Broadband Optical Cooling of AlH + to the Rotational Ground State Christopher M. Seck, Chien-Yu Lien, Brian C. Odom Physics & Astronomy, Northwestern University RH10 ISMS, UIUC June 19, 2014 ISMS, UIUC, June 19, 2014

Motivation Quantum control of atomics revolutionary. Extend quantum control toolbox to molecules. State manipulation requires rotational control. Time-varying constants NJP 11, (2009) Quantum computing Coherent control, ultracold & quantum chemistry, etc. Alignmen t Orientatio n ISMS, UIUC, June 19, 2014 e-e- ? p+p+ 2

Difficulty of Molecules State manipulation in atomics easy. No closed cycling transitions in molecules. Electronic relaxation generally excites vibrations. Large thermal distribution at room temperature. Each populated state requires unique laser frequency. ISMS, UIUC, June 19, 2014 Ba + 3

Difficulty of Molecules AlH + advantages: ∽ 30 electronic excitation-relaxation cycles. 99.9% in v = 0, 96% among N = 0 – 9 at 300 K. P- well separated from Q-, R-branches. 14 cm -1 (420 GHz) between P-/Q-branches. ISMS, UIUC, June 19, nm 1600 cm -1 = 2400 K 4

BROC Broadband Rotational Optical Cooling. Selectively drive P-branch. Parity barrier between N = 0, 1. Timescale of ∽ μs via ∽ 10 electronic excitation-relaxations. < scatters before vibrational excitation. ISMS, UIUC, June 19,

BROC Drive P-branch, avoiding P(1). Spectral cutoff width < 2 cm -1. ISMS, UIUC, June 19,

SFPL for AlH + Spectrally-filtered Pulsed Laser. 4-f configuration common to fs pulse-shaping. SHG Spectra-Physics Mai Tai HP. Vibrational cooling of Cs 2 by Orsay group [Viteau et al, Science 321, 5886 (2008)]. ISMS, UIUC, June 19,

Apparatus and Experiment r 0 = 3 mm z 0 = 15 mm Ω RF = 2π · 2.35 MHz, 300 V PP EC’s = 850 V DC ISMS, UIUC, June 19, 2014 Ablation-load, laser cool Ba +. Ablation-load ∽ 50 Al +. Translational motion sympathetically cooled. AlH + formed from background gas ∽ 1 minute. 8

Apparatus and Experiment Ablation-load, laser cool Ba +. Ablation-load ∽ 50 Al +. Translational motion sympathetically cooled. AlH + formed from background gas ∽ 1 minute. Apply rotational cooling, state-selective (1+1’) REMPD. TOFMS using analog-mode Hamamatsu MCP. ISMS, UIUC, June 19,

Apparatus and Experiment TOF resolves Al + (27 u) and AlH + (28 u). Ion numbers calculated by integrated signal in each bin. Al + fraction is molecule population in targeted rotational state. ISMS, UIUC, June 19,

Results and Discussion Initial (red diamonds) and BROC (green circles) distributions. ISMS, UIUC, June 19,

Results and Discussion Initial (red diamonds) and BROC (green circles) distributions. ISMS, UIUC, June 19, K thermal distribution. 12

Results and Discussion Initial (red diamonds) and BROC (green circles) distributions. Toy Monte Carlo method used for statistical analysis. ISMS, UIUC, June 19, (5)% in N = 0, 1. T (+ parity) < 13 K. T (- parity) < 19 K. 13

VA-BROC Vibrationally-Assisted Broadband Rotational Optical Cooling. Drive P(1) until v’’ = 1 decay. Relaxation to v’’ = 0 provides 3 rd photon. Cooling light then pumps to single-parity rotational ground state. Timescale set by vibrational decay of ∽ 100 ms. ISMS, UIUC, June 19,

VA-BROC Shift mask position to drive P(1). ISMS, UIUC, June 19,

Results and Discussion VA-BROC (blue triangles) results. ISMS, UIUC, June 19,

Results and Discussion VA-BROC (blue triangles) results. Toy Monte Carlo method used for statistical analysis. ISMS, UIUC, June 19,

Results and Discussion VA-BROC timing results. 127 ms expected from theory. ISMS, UIUC, June 19,

Summary ISMS, UIUC, June 19,

Next Steps and Outlook More reliable/faster AlH + production via REMPI. Currently exploring AlH & AlH 3 UHV-compatible chemistry. Expertise/advice is greatly needed! Improve single-parity preparation from ∽ 100 ms to ∽ μs. 2-photon A 2 Π 1/2  X 2 Σ + excitation via (1+1) or (1+1’) process. Laser sources commercially available. Hyperfine state cooling as preliminary to full molecular coherent control. Positioned to perform first molecular spectroscopy in the Lamb-Dicke regime. ISMS, UIUC, June 19,

The Odom Group Grad Students and Postdocs Matthew Dietrich (postdoc) Mark Kokish Chien-Yu Lien Yen-Wei Lin Chris Seck Patrick Stollenwerk Ming-Feng Tu Undergrads Xiaowen Chen Group Alumni Joan Marler (postdoc) Jason Nguyen (postdoc) Vaishnavi Rajagopal (grad) David Tabor (grad) Marc Bourgeois (ugrad) Fillan Grady (ugrad) Scott Williams (ugrad) … and The People Paying for It ISMS, UIUC, June 19, Michael Schmitt Additional details: (1+1’) REMPD: arXiv:1402:0123 Rotational cooling: arXiv:

BROC & VA-BROC Timescales ISMS, UIUC, June 19, 2014 Parity-preserving BROC timescale via simulation at 1% of I sat. Parity-cooling VA-BROC timescale via v’ = 1 lifetime. 22

Toy Monte Carlo Method ISMS, UIUC, June 19, 2014 n-tuple array generated by binomial random number generation using experimental ion numbers. Avoids binomial confidence intervals far from central limit approximation. 1.3σ 23

Time-dependent Fit Function ISMS, UIUC, June 19,