Cavity-controlled formation of ultracold molecules

Abstract

Ultracold ground-state molecules can be formed from ultracold atoms via photoassociation followed by a spontaneous emission process. Typically, the molecular products are distributed over a range of final states. Here, we propose to use an optical cavity with high cooperativity to selectively enhance the population of a pre-determined final state by controlling the spontaneous emission. During this process, a photon will be emitted into the cavity mode. Detection of this photon heralds a single reaction. We discuss the efficiency and the dynamics of cavity-assisted molecule formation in the frame of realistic parameters that can be achieved in current ultracold-atom setups. In particular, we consider the production of Rb 2 molecules in the a 3 Σ u triplet ground state. Moreover, when working with more than two atoms in the cavity, collective enhancement effects in chemistry should be observable.

Collective Dissipative Molecule Formation in a Cavity

“…shows exemplary results for the time evolution of the molecular ground-state fraction N g /N as a function of N , with 1 ≤ N ≤ 10 5 . For N = 1 the figure shows that the presence of a cavity (here C ≈ 0.04) induces an enhancement of N ∞ g /N from ∼ 0.1 % (no cavity, dashed red line) to ∼ 4 %, due to increased state-selectivity [20]. Strikingly, with increasing N , we observe an enhancement towards N ∞ g /N → 1, at the cost of an increased transfer time.…”

“…3, parameters as in Ref. [13,20]) we are in the regime where the chirped pulse results in a higher yield. For example, choosing a vacuum Rabi frequency g/2π ≈ 50 MHz, a laser Rabi frequency Ω/2π = 200 kHz, and a cavity half linewidth κ/2π = 300 MHz, we obtain a ground state population of N g /N ≈ 98 % after 5 ms (T 1 2 ∼ 0.5 ms).…”

“…While more sophisticated methods such as photoassociation followed by pulsed population transfer [17] or re-pumping of vibrationally excited molecules [18,19] have been experimentally demonstrated, efficiencies of ground-state molecular formation are usually lower than those achieved with STIRAP and without rotational state selectivity. It has recently been proposed to overcome some of these limitations by coupling molecular transitions to a cavity mode [20] or a photonic waveguide [21]. Common to all these schemes is the use of formation processes based on single molecules.…”

Enantio-detection of cyclic three-level chiral molecules in a driven cavity

“…In what follows, we further assume that the quantized cavity field is resonantly coupled with the transition |2 Q ↔|1 Q , which means ∆ a = ∆ 21 . And we assume the total number of chiral molecules N = 10 8 [43,51], the decay rates of molecules Γ A /2π = Γ B /2π = 0.1 MHz [10,11], and the total cavity decay rate κ a /2π = 1 MHz [78,79]. Here, we take the weak coupling strength Ω 31 /2π = 8 kHz since such a weak coupling strength usually ensures the low-excitation limit of molecules.…”

Molecule-photon interactions in phononic environments

“…In these cases, the strong light-matter coupling leads to the formation of polaritonic hybrid states with both light and matter components. Experimental and theoretical works are currently exploring fascinating enhanced properties such as exciton and charge transport [64][65][66][67][68], superconductive behavior [69,70], and modified chemical reactivity [71][72][73][74][75]. There is also recent interest in the modification of nonadiabatic light-matter dynamics at so-called conical intersections leading to fast nonradiative decay of electronic excited states [76,77].…”