def test_rho0(self):
muexp = MuonExperiment(['e', 'mu'])
rho0 = muexp.get_starting_state()
self.assertTrue(
np.all(
np.isclose(rho0.matrix,
[[0.25, 0.25, 0, 0], [0.25, 0.25, 0, 0],
[0, 0, 0.25, 0.25], [0, 0, 0.25, 0.25]])))
gmu = constants.MU_GAMMA
ge = constants.ELEC_GAMMA
T = 100
muexp.set_magnetic_field(2.0e-6 * cnst.k * T / (ge * cnst.h))
muexp.set_temperature(T)
muexp.set_muon_polarization('z')
rho0 = muexp.get_starting_state()
Z = np.exp([-1, 1])
Z /= np.sum(Z)
self.assertTrue(
np.all(np.isclose(np.diag(rho0.matrix), [Z[0], 0, Z[1], 0])))
def test_dissipation(self):
# Simple system
g = 1.0
muexp = MuonExperiment(['mu'])
muexp.set_dissipation_coupling(0, g)
times = np.linspace(0, 10)
results = muexp.run_experiment(times)
evol = results['e']
solx = np.real(0.5 * np.exp(-np.pi * g * times))
self.assertTrue(np.all(np.isclose(evol[:, 0], solx)))
# Check for temperature equilibrium
T = 0.1
muexp.set_magnetic_field(-1.0)
muexp.set_temperature(T)
beta = 1.0 / (cnst.k * T)
Z = np.exp(-cnst.h * constants.MU_GAMMA * 1e6 * beta)
# Just let it evolve, see the result at long times
Sz = muexp.spin_system.operator({0: 'z'})
rhoinf = muexp.run_experiment([20], Sz)['e']
self.assertAlmostEqual(rhoinf[0, 0], 0.5 * (1 - Z) / (1 + Z))
import cProfile
import numpy as np
from muspinsim.experiment import MuonExperiment
exp = MuonExperiment(['e', 'mu', 'H'])
exp.spin_system.add_hyperfine_term(1, np.diag([1,1,4])*100)
exp.spin_system.add_hyperfine_term(2, np.diag([1,1,4])*100/3)
exp.set_powder_average(100)
exp.set_magnetic_field(5.0)
exp.set_dissipation_coupling(0, 1.0)
exp.set_muon_polarization('z')
times = np.linspace(0, 1, 1000)
op = exp.spin_system.operator({1: 'z'})
cProfile.run('exp.run_experiment(times, [op], "i")', sort='cumulative')