real determinant

src/qutip_qip/decompositions/general_decompositions.py

@@ -77,7 +77,10 @@ def check_unitary(input_array)-> bool:
     Args:
        input_array : Matrix of a gate in Numpy array form.
     """
-    input_array = normalize_matrix(input_array)
+    try:
+        input_array = normalize_matrix(input_array)
+    except ZeroDivisionError:
+        input_array = input_array
     identity_matrix = np.eye(input_array.shape[0])
     input_array_dagger = input_array.conj().T
     check_unitary_left = np.allclose(identity_matrix, np.dot(input_array_dagger,input_array))
@@ -96,9 +99,13 @@ def extract_global_phase(input_array):
        input_array : Matrix of a gate in Numpy array form.
     """
     if check_unitary(input_array) is True:
-        input_array = normalize_matrix(input_array)
-        power_factor_based_on_matrix_shape = 1/input_array.shape[0]
+        try:
+            input_array = normalize_matrix(input_array)
+        except ZeroDivisionError:
+            input_array = input_array
+
         det = np.linalg.det(input_array)
+        power_factor_based_on_matrix_shape = 1/input_array.shape[0]
 
 
         sin_value_from_determinant = -det.imag
@@ -114,12 +121,11 @@ def extract_global_phase(input_array):
             phase_factor = np.arctan(ratio_sin_cos)
 
         phase_factor = power_factor_based_on_matrix_shape*phase_factor
+        phase_exp_value = np.cos(phase_factor) - 1j*np.sin(phase_factor)
 
-
-        if phase_factor == -0.0:
-            phase_exp_value = -1
-        else:
-            phase_exp_value = np.cos(phase_factor) - 1j*np.sin(phase_factor)
+        # Makes sure the value at |0><0| is positive (not really needed)
+        if phase_exp_value > 0 and input_array[0][0] <0:
+            phase_exp_value = - phase_exp_value
 
         input_to_su_from_phase = np.multiply(input_array,phase_exp_value)
         return((phase_exp_value,input_to_su_from_phase))

src/qutip_qip/decompositions/verify_decompositions.py

@@ -0,0 +1,34 @@
+# This file is part of QuTiP: Quantum Toolbox in Python.
+#
+#    Copyright (c) 2011 and later, Paul D. Nation and Robert J. Johansson.
+#    All rights reserved.
+#
+#    Redistribution and use in sourc e and binary forms, with or without
+#    modification, are permitted provided that the following conditions are
+#    met:
+#
+#    1. Redistributions of source code must retain the above copyright notice,
+#       this list of conditions and the following disclaimer.
+#
+#    2. Redistributions in binary form must reproduce the above copyright
+#       notice, this list of conditions and the following disclaimer in the
+#       documentation and/or other materials provided with the distribution.
+#
+#    3. Neither the name of the QuTiP: Quantum Toolbox in Python nor the names
+#       of its contributors may be used to endorse or promote products derived
+#       from this software without specific prior written permission.
+#
+#    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+#    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+#    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+#    PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+#    HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+#    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+#    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+#    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+#    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+#    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+#    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+###############################################################################
+
+# add functions to check the calculated decomposition is equivalent to input array. 

tests/test_general_decompositions.py

@@ -78,6 +78,13 @@ def test_normalize_matrix_zero_determinant():
     with pytest.raises(ZeroDivisionError, match="Determinant of matrix =0."):
         normalize_matrix(np.array([[0, 0], [0, 0]]))
 
+def test_normalize_matrix_normalized_array():
+    """Check if function tries to divide by 0 norm factor.
+    """
+    pauliz = np.array([[1,0],[0,-1]])
+    calculated_array = normalize_matrix(pauliz)
+    assert all([out==inp] for out, inp in zip(calculated_array,pauliz))
+
 
 def test_check_unitary():
     """Tests if input is correctly idenitified as unitary. """
@@ -89,3 +96,35 @@ def test_extract_global_phase_non_unitary_input():
     a unitary."""
     with pytest.raises(ValueError, match = "Input array is not a unitary matrix."):
         extract_global_phase(np.array([[1, 2], [3, 4]]))
+
+def test_extract_global_phase_valid_input_phase_comparison():
+    """Tests if phase is correctly calculated when input is valid. """
+
+    # Determinant has real part only
+    matrix1 = np.multiply(np.array([[1,1],[1,-1]]),1/np.sqrt(2))
+    determined_list_of_gates = extract_global_phase(matrix1)
+    determined_phase_value = determined_list_of_gates[0]
+    actual_phase_value = 1+0j
+    assert(determined_phase_value==actual_phase_value)
+
+
+def test_extract_global_phase_valid_input_output_comparison():
+    """Tests if product of outputs is equal to input when input is valid. """
+
+    # Determinant has real part only
+    matrix1 = np.multiply(np.array([[1,1],[1,-1]]),1/np.sqrt(2))
+    determined_list_of_gates = extract_global_phase(matrix1)
+    determined_phase_value = determined_list_of_gates[0]
+    calculated_array = np.multiply(determined_list_of_gates[1],determined_phase_value)
+    assert all([out==inp] for out, inp in zip(calculated_array,matrix1))
+
+
+def test_extract_global_phase_valid_input_shape_comparison():
+    """Tests if shape of array is unchanged by function. """
+
+    # Determinant has real part only
+    matrix1 = np.multiply(np.array([[1,1],[1,-1]]),1/np.sqrt(2))
+    determined_list_of_gates = extract_global_phase(matrix1)
+    determined_array_shape = np.shape(determined_list_of_gates[1])
+    input_array_shape = np.shape(matrix1)
+    assert all([out==inp] for out, inp in zip(input_array_shape,determined_array_shape))

tests/test_verify_decompositions.py

@@ -0,0 +1,32 @@
+# This file is part of QuTiP: Quantum Toolbox in Python.
+#
+#    Copyright (c) 2011 and later, Paul D. Nation and Robert J. Johansson.
+#    All rights reserved.
+#
+#    Redistribution and use in sourc e and binary forms, with or without
+#    modification, are permitted provided that the following conditions are
+#    met:
+#
+#    1. Redistributions of source code must retain the above copyright notice,
+#       this list of conditions and the following disclaimer.
+#
+#    2. Redistributions in binary form must reproduce the above copyright
+#       notice, this list of conditions and the following disclaimer in the
+#       documentation and/or other materials provided with the distribution.
+#
+#    3. Neither the name of the QuTiP: Quantum Toolbox in Python nor the names
+#       of its contributors may be used to endorse or promote products derived
+#       from this software without specific prior written permission.
+#
+#    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+#    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+#    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+#    PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+#    HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+#    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+#    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+#    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+#    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+#    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+#    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+###############################################################################