More cleaning shared ops (#560)

* removes unused variables in test_tdmprogram

* First version

strawberryfields/backends/shared_ops.py

@@ -22,36 +22,6 @@
 # ================================+
 
 
-@functools.lru_cache()
-def rotation_matrix(phi):
-    r"""Rotation matrix.
-
-    Args:
-        phi (float): rotation angle
-
-    Returns:
-        array: :math:`2\times 2` rotation matrix
-    """
-    return np.array([[np.cos(phi), -np.sin(phi)], [np.sin(phi), np.cos(phi)]])
-
-
-@functools.lru_cache()
-def sympmat(n):
-    r"""Returns the symplectic matrix of order n
-
-    Args:
-        n (int): order
-
-    Returns:
-        array: symplectic matrix
-    """
-    idm = np.identity(n)
-    omega = np.concatenate(
-        (np.concatenate((0 * idm, idm), axis=1), np.concatenate((-idm, 0 * idm), axis=1)), axis=0
-    )
-    return omega
-
-
 @functools.lru_cache()
 def changebasis(n):
     r"""Change of basis matrix between the two Gaussian representation orderings.

strawberryfields/backends/states.py

@@ -26,11 +26,12 @@
 from scipy.special import factorial
 from scipy.integrate import simps
 
+from thewalrus.symplectic import rotation as _R
+
 import thewalrus.quantum as twq
 
 import strawberryfields as sf
 
-from .shared_ops import rotation_matrix as _R
 from .shared_ops import changebasis
 
 indices = string.ascii_lowercase

strawberryfields/decompositions.py

@@ -21,8 +21,9 @@
 import numpy as np
 from scipy.linalg import block_diag, sqrtm, polar, schur
 from thewalrus.quantum import adj_scaling
+from thewalrus.symplectic import sympmat
 
-from .backends.shared_ops import sympmat, changebasis
+from .backends.shared_ops import changebasis
 
 
 def takagi(N, tol=1e-13, rounding=13):

tests/backend/test_states_polyquad.py

@@ -19,9 +19,11 @@
 from scipy.integrate import simps
 from scipy.linalg import block_diag
 
+from thewalrus.symplectic import rotation as R
+
 from strawberryfields import backends
 from strawberryfields import utils
-from strawberryfields.backends.shared_ops import rotation_matrix as R, changebasis
+from strawberryfields.backends.shared_ops import changebasis
 
 # some tests require a higher cutoff for accuracy
 CUTOFF = 12

tests/backend/test_states_wigner.py

@@ -17,9 +17,10 @@
 import numpy as np
 from scipy.stats import multivariate_normal
 
+from thewalrus.symplectic import rotation as rotm
+
 from strawberryfields import backends
 from strawberryfields import utils
-from strawberryfields.backends.shared_ops import rotation_matrix as rotm
 
 
 A = 0.3 + 0.1j

tests/frontend/test_shared_ops.py

@@ -23,24 +23,6 @@
 class TestPhaseSpaceFunctions:
     """Tests for the shared phase space operations"""
 
-    @pytest.mark.parametrize("phi", np.linspace(0, np.pi, 4))
-    def test_rotation_matrix(self, phi):
-        """Test the function rotation_matrix"""
-        res = so.rotation_matrix(phi)
-        expected = np.array([[np.cos(phi), -np.sin(phi)], [np.sin(phi), np.cos(phi)]])
-
-        assert np.all(res == expected)
-
-    @pytest.mark.parametrize("n", [1, 2, 4])
-    def test_sympmat(self, n):
-        """Test the symplectic matrix function"""
-        res = so.sympmat(n)
-        O = np.zeros([n, n])
-        I = np.identity(n)
-        expected = np.block([[O, I], [-I, O]])
-
-        assert np.all(res == expected)
-
     def test_means_changebasis(self):
         """Test the change of basis function applied to vectors. This function
         converts from xp to symmetric ordering, and vice versa."""

tests/integration/test_decompositions_integration.py

@@ -17,6 +17,8 @@
 import numpy as np
 from scipy.linalg import qr, block_diag
 
+from thewalrus.symplectic import rotation as rot
+
 import strawberryfields as sf
 from strawberryfields import decompositions as dec
 from strawberryfields.utils import (
@@ -26,10 +28,7 @@
     squeezed_state,
 )
 from strawberryfields import ops
-from strawberryfields.backends.shared_ops import (
-    changebasis,
-    rotation_matrix as rot,
-)
+from strawberryfields.backends.shared_ops import changebasis
 
 from strawberryfields.utils import random_interferometer as haar_measure
 # make the test file deterministic