Er simulator

Superradiant in a dipolar BEC

Observation of superradiance in a phase fluctuating dipoar Bose-Einstein condensate

arXiv:221001586 (2022) [preprint]

Despite the extensive study of matter-wave superradiance in a Bose-Einstein condensate (BEC) using its unique coherence property, the controllability of superradiant process has remained limited in the previous studies exploiting a phase-coherent condensate with isotropic contact interactions. Here, we combine tunable s-wave scattering with dipolar interactions in a BEC of Er atoms wherein the asymmetry and threshold of superradiance are independently controlled. By changing the s-wave scattering length near the Feshbach resonance, we tune the superradiance threshold with increasing phase fluctuations. In contrast to collective light scattering from a condensate only with contact interactions, we observe an asymmetric superradiant peak in a dipolar BEC by changing the direction of external magnetic field. This results from the anisotropic excitation spectrum induced by the dipole-dipole interaction. Our observation is expected to bring forth unprecedented application of matter-wave optics leading to controlled emission of matter wave.

BEC of erbium atoms

Apparatus for producing a 168Er Bose-Einstein condensate 

Journal of Korean Physical Society, 82 901 (2023)  published online in 2022  [Journal]

We report on the experimental realization of Bose–Einstein condensate (BEC) of Er atoms with tunable s-wave and dipolar interactions in a newly developed apparatus. Here, we describe an efficient method for trapping slow Er atoms in a narrow linewidth magneto-optical trap. After evaporative cooling in a crossed optical dipole trap, we achieve a spin-polarized condensate of  atoms at the temperature of  50 nK. The efficient preparation of ultracold erbium bosons offers new possibilities for studying many-body physics with dipolar interactions.

Laser stabilization for 401nm lights

Active control of a diode laser with injection locking using a laser line filter

Review of Scientific Instruments 92 123005 (2021) [Journal]  

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 active feedback to the injected laser. Our method is intrinsically cost-effective and does not require bulky devices, such as Fabry–Pérot interferometers or wavemeters, to actively stabilize the diode laser. Based on the 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.

Efficient two-stage slowing for Erbium quantum gases 

Efficient production of a narrow-line erbium magneto-optical trap with two-stage slowing

Phys. Rev. A 102 013319 (2020) [Journal] 

We develope a efficient method for slowing erbium atoms by implementing a pair of angled slowing beams with respect to the Zeeman slower axis.  The second-stage slowing beams further slow down atoms exiting from the Zeeman slowe and enable the narrow-line MOT to trap atoms exiting from the Zeeman slower with higher velocity. This scheme is particularly useful when the Zeeman slower is at low optical power without the conventional transverse cooling between an oven and a Zeeman slower.