Atom Interferometer in Hollow-core Photonic Crystal Fibre

In combination with hollow-core photonic crystal fibers, we are exploring the use of an optically guided matter-wave inside the fibers for precise inertial sensing, demonstration of non-classical phenomena, and tests of fundamental physics through atom interferometric techniques. Progressing over the past two decades, atom interferometry techniques have reached unprecedented sensitivity. However, due to the light diffraction when interrogating atoms, free space matter-wave interferometry has also reached its limitation. Trapping atoms in a well-defined optical wave guide is a promising route to further improve the interferometer performance. We have loaded about 1 million of 85Rb atoms at a temperature of tens of micro-Kelvin into a hollow-core photonic crystal fiber and demonstrated atomic interference inside the fiber. The wave packets in the coherent quantum superposition state are separated by 40 times of the wave packets size.

OD vs probe time graph
OD versus probe time with push beams on and off. The probe time at tp = 0 corresponds to the time of releasing atoms from the MOT. Atoms are reloaded for each data point, and the optical dipole trap is off when the probe field is on. The error bars represent the standard error of five experimental runs. The inset shows an image of the cross section of the hollow-core fiber used in the experiment.
image showing the loading process of Rubidium into hollow-core photonic crystal fiber.
The loading process of the Rubidium atomic cloud into a hollow-core photonic crystal fiber.
Phase shift versus time T. Each data point is extracted from the fitting of a sinusoidal function with the Raman beam direction along and opposite to the gravity. The zero point in the y-axis corresponds to the phase at T = 4 μs. The error bars are the uncertainty of the sinusoidal fits.
a closeup image of the loading of rubidium onto the fiber.
A close up image of the Rubidium atomic cloud suspended on top of the tip of a hollow-core photonic crystal fiber.