268 research outputs found
Multi-level cascaded electromagnetically induced transparency in cold atoms using an optical nanofibre interface
Ultrathin optical fibres integrated into cold atom setups are proving to be
ideal building blocks for atom-photon hybrid quantum networks. Such optical
nanofibres (ONF) can be used for the demonstration of nonlinear optics and
quantum interference phenomena in atomic media. Here, we report on the
observation of multilevel cascaded electromagnetically induced transparency
(EIT) using an optical nanofibre to interface cold Rb atoms through the
intense evanescent fields that can be achieved at ultralow probe and coupling
powers. Both the probe (at 780 nm) and the coupling (at 776 nm) beams propagate
through the nanofibre. The observed multipeak transparency spectra of the probe
beam could offer a method for simultaneously slowing down multiple wavelengths
in an optical nanofibre or for generating ONF-guided entangled beams, showing
the potential of such an atom-nanofibre system for quantum information. We also
demonstrate all-optical-switching in the all fibred system using the obtained
EIT effect.Comment: 11 pages, 6 figure
Plasmonic Optical Tweezers based on Nanostructures: fundamentals, advances and prospects
The ability of metallic nanostructures to confine light at the sub-wavelength
scale enables new perspectives and opportunities in the field of
nanotechnology. Making use of this unique advantage, nano-optical trapping
techniques have been developed to tackle new challenges in a wide range of
areas from biology to quantum optics. In this work, starting from basic
theories, we present a review of research progress in near-field optical
manipulation techniques based on metallic nanostructures, with an emphasis on
some of the most promising advances in molecular technology, such as the
precise control of single-biomolecules. We also provide an overview of possible
future research directions of nano-manipulation techniques.Comment: 19 page
Tailoring a nanofiber for enhanced photon emission and coupling efficiency from single quantum emitters
We present a novel approach to enhance the spontaneous emission rate of
single quantum emitters in an optical nanofiber-based cavity by introducing a
narrow air-filled groove into the cavity. Our results show that the Purcell
factor for single quantum emitters located inside the groove of the
nanofiber-based cavity can be at least six times greater than that for such an
emitter on the fiber surface when using an optimized cavity mode and groove
width. Moreover, the coupling efficiency of single quantum emitters into the
guided mode of this nanofiber-based cavity can reach up to 80 with
only 35 cavity-grating periods. This new system has the potential to act as an
all-fiber platform to realize efficient coupling of photons from single
emitters into an optical fiber for quantum information applications
Efficient Microparticle Trapping with Plasmonic Annular Apertures Arrays
In this work, we demonstrate trapping of microparticles using a plasmonic
tweezers based on arrays of annular apertures. The transmission spectra and the
E- field distribution are simulated to calibrate the arrays. Theoretically, we
observe sharp peaks in the transmission spectra for dipole resonance modes and
these are redshifted as the size of the annular aperture is reduced. We also
expect an absorption peak at approximately 1,115 um for the localised plasmon
resonance. Using a laser frequency between the two resonances, multiple
plasmonic hotspots are created and used to trap and transport micron and
submicron particles. Experimentally, we demonstrate trapping of individual 0.5
um and 1 um polystyrene particles and particle transportation over the surface
of the annular apertures using less than 1.5 mW/um2 incident laser intensity at
980 nm
Autler-Townes splitting via frequency upconversion at ultra-low power levels in cold Rb atoms using an optical nanofiber
The tight confinement of the evanescent light field around the waist of an
optical nanofiber makes it a suitable tool for studying nonlinear optics in
atomic media. Here, we use an optical nanofiber embedded in a cloud of
laser-cooled 87Rb for near-infrared frequency upconversion via a resonant
two-photon process. Sub-nW powers of the two-photon beams, at 780 nm and 776
nm, co-propagate through the optical nanofiber and generation of 420 nm photons
is observed. A measurement of the Autler-Townes splitting provides a direct
measurement of the Rabi frequency of the 780 nm transition. Through this
method, dephasings of the system can be studied. In this work, the optical
nanofiber is used as an excitation and detection tool simultaneously, and it
highlights some of the advantages of using fully fibered systems for nonlinear
optics with atoms
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