[above:] We have observed a phase transition between two dynamical phases in a harmonically trapped ultracold Fermi gas. This transition is between a paramagnet like state (A), in which the total magnetization of the trapped atoms decreases quickly, and a dynamical ferromagnet state (C-E) where the magnetization is protected by the opening of an energy gap. The agreement between our data and theory (red lines) validates the mapping between our harmonically trapped atoms and the collective Heisenberg spin model on a lattice composed of the harmonic oscillator modes. Further details of this mapping and our demonstration of time reversal to restore magnetization using a many-body echo can be found in Smale et al., Science Advances, 5, eaax1568 (2019).
[above:] "Band Mass" for cold fermion conductivity in an optical lattice. Using a.c. conductivity spectra for ultracold potassium 40 in a cubic lattice, we find the spectral weight at low frequency. For variable number (N), deposited heat (Q), scattering length (as), and lattice depth (V), the data collapses onto the expected response of a single-band Hubbard model. At hight T/t (temperature divided by tunnelling energy), the data approaches a 1/T regime (dashed black line). Inset: Scattering does not "destroy" conductivity, but only moves it from one part of the spectrum to another, leaving spectral weight and band mass relatively unchanged.
More details can be found in Anderson et al., Phys. Rev. Lett. 122, 153602 (2019).
[above:] We have observed quantum-limited spin transport in strongly interacting two-dimensional Fermi gases. We measure the rate of demagnetization of polarized samples in the presence of a magnetic field gradient, which drives coherence-eroding spin currents. We found that a lower bound on spin diffusivity, of roughly hbar/m, is respected for all interaction strengths, temperatures, and applied gradients accessible in our setup. See Luciuk et al., PRL 118, 130405 (2017).
[above:] We demonstrate fluorescence microscopy of individual fermionic potassium atoms in a 527-nm-period optical lattice. Using electromagnetically induced transparency (EIT) cooling on the 770.1-nm D1 transition of 40K, we find that atoms remain at individual sites of a 0.3-mK-deep lattice, with a 1/e pinning lifetime of 67(9)s, while scattering ~1000 photons per second. The plane to be imaged is isolated using microwave spectroscopy in a magnetic field gradient, and can be chosen at any depth within the three-dimensional lattice. With a similar protocol, we also demonstrate patterned selection within a single lattice plane. High resolution images are acquired using a microscope objective with 0.8 numerical aperture, from which we determine the occupation of lattice sites in the imaging plane with 94(2)% fidelity per atom. Imaging with single-atom sensitivity and addressing with single-site accuracy are key steps towards the search for unconventional superfluidity of fermions in optical lattices, the initialization and characterization of transport and non-equilibrium dynamics, and the observation of magnetic domains. More experimental details may be found in Edge et al., Phys. Rev. A 92, 063406 .
[above:] Observation of two new physical quantities, the p-wave contacts, via time-resolved spectroscopy. We study how correlations in our system develop after "quenching" the atoms into a state with near resonant p-wave interactions. The contacts appear as a unique frequency scaling in the spectra. These observations suggest a new way to characterize any gas with short-ranged p-wave interactions. More experimental details can be found in Luciuk et al., Nat. Phys. (2016) with a detailed theoretical treatment Yu et al., PRL 115, 135304 (2015).
[ ... see old highlights ...]
02.August.2019: Our dynamical phase transition paper has been published in Science Advances.
17.June.2019: Rongzi Zhou joins the lab as a visiting undergrad. Welcome!
May.2019: Colin Dale and Frank Corapi join the lab on pre-PhD placements. Welcome!
May.2019: Hanzhen Lin and Daniel Venn join the lab for NSERC USRAs. Welcome!
18.April.2019: Our conductivity paper appears in PRL.
25.March.2019: Kenneth is officially Qualified!
March.2019: Alena Nierhauve starts working in the lab. Welcome!
Oct.2018: Lennard Miller (on exchange from Strathclyde) joins the lab for the year. Welcome!
Sept.2018: Haille and Matt both earn their M.Sc. Congratulations!
July.2018: Ben leaves to start a new lab with a faculty position at YaleNUS in Singnapore. Congratulations, and best of luck!
May.2018: Michael Morris, Bernie Hsu, and Wentao Cui start NSERC summer terms. Welcome!
Sept.2017: Graham Edge is awarded the Dimitris N. Chorafas Foundation award for outstanding doctoral work. Congratulations!
Sept.2017: Kenneth Jackson and Matthew Taylor join the group. Welcome!
20.Jun.2017: Vijin passes qualifying exam
17.Jun.2017: Chris is now Dr. Luciuk
Jun.2017: Stefan moves to Metamaterials Technologies (Halifax) as Senior Optical Engineer
26.May.2017: Peihang passes qualifying exam
25.May.2017: Chris passes departmental PhD exam
03.Apr.2017: Tristan Gauti arrives for a summer internship. Welcome!
31.Mar.2017: 2D spin transport paper appears in PRL.
15.Dec.2016: Graham Edge passes final Ph.D. defence! Next up: postdoc in the Vutha group.
05.Dec.2016: Preprint available describing our observations of quantum-limited spin transport in 2D Fermi gases.
Sept.2016: Ben Olsen and Fudong Wang arrive and join the lab as new post-docs. Welcome!
Sept.2016: Vijin passes MSc exam!
22.Aug.2016: Joseph presenting at Quantum Gases 2016 in Beijing.
11.July.2016: Geyue (Frank) Cai arrives from HKUST for a 10-week internship
2015-16: Five group alum have recently started faculty positions: Brian Shuve (at Harvey Mudd), Swati Singh (at Williams), David Shirokoff (at NJIT), John Simpson (at Waterloo), and Hyun Youk (at TU Delft). Congratulations all !
08.June.2016: Joseph presenting p-wave results at EQM2016 in St. Andrews, Scotland
24-27.May.2016: Group gives three talks and two posters at DAMOP in Providence RI
4.Apr.2016:Masahito Ueda writes Fermi gases: anisotropic universality in Nature News & Views, on our p-wave contact observation.
29.Feb.2016: Fabian Böttcher arrives from Stuttgart for a 3-month visit
22.Feb.2016: Our p-wave contact discovery appears online in Nature Physics!
11.Dec.2015: Fermi gas microscopes chosen as one of the Physics World top ten breakthroughs of 2015
8.Dec.2015: Fermi gas microscope paper chosen as ``Editor's Suggestion'' in PRA
15.Oct.2015: Preprint available on our imaging of individual fermionic atoms in an optical lattice
Sept.2015: Marcius joins XPRIZE as Director of Technical Operations for the Carbon XPRIZE
5-11.Sep.2015: Joseph presenting at the BEC conference in Sant Feliu, Spain
Sep.2015: Vijin, Peihang, and Haille join the group. Welcome!
18.Aug.2015: Rhys passes qualifying exam
17.Aug.2015: p-wave theory paper accepted to PRL
6.Aug.2015: Daniel passes M.Sc exam!
14-19.Jun.2015: Joseph presenting at Gordon conference
8-12.Jun.2015: Joseph, Rhys, and Chris presenting at DAMOP in Columbus
June.2015: Alma joins Morgan Solar, Inc. !
Apr.2015: Graham presenting at YAO in Zurich
Jan.2015: David McKay starts Research Staff position at IBM Watson Labs. Congratulations!
9.Mar.2015: First images of individual 40K atoms in a lattice!
16.Dec.2014: Scott passes M.Sc. exam!
5.Dec.2014: Leggett-Rice paper accepted to PRL!
30.Oct.2014:Preprint available on our observation of the Leggett-Rice effect in a unitary Fermi gas
Oct.2014: Nicolas Zuber arrives from Stuttgart for an 18-week research training visit
Aug.2014: Ryan becomes "Master Day"
Jul.2014: Dylan starts new job at Aerodyne Research; Alma starts postdoc at Sunnybrook.
16.Jun.2014: Dylan defends Ph.D. Congratulations!
22.May.2014: Alma defends Ph.D. Congratulations!
16.May.2014: Our article out in Science!
6.May.2014: Chris passes qualifying exam: now ABD...all-but-dissertation.
Mar.2014: Scott Beattie accepts position at NRC in Ottawa. Congratulations!
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