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Kyu Min Shim

Publications and source records attributed to Kyu Min Shim.

2 recordsLinked to original sources

Sequential Test for Practical Significance: Truncated Mixture Sequential Probability Ratio Test

We present a sequential testing method to identify a practically significant effect. We build on the existing mixture sequential probability ratio test (mSPRT) that can sequentially test for a non-zero treatment effect by using a truncated mixing distribution to differentiate between effects that are large enough to merit a real world action versus that are non-zero but too small to merit a real world action. We verify the Type-I error control of our method theoretically and empirically. We also extend this idea to sequentially test for one-sided practical significance such as non-inferiority testing, and show that we may still effectively control the Type-I error rate.

stat.ME

Laser mode-hopping assisted all-optical single beam pulsed atomic magnetometer

We demonstrate an all-optical single beam pulsed atomic magnetometer assisted by laser mode-hopping in a distributed Bragg reflector (DBR) laser. We implement a temporal sequence of the laser current, with sinusoidal current modulation including the laser mode-hop current for synchronous optical pumping, and a following constant current for paramagnetic Faraday rotation measurements, to probe the free induction decay (FID) of transverse $^{87}$Rb spin polarization. Repetitive sudden frequency shifts of 20 GHz around the pressure-broadened $^{87}$Rb spectra, originating from laser mode-hopping, enable discontinuous optical pumping modulation with a large depth, which enhances transverse spin polarization. We achieved a sensitivity of 0.6 pT/Hz$^{1/2}$ in a magnetic field of 27 $μ$T, mainly limited by the photon-shot-noise and the magnetic field noise induced by the current noise in the current supply for driving the bias magnetic field coil. The Cramer-Rao lower bound (CRLB) of the sensitivity due to the non-magnetic noise such as photon shot-noise is 131 fT/Hz$^{1/2}$. Our approach based on laser mode-hopping can be applied for the miniaturization of all-optical atomic magnetometers with sub-pT/Hz$^{1/2}$ sensitivities.

physics.atom-ph