Cold Atom Molecule Interactions (CATMIN)

Jul 13, 2022, 4:00 p.m. → Jul 15, 2022, 9:00 p.m. America/Toronto

Theatre (Perimeter Institute for Theoretical Physics)

James Shaffer (Quantum Valley Ideas Laboratories), Luis Marcassa (University of Sao Paulo), Rosario Gonzalez-Ferez (University of Granada)

In the first edition of the meeting, CATMIN (Cold ATom Molecule INteractions) was a new satellite meeting of ICPEAC devoted to the study of atomic and molecular systems, where long-range interactions and the extreme properties of highly excited electrons produce new physics and lead to new technologies. CATMIN's objective is to strengthen the links between cold atom physics, molecular physics, chemistry and condensed matter physics, so that new concepts and breakthroughs can emerge. Ions, atoms and molecules are naturally made quantum systems that can be controlled with light and low frequency electromagnetic fields, thus lending themselves to precision investigations and use in quantum technologies. The second CATMIN conference will be held a few days before the ICAP, which is a major conference in AMO physics, with the idea that scientists can attend both meetings. The CATMIN meeting will be a two-day conference held at the Perimeter Institute in Waterloo, ON, centered on Rydberg-atom physics, cold ion physics and the interplay between these experimental platforms. Rydberg atom physics is experiencing a renaissance due to the application of the exaggerated properties of highly excited atoms for quantum information and quantum simulation. Rydberg states can even be observed in solids which is a subject of increasing interest. Cold ions, similarly, are exciting for quantum simulation and computing, becoming one of the central platforms in the race to build a quantum computer. Many exciting developments are also in progress in the area of cold-molecules. Long-range interactions open up fields of research such as the photo-association of cold atoms to form ultra-cold molecules, and the excitation of Rydberg molecules demonstrating novel kinds of molecular bonding. Strong long-range interactions in all the systems permit the investigation of the few-body and many-body regimes, including the few- to many-body transition. The conference aims to share the latest developments and results in these exciting fields among the various ICAP communities as well as the broader physics and chemistry communities. Overall, the conference can forward quantum science and the application of quantum science, which furthers these fields of research by concentrating interest to attract people and resources to the field.

Sponsorship for this event has been provided by:

https://pirsa.org/C22028

Perimeter Institute will make every effort to host the conference as an in-person event.  However, we reserve the right to change to an online program to align with changes in regulations due to the COVID-19 pandemic.

 

Territorial Land Acknowledgement

Perimeter Institute acknowledges that it is situated on the traditional territory of the Anishinaabe, Haudenosaunee, and Neutral peoples.

Perimeter Institute is located on the Haldimand Tract. After the American Revolution, the tract was granted by the British to the Six Nations of the Grand River and the Mississaugas of the Credit First Nation as compensation for their role in the war and for the loss of their traditional lands in upstate New York. Of the 950,000 acres granted to the Haudenosaunee, less than 5 percent remains Six Nations land. Only 6,100 acres remain Mississaugas of the Credit land. 

We thank the Anishinaabe, Haudenosaunee, and Neutral peoples for hosting us on their land.

Wednesday, July 13

4:00 p.m. → 6:00 p.m. Welcome Reception

Thursday, July 14

8:00 a.m. → 8:30 a.m. Registration

8:30 a.m. → 8:45 a.m. Introduction & Welcoming Remarks

Speaker: James Shaffer (Quantum Valley Ideas Laboratories)

8:45 a.m. → 9:00 a.m. Perimeter Greeting

Speaker: Paul Smith (Perimeter Institute)

9:00 a.m. → 9:40 a.m. Observation of a molecular bond between ions and Rydberg atoms using a high-resolution pulsed ion microscope

"We present our recent studies on Rydberg atom-Ion interactions and the spatial imaging of a novel type of molecular ion using a high-resolution ion microscope. The ion microscope provides an exceptional spatial and temporal resolution on a single atom level, where a highly tuneable magnification ranging from 200 to over 1500, a resolution better than 200nm and a depth of field of more than 70µm were demonstrated [1]. A pulsed operation mode of the microscope combined with the excellent electric field compensation enables the study of highly excited Rydberg atoms and ion-Rydberg atom hybrid systems.
Using the ion microscope, we observed a novel molecular ion, where the bonding mechanism is based on the interaction between the ionic charge and an induced flipping dipole of a Rydberg atom [2]. Furthermore, we could measure the vibrational spectrum and spatially resolve the bond length and the angular alignment of the molecule. The excellent time resolution of the microscope enables probing of the interaction dynamics between the Rydberg atom and the ion.
[1] C. Veit, N. Zuber, O. A. Herrera-Sancho, V. S. V. Anasuri, T. Schmid, F. Meinert, R. Löw, and T. Pfau, Pulsed Ion Microscope to Probe Quantum Gases, Phys. Rev. X 11, 011036 (2021).
[2] N. Zuber, V. S. V. Anasuri, M. Berngruber, Y.-Q. Zou, F. Meinert, R. Löw, T. Pfau, Spatial imaging of a novel type of molecular ions, Nature 5, 453 (2022)"

Speaker: Tilman Pfau (University of Stuttgart)

9:40 a.m. → 10:20 a.m. Indirect spin-spin interactions with Rydberg molecules

Simulation of quantum magnetism with AMO systems is now a fully fledged enterprise. In this talk, I will discuss how Rydberg molecular interactions can be exploited to simulate indirect spin-spin coupling, with Rydberg atoms acting as localized impurities. Engineering chiral spin Hamiltonians with Rydberg atoms is also described.

Speaker: Hossein Sadeghpour (Harvard University)

10:20 a.m. → 10:50 a.m. Coffee Break

10:50 a.m. → 11:30 a.m. Realizing topological edge states with Rydberg-atom synthetic dimensions

"A quantum system evolving on a manifold of discrete states can be viewed as a particle moving in a real-space lattice potential. Such a synthetic dimension provides a powerful tool for quantum simulation because of the ability to engineer many aspects of the Hamiltonian describing the system. In this talk, I will describe a synthetic dimension created from Rydberg levels in an 84-Sr atom, in which coupling between the states is induced with millimeter-waves. Tunneling amplitudes between synthetic lattice sites and on-site potentials are set by the millimeter-wave amplitudes and detunings respectively. Alternating weak and strong tunneling in a one-dimensional configuration realizes the single-particle Su-Schrieffer-Heeger Hamiltonian, a paradigmatic model of topological matter. I will also briefly describe our recent results creating ultralong-range Rydberg molecule (ULRRM) dimers in an interacting Bose gas and probing nonlocal three-body spatial correlations with ULRRM trimers.
Kanungo, S.K., Whalen, J.D., Lu, Y. et al. Realizing topological edge states with Rydberg-atom synthetic dimensions. Nat Commun 13, 972 (2022). https://doi.org/10.1038/s41467-022-28550-y
"

Speaker: Thomas Killian (Rice University)

11:30 a.m. → 11:50 a.m. Resonant dipole-dipole interactions between Rydberg atoms and polar molecules at temperatures below 1 K

Junwen Zou and Stephen Hogan

Resonant dipole-dipole interactions between Rydberg helium atoms and cold ground-state ammonia molecules allow Förster resonance energy transfer between the electronic degrees of freedom in the atom, and the nuclear degrees of freedom associated with the inversion of the molecule [1,2]. In this talk I will describe recent experiments in which we have exploited the Stark effect in the triplet Rydberg states in helium, with values of the principal quantum number n between 38 and 40, to tune these interactions through resonance using electric fields below 10 V/cm. Resonance widths as narrow as 70 MHz have been observed in this work. These are indicative of mean centre-of-mass collision speeds on the order of 10 m/s, and collisions that occur at temperatures significantly below 1 K. Studies of Förster resonances in this collision system are of interest in the search for dipole-bound states [3] of Rydberg atoms or molecules and polar ground-state molecules, in the exploitation of long-range dipole-dipole interactions to regulate access to ion-molecule chemistry that can occur if the polar molecule penetrates inside the Rydberg electron charge distribution [4], and for coherent control and non-destructive detection [5,6].

[1] V. Zhelyazkova and S. D. Hogan, Phys. Rev. A 95, 042710 (2017)
[2] K. Gawlas and S. D. Hogan, J. Phys. Chem. Lett. 11, 83 (2020)
[3] S. M. Farooqi, D. Tong, S. Krishnan, J. Stanojevic, Y. P. Zhang, J. R. Ensher, A. S. Estrin, C. Boisseau, R. Côté, E. E. Eyler and P. L. Gould, Phys. Rev. Lett. 91, 183002 (2003).
[4] V. Zhelyazkova, F. B. V. Martins, J. A. Agner, H. Schmutz and F. Merkt, Phys. Rev. Lett. 125, 263401 (2020)
[5] E. Kuznetsova, S. T. Rittenhouse, H. R. Sadeghpour and S. F. Yelin, Phys. Chem. Chem. Phys. 13, 17115 (2011)
[6] M. Zeppenfeld, Euro. Phys. Lett. 118, 13002 (2017)

Speaker: Stephen Hogan (University College London)

11:50 a.m. → 12:10 p.m. Polyatomic ultralong range Rydberg molecules

In cold and ultracold mixtures of atoms and molecules, Rydberg interactions with surrounding atoms or molecules may, under certain conditions, lead to the formation of special long-range Rydberg molecules [1,2,3]. These exotic molecules provide an excellent toolkit for manipulation and control of interatomic and atom-molecule interactions, with applications in ultracold chemistry, quantum information processing and many-body quantum physics.

In this talk, we will discuss ultralong-range polyatomic Rydberg molecules formed when a heteronuclear diatomic molecule is bound to a Rydberg atom [3,4]. The binding mechanism appears due to anisotropic scattering of the Rydberg electron from the permanent electric dipole moment of the polar molecule. We propose an experimentally realizable scheme to produce these triatomic ultralong-range Rydberg molecules in ultracold RbCs traps, which might use the excitation of cesium or rubidium [5]. By exploiting the Rydberg electron-molecule anisotropic dipole interaction, we induce a near resonant coupling of the non-zero quantum defect Rydberg levels with the RbCs molecule in an excited rotational level. This coupling enhances the binding of the triatomic ultralong-range Rydberg molecule and produces favorable Franck-Condon factors.

References
[1] C. H. Greene, A. S. Dickinson, and H. R. Sadeghpour, Phys. Rev. Lett. 85, 2458 (2000).
[2] S. T. Rittenhouse and H. R. Sadeghpour, Phys. Rev. Lett. 104, 243002 (2010).
[3] V. Bendkowsky, B. Butscher, J. Nipper, J. P. Shaffer, R. Löw, and T. Pfau, Nature 458, 1005 (2009).
[4] R. González-Férez, H. R. Sadeghpour, and P. Schmelcher, New J. Phys. 17, 013021 (2015).
[5] R. González-Férez, S.T. Rittenhouse, P. Schmelcher and H.R. Sadeghpour, J. Phys. B 53, 074002 (2020)."

Speaker: Rosario Gonzalez-Ferez (University of Granada)

12:10 p.m. → 2:00 p.m. Lunch

2:00 p.m. → 2:20 p.m. Observation of linewidth narrowing in EIT polarization spectroscopy involving hot Rydberg atoms with Laguerre Gaussian modes

Naomy Duarte Gomes1, Barbara da Fonseca Magnani1, Jorge Douglas Massayuki Kondo2, Luis Gustavo Marcassa1

1 Instituto de Fısica de Sao Carlos, Universidade de Sao Paulo
2 Departamento de Fısica, Universidade Federal de Santa Catarina

In this work, we investigate the narrowing of the electromagnetically induced transparency (EIT) profile in a three-level ladder of rubidium atoms at room temperature using a Rydberg state and a Laguerre-Gaussian mode laser. The Gaussian probe field couples the 5S1/2 → 5P3/2 states. The control field, which can be in either Gaussian or Laguerre-Gaussian (LG) modes, couples the 5P3/2 → 44D state. The EIT spectrum is measured with the polarization spectroscopy (PS) technique, resulting in a dispersive signal. The dispersive PS EIT linewidth is 20% narrower for the LG mode than for a Gaussian mode, due to the donut spatial distribution of the LG mode used. We have implemented a probe transmission model using a simplified Lindblad master equation, which allows us to calculate the PS signal and reproduces well the experimental results. The use of the PS signal eliminates the need to fit a curve when measuring EIT linewidths while still providing subnatural widths. Narrowing the transmission profile is of great interest to measure effects such as atomic collisions and mi-crowave fields.

*This work is supported by grants 2016/21311-2, 2019/10971-0 and 2021/06371-7, Sao Paulo Research Foundation (FAPESP) and grant 142410/2019-5, Brazilian National Council for Scientific and Technological Development (CNPq). It is also supported by grant (W911NF2110211) from the US Army.

Speaker: Luis Marcassa (University of Sao Paulo)

2:20 p.m. → 2:40 p.m. Cs as a low-frequency RF field sensor

"133Cs as a low-frequency RF field sensor Seth T. Rittenhouse,1 Seth Meiselman,2 Vanessa Ortiz,1 and Geoffrey A. Cranch2
1Department of Physics, the United States Naval Academy, Annapolis, MD 21402, USA
2Optical Sciences Division, U. S. Naval Research Laboratory, Washington, DC 20375, USA

Do to the extreme sensitivity of Rydberg systems to external fields, there has been a great deal of interest in using them as high precision quantum mechanical sensors. However, for intermediate principle quantum numbers (n ∼ 20 − 40), using the AC Stark effect to measure the intensity ofan RF field is limited to amplitudes on the order of ERF ∼ 1 V/cm. In this poster we examine the feasibility of using 133Cs as a high precision, low frequency (10-100 MHz) RF field sensor.

We propose using a DC field offset to increase the field sensitivity of the AC Stark spectrum to the intensity of the RF field. The presence of the DC offset field leads to sideband states with Rabbi frequencies that are highly sensitive to RF field intensity. Using electromagnetically induced transpareny, our initial theoretical modeling indicates that this approach might be used to create a RF field sensor with sub-millivolt per centimeter accuracy."

Speaker: Seth Rittenhouse (US Naval Academy)

2:40 p.m. → 3:20 p.m. Collective effects when photons interact with many atoms

Atoms separated by distances comparable to or less than the wavelength of a photon for a dipole allowed transition can manifest collective effects. These effects can be apparent in the radiative lifetime of an excited state, how the atoms recoil when a photon is emitted, the transmission/reflectivity of an atomic cloud, etc. This talk will describe some of these processes and the theoretical machinery used to model them. This work is supported by the National Science Foundation under Award No. 2109987-PHY.

Speaker: Francis Robicheaux (Purdue University)

3:20 p.m. → 4:10 p.m. Coffee Break

4:10 p.m. → 6:00 p.m. Poster Session

6:00 p.m. → 8:00 p.m. BBQ

Friday, July 15

9:00 a.m. → 9:40 a.m. Programmable quantum systems based on Rydberg atom arrays

We will discuss the recent advances involving programmable, coherent manipulation of quantum many-body systems using neutral atom arrays excited into Rydberg states, allowing the control over 200 qubits in two dimensions. These systems can be used for realization and probing of exotic quantum phases of matter and exploration of their non-equilibrium dynamics. Recent advances involving the realization and probing of quantum spin liquid states - the exotic topological states of matter have thus far evaded direct experimental detection and the observation of quantum speedup for solving optimization problems will be described. In addition, the realization of novel quantum processing architecture based on dynamically reconfigurable entanglement and the steps towards quantum error correction will be discussed. Finally, we will discuss prospects for using these techniques for realization of large-scale quantum processors.

Speaker: Mikhail Lukin (Harvard University)

9:40 a.m. → 10:20 a.m. Exploring quantum spin models with tunable arrays of Rydberg atoms

"Rydberg atoms in arrays of optical tweezers offer a new perspective for the quantum simulation
of many body systems. In this talk, I will give a brief overview about this platform and describe
our efforts to control Rydberg interactions to explore different types of Hamiltonians. Through
recent experimental results, I will illustrate the implementation of the Ising [1] and XXZ [2]
Hamiltonians to study quantum magnetism. Finally, I will show our first steps to scale up the
atom numbers in our platform by using a cryogenic environment [3].
References:
[1] P. Scholl et al., Nature 595, 233 (2021).
[2] P. Scholl et al., PRX Quantum 3, 020303 (2022).
[3] K.N. Schymik et al., Phys. Rev. Applied 16, 034013 (2021)."

Speaker: Daniel Barredo (Institut d'Optique-CNRS & CINN-CSIC)

10:20 a.m. → 10:50 a.m. Coffee Break

10:50 a.m. → 11:30 a.m. Quantum circuits on neutral atom computers

"Neutral atom quantum computers with Rydberg mediated entangling gates are rapidly advancing as a leading platform for quantum information processing. I will present recent results running quantum algorithms for preparation of multi-qubit GHZ states, phase estimation, and hybrid quantum/classical optimization. Future fault tolerant quantum processors will require large numbers of qubits, high fidelity gates, and error correcting protocols. Work in progress towards fault tolerance including preparation of arrays of more than 1000 atoms, mid-circuit measurements, and multi-qubit gates will be presented"

Speaker: Mark Saffman (University of Wisconsin-Madison)

11:30 a.m. → 11:50 a.m. Time-optimal gates for quantum computing with Rydberg atoms

"Neutral atoms have emerged as a competitive platform for digital quantum simulations and computing.
In this talk, we discuss recent results on the design of time-optimal two- and three-qubit gates for neutral
atoms, where entangling gates are implemented via the strong and long-range interactions provided by
highly excited Rydberg states. We combine numerical and semi-analytical quantum optimal control
techniques to obtain theoretically laser pulses that are “smooth”, time-optimal and “global” -- that is,
they do not require individual addressability of the atoms. This technique improves upon current
implementations of the controlled-Z (CZ) and the three-qubit C2Z gates with just a limited set of
variational parameters, demonstrating the potential of quantum optimal control techniques for advancing quantum computing with Rydberg atoms."

Speaker: Guido Pupillo (University of Strasbourg)

11:50 a.m. → 12:10 p.m. Coherent Light Shift of Alkaline-Earth Rydberg Atoms

Speaker: Patrick Cheinet (Laboratoire Aimé Cotton, CNRS)

12:10 p.m. → 1:50 p.m. Lunch

1:50 p.m. → 2:30 p.m. Advances in Sensitivity and Pulse Detection with Rydberg-Atom Electrometry

The strong interaction of optically excited Rydberg atoms with external fields has made them promising
for the detection of radio frequency (RF) electric fields with high sensitivity. Such Rydberg-atom based
sensors offer advantages over conventional metal antennas in RF transparency and self-calibration, enabled
by all-dielectric construction and extremely well-known atomic properties. In this talk, we describe recent
advances in the sensing of low amplitude RF electric fields and the timing of sub-microsecond RF pulses
using room temperature Cesium vapour cells. We examine their transient response to RF pulses with
durations ranging from 10 μs to 50 ns, identifying the dependence of atomic time scales on Rabi frequencies
and dephasing mechanisms. We present a method for extracting the arrival time of RF pulses in a typical
two-photon setup using a matched filter tailored to the atomic response, achieving a field sensitivity down
to ~240 nV cm-1 Hz-1/2 and a timing precision of ~30 ns. On the other hand, practical operation at room
temperature results in the self-calibration and sensitivity of this setup being limited by residual Doppler
broadening. We therefore develop a novel sub-Doppler approach using a colinear three-photon scheme,
which extends the self-calibrated Autler-Townes regime to significantly weaker RF electric fields. With
this setup, we achieve a ~200 kHz spectral linewidth of the Rydberg atoms’ electromagnetically induced
transparency within a room temperature vapour cell. The results demonstrate the potential of Rydberg atombased sensors for use in test and measurement, communications, and radar applications. "

Speaker: Stephanie Bohaichuk (Quantum Valley Ideas Laboratories)

2:30 p.m. → 3:10 p.m. Opportunities and Limitations for Warm Rydberg Electric Field Sensors

Electric field sensors based on warm vapors of Rydberg atoms have distinguishing features that offer new application possibilities. A single sensor can operate over a wide spectrum of frequencies, from DC to THz, with a consistent instantaneous baseband bandwidth of approximately 10MHz. The sensor head containing the vapor is highly transparent and can be made small relative to the electric field wavelengths, enabling accurate measurements with sub-wavelength spatial resolution. Presently Rydberg sensors rely on the spectroscopic method of electromagnetically induced transparency (EIT) for preparing and probing the atoms, and though simple and effective, this places limits on the sensitivity and instantaneous bandwidth of the sensor. I will discuss these limitations and the optimal EIT parameter regime considering presently available laser technology, and show performance of a promising new prototype vertical external cavity surface emitting laser (VECSEL). Finally, I will present results on recent demonstrations, such as a Rydberg-based spectrum analyzer with sensitivity of -145dBm/Hz and dynamic range >80 dB.

Speaker: Paul Kunz (Army Research Laboratories)

3:10 p.m. → 3:30 p.m. Towards an optogalvanic flux sensor for nitric oxide based on Rydberg excitations

I will talk about the applicability of a new kind of gas sensor based on Rydberg excitations. From a gas mixture the molecule in question is excited to a Rydberg state. By succeeding collisions with all other gas components this molecule ionizes and the emerging electrons can be measured as a current.

I will show Doppler-free spectra for the A <- X transition, an estimate of the excitation efficiency dependent on the used laser powers, the applied charge-extraction voltage as well as the overall gas pressure and a first Stark map of NO Rydberg states recorded with cw excitation.

Speaker: Harald Kübler (University of Stuttgart)

3:30 p.m. → 4:00 p.m. Coffee Break

4:00 p.m. → 4:40 p.m. Measurements of blackbody-radiation-induced transition rates between high-lying S, P, and D Rydberg levels

We report experimental measurements of the rates of blackbody-radiation-induced transitions between
highlying (n > 60) S, P, and D Rydberg levels of rubidium atoms in a magneto-optical trap using a hybrid field
ionization and state-selective depumping technique. Our results reveal significant deviations of the measured
transition rates from theory for well-defined ranges of the principal quantum number. We assume that the
most likely cause for those deviations is a modified blackbody spectrum inside the glass cell in which the
magneto-optical trap is formed, and we test this assumption by installing electrodes to create an additional
microwave cavity around the cell. From the results, we conclude that it should be possible to use such external cavities to control and suppress the blackbody-radiation-induced transitions."

Speaker: Donatella Ciampini (Università di Pisa)

4:40 p.m. → 5:00 p.m. Rydberg atoms in Bose-Einstein condensed environments: cold bubble chambers and mesoscopic entanglement

"S. Tiwari, S. Rammohan, A. Mishra, A. Pendse, A. K. Chauhan, R. Nath, F. Engel, M. Wagner, R.Schmidt, F. Meinert, A. Eisfeld and S. Wüster

Indian Institute of Science Education and Research, Bhopal India Palacký University, Olomouc, Czech Republic Indian Institute of Science Education and Research, Pune, India Max Planck Institute for the Physics of Complex Systems, Dresden, Germany Universität Stuttgart, Germany Max-Planck-Institute of Quantum Optics and MCQST, Garching, Germany

Rydberg Atoms in highly excited electronic states with n=30-200 can be excited within BoseEinstein condensates (BECs), and while lifetimes are shorter than in vacuum [1,2], they live long enough to cause a response of the BEC mean field [3]. During this, thousands of ground-state atoms are present within the Rydberg orbit, allowing the study of atoms moving within atoms [4]. We present beyond-mean field models of the joint Rydberg-BEC dynamics, showing how either
can be used to probe the other.

For multiple Rydberg atoms in a single electronic state, we show that the phase coherence of thecondensate allows the tracking of mobile Rydberg impurities akin to the function of bubblechambers in particle physics [5]. For a single Rydberg atom with multiple electronic states, weprovide spectral densities of the BEC as a decohering environment [6], and show that the BECcan image a signature of the entangling evolution that causes Rydberg q-bit decoherence [7] or
serve as non-Markovian environment for quantum simulations.

[1] Schlagmüller et al. PRX 6 (2016) 031020.
[2] Kanungo et al. PRA 102 (2020) 063317.
[3] Balewski et al. Nature 502 (2013) 664.
[4] Tiwari et al. arXiv:2111.05031 (2021)
[5] Tiwari et al. PRA 99 (2019) 043616.
[6] Rammohan et al. PRA 103 (2021) 063307.
[7] Rammohan et al. PRA(Letters) 104 (2021) L060202."

Speaker: Sebastian Wüster (Indian Institute of Science Education and Research Bhopal)

5:00 p.m. → 5:20 p.m. Photon-bubble turbulence in cold atomic gases

Turbulent radiation flow is ubiquitous in many physical systems where light–matter interaction becomes relevant. Photon bubble instabilities, in particular, have been identified as a possible source of turbulent radiation transport in astrophysical objects such as massive stars and black hole accretion disks. Here, we report on the experimental observation of a photon bubble instability in cold atomic gases, in the presence of multiple scattering of light. A two-fluid theory is developed to model the coupled atom–photon gas and to describe both the saturation of the instability in the regime of quasi-static bubbles and the low-frequency turbulent phase associated with the growth and collapse of photon bubbles inside the atomic sample. We also employ statistical dimensionality reduction techniques to describe the low-dimensional nature of the turbulent regime. The experimental results reported here, along with the theoretical model we have developed, may shed light on analogue photon bubble instabilities in astrophysical scenarios. Our findings are consistent with recent analyses based on spatially resolved pump–probe measurements.

Speaker: Hugo Terças (Instituto de Plasmas e Fusão Nuclear)

5:20 p.m. → 5:40 p.m. Quantum state control of ultracold chemistry

The advent of ultracold molecules opens the possibility to explore chemical reactions with perfect control of the quantum states of the reactants. We report on several surprising results of our work with ultracold NaLi molecules. First, we demonstrate a factor of 100 control of reaction rates between NaLi molecules and Na atoms by changing the atom's spin state. This ability to slow reactions allowed us to demonstrate sympathetic cooling of molecules for the first time. Next, we explore two very different collisional resonances. A resonance in NaLi+Na reactions exemplifies the standard description of chemical resonances. The other, for NaLi+NaLi, is the first ultracold molecule-molecule resonance observed and runs completely counter to the standard description. Simple models relate the complex chemical dynamics to the simple physics of a Fabry-Perot resonantor and point a number of open questions in chemical dynamics that can be explored with ultracold molecules.

Speaker: Alan Jamison (University of Waterloo)

6:00 p.m. → 9:00 p.m. Farewell Party - Offsite