Recent progresses of ultracold two-electron atoms

He, Chengdong; Hajiyev, Elnur; Ren, Zejian; Song, Bo; Jo, Gyu-Boong

doi:10.1088/1361-6455/ab153e

Cited by 19 publications

(10 citation statements)

References 195 publications

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“…Recent advances in the field of ultracold alkaline earthlike atoms [1] have opened new possibilities to investigate fermionic systems with SU(N ) symmetry [2]. The strong decoupling between nuclear spins (I) from electronic angular momentum of these atoms leads to SU(N ) symmetric interactions with N = 1, · · · , 2I + 1 tunable by controlling their nuclear spins.…”

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confidence: 99%

Collective excitations in two-dimensional SU( N ) Fermi gases with tunable spin

Ren

Song

et al. 2020

Phys. Rev. Research

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We measure collective excitations of a harmonically trapped two-dimensional (2D) SU(N ) Fermi gas of 173 Yb confined to a stack of layers formed by a one-dimensional optical lattice. Quadrupole and breathing modes are excited and monitored in the collisionless regime |ln(kF a2D)| 1 with tunable spin. We observe that the quadrupole mode frequency decreases with increasing number of spin component N due to the amplification of the interaction effect by N in agreement with theoretical prediction based on 2D kinetic equations. The breathing mode frequency, however, is twice the dipole oscillation frequency. We also follow the evolution of collective excitations in the dimensional crossover from two to three dimensions and characterize the damping rate of quadrupole and breathing modes for tunable SU(N ) fermions, both of which reveal the enhanced inter-particle collisions for large spin. Our result paves the way to investigate the collective property of 2D SU(N ) Fermi liquid with high spin. * Electronic address: gbjo@ust.hk * Electronic address: gbjo@ust.hk[1] D. Guéry-Odelin, Phys. Rev. A 66 033613 (2002).

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confidence: 99%

Collective excitations in two-dimensional SU( N ) Fermi gases with tunable spin

Ren

Song

et al. 2020

Phys. Rev. Research

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“…Recent developments in cooling non-alkali atoms for quantum simulation [23] and computing [24] require stable highpower laser sources at the wavelength of 400-500 nm. In early experiments, those wavelengths are obtained by frequency doubling infrared lasers because of the limited power of the blue laser diode.…”

Section: Application In Laser Cooling Of Cold Atomsmentioning

confidence: 99%

Active control of a diode laser with injection locking

Chen¹,

Seo²,

Huang³

et al. 2021

Preprint

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We present a simple and effective method to implement an active stabilization of a diode laser with injection locking, which requires minimal user intervenes. The injection locked state of the diode laser is probed by a photodetector, of which sensitivity is enhanced by a narrow laser-line filter. Taking advantage of the characteristic response of laser power to spectral modes from the narrow laser-line filter, we demonstrate that high spectral purity and low intensity noise of the diode can be simultaneously maintained by an active feedback to the injected laser. Our method is intrinsically cost-effective, and does not require bulky devices, such as Fabry-Perot interferometers or wavemeters, to actively stabilize the diode laser. Based on successful implementation of this method in our quantum gas experiments, it is conceivable that our active stabilization will greatly simplify potential applications of injection locking of diode lasers in modularized or integrated optical systems.

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“…In quantum chromodynamics, nuclear interactions are represented by SU(3) symmetry 3 , 4 . In the past decades, developments in cooling and trapping of alkaline-earth-like fermions 5 have opened possibilities to achieve even higher spin symmetries, owing to their distinctive inter-particle interactions, and thus provided ideal platforms to study various SU( N ) fermionic systems 1 , 6 , 7 . Although the role of SU( N ) symmetry has been probed in optical lattices 8 – 15 , the comprehensive characterization of interacting SU( N ) fermions in bulk, wherein the SU( N ) Fermi liquid description is valid, has still remained challenging 16 – 19 .…”

Section: Introductionmentioning

confidence: 99%

Heuristic machinery for thermodynamic studies of SU(N) fermions with neural networks

Zhao

Lee

et al. 2021

Nat Commun

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The power of machine learning (ML) provides the possibility of analyzing experimental measurements with a high sensitivity. However, it still remains challenging to probe the subtle effects directly related to physical observables and to understand physics behind from ordinary experimental data using ML. Here, we introduce a heuristic machinery by using machine learning analysis. We use our machinery to guide the thermodynamic studies in the density profile of ultracold fermions interacting within SU(N) spin symmetry prepared in a quantum simulator. Although such spin symmetry should manifest itself in a many-body wavefunction, it is elusive how the momentum distribution of fermions, the most ordinary measurement, reveals the effect of spin symmetry. Using a fully trained convolutional neural network (NN) with a remarkably high accuracy of ~94% for detection of the spin multiplicity, we investigate how the accuracy depends on various less-pronounced effects with filtered experimental images. Guided by our machinery, we directly measure a thermodynamic compressibility from density fluctuations within the single image. Our machine learning framework shows a potential to validate theoretical descriptions of SU(N) Fermi liquids, and to identify less-pronounced effects even for highly complex quantum matter with minimal prior understanding.

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Recent progresses of ultracold two-electron atoms

Cited by 19 publications

References 195 publications

Collective excitations in two-dimensional SU( N ) Fermi gases with tunable spin

Collective excitations in two-dimensional SU( N ) Fermi gases with tunable spin

Active control of a diode laser with injection locking

Heuristic machinery for thermodynamic studies of SU(N) fermions with neural networks

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