Production of rovibronic-ground-state RbCs molecules via two-photon-cascade decay

Abstract

We report the production of ultracold RbCs molecules in the rovibronic ground state, i.e., X 'E +(i; = 0, 7 = 0), by short-range photoassociation to the 23n0 state followed by spontaneous emission. We use narrow-band depletion spectroscopy to probe the distribution of rotational levels formed in the X lL +(u = 0) state. We conclude, based on selection rules, that the primary decay route to X 'E +(i; = 0) is a two-step cascade decay that leads to as much as 33% branching into the 7 = 0 rotational level. The experimental simplicity of our scheme opens up the possibility of easier access to the study and manipulation of ultracold heteronuclear molecules in the rovibronic ground state.Tremendous efforts have been devoted to the produc tion of ultracold samples of heteronuclear molecules over recent years. Promising applications range from quantum computation [1] to ultracold chemistry [2], quantum dipolar physics [3,4], and tests of fundamental physics [3,5]. However, access to dense samples of ground-state ultracold polar molecules has so far been limited to a few outstanding ex periments [6,7], which utilized magnetoassociation followed by transfer to the ground state by stimulated Raman adiabatic passage [8]. A less experimentally complex path toward a sample of ultracold molecules is short-range photoassociation (PA) [9]. Recent discoveries of short-range PA transitions in RbCs [10], NaCs [11], KRb [12], and Rb2 [13,14] proved the general applicability of the process to alkali-metal dimers. Short-range PA is a convenient means to produce ultracold molecules due to its simplicity and possible continuous operation, although PA leads to an unavoidable distribution of molecules over many vibrational, rotational, and hyperfine levels. In fact, to date, short-range PA has predominantly produced molecules in rotationally excited states: ~2% of molecules were observed in J = 0 for LiCs [9] and no 7 = 0 molecules were observed for NaCs [11], However, it has been argued that simple measures may allow removal of excited states following PA [15,16]. Also, it is possible to increase the yield of molecules in the ground state by using vibrational cooling [17] and rotational cooling [18].In this paper, we perform high-resolution depletion spec troscopy [9,19] to measure the distribution of rotational levels in RbCs molecules produced via short-range PA to the 2 3n0 electronic state. We confirm that a large fraction of these X(v = 0) molecules, up to 33%, are in their rovibronic ground states, i.e., X(v = 0,7 = 0). We also show that the formation pathway to X(v = 0) is a two-photon-cascade decay as shown in Fig. 1 (a), as opposed to a direct one-photon decay as was previously supposed [16].Most of our experimental setup has been previously described [16]. 85Rb and Cs atoms are laser cooled and trapped in a dual-species forced dark spontaneous force optical trap (dark SPOT) [21] loaded by alkali-metal dispensers. The overlap of the two atom clouds is optimized 'Present address; PACS number(s): 37.10.M n, 3 3 .1 5 .-e , 3 3 .8 0 ....

Molecular beam study of thea3Σ+state of NaK up to the dissociation limit

“…Photoassociation connected w ith spontaneous decay is much sim pler to apply, but needs careful selection o f the excitation for an efficient decay to the desired quantum state. It was dem onstrated for LiCs [8], RbCs [9][10][11], N aCs [12], and KRb [13], For both procedures a fairly deep know ledge o f the electronic states Corresponding author: Tiemann@iqo.uni-hannover.de is advantageous, m ostly obtained by m olecular spectroscopy w ith guidance o f ab initio calculations.…”

Dynamic dipole polarizabilities of heteronuclear alkali dimers: optical response, trapping and control of ultracold molecules

“…Exposing these pairs to a suitable ramp of magnetic field allowed to stabilize these resonances as weaklyarXiv:1707.02168v1 [quant-ph] 7 Jul 2017 bound molecules, which can then be transformed into molecules lying in the lowest energy level of their ground state. Over the past few years, this has been achieved through the Stimulated Raman Adiabatic Passage (STI-RAP) optical technique [25] for several homonuclear and heteronuclear species : Cs 2 [26], Rb 2 [27], KRb [28,29], RbCs [30][31][32], NaK [33], NaRb [34].…”

Photoionization spectrum of 85RbCs molecules produced by short range photoassociation

“…Another elegant but much more complex coherent control techniques, two-photon stimulated Raman adiabatic passage (STIRAP) process, recently has been used to produce the rovibrational ground state 87 RbCs molecules starting from Feshbach resonance molecules [22,20]. Especially, short range photoassociated RbCs molecules in ð2Þ 3 Π 0 7 excited state attract many researchers' attention for its simplify and continuous formation scheme to singlet Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jqsrt ground state molecules directly from ultracold atoms [23][24][25][26][27][28], just like the cases of LiCs [29], NaCs [30], KRb [31]. It needs to be declared that ð2Þ 3 Π 0 7 state is a co-written label of ð2Þ 3 Π 0 þ and ð2Þ 3 Π 0 À states.…”