H 2 CO OH H2OH2O HCO QED e- Quantum dipolar gas Precision test Chemical reactions Quantum measurement Cold and Ultracold Molecules EuroQUAM, Durham, April 18, 2009 J. Ye, JILA, NIST & CU Ye Labs

Why ultracold matter? We can understand it We can control it  The most precise measurements ever !  Quantum control, Quantum simulations, Quantum information  Fundamental understandings in condensed matter

Dipolar quantum systems Atoms Polar molecules R + _ + _ R Magnetic dipoles Electric dipoles d ~ Debye d ~ Bohr magneton e.g. BEC of Cr d=6  B (T. Pfau, Stuttgart) E I ~ n= /cm 3 E I ~ n= /cm 3

log 10 (density [cm -3 ]) log 10 (temperature [K]) Dipolar crystal Phase transition & many-body Dipolar quantum gas Quantum information Ultracold Chemistry Molecule optics & circuitry Cold controlled chemistry Novel collisions Fundamental tests Precision measurement Science with cold molecules High density, Ultracold temperature ~ K B T

log 10 (density [cm -3 ]) log 10 (temperature [K]) Stark, magnetic, optical deceleration Buffer-gas cooling Photo-association Coherent state transfer Quantum degeneracy Enhanced PA? Laser cooling? Sympathetic cooling? Evaporative cooling? Technology for cold molecules Carr, DeMille, Krems, & Ye, New. J. Phys. Special Issue (2009).

Molecules in single quantum states, under precise control, for internal & external motions Unprecedented study of fundamentally important reactions (Dial the rates): OH + HBr, OH + H 2 CO, CN + O 2, OH + NO, OH + OH, CN + NH 3, OH + H Ultracold molecules: Precision Chemistry H 2 CO OH H2OH2O HCO Controlled molecular collisions Ultracold chemical reactions Electric field Stereo-Chemistry E. Hudson et al., Phys. Rev. A 73, (2006).

Cold ground-state molecules - Stark slower 370 m/s 336 m/s 300 m/s 259 m/s 211 m/s 148 m/s 33 m/s Bethlem, Berden, Meijer, Phys. Rev. Lett (1999). Bochinski et al, Phys. Rev. Lett. 91, (2003). vv   0 = m/s to rest 1 K to 10 mK 10 4 – 10 6 molecules Density: 10 5 – 10 7 /cm 3 H 2 CO OH

Magnetic trapping of OH Sawyer et al., Phys. Rev. Lett. 98, (2007). decelerator Magnetic trap O d s H

Permanent-Magnet Trap NdFeB (N42SH) T op = 120 o C B res = 1.24 T 10mm

Trap Loading 0 V+12 kV-12 kV

0 V Trap Loading ~ 2 x 10 6 cm mK

OH He, D 2, NH 3, … beam source E cm ~ 5 cm -1 – 230 cm -1  Quantum threshold collisions  Resonant energy transfer Sawyer et al., Phys. Rev. Lett. 101, (2008). Trap and collisions

Absolute collision cross sections E cm (cm -1 ) J = 5/2 J = 3/2 2  3/2 84 cm -1 OH D 2 : (1) J = 1 quadrupole moment (2) J = 1  J =3 (300 cm -1 )

Electric Quadrupole guide: 13.5 cm ROC +/- 5 kV ~130 m/s ND 3 OH Magnet trap Buffer gas-cooled molecule source H O N H/D E cm < 5 cm -1 H/D The possibility to probe polar collisions? Doyle, Rempe, …

(a) (b) (c) (d) A Molecular MOT ? B. K. Stuhl et al., “A magneto-optical trap for polar molecules,” Phys. Rev. Lett. 101, (2008). TiO

Polar molecules near quantum degeneracy J. Bohn (JILA), J. Hutson (Durham) S. Ospelkaus, K.-K. Ni, M. Miranda, B. Neyenhuis, D. Wang, S. Kotochigova, P. S. Julienne, D. Jin, and J. Ye KRb molecules 40 K Fermions 87 Rb Bosons  Temperature ~400nK  T/T F =3  Density ~10 12 /cm 3  =0.01  Dipole ~0.5 Debye  Long lived (~200ms)

|  f (R) | 2 EKEK |  g ( R )| 2 |  e ( R )| 2 Laser Internuclear distance R Energy Traditional photo-association Pillet Stwalley Heinzen Bigelow …

|  f (R) | 2 EKEK Laser |  e ( R )| 2 |  g ( R )| 2 Energy Internuclear distance R Resonant enhancement DeMille Weidemüller

|  FR (R) | 2 |  e ( R )| 2 EKEK Laser Internuclear distance R Energy Resonant enhancement – in the ground Côte

molecules > V(R) E binding Magnetic field Colliding atoms B R R R R Energy Magnetic-field Feshbach resonance Field-tunable scattering resonance Zirbel et al., Phys. Rev. Lett. 100, (2008).

Going to really deep ground potential The problem – overlap Laser fields: 1. Impractically strong 2. Nonlinear excitations Ground Electronic state Pump Dump Excited electronic state

Coherent weak fields to achieve strong field effect Pump pulse Dump pulse Wave-packet dynamics bridge the overlap mismatch Coherent accumulations resolve single quantum state Pe’er, Shapiro, Stowe, Shapiro, Ye, Phys. Rev. Lett. 98, (2007). Excited electronic state Ground Electronic state Pump Dump

11 22 33 11 33 11 Inter-nuclear distance R Energy v = 0, N = 0, J = 0 Good Franck-Condon for both up and down transitions. Excited state is triplet + singlet mixture Sr 2 11 22 Frequency comb assisted STIRAP Feshbach + STIRAP Ni et al., Science 322, 231 (2008) Ospelkaus et al., Nature Phys. 4, 622 (2008)

JILA Sr optical atomic clocks Inaccuracy ~ 1 x (uncertainty in SI unit of time: 4 x ) Ludlow et al., Science 319, 1805 (2008). Campbell et al., Science 324, 360 (2009). Counting the light ripple

Raman + EIT Dark Resonance  1 scanned,  2 fixed  1 fixed,  2 scanned

Stark Shift (MHz) B=1.1139(1) GHz d=0.566(17) Debye Stark Spectroscopy

4μs one-way transfer Coherent Transfer - STIRAP 92% efficiency No heating T/T F =2.5

No Heating in Transfer Process Direct Imaging of Molecules 0 ms 1 ms 3 ms 6 ms

Trapped Ground state polar molecules Trap oscillation Lifetime ~ 150 ms E Pol Ospelkaus et al., Faraday Discussions 142

Atom-molecule collisions 3x10 4 K,  =70(10)ms 3x10 5 K,  =6(1)ms KRb+ K

KRb+ Rb =5.4(1.0) cm 3 /s =6.5(1.0) cm 3 /s Atom-molecule collisions

A harpoon mechanism? J. Bohn D. Herschbach J. Hutson P. Julienne ionization energy - electron affinity (1) Near unity probability loss due to short-range reactions (2) Quantum threshold behavior - long-range potential (van der Waals “Length”) characterizes universal inelastic scattering Upper bound: 11 x cm 3 /s (KRb + K); 7.9 x cm 3 /s (KRb + Rb)

Rb 2 KRb K2K2 KRb+ K -> K 2 +Rb+ exothermic endothermic KRb+ Rb -> Rb 2 +K- Atom-molecule collisions

Nuclear spin states for v = 0, N = 0 We populate a single nuclear spin state J. Aldegunde J. Hutson

Dipolar collision resonance? Collisions of two ground-state Fermionic polar molecules Evaporative cooling? Control of elastic/inelastic collisions? J. Bohn U(R) (nK) Shape or Feshbach? We will know soon.

Quantum information (strong dipolar interactions, long coherence time) Quantum degeneracy (e.g. BEC) (anisotropic interactions) Dipolar phase transition (Condensed matter system) Ultracold molecules: quantum physics DeMille, Phys. Rev. Lett. 88, (2002). H.P. Buchler et al., PRL 98, (2007). T. Koch et al., Nature Phys. 4, 218 (2008). Micheli, Brennen, Zoller, Nature Physics 2, 341 (2006).

Special thanks J. Bohn (JILA) P. Julienne (NIST), S. Kotochigova (Temple), J. Hutson (Durham) OH and H 2 CO B. Sawyer B. Stuhl M. Yeo E. Hudson (UCLA) B. Lev (Illinois UC) H. Lewandowski (JILA) J. Bochinski (NC State) KRb S. Ospelkaus K.-K. Ni M. Miranda B. Neyenhuis D. Wang A. Pe’er (Israel) J. Zirbel Deborah Jin