JaunatisBlue
c4a82614b3
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48 lines
1.5 KiB
Python
48 lines
1.5 KiB
Python
import math
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import random
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import pytest
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from qibo import Circuit, construct_backend, gates, hamiltonians
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from qibo.symbols import X, Z
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def build_observable(nqubits):
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"""Helper function to construct a target observable."""
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hamiltonian_form = 0
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for i in range(nqubits):
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hamiltonian_form += 0.5 * X(i % nqubits) * Z((i + 1) % nqubits)
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hamiltonian = hamiltonians.SymbolicHamiltonian(form=hamiltonian_form)
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return hamiltonian, hamiltonian_form
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def build_circuit(nqubits, nlayers, seed=42):
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"""Helper function to construct a layered quantum circuit."""
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random.seed(seed)
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circ = Circuit(nqubits)
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for _ in range(nlayers):
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for q in range(nqubits):
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circ.add(gates.RY(q=q, theta=random.uniform(-math.pi, math.pi)))
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circ.add(gates.RZ(q=q, theta=random.uniform(-math.pi, math.pi)))
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[circ.add(gates.CNOT(q % nqubits, (q + 1) % nqubits) for q in range(nqubits))]
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circ.add(gates.M(*range(nqubits)))
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return circ
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@pytest.mark.parametrize("nqubits", [2, 5, 10])
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def test_observable_expval(backend, nqubits):
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numpy_backend = construct_backend("numpy")
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ham, ham_form = build_observable(nqubits)
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circ = build_circuit(nqubits=nqubits, nlayers=1)
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exact_expval = numpy_backend.calculate_expectation_state(
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hamiltonian=ham,
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state=circ().state(),
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normalize=False,
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)
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tn_expval = backend.expectation(circuit=circ, observable=ham_form)
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assert math.isclose(exact_expval, tn_expval, abs_tol=1e-7)
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