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We create ultracold NaCs (sodium cesium) molecules in the absolute rotational and vibrational ground state using a variety of methods. The molecules are created via photoassociation from two overlapped magneto-optical traps (MOTs), and are detected using a photoionization process.
Our deeply bound, absolute ground state NaCs molecules have been trapped using electrostatic fields created by the Thin WIre electroStatic Trap (TWIST). This configuration takes advantage of the 4.6 Debye electric dipole moment of NaCs, which is one of the largest for bi-alkali molecules. The TWIST enabled our molecular sample to be isolated from the sodium and cesium atomic clouds. For the first time, any atomic signal detected during photoionization had to be from photofragmented molecules.
The TWIST also provided an environment to study atom-molecule collisions, which become significant when studying sypmathetic cooling of the molecular sample. We have demonstrated efficient cooling of the rotational degree of freedom of ultracold NaCs molecules through narrow line optical pumping. Molecules in v''=0, N''=2 and 4 are excited to the lowest vibrational level of the A-singlet-Σ+ − b-triplet-Π complex from which they decay to v''=0, N''=0. We achieve cooling of both rotational and vibrational degrees of freedom by applying this technique in conjunction with broadband optical pumping. This technique also allows transfer of population between any of the lowest vibrational states (v''=0-2) at kHz rates.
Our other main effort is spectroscopy. We have taken over 60 nm worth of photoionization spectra to determine vibrational distribution in the ground state. We have also performed depletion spectrosocpy to determine rotational structure within a given vibrational state.
Selected publications:
'Lumino-Refrigeration: Deep Cooling Polar Molecules by Optical Pumping.'
Optics in 2012, Optics and Photonics News, December 2012 [pdf]
'Luminorefrigeration: vibrational cooling of NaCs.'
A. Wakim, P. Zabawa, M. Haruza, and N. P. Bigelow
Optics Express, 20, 16083 (2012)
'Formation of ultracold X 1Σ+(v′′=0) NaCs molecules via coupled photoassociation channels.'
P. Zabawa, A. Wakim, M. Haruza, and N. P. Bigelow
Phys. Rev. A 84, 061401(R) (2011)
'Photoassociation studies of ultracold NaCs from the Cs 62P3/2 asymptote'
A Wakim, P Zabawa, N P Bigelow
Phys. Chem. Chem. Phys. 13, 18887 (2011)
'Spin-forbidden c 3Σ+(Ω=1)←X 1Σ+ transition in NaCs: Investigation of the Ω=1 state in hot and cold environments'
A Grochola, P Kowalczyk, J Szczepkowski and W Jastrzebski, A Wakim, P Zabawa, and N P Bigelow
'Near-dissociation photoassociative production of deeply bound NaCs molecules'
P Zabawa, A Wakim, A Neukirch, C Haimberger, N P Bigelow, A V Stolyarov, E A Pazyuk, M Tamanis and R Ferber
'Formation of ultracold, highly polar X1S+ NaCs molecules'
C Haimberger1, J Kleinert, P Zabawa, A Wakim and N P Bigelow
New J. Phys. 11, 055042 (2009)
'Trapping of Ultracold Polar Molecules with a Thin-Wire Electrostatic Trap'
J. Kleinert, C. Haimberger, P. J. Zabawa, and N. P. Bigelow
Phys. Rev. Lett. 99, 143002 (2007)
Recent graduates
Recent graduates
Patrick Zabawa [thesis], industry
Amy Wakim [thesis], industry
Christopher Haimberger [thesis], industry, laser R&D
Michaela (Tscherneck) Kleinart [thesis], academia, professor at Willamette University
Jan Kleinert [thesis], industry, laser R&D
Michael Holmes, industry
Mishkatul Bhattacharya, academia, professor at Rochester Institute of Technology
Marek Haruza
Maitreyi Jayaseelan [thesis]
Lasers involved in the effort:
(2) 10 Watt Verdi lasers, aka 'herb' and 'the other one'
(2) 699 ring dye lasers, aka 'skippy' and 'mot laser' (learn more here)
(1) 899 ring titanium sapphire laser
(4) diode lasers
(2) tapered amplifer lasers
(1) Quanta-Ray pulsed YAG laser
(1) Minilite II pulsed YAG laser
(2) Lambda Physik FL3002 dye lasers, aka 'flo' and 'junior'
(1) Argon Ion laser
This work has been supported by The National Science Foundation (NSF), The Army Research Office (ARO) of the United States Army Research Laboratory (ARL), The Defense Advanced Research Projects Agency (DARPA) of The United States Department of Defense (DOD), and the NASA-JPL Physical Science Research Program Cold Atom Laboratory (CAL).
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