test_spinchain.py

# This file is part of QuTiP: Quantum Toolbox in Python.
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import numpy as np
from numpy.testing import assert_, run_module_suite
from qutip.qip.gates import gate_sequence_product
from qutip.qip.circuit import QubitCircuit
from qutip.qip.models.spinchain import LinearSpinChain, CircularSpinChain


class TestSpinChain:
    """
    A test class for the QuTiP functions for physical implementation of
    linear and circular spin chain models.
    """

    def test_linear_ISWAP(self):
        """
        Linear Spin Chain Setup: compare unitary matrix for ISWAP and
        propogator matrix of the implemented physical model.
        """
        N = 3

        qc1 = QubitCircuit(N)
        qc1.add_gate("ISWAP", targets=[0, 1])
        U_ideal = gate_sequence_product(qc1.propagators())

        p = LinearSpinChain(N, correct_global_phase=True)
        U_list = p.run(qc1)
        U_physical = gate_sequence_product(U_list)

        assert_((U_ideal - U_physical).norm() < 1e-12)

    def test_linear_SQRTISWAP(self):
        """
        Linear Spin Chain Setup: compare unitary matrix for SQRTISWAP and
        propogator matrix of the implemented physical model.
        """
        N = 3

        qc = QubitCircuit(N)
        qc.add_gate("SQRTISWAP", targets=[0, 1])
        U_ideal = gate_sequence_product(qc.propagators())

        p = LinearSpinChain(N, correct_global_phase=True)
        U_list = p.run(qc)
        U_physical = gate_sequence_product(U_list)

        assert_((U_ideal - U_physical).norm() < 1e-12)

    def test_linear_combination(self):
        """
        Linear Spin Chain Setup: compare unitary matrix for ISWAP, SQRTISWAP,
        RX and RY gates and the propogator matrix of the implemented physical
        model.
        """
        N = 3

        qc = QubitCircuit(N)
        qc.add_gate("ISWAP", targets=[0, 1])
        qc.add_gate("SQRTISWAP", targets=[0, 1])
        qc.add_gate("RZ", arg_value=np.pi/2, arg_label=r"\pi/2", targets=[1])
        qc.add_gate("RX", arg_value=np.pi/2, arg_label=r"\pi/2", targets=[0])
        U_ideal = gate_sequence_product(qc.propagators())

        p = LinearSpinChain(N, correct_global_phase=True)
        U_list = p.run(qc)
        U_physical = gate_sequence_product(U_list)

        assert_((U_ideal - U_physical).norm() < 1e-12)

    def test_circular_ISWAP(self):
        """
        Circular Spin Chain Setup: compare unitary matrix for ISWAP and
        propogator matrix of the implemented physical model.
        """
        N = 3

        qc = QubitCircuit(N)
        qc.add_gate("ISWAP", targets=[0, 1])
        U_ideal = gate_sequence_product(qc.propagators())

        p = CircularSpinChain(N, correct_global_phase=True)
        U_list = p.run(qc)
        U_physical = gate_sequence_product(U_list)

        assert_((U_ideal - U_physical).norm() < 1e-12)

    def test_circular_SQRTISWAP(self):
        """
        Circular Spin Chain Setup: compare unitary matrix for SQRTISWAP and
        propogator matrix of the implemented physical model.
        """
        N = 3

        qc = QubitCircuit(N)
        qc.add_gate("SQRTISWAP", targets=[0, 1])
        U_ideal = gate_sequence_product(qc.propagators())

        p = CircularSpinChain(N, correct_global_phase=True)
        U_list = p.run(qc)
        U_physical = gate_sequence_product(U_list)

        assert_((U_ideal - U_physical).norm() < 1e-12)

    def test_circular_combination(self):
        """
        Linear Spin Chain Setup: compare unitary matrix for ISWAP, SQRTISWAP,
        RX and RY gates and the propogator matrix of the implemented physical
        model.
        """
        N = 3

        qc = QubitCircuit(N)
        qc.add_gate("ISWAP", targets=[0, 1])
        qc.add_gate("SQRTISWAP", targets=[0, 1])
        qc.add_gate("RZ", arg_value=np.pi/2, arg_label=r"\pi/2", targets=[1])
        qc.add_gate("RX", arg_value=np.pi/2, arg_label=r"\pi/2", targets=[0])
        U_ideal = gate_sequence_product(qc.propagators())

        p = CircularSpinChain(N, correct_global_phase=True)
        U_list = p.run(qc)
        U_physical = gate_sequence_product(U_list)

        assert_((U_ideal - U_physical).norm() < 1e-12)


if __name__ == "__main__":
    run_module_suite()