Direct observation of bimolecular reactions of ultracold KRb molecules

Abstract

Femtochemistry techniques have been instrumental in accessing the short time scales necessary to probe transient intermediates in chemical reactions. In this study, we took the contrasting approach of prolonging the lifetime of an intermediate by preparing reactant molecules in their lowest rovibronic quantum state at ultralow temperatures, thereby markedly reducing the number of exit channels accessible upon their mutual collision. Using ionization spectroscopy and velocity-map imaging of a trapped gas of potassium-rubidium (KRb) molecules at a temperature of 500 nanokelvin, we directly observed reactants, intermediates, and products of the reaction 40K87Rb + 40K87Rb → K2Rb2* → K2 + Rb2. Beyond observation of a long-lived, energy-rich intermediate complex, this technique opens the door to further studies of quantum-state–resolved reaction dynamics in the ultracold regime.

Robust entangling gate for polar molecules using magnetic and microwave fields

“…The field of ultracold molecules has seen enormous progress in the past few years, with landmark achievements such as the production of the first quantum-degenerate molecular Fermi gas [1], low-entropy molecular samples in optical lattices [2,3], trapping of single molecules in optical tweezers [4][5][6], and magneto-optical trapping and sub-Doppler cooling of molecules [7][8][9][10][11]. These results bring significantly closer a broad range of applications of ultracold molecules, from state-controlled chemistry [12][13][14][15][16][17] and novel tests of fundamental laws of nature [18][19][20][21] to new architectures for quantum computation [22][23][24][25][26], quantum simulation [27][28][29][30][31][32], and quantum sensing [33,34].…”

Controlling the ac Stark effect of RbCs with dc electric and magnetic fields

“…Experimental interest in ultracold molecules is growing rapidly, spurred on by applications spanning precision measurement [1][2][3][4][5][6][7][8][9][10][11], state-resolved chemistry [12][13][14][15][16][17], dipolar quantum matter [18][19][20][21][22], quantum simulation [23][24][25][26][27][28], and quantum-information processing [29][30][31][32][33][34][35]. Two prominent methods have emerged for producing molecular gases in the ultracold regime.…”

Loss of Ultracold Rb87Cs133 Molecules via Optical Excitation of Long-Lived Two-Body Collision Complexes

“…Here, the lifetime is limited by reactive two-body collisions of the form 2KRb → K 2 + Rb 2 . The reactive nature of KRb collisions has been recently confirmed through direct detection of the intermediate complexes and reaction products [41]. Thankfully not all bialkali molecules have energetically allowed two-body reactive collisions [42], offering hope that stable molecular gases may be produced.…”