# -*- coding: utf-8 -*- """ Optical pumping in 171YbOH -------------------------- Beyond diatomic molecules, recent years have seen major advances in the direct laser cooling and control of polyatomic species. A particularly relevant case is ytterbium monohydroxide (YbOH), whose odd isotopologues :math:`^{173}\\text{YbOH}` and :math:`^{171}\\text{YbOH}` are of great interest as sensitive probes for nuclear properties and tests of fundamental symmetries. Motivated by these applications, optical cycling in these isotopologues has recently been demonstrated for the first time. In this tutorial, we will model the optical cycling process in 171YbOH to highlight the key mechanisms that enable photon scattering in such polyatomic systems. """ # %% # Import and function definition # ------------------------------ from MoleCool import System, np, plt, save_object, open_object from MoleCool.spectra import multiindex_filter as filt from MoleCool.tools import gaussian import os.path def fun(system): t_cut = (system.lasers[-1].r_k[0]-3e-3)/system.v0[0] Nscatt = np.where(system.t>t_cut, system.Nscattrate[0], 0) Nscatt = np.interp(system.t_plt, system.t, Nscatt, right=0, left=0) return {'Nscatt':Nscatt} # %% # Level system initialization # --------------------------- if __name__ == '__main__': if not os.path.isfile("YbOH.pkl"): system = System(load_constants='171YbOH') system.levels.add_electronicstate('X','gs') system.levels.add_electronicstate('A','exs') system.levels.X.load_states(v=[0,1]) system.levels.A.load_states(v=[0]) system.levels.X.add_lossstate() # %% # Since we added a loss state which includes a vibrational state with the # vibrational quantum number which is by 1 greater than the maximum ``v``. # So, we deliberately must add another vibrational level in the pandas.DataFrame # ``system.levels.vibrbranch`` and ``system.levels.wavelengths`` for the loading # to be working. system.levels.vibrbranch.loc[('X',2),:] = 1 - system.levels.vibrbranch.sum() system.levels.wavelengths.loc[('X',2),:] = 700 # system.levels.print_properties() # %% # Transition spectrum # ------------------- # Let's have a look how the transition spectrum looks like: system.levels.plot_transition_spectrum( wavelengths = [float(system.levels.wavelengths.loc[('X',0)])*1e-9], subplot_sep = 2000, N_points = 1000, relative_to_wavelengths = True, # QuNrs = [['G','F'],['F']], # formatting for legend legend = False, ) # %% # .. image:: /_figures/core/YbOH_fig1.svg # :alt: Demo plot # :align: center # %% # Initial population and velocity # ------------------------------- system.levels.X.set_init_pops({'v=0':1/1.11,'v=1':0.11/1.11}) # system.levels.X.set_init_pops({'v=0,G=1,F1=1':1/1.11*6/24, # 'v=1,G=1,F1=1':0.11/1.11*6/24}) system.set_v0( # v0 = [170,0,0], v0 = np.linspace(80,400,100), direction = 'x', ) system.t_plt = np.linspace(0,0.2e-3,800) # %% # Calculation routine # ------------------- colors = dict(ro='C0', rc='C1', nopump='k') D_exp = dict(ro=0.48+0.17*np.array([+1,-1]), rc=7.4+1.3*np.array([+1,-1])) labels = dict(rc='rc pumping',ro='ro pumping',nopump='no pumping') x_pump = 5e-3 x_probe = 17e-3 P_pump = 10e-3 for P, F1_pump, label in zip([1e-8,P_pump,P_pump], [0,0,1], ['nopump','rc','ro']): del system.lasers[:] #pump system.lasers.add( lamb = system.levels.wavelengths.loc[('X',0),('A',0)]*1e-9, P = P, FWHM = 5e-3, k = [0,0,1], r_k = [x_pump,0,0], freq_shift = 1e6*(filt(system.levels.A.freq, dict(F1=F1_pump)).mean() - filt(system.levels.X.freq, dict(G=1,F1=1)).mean()), ) #probe system.lasers.add( lamb = system.levels.wavelengths.loc[('X',1),('A',0)]*1e-9, P = 0.1e-3, w = 1e-3, k = [0,0,1], r_k = [x_probe,0,0], freq_shift = 1e6*(filt(system.levels.A.freq, dict(F1=0)).mean() - filt(system.levels.X.freq, dict(G=1,F1=1)).mean()), ) # system.lasers.plot_I_2D(ax='z',limits=([0,17e-3],[-7e-3,7e-3])) # # system.lasers[-1].I # system.draw_levels(QuNrs_sep=['v']) #%% system.multiprocessing.update({ 'processes' : 2, # 'maxtasksperchild' : None, # 'show_progressbar' : True, 'savetofile' : False }) system.calc_rateeqs( # t_int=10e-6, t_int = x_probe/80, magn_remixing = True, magn_strength = 7, trajectory = True, position_dep = True, max_step = 1e-6, verbose = False, return_fun = fun, ) save_object(system, 'YbOH_'+label) # %% # Loading data and plotting # ------------------------- plt.figure() unit_x = 1e6 lifs_arr = dict() for label in ['nopump','ro','rc']: system = open_object('YbOH_'+label) LIFs_i = system.results.vals['Nscatt']*gaussian(system.v0[:,0],a=1,x0=180,std=40)[:,None]*1e-3 LIFs = LIFs_i.sum(axis=0) if label == 'rc': plt.plot(system.t_plt*unit_x, 2.2 * LIFs_i[::(LIFs_i.shape[0]//25),:].T, c='grey', alpha=0.3) # for i, ls in enumerate(['-','--']): plt.plot(system.t_plt*unit_x, LIFs, ls=dict(rc='-',ro='-',nopump='--')[label], label=labels[label], c=colors[label], ) lifs_arr[label] = LIFs if label in ['ro','rc']: lif_pump = lifs_arr[label].max() lif_nopump = lifs_arr['nopump'].max() D = (lif_pump - lif_nopump)/lif_nopump lif_pump_exp = (D_exp[label]+1)*lif_nopump plt.axhspan(*lif_pump_exp, alpha=0.25, color=colors[label]) print(f'Max ({label})',lif_pump/lif_nopump) print(f'D ({label})',D) plt.xlim(left=0.9*x_probe/system.v0.max()*unit_x) plt.xlabel('Time (us)') plt.ylabel('Photon scattering rate (kHz)') plt.legend() # %% # .. image:: /_figures/core/YbOH_fig2.svg # :alt: Demo plot # :align: center # sphinx_gallery_thumbnail_path = '_figures/core/YbOH_fig2.svg'