We present an experimental setup for studying strongly nonlinear light-matter interactions using cold atoms inside a hollow core fiber. A Rydberg EIT process can potentially be used to generate strong and tunable effective photon-photon interactions.
Our goal is to study quantum optical phenomena in a strong nonlinear optical system. For this purpose, we create a hollow-core photonic-crystal (HCPC) fiber-based platform that confines photons and atomic ensembles together. This enables strong light-matter interactions which are crucial for implementing optical nonlinearities at single-photon levels [1]. We use an optical dipole trap at cesium's magic wavelength to guide laser cooled cesium atoms into and inside the fiber core. This approach will allow us to perform experiments with the dipole trap continuously on as opposed to the previously reported fiber-loading systems [2,3] in which the dipole trap was rapidly amplitude-modulated to avoid the effect from the spatially dependent AC Stark shift. In this system, we perform experiments on electromagnetically induced transparency (EIT) and demonstrate slow light and all optical switch. We also aim to observe large cross-phase modulation (XPM) using a three-level ladder scheme [4,5]. Lastly, the approaches to integrate a cavity into HCPCFs to increase light-matter interactions, thus the optical nonlinearities, will be described.
Cold atoms confined inside a hollow core photonic crystal fiber with core diameter of a few photon wavelengths are a promising medium for studying nonlinear optical interactions at extremely low light levels. The high electric field intensity per photon, large optical depths, and interaction lengths not limited by diffraction are some of the unique features of this system. We describe recent progress in our experiment that uses a combination of magnetic trapping and a red-detuned optical dipole trap to transfer cold rubidium atoms into the hollow-core fiber. We present data on transfer efficiencies as well as preliminary experiments towards nonlinear optics with few photon pulses.
We report on a versatile, highly controllable hybrid cold Rydberg atom fiber interface, based on laser cooled atoms transported into a hollow-core kagome crystal fiber. Our experiments demonstrate the feasibility of exciting cold Rydberg atoms inside a hollow-core fiber and we study the influence of the fiber on Rydberg electromagnetically induced transparency (EIT) signals. Using a temporally resolved detection method to distinguish between excitation and loss, we observe two different regimes of the Rydberg excitations: one EIT regime and one regime dominated by atom loss. These results are a substantial advancement towards future use of our system for quantum simulation or information.
Cold atoms confined inside a hollow-core photonic-crystal fiber with core diameters of a few photon wavelengths are a promising medium for studying nonlinear optical interactions at extremely low light levels. The high electric field intensity per photon and interaction lengths not limited by diffraction are some of the unique features of this system. Here, we present the results of our first nonlinear optics experiments in this system including a demonstration of an all-optical switch that is activated at energies corresponding to few hundred optical photons per pulse.