We describe the classical and quantum two dimensional nonlinear dynamics of large blue-detuned eveanescent-wave guiding cold atoms in hollow fiber. We show that chaotic dynamics exists for classic dynamics, when the intensity of the beam is periodically modulated. The two dimensional distributions of atoms in (x,y) plane are simulated. We show that the atoms will accumulate on several annular regions when the system enters a regime of global chaos. Our simulation shows that, when the atomic flux is very small, a similar distribution will be obtained if we detect the atomic distribution once each the modualtion period and integrate the signals.
For quantum dynamics, quantum collapses and revivals appear . For periodically modulated optical potential, the variance of atomic position will be supressed compared to the no modulation case. The atomic angular momentum will influnce the evolution of wave function in two dimensional quantum system of hollow fiber.
We demonstrate theoretically and experimentally a high level of control of the four-wave mixing process in an inert gas filled inhibited-coupling guiding hollow-core photonic crystal fiber in order to generate photon pairs. The specific multiple-branch dispersion profile in such fibers allows both entangled and separable bi-photon states to be produced. By controlling the choice of gas, its pressure and the fiber length, we experimentally generate various joint spectral intensity profiles in a stimulated regime that is transferable to the spontaneous regime. The generated profiles cover both s…
We suggest using a two-color evanescent light field around a subwavelength-diameter fiber to trap and guide atoms. The optical fiber carries a red-detuned light and a blue-detuned light, with both modes far from resonance. When both input light fields are circularly polarized, a set of trapping minima of the total potential in the transverse plane is formed as a ring around the fiber. This design allows confinement of atoms to a cylindrical shell around the fiber. When one or both of the input light fields are linearly polarized, the total potential has two local minimum points in the transver…
We calculate the optical potentials, i.e. the light shifts, of the ground and excited states of atomic cesium in a two-color evanescent field around a subwavelength-diameter fiber. We show that the light shifts of the $6S_{1/2}\leftrightarrow 6P_{3/2}$ transitions can be minimized by tuning one trapping light to around 934.5 nm in wavelength (central red-detuned magic wavelength) and the other light to around 685.5 nm in wavelength (central blue-detuned magic wavelength). The simultaneous use of the red- and blue-detuned magic wavelengths allows state-insensitive two-color trapping and guiding…
We demonstrate a fiber-optical switch that is activated at tiny energies corresponding to few hundred optical photons per pulse. This is achieved by simultaneously confining both photons and a small laser-cooled ensemble of atoms inside the microscopic hollow core of a single-mode photonic-crystal fiber and using quantum optical techniques for generating slow light propagation and large nonlinear interaction between light beams.
By performing quantum-noise-limited optical heterodyne detection, we observe polarization noise in light after propagation through a hollow-core photonic crystal fiber (PCF). We compare the noise spectrum to the one of a standard fiber and find an increase of noise even though the light is mainly transmitted in air in a hollow-core PCF. Combined with our simulation of the acoustic vibrational modes in the hollow-core PCF, we are offering an explanation for the polarization noise with a variation of guided acoustic wave Brillouin scattering (GAWBS). Here, instead of modulating the strain in the…
We report on a versatile, highly controllable hybrid cold Rydberg atom fiber interface, based on laser cooled atoms transported into a hollow core Kagomé crystal fiber. Our experiments are the first to 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. T…
We report on the first observation of stationary light pulses and narrowband light storage inside a hollow-core photonic crystal fiber. Laser-cooled atoms were first loaded into the fiber core providing strong light-matter coupling. Light pulses were then stored in a collective atomic excitation using a single control laser beam. By applying a second counterpropagating control beam, a light pulse could be brought to a standstill. Our work paves the way towards the creation of strongly-correlated many-body systems with photons and applications in the field of quantum information processing.
An experimental platform operating at the level of individual quanta and providing strong light-matter coupling is a key requirement for quantum information processing. We report on narrowband light storage and retrieval as well as stationary light, based on electromagnetically induced transparency, for weak coherent light pulses down to the single-photon level with a signal-to-noise ratio of 59. The experiments were carried out with laser-cooled atoms loaded into a hollow-core photonic crystal fiber to provide strong light-matter coupling, thereby demonstrating the prospects for future quantu…
We report on the observation of strong transmission line shape alterations in a cold-atom hollow-core fiber interface. We show that this can lead to a significant overestimation of the assigned resonant optical depth for high atom densities. By modeling light beam propagation in an inhomogeneous dispersive medium, we attribute the observations to micro lensing in the atomic ensemble in combination with the mode selection of the atom-fiber interface. The approach is confirmed by studies of Rydberg EIT line shapes.
We describe the loading of laser-cooled rubidium atoms into a single-mode hollow-core photonic-crystal fiber. Inside the fiber, the atoms are confined by a far-detuned optical trap and probed by a weak resonant beam. We describe different loading methods and compare their trade-offs in terms of implementation complexity and atom-loading efficiency. The most efficient procedure results in loading of ~30,000 rubidium atoms, which creates a medium with optical depth ~180 inside the fiber. Compared to our earlier study this represents a six-fold increase in maximum achieved optical depth in this s…
We report the radiation trapping effect inside a hollow-core photonic crystal fiber (PCF). An optical dipole trap was used to load and confine the atoms in the PCF without contacting the wall of the fiber. The transmission of a probe light propagating through the PCF was studied experimentally and theoretically. With the experimental results and theoretical predictions, we conclude that the radiation trapping can play a significant role and should be taken into account in the spectroscopic measurements inside the PCF.
Coherent interactions between electromagnetic and matter waves lie at the heart of quantum science and technology. However, the diffraction nature of light has limited the scalability of many atom-light based quantum systems. Here, we use the optical fields in a hollow-core photonic crystal fiber to spatially split, reflect, and recombine a coherent superposition state of free-falling 85Rb atoms to realize an inertia-sensitive atom interferometer. The interferometer operates over a diffraction-free distance, and the contrasts and phase shifts at different distances agree within one standard er…
We report on an efficient and highly controlled cold atom hollow-core fiber interface, suitable for quantum simulation, information, and sensing. The main focus of this manuscript is a detailed study on transporting cold atoms into the fiber using an optical conveyor belt. We discuss how we can precisely control the spatial, thermal, and temporal distribution of the atoms by, e.g., varying the speed at which the atoms are transported or adjusting the depth of the transport potential according to the atomic position. We characterize the transport of atoms to the fiber tip for these different pa…
We show that a pinning quantum phase transition for photons could be observed in a hollow-core one-dimensional fiber loaded with a cold atomic gas. Utilizing the strong light confinement in the fiber, a range of different strongly correlated polaritonic and photonic states, corresponding to both strong and weak interactions can be created and probed. The key ingredient is the creation of a tunable effective lattice potential acting on the interacting polaritonic gas which is possible by slightly modulating the atomic density. We analyze the relevant phase diagram corresponding to the realizabl…
We theoretically investigate the process of coupling cold atoms into the core of a hollow-core photonic-crystal optical fiber using a blue-detuned Laguerre-Gaussian beam. In contrast to the use of a red-detuned Gaussian beam to couple the atoms, the blue-detuned hollow-beam can confine cold atoms to the darkest regions of the beam thereby minimizing shifts in the internal states and making the guide highly robust to heating effects. This single optical beam is used as both a funnel and guide to maximize the number of atoms into the fiber. In the proposed experiment, Rb atoms are loaded into a …
We demonstrate an atomic Faraday dichroic beam splitter suitable to spatially separate signal and idler fields from pump degenerate four-wave mixing in an atomic source. By rotating the plane of polarization of one mode $90^{\circ}$ with respect to the other, a subsequent polarizing beam splitter separates the two frequencies, which differ by only 13.6 GHz, and achieves a suppression of $(-26.3\pm0.1)$ and $(-21.2\pm0.1)$ dB in the two outputs, with a corresponding transmission of 97 and 99 %. This technique avoids the need to use spatial separation of four-wave mixing modes and thus opens the…
High-rate continuous-variable quantum key distribution coexisting with Tb/s coherent classical transmission in hollow-core fiber
Huazhong University of Science and Technology（华中科技大学）；Yangtze Optica Fibre and Cable Joint Stock Limited Company (YOFC)（长飞光纤光缆股份有限公司）；Chalmers University of Technology（查尔姆斯理工大学）；University of Florence（佛罗伦萨大学）
Polarization Purity and Dispersion Characteristics of Nested Antiresonant Nodeless Hollow-Core Optical Fiber at Near- and Short-wave-IR Wavelengths for Quantum Communications
