We report the single-photon-level storage of light tightly guided in an optical nanofiber. Our setup is based on electromagnetically induced transparency for atoms interacting with the evanescent field surrounding the nanofiber.
Developing light-matter interfaces is a crucial capability with unique applications to quantum optics and quantum information networks. In this context, our group focuses on the development of quantum memories in cold, neutral atom clouds, using both electromagnetically-induced transparency (EIT) and DLCZ as interacting schemes [1]. We recently reported for instance the quantum storage of qubits encoded in the orbital angular momentum degree of freedom [2]. Here, we demonstrate [3] for the first time EIT and optical storage at the single-photon level for the light tightly guided by a subwavelength-diameter optical fiber, aka nanofiber. In a nanofiber, the guided photons are highly confined and the majority of the light power travels in the evanescent field outside the glass. This new setting is a promising alternative to free-space focusing, which limits the interaction one can obtain, and provides a novel platform for developing all-fibered quantum networks.
Summary form only given. Developing light-matter interfaces is a crucial capability with unique applications to quantum optics and quantum information networks [1]. In this context, our group focuses on the study of interactions between photons guided by nanoscale waveguides and arrays of trapped atoms. Nanoscale waveguides offer a compelling platform because of the tight transverse confinement of the propagating light, the strong photon-atom coupling in single pass, and the potential long-range atom-atom interaction mediated by the guided photons [2]. Our platform, based on an optical nanofiber, already allowed the demonstration of an all-fibered optical memory with a storage and retrieval efficiency ri = 10% and a high SNR at the single photon level [3]. Then, by using an optical lattice in the evanescent field surrounding the nanofiber with a period close to commensurate with the resonant wavelength, we demonstrated large Bragg reflection by the 1D array of trapped atoms [4].
Tapered optical fibers with a nanofiber waist are versatile tools for interfacing light and matter. In this context, laser-cooled atoms trapped in the evanescent field surrounding the optical nanofiber are of particular interest: They exhibit both long ground-state coherence times and efficient coupling to fiber-guided fields. Here, we demonstrate electromagnetically induced transparency, slow light, and the storage of fiber-guided optical pulses in an ensemble of cold atoms trapped in a nanofiber-based optical lattice. We measure a slow-down of light pulses to group velocities of 50 m/s. Moreover, we store optical pulses at the single photon level and retrieve them on demand in the fiber after 2 microseconds with an overall efficiency of (3.0 +/- 0.4) %. Our results show that nanofiber-based interfaces for cold atoms have great potential for the realization of building blocks for future optical quantum information networks.
Optical nanofibers provide a versatile platform for exploring strong light-matter interactions at the single-quantum level, a central goal of quantum optics. Their subwavelength diameter supports tightly confined guided modes with strong evanescent fields, enabling efficient coupling between photons and nearby atoms. By incorporating fiber Bragg gratings, nanofibers can form fully fiber-integrated high-finesse cavities, combining strong atom-photon coupling with efficient and low-loss optical input-output interfacing in the setting of cavity quantum electrodynamics (QED). In parallel, nanofiber systems naturally realize waveguide QED, where atoms interact strongly with propagating photons in a one-dimensional geometry. In this review, we introduce the underlying physical principles, summarize key experimental techniques and representative phenomena, and discuss prospects for applications in quantum information processing, quantum networks, and related quantum technologies.
Abstract Recent advances in the coherent control of single quanta of light, photons , is a topic of prime interest, and is discussed under the banner of quantum photonics . In the last decade, the subwavelength diameter waist of a tapered optical fiber, referred to as an optical nanofiber , has opened promising new avenues in the field of quantum optics, paving the way toward a versatile platform for quantum photonics applications. The key feature of the technique is that the optical field can be tightly confined in the transverse direction while propagating over long distances as a guided mode and enabling strong interaction with the surrounding medium in the evanescent region. This feature has led to surprising possibilities to manipulate single atoms and fiber-guided photons, e.g. the efficient channeling of emission from single atoms and solid-state quantum emitters into the fiber-guided modes, high optical depth with a few atoms around the nanofiber, trapping atoms around a nanofiber, and atomic memories for fiber-guided photons. Furthermore, implementing a moderate longitudinal confinement in nanofiber cavities has enabled the strong coupling regime of cavity quantum electrodynamics to be reached, and the long-range dipole–dipole interaction between quantum emitters mediated by the nanofiber offers a platform for quantum nonlinear optics with an ensemble of atoms. In addition, the presence of a longitudinal component of the guided field has led to unique capabilities for chiral light–matter interactions on nanofibers. In this article, we review the key developments of the nanofiber technology toward a vision for quantum photonics on an all-fiber interface.
We report the experimental observation of slow-light and coherent storage in a setting where light is tightly confined in the transverse directions. By interfacing a tapered optical nanofiber with a cold atomic ensemble, electromagnetically induced transparency is observed and light pulses at the single-photon level are stored in and retrieved from the atomic medium. The decay of efficiency with storage time is also measured and related to concurrent decoherence mechanisms. Collapses and revivals can be additionally controlled by an applied magnetic field. Our results based on subdiffraction-limited optical mode interacting with atoms via the strong evanescent field demonstrate an alternative to free-space focusing and a novel capability for information storage in an all-fibered quantum network.