30 research outputs found
Deviations from early--time quasilinear behaviour for the quantum kicked rotor near the classical limit
We present experimental measurements of the mean energy for the atom optics
kicked rotor after just two kicks. The energy is found to deviate from the
quasi--linear value for small kicking periods. The observed deviation is
explained by recent theoretical results which include the effect of a
non--uniform initial momentum distribution, previously applied only to systems
using much colder atoms than ours
Position-controlled trapping of nanoparticles and quantum dots on a fiber taper
We investigate numerically and experimentally the properties of a two color
optical fiber taper trap, for which the evanescent field of the modes in the
fiber taper give rise to a three-dimensional trapping potential.
Experimentally, we use the technique to confine colloidal nanoparticles near
the surface of an optical fiber taper, and show that the trapping position of
the particles is adjustable by controlling the relative power of two modes in
the fiber. We also demonstrate a proof of principle application by trapping
quantum dots together with gold nanoparticles in a configuration where the
trapping fields double as the excitation field for the quantum dots. This
scheme will allow the positioning of quantum emitters in order to adjust
coupling to resonators combined with the fiber taper.Comment: 13 pages, 9 figures. Comments welcom
The role of quasi-momentum in the resonant dynamics of the atom-optics kicked rotor
We examine the effect of the initial atomic momentum distribution on the
dynamics of the atom-optical realisation of the quantum kicked rotor. The atoms
are kicked by a pulsed optical lattice, the periodicity of which implies that
quasi-momentum is conserved in the transport problem. We study and compare
experimentally and theoretically two resonant limits of the kicked rotor: in
the vicinity of the quantum resonances and in the semiclassical limit of
vanishing kicking period. It is found that for the same experimental
distribution of quasi-momenta, significant deviations from the kicked rotor
model are induced close to quantum resonance, while close to the classical
resonance (i.e. for small kicking period) the effect of the quasi-momentum
vanishes.Comment: 10 pages, 4 figures, to be published in J. Phys. A, Special Issue on
'Trends in Quantum Chaotic Scattering
Scaling law and stability for a noisy quantum system
We show that a scaling law exists for the near resonant dynamics of cold
kicked atoms in the presence of a randomly fluctuating pulse amplitude.
Analysis of a quasi-classical phase-space representation of the quantum system
with noise allows a new scaling law to be deduced. The scaling law and
associated stability are confirmed by comparison with quantum simulations and
experimental data.Comment: Published in Physical Review E (Rapid Comm.
Nanofiber quantum photonics
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