P. Solano

Ultrahigh transmission optical nanofibers

We present a procedure for reproducibly fabricating ultrahigh transmission optical nanofibers (530 nm diameter and 84 mm stretch) with single-mode transmissions of 99.95 ± 0.02%, which represents a loss from tapering of 2.6  ×  10−5 dB/mm when normalized to the entire stretch. When controllably launching the next family of higher-order modes on a fiber with 195 mm stretch, we achieve a transmission of 97.8 ± 2.8%, which has a loss from tapering of 5.0  ×  10−4 dB/mm when normalized to the entire stretch. Our pulling and transfer procedures allow us to fabricate optical nanofibers that transmit more than 400 mW in high vacuum conditions. These results, published as parameters in our previous work, present an improvement of two orders of magnitude less loss for the fundamental mode and an increase in transmission of more than 300% for higher-order modes, when following the protocols detailed in this paper. We extract from the transmission during the pull, the only reported spectrogram of a fundamental mode launch that does not include excitation to asymmetric modes; in stark contrast to a pull in which our cleaning protocol is not followed. These results depend critically on the pre-pull cleanliness and when properly following our pulling protocols are in excellent agreement with simulations.

Super-radiance reveals infinite-range dipole interactions through a nanofiber

Atoms interact with each other through the electromagnetic field, creating collective states that can radiate faster or slower than a single atom, i.e., super- and sub-radiance. When the field is confined to one dimension it enables infinite-range atom–atom interactions. Here we present the first report of infinite-range interactions between macroscopically separated atomic dipoles mediated by an optical waveguide. We use cold 87Rb atoms in the vicinity of a single-mode optical nanofiber (ONF) that coherently exchange evanescently coupled photons through the ONF mode. In particular, we observe super-radiance of a few atoms separated by hundreds of resonant wavelengths. The same platform allows us to measure sub-radiance, a rarely observed effect, presenting a unique tool for quantum optics. This result constitutes a proof of principle for collective behavior of macroscopically delocalized atomic states, a crucial element for new proposals in quantum information and many-body physics.The confinement of electromagnetic field in one dimension is known to allow peculiar effects such as infinite-range coupling. Here, the authors report on the observation of light-mediated infinite-range interactions between spatially separated atomic clouds mediated by an optical nanofiber.

Photon-correlation measurements of atomic-cloud temperature using an optical nanofiber

We develop a temperature measurement of an atomic cloud based on the temporal correlations of fluorescence photons evanescently coupled into an optical nanofiber. We measure the temporal width of the intensity-intensity correlation function due to atomic transit time and use it to determine the most probable atomic velocity, hence the temperature. This technique agrees well with standard time-of-flight temperature measurements. We confirm our results with trajectory simulations.

Chapter Seven - Optical Nanofibers: A New Platform for Quantum Optics

Abstract The development of optical nanofibers (ONFs) and the study and control of their optical properties when coupling atoms to their electromagnetic modes has opened new possibilities for their use in quantum optics and quantum information science. These ONFs offer tight optical mode confinement (less than the wavelength of light) and diffraction-free propagation. The small cross section of the transverse field allows probing of linear and nonlinear spectroscopic features of atoms with exquisitely low power. The cooperativity—the figure of merit in many quantum optics and quantum information systems—tends to be large even for a single atom in the mode of an ONF, as it is proportional to the ratio of the atomic cross section to the electromagnetic mode cross section. ONFs offer a natural bus for information and for inter-atomic coupling through the tightly confined modes, which opens the possibility of one-dimensional many-body physics and interesting quantum interconnection applications. The presence of the ONF modifies the vacuum field, affecting the spontaneous emission rates of atoms in its vicinity. The high gradients in the radial intensity naturally provide the potential for trapping atoms around the ONF, allowing the creation of one-dimensional arrays of atoms. The same radial gradient in the transverse direction of the field is responsible for the existence of a large longitudinal component that introduces the possibility of spin–orbit coupling of the light and the atom, enabling the exploration of chiral quantum optics.

Dynamics of trapped atoms around an optical nanofiber probed through polarimetry

The evanescent field outside an optical nanofiber (ONF) can create optical traps for neutral atoms. We present a non-destructive method to characterize such trapping potentials. An off-resonance linearly polarized probe beam that propagates through the ONF experiences a slow axis of polarization produced by trapped atoms on opposite sides along the ONF. The transverse atomic motion is imprinted onto the probe polarization through the changing atomic index of refraction. By applying a transient impulse, we measure a time-dependent polarization rotation of the probe beam that provides both a rapid and non-destructive measurement of the optical trapping frequencies.

Movable Thin-Film Superconducting Resonator Coupled to a Tapered Optical Microfiber at 15 mK

We have coupled a tapered optical microfiber to a translatable thin-film lumped-element superconducting Al microwave resonator that is cooled to 15 mK. The thin-film resonator has a resonance frequency of 6.14 GHz, a quality factor of Q = 2.59 × 105, and is mounted inside a 3-D Al microwave cavity that provides a well-isolated electromagnetic environment. The microfiber is held fixed while the cavity is mounted on an x-z translation stage that allows the lumped-element resonator and the optical fiber to be brought close to each other (less than 1 mm). When 780-nm light is sent through the fiber, Rayleigh scattering in the fiber causes a weak position-dependent nonuniform illumination of the thin-film resonator, exciting quasiparticles in the superconducting film and thereby affecting its resonance frequency fo and Q. We report on the response of the resonator to both the scattered optical power and the presence of the fibers dielectric, as the thin-film resonator is moved in situ with respect to the fiber.

Realizing quantum advantage without entanglement in single-photon states

We discuss the realization of quantum advantage in a system without quantum entanglement but with non-zero quantum discord. We propose an optical realization of symmetric two-qubit

Subradiance in a nanofiber mode by an ensemble of a few cold Rb atoms

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A hybrid quantum system of atoms trapped on ultrathin optical fibers coupled to superconductors

-states with controllable anti-diagonal elements. This approach does not requires initially entangled states, and it can generate states that have quantum discord, with or without entanglement. We discuss how quantum advantage can be attained in the context of a two-qubit game. We show that when entanglement is not present, the maximum quantum advantage is 1/3 bit. A comparable quantum advantage, 0.311 bit, can be realized with a simplified transaction protocol involving one vs. the three unitary operations needed for the maximum advantage.

Modal interference in optical nanofibers for sub-Angstrom radius sensitivity

The excitation-decay from a few cold Rb atoms into the mode of an optical nanofiber shows two distinct time-scales: First the normal lifetime, and then a longer subradiant lifetime that scales linearly with optical density.