PERIODIC PROGRESS REPORT

1st year

for the research training network

COLD MOLECULES:

FORMATION, TRAPPING, and DYNAMICS

Short title: COLD MOLECULES

Contract # HPRN-CT-2002-00290

Starting date: September 1st, 2002

Duration: 48 months

Co-ordinator: Dr Françoise Masnou-Seeuws

Laboratoire Aimé Cotton, CNRS

Bât. 505, Campus d’Orsay

91405 Orsay Cedex

France

Tel: 33-1-69352052

Fax: 33-1-69352100

e-mail:

- INTRODUCTION

The first year of our network can be characterized by four main aspects:

1)  Several important experimental and theoretical results have been obtained, as described in Section A of this report. Several objectives of the network are being fulfilled, the milestones planned for the first year have indeed been reached, and even a few more milestones have already been achieved.

2)  The amount of money spent during the first year is smaller than expected in our tentative budget reported in the contract, due to the low level of hiring during the first year. The situation is expected to improve significantly for the second year, according to the forecast provided by the teams (see for instance the Cost Statement Forms).

3)  Three groups changed location within their own country, and one moved from the Netherlands to Germany, the contract being accordingly amended. The relocations are described in the table below, where we define new acronyms which will be used in the present report.

Node / Name / Present acronym / Previous acronym / Location
1a&b / CNRS Ile-de-France Sud
(Laboratoire Aimé Cotton) / [ORSAY THE,EXP] / [ORSAY THE,EXP] / Orsay
(France)
2 / Fritz Haber Institute, Berlin; Formerly Stichting voor Fundamenteel Onderzoek der Materie established in The Netherlands / [FHI-BERLIN] / [FOM-RIJNH] / Berlin
(Germany)
3 / Universität Hannover
The sub-node FREIBURG, located at Freiburg University, was formerly located at Max-Planck Institute in Heidelberg / [HANNOVER/
FREIBURG] / [HANNOVER/
MPI-K] / Hannover and
Freiburg
(Germany)
4 / Consiglio Nazionale delle Ricerche / [PISA] / [PISA] / Pisa (Italy)
5 / The Hebrew University of Jerusalem / [JERUSALEM] / [JERUSALEM] / Jerusalem (Israel)
6 / Technische Universität Graz; Contains the main node in GRAZ, and a sub-node in INNSBRUCK / [AUSTRAP] / [AUSTRAP] / Graz and
Innsbruck (Austria)
7 / Heinrich-Heine Universität Düsseldorf;
The sub-node Humbold, , was formerly located in Konstanz / [DUESS/
HUMBOLDT] / [DUESS/
KONS] / Düsseldorf
and Berlin (Germany)
8 / The Imperial College of London;
Formerly established at University of Sussex / [IMPERIAL] / [SUSSEX] / London (United Kingdom)
9 / Università di Roma “La Sapienza” / [ROMA] / [ROMA] / Roma (Italy)
10 / Utrecht University / [UTRECHT] / [UTRECHT-UU] / Utrecht (The Netherlands)
11 / The University of Connecticut / [STORRS] / [STORRS] / Storrs, Connecticut (United States)
12 / Institute of Physics, Zagreb / [ZAGREB] / [ZAGREB] / Zagreb (Croatia)

4) One experimental training school, with open-door week took place in September 2002, the first workshop was held in December 2002. Both activities were very successful as reported in the Annex of the present report.


A– RESEARCH RESULTS

A.1 – Scientific highlights

Many outstanding scientific results have already been obtained during the first year of the network. In the following, we refer to the tasks (T) and milestones (M) as described in the original proposal, and reference to the published papers (listed in section A.2) is given in square brackets; joint papers are labelled with a [J].

·  Spectacular progress has been made in the achievement of a condensate of molecules by the AUSTRAP-Innsbruck group (T3 and T5; M4, M7 and M8):

" First achievement of Bose-Einstein condensation of cesium [INS7], using a combination of optical and non-optical techniques (M7) for cooling.

" Formation of an ultracold molecular quantum gas of cesium [INS5] (T3, T5).

" Formation of a sample of trapped bosonic molecules from a Fermi gas [INS3] of lithium atoms (T3, T5)

The AUSTRAP-Innsbruck group has therefore succeeded in forming a quantum gas with molecules both from fermionic and from bosonic atoms:

·  The DUESS group has succeeded in “sympathetic cooling of different molecules” (M3).

" Production of a Coulomb crystal of trapped ultracold D2+ ions by sympathetic cooling with laser-cooled Ba+and Be+ ions [DUS1] (T3, T6) .

The ions will be used for further precision measurements (T5). Their temperature is presently ~1 mK.

·  The ORSAY-EXP group has succeeded in trapping ultracold molecules formed by photoassociation (M1):

" Achievement of a mixed atomic-molecular trap for Cs2 [ORS11] (T3).

The FREIBURG group is close to reach the same milestone for Cs2 molecules inside a CO2 laser trap.

·  The ORSAY-THE group has gained more than one order of magnitude on the precision of the Cs(6p) lifetime by analysis of Cs2 photoassociation spectra [ORS10] (T6) and succeeded in computing the last least bound levels of the Na3 molecule, which will lead to a first determination of atom-diatom scattering lengths (M9)

·  The FHI-BERLIN group has achieved a “molecular storage ring¨ for dipolar molecules, and has improved the storage time to more than 50 round-trips, thereby enabling a study of ring dynamics (M2).

·  A collaboration between IMPERIAL and FHI-BERLIN has succeeded in decelerating a heavy dipolar molecule (YbF), installing a prototype alternate gradient Stark decelerator on the molecular beam line.The velocity is at present only reduced by a few m/s, and should still be decreased much further (M6). A precise measurement of the dipole moment of the electron with an YbF beam has already been performed [IMP2], and the precision is expected to be markedly improved by use of decelerated molecules (T5).

·  The HANNOVER group has worked on the spectroscopy of Ca2 in order to analyze previous and future results on Ca photoassociation and Ca2 ultracold molecules (T1), opening the route to alkaline-earth ultracold dimers:

" Spectroscopy and theoretical study of the Ca2 ground state potential [HAN1,HAN2].

·  A collaboration between HANNOVER and ORSAY-THE has demonstrated control of internal de grees of freedom (T3):

" Manipulation of the long-range interaction between ground- and excited-state sodium atoms [J1].

·  FREIBURG in collaboration with AUSTRAP has developed another aspect of control of scattering properties (T3):

" the elastic scattering of fermionic lithium atoms is controlled by a magnetic field [J6].

·  The PISA group has demonstrated optical trapping of Rb-dimers at a density of 108 mol/cm3 and at a trapping time of 100 ms. An accurate determination of the lifetime of the Rb (5p) state is obtained [J4] (T6) in collaboration with ORSAY-THE.

·  The JERUSALEM group has obtained novel results on coherent control of a matter wave and an atom laser [JER1, JER2].

·  A collaboration between ORSAY-THE and JERUSALEM has investigated the use of chirped laser pulses for optimizing photoassociation and formation of ultracold molecules as well as for vibrational cooling of molecules (T1, T4).

·  The AUSTRAP-Graz group has obtained trap loss rates for different combinations of the lightest alkalis.

·  The experiment on buffer gas cooling and magnetic trapping of molecules is being moved from KONSTANZ to HUMBOLD (Berlin). The complete cryogenic infrastructure is working, and molecular oxygen has been successfully trapped in a cryogenic environment. Several detection schemes have been checked.

·  The ROMA group has focussed its activity on the description of chemical processes and on the calculation of collision rates at ultralow energies, computing potential energy surfaces up to large distances and using quantum molecular dynamics to unravel the role played by specific structural features:

"cooling of polar diatomics in 3He and 4He buffer gas [ROM5].

" rotational quenching of ionic systems at ultralow temperatures [ROM3].

·  The UTRECHT group has obtained new results on the photoassociation of metastable helium, in collaboration with the group of Leduc at ENS Paris (T1). Theoretical work on the quantum phase transition from a superfluid to a Mott insulator [UTR1] is supporting an ongoing experiment on the production of a Bose-Einstein condensate of Na in an optical lattice (T5).

·  A collaboration between the ORSAY-THE, ORSAY-EXP and ZAGREB groups has analyzed in more detail the detection method of ultracold Cs2 molecules via diffuse bands [J3].

·  A collaboration between STORRS and ZAGREB has studied the formation of ultracold Cs2 molecules via a double-minimum Rydberg state [J7]. This work is related to the work on ion-pair long range Na2 molecules in collaboration between HANNOVER and ORSAY-THE [J2], and to the work on ion-pair long range Rb2 in collaboration between ZAGREB and PISA [J8].

The field of molecular condensates is more rapidly developing than anticipated at the start of this network, and our network is well represented in this field. A common meeting with the Coherent Quantum Gases network, coordinated by Ennio Arimondo, will be organized in Durham in March-April 2004.


A.2 – Publications resulting from the activities of the network:

A.2.1 Joint Publications

The following list displays 8 publications resulting from on-going collaborations within the network. Young researchers are typed in boldface, the relevant tasks in the project being given within brackets.

Hannover/Orsay

-[J1] C. Samuelis, S. Falke, T. Laue, O. Dulieu, H. Knöckel, P. Pellegrini and E. Tiemann Optical manipulation of long-range interactions at the 3s+3p asymptote of Na2 physics/0309024 (submitted to Eur. Phys. J. D) [T1, T3]

-[J2] T. Laue, P. Pellegrini, O. Dulieu, C. Samuelis, H. Knöckel, F. Masnou-Seeuws and E. Tiemann Observation of the long-range potential well of the (6)1S+g(3s+5s) state of Na 2 Eur. Phys. J. D 26 p. 173 (2003) [T1, T4]

Orsay/Zagreb

-[J3] C. M. Dion, O. Dulieu, D. Comparat, W. de Souza Melo, N. Vanhaecke, P. Pillet , R. Beuc, S. Milosevic and G. Pichler Photoionization and detection of ultracold Cs2 molecules through diffuse bands Eur. Phys. J. D 18 p. 365 (2002) [T1]

Orsay/Pisa

-[J4] R. Gutterres, C. Amiot, A. Fioretti, C. Gabbanini, M. Mazzoni and O. Dulieu Determination of the 87Rb 5p state dipole matrix element and radiative lifetime from the photoassociation spectroscopy of the Rb2 0g-(P3/2) long-range state Phys. Rev. A 66 p. 024502 (2002) [T4, T6]

Austrap-Innsbruck/Freiburg

-[J5] S. Jochim, M. Bartenstein, G. Hendl, J. Hecker Denschlag, R. Grimm, A. Mosk, M. Weidemüller Magnetic field control of elastic scattering in a cold gas of fermionic lithium atoms Phys. Rev. Lett. 89, 273202 (2002) [T3]

-[J6] M. Mudrich, S. Kraft, K. Singer, R. Grimm, A. Mosk and M. Weidemüller Sympathetic Cooling with Two Atomic Species in an Optical Trap, Phys. Rev. Lett. 88, 253001 (2002). [T1, T3]

Storrs /Zagreb

-[J7] M. Pichler, W. C. Stwalley, R. Beuc and G. Pichler, Formation of ultracold Cs2 molecules through the double minimum Cs2 3 1S+u state, Physical Review A, in press [T1]

Pisa/Zagreb

[J8] A. Fioretti, M; Fazzi, M. Mazzoni, T. Ban, and C. Gabbanini, “Ultracold molecules”, submitted to Physica Scripta [T1]

A.2.2 Single Institute Publications:

ORSAY

-ORS1) K. Willner, O. Dulieu and F. Masnou-Seeuws Mapped grid methods for long-range molecules and cold collisions , J. Chem. Phys. , in press

-ORS2) B. Laburthe-Tolra, N. Hoang, B. T’Jampens, N. Vanhaecke, C. Drag, A. Crubellier, D. Comparat et P. Pillet Using a Feshbach resonance to control the formation of cold molecules, to appear in Europhysics Letters.

-ORS3) S. Boussen, N. Hoang, S. Guibal, N. Zahzam, L. Pruvost, D. Marescaux, J. Pinard, P. Pillet Prospects for BEC in Cs Gas: one dimensional evaporative cooling in a hybrid magnetic and optical trap, Eur.Phys.J.D, in press.

-ORS4) P. Naidon and F. Masnou-Seeuws Pair dynamics in the formation of molecules in a Bose-Einstein condensate Phys. Rev. A 68 p. 033612 (2003)

-ORS5) O. Dulieu and F. Masnou-Seeuws Formation of ultracold molecules by photoassociation: theoretical developments J. Opt. Soc. Am. B 20 p. 1083-1090 (2003)

-ORS6) M. Vatasescu and F. Masnou-Seeuws Time-dependent analysis of tunneling effect in the formation of ultracold molecules via photoassociation of laser-cooled atoms Eur. Phys. J. D 21 p. 191-204 (2002)

-ORS7) C. Amiot, O. Dulieu, R. F. Gutterres and F. Masnou-Seeuws Determination of the Cs2 0g-(P3/2) state and of the Cs 6P1/2,3/2 atomic radiative lifetimes from photoassociation spectroscopy Phys. Rev. A 66 p. 052506 (2002)

-ORS8) P. Pellegrini, O. Dulieu and F. Masnou-Seeuws Formation of Cs2 molecules via Feshbach resonances stabilized by spontaneous emission: theoretical treatment with the Fourier grid method Eur. Phys. J. D 20 p. 77 (2002)

-ORS9) V. Kokoouline, C. Drag, P. Pillet and F. Masnou-Seeuws Lu-Fano plot for interpretation of the photoassociation spectra Phys. Rev. A 65 p. 062710 (2002)

-ORS10) C. Amiot and O. Dulieu The Cs2 ground electronic state by Fourier transform spectroscopy: dispersion coefficients J. Chem. Phys. 117, 5155 (2002)

-ORS11) N. Vanhaecke, W. de Souza Melo, B. Laburthe Tolra, D. Comparat, P. Pillet Accumulation of cold cesium molecules via photoassociation in a mixed atomic and molecular trap, Phys. Rev. Lett. 89, 063001 (2002).

-ORS12) C. Lisdat, N. Vanhaecke, D. Comparat, P. Pillet Line shape analysis of two-color photoassociation spectra on the sample of Cs2 ground state, Eur.Phys.J. D 21, 299-309 (2002).

FHI-BERLIN (FOM-RIJNH)

-FHI1) H. L. Bethlem and G. Meijer Production and application of translationally cold molecules Int. Rev. Phys. Chem. 22, 73-128 (2003)

-FHI2) J. van Veldhoven, R.T. Jongma. B. Sartakov, W.A. Bongers, and G. Meijer: Hyperfine structure of ND3, Phys. Rev. A 66, 032501 (2002).

-FHI3) F.M.H. Crompvoets, R.T. Jongma, H.L. Bethlem, A.J.A. van Roij, and G. Meijer: Longitudinal focusing and cooling of a molecular beam, Phys. Rev. Lett. 89, 093004 (2002).

-FHI4) H.L. Bethlem, F.M.H. Crompvoets, R.T. Jongma, S.Y.T. van de Meerakker, and G. Meijer: Deceleration and trapping of ammonia using time-varying electric fields, Phys. Rev. A 65, 053416 (2002).

-FHI5) H.L. Bethlem, A.J.A. van Roij, R.T. Jongma, and G. Meijer: Alternate gradient focusing and deceleration of a molecular beam, Phys. Rev. Lett. 88, 133003 (2002).

HANNOVER

-HAN1) O. Allard, C. Samuelis, A. Pashov, H. Knöckel, E. Tiemann Experimental study of the Ca2 1S+1S asymptote Eur. Phys. J. D 26, 155-164 (2003)

-HAN2) O. Allard, A. Pashov, H. Knöckel, E. Tiemann, Ground-state potential of the Ca dimer from Fourier-transform spectroscopy, Phys. Rev. A 66, 042503 (2002)