add test lifetime

Author: johannes-moegerle

tests/test_lifetimes.py

@@ -0,0 +1,58 @@
+import numpy as np
+import pytest
+from rydstate import RydbergStateSQDTAlkali
+from rydstate.angular.angular_ket import AngularKetLS
+from rydstate.rydberg.rydberg_sqdt import RydbergStateSQDT
+from rydstate.species.sqdt.species_object_sqdt import SpeciesObjectSQDT
+
+
+# Reference values from NIST Atomic Spectra Database (ASD), Einstein A coefficients:
+#   H 2p -> 1s: A = 6.2648e8 s^-1
+#   H 3p -> all lower: A_tot = 1.8971e8 s^-1  (A(3p->1s)=1.6725e8, A(3p->2s)=2.245e7)
+#   H 3d -> 2p: A = 6.4651e7 s^-1
+# Source: https://physics.nist.gov/PhysRefData/ASD/lines_form.html
+@pytest.mark.parametrize(
+    ("n", "l", "j", "expected_gamma"),
+    [
+        (2, 1, 1.5, 6.2648e8),
+        (3, 1, 1.5, 1.8971e8),
+        (3, 2, 2.5, 6.4651e7),
+    ],
+)
+def test_hydrogen_textbook_lifetimes(n: int, l: int, j: float, expected_gamma: float) -> None:
+    """Test that calculated H lifetimes match NIST textbook values within 5%."""
+    state = RydbergStateSQDTAlkali("H_textbook", n=n, l=l, j=j, m=0.5)
+    tau = state.get_lifetime(unit="s")
+    np.testing.assert_allclose(tau, 1 / expected_gamma, rtol=0.05)
+
+
+def test_bbr_shortens_lifetime() -> None:
+    """Test that black body radiation at 300 K shortens the lifetime relative to T=0."""
+    state = RydbergStateSQDTAlkali("Rb", n=30, l=0, j=0.5, m=0.5)
+    tau_0 = state.get_lifetime(unit="mus")
+    tau_300 = state.get_lifetime(300, temperature_unit="K", unit="mus")
+    assert tau_300 < tau_0
+
+
+@pytest.mark.parametrize("species_name", SpeciesObjectSQDT.get_available_species())
+def test_lifetime_n_scaling(species_name: str) -> None:
+    """Test that Rydberg state lifetimes scale as nu^3 (effective quantum number)."""
+    if species_name in ["Sr87", "Yb171", "Yb173"]:
+        pytest.skip("No quantum defect data available")
+    if species_name == "Yb174":
+        pytest.skip("Quantum defects not correct for low n states")
+
+    n1, n2 = 30, 60
+    species = SpeciesObjectSQDT.from_name(species_name)
+    s_tot = (species.number_valence_electrons / 2) % 1
+    f = abs(s_tot - species.i_c_number)
+    angular = AngularKetLS(l_r=0, s_tot=s_tot, f_tot=f, m=f, species=species)
+
+    state1 = RydbergStateSQDT.from_angular_ket(species, angular, n=n1)
+    state2 = RydbergStateSQDT.from_angular_ket(species, angular, n=n2)
+    tau1 = state1.get_lifetime(unit="mus")
+    tau2 = state2.get_lifetime(unit="mus")
+    nu1 = state1.nu
+    nu2 = state2.nu
+    expected_ratio = (nu2 / nu1) ** 3
+    np.testing.assert_allclose(tau2 / tau1, expected_ratio, rtol=0.05)