arXiv subjects

Chuanpeng Hao

Publications and source records attributed to Chuanpeng Hao.

4 recordsLinked to original sources

arXiv2021

Search for topological defect dark matter with a global network of optical magnetometers

Ultralight bosons such as axion-like particles are viable candidates for dark matter. They can form stable, macroscopic field configurations in the form of topological defects that could concentrate the dark matter density into many distinct, compact spatial regions that are small compared to the galaxy but much larger than the Earth. Here, we report the results of a search for transient signals from axion-like particle domain walls with the Global Network of Optical Magnetometers for Exotic physics searches (GNOME). We search the data, consisting of correlated measurements from optical atomic magnetometers located in laboratories all over the world, for patterns of signals propagating through the network consistent with domain walls. The analysis of data from a continuous month-long operation of the GNOME finds no statistically significant signals, thus placing experimental constraints on such dark matter scenarios.

astro-ph.CO↗

arXiv2021

Herriott-Cavity-Assisted Closed-Loop Xe Isotope Comagnetometer

We present in this paper a Herriott-cavity-assisted closed-loop Xe isotope gas comagnetometer. In this system, $^{129}$Xe and $^{131}$Xe atoms are pumped and probed by polarized Rb atoms, and continuously driven by oscillating magnetic fields, whose frequencies are kept on resonance by phase-locked loops (PLLs). Different from other schemes, we use a Herriott cavity to improve the Rb magnetometer sensitivity instead of the parametric modulation method, and this passive method is aimed to improve the system stability while maintaining the sensitivity. This system has demonstrated an angle random walk (ARW) of 0.06 $^\circ$/h$^{1/2}$, and a bias instability of 0.2 $^\circ$/h (0.15 $μ$Hz) with a bandwidth of 1.5 Hz. By adding a closed-loop Rb isotope comagnetometer, we can extend this system to dual simultaneously working comagnetometers sharing the same cell. This extended system has wide applications in precision measurements, where we can simultaneously and independently measure the coupling of anomalous fields with proton spin and neutron spin.

physics.atom-ph↗

arXiv2020

Herriott-cavity-assisted all-optical atomic vector magnetometer

We report an all-optical atomic vector magnetometer using dual Bell-Bloom optical pumping beams in a Rb vapor cell. This vector magnetometer consists of two orthogonal optical pumping beams, with amplitude modulations at $^{85}$Rb and $^{87}$Rb Larmor frequencies respectively. We simultaneously detect atomic signals excited by these two pumping beams using a single probe beam in the third direction, and extract the field orientation information using the phase delays between the modulated atomic signals and the driving beams. By adding a Herriott cavity inside the vapor cell, we improve the magnetometer sensitivity. We study the performance of this vector magnetometer in a magnetic field ranging from 100~mG to 500~mG, and demonstrate a field angle sensitivity better than 10~$μ$rad/Hz$^{1/2}$ above 10~Hz.

physics.atom-ph↗

arXiv2019

Interactions between non-resonant rf fields and atoms with strong spin-exchange collisions

We study the interactions between oscillating non-resonant rf fields and atoms with strong spin-exchange collisions in the presence of a weak dc magnetic field. We find that the atomic Larmor precession frequency shows a new functional form to the rf field parameters when the spin-exchange collision rate is tuned. In the weak rf field amplitude regime, a strong modification of atomic Larmor frequency appears when the spin-exchange rate is comparable to the rf field frequency. This new effect has been neglected before due to its narrow observation window. We compare the experimental results with density matrix calculations, and explain the data by an underdamped oscillator model. When the rf field amplitude is large, there is a minimum atomic gyromagnetic ratio point due to the rf photon dressing, and we find that strong spin-exchange interactions modify the position of such a point.

physics.atom-ph↗