SU2CliffordT = _zw.SQRT_2 * SU2CliffordT(
     np.array([[_zw.One, _zw.Zero], [_zw.Zero, _zw.One]]), ()
@@ -372,6 +364,7 @@ def _key_map():
 # Tx, Ty, Tz scaled by sqrt(2*(2+sqrt(2)))
 Tx = SU2CliffordT(_I * _zw.SQRT_2 + _I - _X * _zw.J, ("Tx",))
 Ty = SU2CliffordT(_I * _zw.SQRT_2 + _I - _Y * _zw.J, ("Ty",))
+# Tz = sqrt(2) * (1 + w^*) * T and has determinant = 2(2+sqrt(2))
 Tz = SU2CliffordT(_I * _zw.SQRT_2 + _I - _Z * _zw.J, ("Tz",))
 Ts = [Tx, Ty, Tz]
 

qualtran/rotation_synthesis/matrix/clifford_t_repr_test.py

@@ -75,7 +75,7 @@ def test_to_cirq(g: _su2_ct.SU2CliffordT, fmt: str):
     [
         [_su2_ct.HSqrt2, "t", ('"Z^½"', '"X"', '"Z^½"', '"X"', '"H"')],
         [_su2_ct.SSqrt2, "t", ('{"id":"Rzft","arg":"pi/2"}',)],
-        [_su2_ct.TSqrt2, "t", ('{"id":"Rzft","arg":"pi/4"}',)],
+        [_su2_ct.Tz, "t", ('{"id":"Rzft","arg":"pi/4"}',)],
     ],
 )
 def test_to_quirk(g: _su2_ct.SU2CliffordT, fmt: str, expected: tuple[str, ...]):

qualtran/rotation_synthesis/matrix/su2_ct_test.py

@@ -125,7 +125,7 @@ def test_num_t_gates():
     [
         [_su2_ct.HSqrt2, _H_bloch_form_numpy, 0],
         [_su2_ct.SSqrt2, _S_bloch_form_numpy, 0],
-        [_su2_ct.TSqrt2, _T_bloch_form_numpy, 1],
+        [_su2_ct.Tz, _T_bloch_form_numpy, 1],
     ],
 )
 def test_bloch_sphere_form_generators(g: _su2_ct.SU2CliffordT, bloch_form: np.ndarray, n: int):
@@ -157,9 +157,9 @@ def test_bloch_sphere_form_random(g: _su2_ct.SU2CliffordT, vector: np.ndarray):
 @pytest.mark.parametrize(
     ["g", "parity"],
     [
-        [_su2_ct.TSqrt2, _T_parity_numpy],
-        [_su2_ct.HSqrt2 @ _su2_ct.TSqrt2, _HT_parity_numpy],
-        [_su2_ct.SSqrt2 @ _su2_ct.HSqrt2 @ _su2_ct.TSqrt2, _SHT_parity_numpy],
+        [_su2_ct.Tz, _T_parity_numpy],
+        [_su2_ct.HSqrt2 @ _su2_ct.Tz, _HT_parity_numpy],
+        [_su2_ct.SSqrt2 @ _su2_ct.HSqrt2 @ _su2_ct.Tz, _SHT_parity_numpy],
     ],
 )
 def test_bloch_form_parity(g: _su2_ct.SU2CliffordT, parity: np.ndarray):