#107 create avg_photon_num for full circuit state

c2qa/util.py

@@ -713,17 +713,35 @@ def fockmap(matrix, fock_input, fock_output, amplitude=[]):
         raise ValueError("Please ensure that your args are correctly defined.")
 
 
-def avg_photon_num(state, decimals: int=2):
-    """Returns average photon number of state using the number operator.
+def avg_photon_num(circuit: CVCircuit, state, decimals: int=2):
+    """Returns average photon number of state for each qumode within the circuit using the number operator.
 
     Args:
-        state (Statevector or DensityMatrix): State to operate on
+        circuit (CVCircuit): Circuit definine qumodes present in given state
+        state (Statevector or DensityMatrix): full state to operate on
         decimals: Determines precision of calculation
 
     Returns:
         float: Average photon number to specified precision
     """
+    averages = []
+    for qumode_qubits in circuit.qumode_qubits_indices_grouped:
+        traced_state = qiskit.quantum_info.partial_trace(state, qumode_qubits)
+        averages.append(qumode_avg_photon_num(traced_state, decimals))
 
+    return averages
+
+def qumode_avg_photon_num(state, decimals: int=2):
+    """Returns average photon number of an individual qumode's state using the number operator.
+
+    Args:
+        state (Statevector or DensityMatrix): State to operate on for an individual qumode
+        decimals: Determines precision of calculation
+
+    Returns:
+        float: Average photon number to specified precision
+    """
+
     # Generate number operator based on dimension of state
     dim = state.dim
     N = np.diag(range(dim))
@@ -742,4 +760,4 @@ def avg_photon_num(state, decimals: int=2):
     if round(avg_photon.imag, 6) != 0:
         raise Exception("Magnitude of average photon is complex, check inputs. Imaginary portion = {}".format(avg_photon.imag))
 
-    return np.round(avg_photon.real, decimals)
+    return np.round(avg_photon.real, decimals)

tests/test_util.py

@@ -266,7 +266,7 @@ def test_counts_to_fockcounts(capsys):
             assert(fock_counts == c2qa.util.cv_fockcounts(result.get_counts(), regs))
 
 
-def test_avg_photon_num(capsys):
+def test_qumode_avg_photon_num(capsys):
     with capsys.disabled():
         for _ in range(5): # Repeat test 5 times
             # Decimals
@@ -284,6 +284,6 @@ def test_avg_photon_num(capsys):
             avg_num = numpy.mean(numpy.dot(element_norm, numpy.array(range(dim))))/norm
 
             # Average photon number of statevector, density matrix, and random vector must all match
-            assert(c2qa.util.avg_photon_num(Statevector(vector), decimals) == c2qa.util.avg_photon_num(DensityMatrix(vector), decimals) == round(avg_num.real, decimals))
+            assert(c2qa.util.qumode_avg_photon_num(Statevector(vector), decimals) == c2qa.util.qumode_avg_photon_num(DensityMatrix(vector), decimals) == round(avg_num.real, decimals))
 
 

tutorials/bosonic-kitten-code/bosonic-kitten-code.ipynb

@@ -723,7 +723,7 @@
     "            cycle_list_probB.append([fid0, fiderr]) # w/ respect to specific states\n",
     "            \n",
     "            # Avg photon num\n",
-    "            #cycle_list_avg_photon.append(c2qa.util.avg_photon_num(matrix))\n",
+    "            #cycle_list_avg_photon.append(c2qa.util.qumode_avg_photon_num(matrix))\n",
     "\n",
     "        expectation_list.append(cycle_list_expectation)\n",
     "        exp_prob_list.append(cycle_list_exp_prob)\n",
@@ -2413,7 +2413,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.6"
+   "version": "3.11.1"
   }
  },
  "nbformat": 4,