Merge pull request #457 from sandialabs/bugfix-ecr-qasm

Add ECR support to QASM translation

pygsti/circuits/circuit.py

@@ -4250,6 +4250,9 @@ def convert_to_openqasm(self, num_qubits=None,
             # Include a delay instruction
             openqasm += 'opaque delay(t) q;\n\n'
 
+        # Add a template for ECR commands that we will replace/remove later
+        openqasm += "ECRPLACEHOLDER"
+
         openqasm += 'qreg q[{0}];\n'.format(str(num_qubits))
         # openqasm += 'creg cr[{0}];\n'.format(str(num_qubits))
         openqasm += 'creg cr[{0}];\n'.format(str(num_qubits + num_IMs))
@@ -4349,6 +4352,13 @@ def convert_to_openqasm(self, num_qubits=None,
             # openqasm += "measure q[{0}] -> cr[{1}];\n".format(str(qubit_conversion[q]), str(qubit_conversion[q]))
             openqasm += "measure q[{0}] -> cr[{1}];\n".format(str(qubit_conversion[q]),
                                                               str(num_IMs_used + qubit_conversion[q]))
+
+        # Replace ECR placeholder
+        ecr_replace_str = ""
+        if 'ecr' in openqasm:
+            ecr_replace_str = "gate rzx(param0) q0,q1 { h q1; cx q0,q1; rz(param0) q1; cx q0,q1; h q1; }\n"
+            ecr_replace_str += "gate ecr q0,q1 { rzx(pi/4) q0,q1; x q0; rzx(-pi/4) q0,q1; }\n\n"
+        openqasm = openqasm.replace("ECRPLACEHOLDER", ecr_replace_str)
 
         return openqasm
 

pygsti/tools/internalgates.py

@@ -729,6 +729,8 @@ def standard_gatenames_openqasm_conversions(version='u3'):
         std_gatenames_to_qasm['Gc22'] = ['u3(1.570796326794897, 1.570796326794897, 1.570796326794897)']  # [1,1,1]*pi/2
         std_gatenames_to_qasm['Gc23'] = ['u3(0, 0, 4.71238898038469)']  # [0, 0, 3] * pi/2 (this is Gzmpi2 / Gpdag)
 
+        std_gatenames_to_qasm['Gecr'] = ['ecr']
+
         std_gatenames_to_argmap = {}
         std_gatenames_to_argmap['Gzr'] = lambda gatearg: ['u3(0, 0, ' + str(gatearg[0]) + ')']
         std_gatenames_to_argmap['Gczr'] = lambda gatearg: ['crz(' + str(gatearg[0]) + ')']
@@ -782,6 +784,8 @@ def standard_gatenames_openqasm_conversions(version='u3'):
         std_gatenames_to_qasm['Gt'] = ['rz(0.7853981633974485)']
         std_gatenames_to_qasm['Gtdag'] = ['rz(5.497787143782138)']
 
+        std_gatenames_to_qasm['Gecr'] = ['ecr']
+
         std_gatenames_to_argmap = {}
         std_gatenames_to_argmap['Gzr'] = lambda gatearg: ['rz(' + str(gatearg[0]) + ')']
         std_gatenames_to_argmap['Gczr'] = lambda gatearg: ['crz(' + str(gatearg[0]) + ')']