Adding a random gate

qiskit/converters/ast_to_dag.py

@@ -54,6 +54,7 @@
 from qiskit.extensions.standard.crz import CrzGate
 from qiskit.extensions.standard.cu3 import Cu3Gate
 from qiskit.extensions.standard.rzz import RZZGate
+from qiskit.extensions.standard.i import IGate
 
 
 def ast_to_dag(ast):
@@ -81,6 +82,7 @@ class AstInterpreter:
                           "u1": U1Gate,
                           "u2": U2Gate,
                           "u3": U3Gate,
+                          "i": IGate,
                           "x": XGate,
                           "y": YGate,
                           "z": ZGate,
@@ -176,7 +178,8 @@ def _process_custom_unitary(self, node):
                 self.bit_stack.append({gbits[j]: bits[j][element[j]]
                                        for j in range(len(gbits))})
                 self._create_dag_op(name,
-                                    [self.arg_stack[-1][s].sym() for s in gargs],
+                                    [self.arg_stack[-1][s].sym()
+                                     for s in gargs],
                                     [self.bit_stack[-1][s] for s in gbits])
                 self.arg_stack.pop()
                 self.bit_stack.pop()
@@ -196,7 +199,8 @@ def _process_gate(self, node, opaque=False):
         de_gate["n_args"] = node.n_args()
         de_gate["n_bits"] = node.n_bits()
         if node.n_args() > 0:
-            de_gate["args"] = [element.name for element in node.arguments.children]
+            de_gate["args"] = [
+                element.name for element in node.arguments.children]
         else:
             de_gate["args"] = []
         de_gate["bits"] = [c.name for c in node.bitlist.children]
@@ -217,11 +221,14 @@ def _process_cnot(self, node):
         maxidx = max([len(id0), len(id1)])
         for idx in range(maxidx):
             if len(id0) > 1 and len(id1) > 1:
-                self.dag.apply_operation_back(CXBase(), [id0[idx], id1[idx]], [], self.condition)
+                self.dag.apply_operation_back(
+                    CXBase(), [id0[idx], id1[idx]], [], self.condition)
             elif len(id0) > 1:
-                self.dag.apply_operation_back(CXBase(), [id0[idx], id1[0]], [], self.condition)
+                self.dag.apply_operation_back(
+                    CXBase(), [id0[idx], id1[0]], [], self.condition)
             else:
-                self.dag.apply_operation_back(CXBase(), [id0[0], id1[idx]], [], self.condition)
+                self.dag.apply_operation_back(
+                    CXBase(), [id0[0], id1[idx]], [], self.condition)
 
     def _process_measure(self, node):
         """Process a measurement node."""
@@ -231,7 +238,8 @@ def _process_measure(self, node):
             raise QiskitError("internal error: reg size mismatch",
                               "line=%s" % node.line, "file=%s" % node.file)
         for idx, idy in zip(id0, id1):
-            self.dag.apply_operation_back(Measure(), [idx], [idy], self.condition)
+            self.dag.apply_operation_back(
+                Measure(), [idx], [idy], self.condition)
 
     def _process_if(self, node):
         """Process an if node."""
@@ -291,7 +299,8 @@ def _process_node(self, node):
             args = self._process_node(node.children[0])
             qid = self._process_bit_id(node.children[1])
             for element in qid:
-                self.dag.apply_operation_back(UBase(*args, element), self.condition)
+                self.dag.apply_operation_back(
+                    UBase(*args, element), self.condition)
 
         elif node.type == "cnot":
             self._process_cnot(node)
@@ -322,7 +331,8 @@ def _process_node(self, node):
         elif node.type == "reset":
             id0 = self._process_bit_id(node.children[0])
             for i, _ in enumerate(id0):
-                self.dag.apply_operation_back(Reset(), [id0[i]], [], self.condition)
+                self.dag.apply_operation_back(
+                    Reset(), [id0[i]], [], self.condition)
 
         elif node.type == "if":
             self._process_if(node)
@@ -357,10 +367,12 @@ def _create_dag_op(self, name, params, qargs):
         elif name in self.gates:
             if self.gates[name]['opaque']:
                 # call an opaque gate
-                op = Gate(name=name, num_qubits=self.gates[name]['n_bits'], params=params)
+                op = Gate(
+                    name=name, num_qubits=self.gates[name]['n_bits'], params=params)
             else:
                 # call a custom gate
-                raise QiskitError('Custom non-opaque gates are not supported by as_to_dag module')
+                raise QiskitError(
+                    'Custom non-opaque gates are not supported by as_to_dag module')
         else:
             raise QiskitError("unknown operation for ast node name %s" % name)
 

qiskit/extensions/standard/__init__.py

@@ -34,6 +34,7 @@
 from .u3 import U3Gate
 from .ubase import UBase
 from .x import XGate
+from .i import IGate
 from .y import YGate
 from .z import ZGate
 from .rx import RXGate

qiskit/extensions/standard/ch.py

@@ -22,6 +22,7 @@
 from qiskit.circuit import QuantumCircuit
 from qiskit.circuit import QuantumRegister
 from qiskit.extensions.standard.x import XGate
+from qiskit.extensions.standard.i import IGate
 from qiskit.extensions.standard.h import HGate
 from qiskit.extensions.standard.cx import CnotGate
 from qiskit.extensions.standard.t import TGate

qiskit/extensions/standard/i.py

@@ -0,0 +1,69 @@
+# -*- coding: utf-8 -*-
+
+# This code is part of Qiskit.
+#
+# (C) Copyright IBM 2017.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+"""
+Pauli X (bit-flip) gate.
+
+Identity operator
+"""
+
+import numpy
+
+from qiskit.circuit import CompositeGate
+from qiskit.circuit import Gate
+from qiskit.circuit import QuantumCircuit
+from qiskit.circuit import QuantumRegister
+from qiskit.qasm import pi
+from qiskit.extensions.standard.u3 import U3Gate
+
+
+class IGate(Gate):
+    """Pauli X (bit-flip) gate."""
+
+    def __init__(self, label=None):
+        """Create new X gate."""
+        super().__init__("i", 1, [], label=label)
+
+    def _define(self):
+        """
+        gate x a {
+        u3(pi,0,pi) a;
+        }
+        """
+        definition = []
+        q = QuantumRegister(1, "q")
+        rule = [
+            (U3Gate(pi, 0, pi), [q[0]], [])
+        ]
+        for inst in rule:
+            definition.append(inst)
+        self.definition = definition
+
+    def inverse(self):
+        """Invert this gate."""
+        return IGate()  # self-inverse
+
+    def to_matrix(self):
+        """Return a Numpy.array for the X gate."""
+        return numpy.array([[1, 0],
+                            [0, i]], dtype=complex)
+
+
+def i(self, q):
+    """Apply X to q."""
+    return self.append(IGate(), [q], [])
+
+
+QuantumCircuit.i = i
+CompositeGate.i = i

qiskit/quantum_info/operators/pauli.py

@@ -310,8 +310,8 @@ def to_operator(self):
     def to_instruction(self):
         """Convert to Pauli circuit instruction."""
         from qiskit.circuit import QuantumCircuit, QuantumRegister
-        from qiskit.extensions.standard import IdGate, XGate, YGate, ZGate
-        gates = {'I': IdGate(), 'X': XGate(), 'Y': YGate(), 'Z': ZGate()}
+        from qiskit.extensions.standard import IdGate, XGate, YGate, ZGate, IGate
+        gates = {'I': IdGate(), 'X': XGate(), 'Y': YGate(), 'Z': ZGate() , 'i' : IGate()}
         label = self.to_label()
         n_qubits = self.numberofqubits
         qreg = QuantumRegister(n_qubits)

test/python/quantum_info/test_synthesis.py

@@ -22,7 +22,7 @@
 from qiskit.circuit import QuantumCircuit, QuantumRegister
 from qiskit.extensions import UnitaryGate
 from qiskit.extensions.standard import (HGate, IdGate, SdgGate, SGate, U3Gate,
-                                        XGate, YGate, ZGate)
+                                        XGate, YGate, ZGate, IGate)
 from qiskit.providers.basicaer import UnitarySimulatorPy
 from qiskit.quantum_info.operators import Operator, Pauli
 from qiskit.quantum_info.random import random_unitary
@@ -35,7 +35,7 @@
 
 def make_oneq_cliffords():
     """Make as list of 1q Cliffords"""
-    ixyz_list = [g().to_matrix() for g in (IdGate, XGate, YGate, ZGate)]
+    ixyz_list = [g().to_matrix() for g in (IdGate, XGate, YGate, ZGate, IGate)]
     ih_list = [g().to_matrix() for g in (IdGate, HGate)]
     irs_list = [IdGate().to_matrix(),
                 SdgGate().to_matrix() @ HGate().to_matrix(),