Update parameters to accommodate with RZZ constraints

qiskit_ibm_runtime/transpiler/passes/basis/fold_rzz_angle.py

@@ -12,15 +12,19 @@
 
 """Pass to wrap Rzz gate angle in calibrated range of 0-pi/2."""
 
-from typing import Tuple
+from typing import Tuple, Union
 from math import pi
+from operator import mod
+from itertools import chain
 
 from qiskit.converters import dag_to_circuit, circuit_to_dag
-from qiskit.circuit.library.standard_gates import RZZGate, RZGate, XGate, GlobalPhaseGate
-from qiskit.circuit.parameterexpression import ParameterExpression
+from qiskit.circuit import CircuitInstruction, Parameter, ParameterExpression, CONTROL_FLOW_OP_NAMES
+from qiskit.circuit.library.standard_gates import RZZGate, RZGate, XGate, GlobalPhaseGate, RXGate
 from qiskit.circuit import Qubit, ControlFlowOp
 from qiskit.dagcircuit import DAGCircuit
 from qiskit.transpiler.basepasses import TransformationPass
+from qiskit.primitives.containers.estimator_pub import EstimatorPub, EstimatorPubLike
+from qiskit.primitives.containers.sampler_pub import SamplerPub, SamplerPubLike
 
 import numpy as np
 
@@ -244,3 +248,163 @@ def _quad4(angle: float, qubits: Tuple[Qubit, ...]) -> DAGCircuit:
             check=False,
         )
         return new_dag
+
+
+def convert_to_rzz_valid_pub(
+    program_id: str, pub: Union[SamplerPubLike, EstimatorPubLike]
+) -> Union[SamplerPub, EstimatorPub]:
+    """
+    Return a pub which is compatible with Rzz constraints.
+
+    Current limitations:
+    1. Does not support dynamic circuits.
+    2. Does not preserve global phase.
+    """
+    if program_id == "sampler":
+        pub = SamplerPub.coerce(pub)
+    elif program_id == "estimator":
+        pub = EstimatorPub.coerce(pub)
+    else:
+        raise ValueError(f"Unknown program id {program_id}")
+
+    val_data = pub.parameter_values.data
+    pub_params = np.array(list(chain.from_iterable(val_data)))
+    # first axis will be over flattened shape, second axis over circuit parameters
+    arr = pub.parameter_values.ravel().as_array()
+
+    new_circ = pub.circuit.copy_empty_like()
+    new_data = []
+    rzz_count = 0
+
+    for instruction in pub.circuit.data:
+        operation = instruction.operation
+
+        if operation.name in CONTROL_FLOW_OP_NAMES:
+            raise ValueError(
+                "The function convert_to_rzz_valid_pub currently does not support dynamic instructions."
+            )
+
+        if operation.name != "rzz" or not isinstance(
+            (param_exp := instruction.operation.params[0]), ParameterExpression
+        ):
+            new_data.append(instruction)
+            continue
+
+        param_names = [param.name for param in param_exp.parameters]
+
+        col_indices = [np.where(pub_params == param_name)[0][0] for param_name in param_names]
+        # col_indices is the indices of columns in the parameter value array that have to be checked
+
+        # project only to the parameters that have to be checked
+        projected_arr = arr[:, col_indices]
+        num_param_sets = len(projected_arr)
+
+        rz_angles = np.zeros(num_param_sets)
+        rx_angles = np.zeros(num_param_sets)
+        rzz_angles = np.zeros(num_param_sets)
+
+        for idx, row in enumerate(projected_arr):
+            angle = float(param_exp.bind(dict(zip(param_exp.parameters, row))))
+
+            if (angle + pi / 2) % (2 * pi) >= pi:
+                rz_angles[idx] = pi
+            else:
+                rz_angles[idx] = 0
+
+            if angle % pi >= pi / 2:
+                rx_angles[idx] = pi
+            else:
+                rx_angles[idx] = 0
+
+            rzz_angles[idx] = pi / 2 - abs(mod(angle, pi) - pi / 2)
+
+        rzz_count += 1
+        param_prefix = f"rzz_{rzz_count}_"
+        qubits = instruction.qubits
+
+        is_rz = False
+        if any(not np.isclose(rz_angle, 0) for rz_angle in rz_angles):
+            is_rz = True
+            if all(np.isclose(rz_angle, pi) for rz_angle in rz_angles):
+                new_data.append(
+                    CircuitInstruction(
+                        RZGate(pi),
+                        (qubits[0],),
+                    )
+                )
+                new_data.append(
+                    CircuitInstruction(
+                        RZGate(pi),
+                        (qubits[1],),
+                    )
+                )
+            else:
+                param_rz = Parameter(f"{param_prefix}rz")
+                new_data.append(
+                    CircuitInstruction(
+                        RZGate(param_rz),
+                        (qubits[0],),
+                    )
+                )
+                new_data.append(
+                    CircuitInstruction(
+                        RZGate(param_rz),
+                        (qubits[1],),
+                    )
+                )
+                val_data[f"{param_prefix}rz"] = rz_angles
+
+        is_rx = False
+        is_x = False
+        if any(not np.isclose(rx_angle, 0) for rx_angle in rx_angles):
+            is_rx = True
+            if all(np.isclose(rx_angle, pi) for rx_angle in rx_angles):
+                is_x = True
+                new_data.append(
+                    CircuitInstruction(
+                        XGate(),
+                        (qubits[0],),
+                    )
+                )
+            else:
+                is_x = False
+                param_rx = Parameter(f"{param_prefix}rx")
+                new_data.append(
+                    CircuitInstruction(
+                        RXGate(param_rx),
+                        (qubits[0],),
+                    )
+                )
+                val_data[f"{param_prefix}rx"] = rx_angles
+
+        if is_rz or is_rx:
+            # param_exp * 0 to prevent an error complaining that the original parameters,
+            # still present in the parameter values, are missing from the circuit
+            param_rzz = param_exp * 0 + Parameter(f"{param_prefix}rzz")
+            new_data.append(CircuitInstruction(RZZGate(param_rzz), qubits))
+            val_data[f"{param_prefix}rzz"] = rzz_angles
+        else:
+            new_data.append(instruction)
+
+        if is_rx:
+            if is_x:
+                new_data.append(
+                    CircuitInstruction(
+                        XGate(),
+                        (qubits[0],),
+                    )
+                )
+            else:
+                new_data.append(
+                    CircuitInstruction(
+                        RXGate(param_rx),
+                        (qubits[0],),
+                    )
+                )
+
+    new_circ.data = new_data
+
+    if program_id == "sampler":
+        return SamplerPub.coerce((new_circ, val_data), pub.shots)
+    else:
+        return EstimatorPub.coerce((new_circ, pub.observables, val_data), pub.precision)

release-notes/unreleased/2126.other.rst

@@ -0,0 +1 @@
+A new function :func:`.convert_to_rzz_valid_pub`, to transform a PUB into equivalent PUB that is compatible with Rzz constraints. The function currently does not support dynamic circuits and does not preserve global phase.

test/unit/transpiler/passes/basis/test_fold_rzz_angle.py

@@ -13,20 +13,29 @@
 """Test folding Rzz angle into calibrated range."""
 
 from math import pi
-from ddt import ddt, named_data
+from itertools import chain
+import unittest
 import numpy as np
+from ddt import ddt, named_data, data, unpack
 
 from qiskit.circuit import QuantumCircuit
 from qiskit.circuit.parameter import Parameter
 from qiskit.transpiler.passmanager import PassManager
 from qiskit.transpiler.preset_passmanagers import generate_preset_pass_manager
-from qiskit.quantum_info import Operator
+from qiskit.quantum_info import Operator, SparsePauliOp
 
-from qiskit_ibm_runtime.transpiler.passes.basis import FoldRzzAngle
+from qiskit_ibm_runtime.transpiler.passes.basis.fold_rzz_angle import (
+    FoldRzzAngle,
+    convert_to_rzz_valid_pub,
+)
 from qiskit_ibm_runtime.fake_provider import FakeFractionalBackend
+from qiskit_ibm_runtime.utils.utils import is_valid_rzz_pub
 from .....ibm_test_case import IBMTestCase
 
 
+# pylint: disable=not-context-manager
+
+
 @ddt
 class TestFoldRzzAngle(IBMTestCase):
     """Test FoldRzzAngle pass"""
@@ -75,9 +84,9 @@ def test_controlflow(self):
         """Test non-ISA Rzz gates inside/outside a control flow branch."""
         qc = QuantumCircuit(2, 1)
         qc.rzz(-0.2, 0, 1)
-        with qc.if_test((0, 1)):  # pylint: disable=not-context-manager
+        with qc.if_test((0, 1)):
             qc.rzz(-0.1, 0, 1)
-            with qc.if_test((0, 1)):  # pylint: disable=not-context-manager
+            with qc.if_test((0, 1)):
                 qc.rzz(-0.3, 0, 1)
 
         pm = PassManager([FoldRzzAngle()])
@@ -87,11 +96,11 @@ def test_controlflow(self):
         expected.x(0)
         expected.rzz(0.2, 0, 1)
         expected.x(0)
-        with expected.if_test((0, 1)):  # pylint: disable=not-context-manager
+        with expected.if_test((0, 1)):
             expected.x(0)
             expected.rzz(0.1, 0, 1)
             expected.x(0)
-            with expected.if_test((0, 1)):  # pylint: disable=not-context-manager
+            with expected.if_test((0, 1)):
                 expected.x(0)
                 expected.rzz(0.3, 0, 1)
                 expected.x(0)
@@ -115,3 +124,70 @@ def test_fractional_plugin(self):
         self.assertEqual(isa_circ.data[0].operation.name, "global_phase")
         self.assertEqual(isa_circ.data[1].operation.name, "rzz")
         self.assertTrue(np.isclose(isa_circ.data[1].operation.params[0], 7 - 2 * pi))
+
+    @data(
+        [0.2, 0.1, 0.4, 0.3, 2],  # no modification in circuit
+        [0.2, 0.1, 0.3, 0.4, 4],  # rzz_2_rx with values 0 and pi
+        [0.1, 0.2, 0.3, 0.4, 3],  # x
+        [0.2, 0.1, 0.3, 2, 7],  # rzz_1_rx, rzz_1_rz, rzz_2_rz with values 0 and pi
+        [0.3, 2, 0.3, 2, 4],  # circuit changes but no new parameters
+    )
+    @unpack
+    def test_rzz_pub_conversion(self, p1_set1, p2_set1, p1_set2, p2_set2, expected_num_params):
+        """Test the function `convert_to_rzz_valid_circ_and_vals`"""
+        p1 = Parameter("p1")
+        p2 = Parameter("p2")
+
+        circ = QuantumCircuit(3)
+        circ.rzz(p1 + p2, 0, 1)
+        circ.rzz(0.3, 0, 1)
+        circ.x(0)
+        circ.rzz(p1 - p2, 2, 1)
+
+        param_vals = [(p1_set1, p2_set1), (p1_set2, p2_set2)]
+        isa_pub = convert_to_rzz_valid_pub("sampler", (circ, param_vals))
+
+        isa_param_vals = isa_pub.parameter_values.ravel().as_array()
+        num_isa_params = len(isa_param_vals[0])
+        self.assertEqual(num_isa_params, expected_num_params)
+
+        self.assertEqual(is_valid_rzz_pub(isa_pub), "")
+        for param_set_1, param_set_2 in zip(param_vals, isa_param_vals):
+            self.assertTrue(
+                Operator.from_circuit(circ.assign_parameters(param_set_1)).equiv(
+                    Operator.from_circuit(isa_pub.circuit.assign_parameters(param_set_2))
+                )
+            )
+
+    @unittest.skip("convert_to_rzz_valid_pub does not support dynamic circuits currently")
+    def test_rzz_pub_conversion_dynamic(self):
+        """Test the function `convert_to_rzz_valid_circ_and_vals` for dynamic circuits"""
+        p = Parameter("p")
+        observable = SparsePauliOp("ZZZ")
+
+        circ = QuantumCircuit(3, 1)
+        with circ.if_test((0, 1)):
+            circ.rzz(p, 1, 2)
+            circ.rzz(p, 1, 2)
+        circ.rzz(p, 0, 1)
+        with circ.if_test((0, 1)):
+            circ.rzz(p, 1, 0)
+            circ.rzz(p, 1, 0)
+        circ.rzz(p, 0, 1)
+
+        isa_pub = convert_to_rzz_valid_pub("estimator", (circ, observable, [1, -1]))
+        self.assertEqual(is_valid_rzz_pub(isa_pub), "")
+        self.assertEqual([observable], isa_pub.observables)
+
+        # TODO: test qubit indices
+        isa_pub_param_names = np.array(list(chain.from_iterable(isa_pub.parameter_values.data)))
+        self.assertEqual(len(isa_pub_param_names), 6)
+        for param_name in [
+            "rzz_block1_rx1",
+            "rzz_block1_rx2",
+            "rzz_rx1",
+            "rzz_block2_rx1",
+            "rzz_block2_rx2",
+            "rzz_rx2",
+        ]:
+            self.assertIn(param_name, isa_pub_param_names)