2,340 research outputs found
Single-photon nonlinear optics with Kerr-type nanostructured materials
We employ a quantum theory of the nonlinear optical response from an actual
solid-state material possessing an intrinsic bulk contribution to the
third-order nonlinear susceptibility (Kerr-type nonlinearity), which can be
arbitrarily nanostructured to achieve diffraction-limited electromagnetic field
confinement. By calculating the zero-time delay second-order correlation of the
cavity field, we set the conditions for using semiconductor or insulating
materials with near-infrared energy gaps as efficient means to obtain
single-photon nonlinear behavior in prospective solid-state integrated devices,
alternative to ideal sources of quantum radiation such as, e.g., single
two-level emitters.Comment: 5 pages, three figure
Unconventional photon blockade in doubly resonant microcavities with second-order nonlinearity
It is shown that non-centrosymmetric materials with bulk second-order
nonlinear susceptibility can be used to generate strongly antibunched radiation
at an arbitrary wavelength, solely determined by the resonant behavior of
suitably engineered coupled microcavities. The proposed scheme exploits the
unconventional photon blockade of a coherent driving field at the input of a
coupled cavity system, where one of the two cavities is engineered to resonate
at both fundamental and second harmonic frequencies, respectively. Remarkably,
the unconventional blockade mechanism occurs with reasonably low quality
factors at both harmonics, and does not require a sharp doubly-resonant
condition for the second cavity, thus proving its feasibility with current
semiconductor technology
Topological aspects in the photonic crystal analog of single-particle transport in quantum Hall systems
We present a perturbative approach to derive the semiclassical equations of
motion for the two-dimensional electron dynamics under the simultaneous
presence of static electric and magnetic fields, where the quantized Hall
conductance is known to be directly related to the topological properties of
translationally invariant magnetic Bloch bands. In close analogy to this
approach, we develop a perturbative theory of two-dimensional photonic
transport in gyrotropic photonic crystals to mimic the physics of quantum Hall
systems. We show that a suitable permittivity grading of a gyrotropic photonic
crystal is able to simulate the simultaneous presence of analog electric and
magnetic field forces for photons, and we rigorously derive the
topology-related term in the equation for the electromagnetic energy velocity
that is formally equivalent to the electronic case. A possible experimental
configuration is proposed to observe a bulk photonic analog to the quantum Hall
physics in graded gyromagnetic photonic crystals.Comment: to be published in Phys Rev
Probing physics students' conceptual knowledge structures through term association
Traditional tests are not effective tools for diagnosing the content and
structure of students' knowledge of physics. As a possible alternative, a set
of term-association tasks (the "ConMap" tasks) was developed to probe the
interconnections within students' store of conceptual knowledge. The tasks have
students respond spontaneously to a term or problem or topic area with a
sequence of associated terms; the response terms and timeof- entry data are
captured. The tasks were tried on introductory physics students, and
preliminary investigations show that the tasks are capable of eliciting
information about the stucture of their knowledge. Specifically, data gathered
through the tasks is similar to that produced by a hand-drawn concept map task,
has measures that correlate with inclass exam performance, and is sensitive to
learning produced by topic coverage in class. Although the results are
preliminary and only suggestive, the tasks warrant further study as
student-knowledge assessment instruments and sources of experimental data for
cognitive modeling efforts.Comment: 31 pages plus 2 tables and 8 figure
Optimal antibunching in passive photonic devices based on coupled nonlinear resonators
We propose the use of weakly nonlinear passive materials for prospective
applications in integrated quantum photonics. It is shown that strong
enhancement of native optical nonlinearities by electromagnetic field
confinement in photonic crystal resonators can lead to single-photon generation
only exploiting the quantum interference of two coupled modes and the effect of
photon blockade under resonant coherent driving. For realistic system
parameters in state of the art microcavities, the efficiency of such
single-photon source is theoretically characterized by means of the
second-order correlation function at zero time delay as the main figure of
merit, where major sources of loss and decoherence are taken into account
within a standard master equation treatment. These results could stimulate the
realization of integrated quantum photonic devices based on non-resonant
material media, fully integrable with current semiconductor technology and
matching the relevant telecom band operational wavelengths, as an alternative
to single-photon nonlinear devices based on cavity-QED with artificial atoms or
single atomic-like emitters.Comment: to appear in New J. Physic
An all-silicon single-photon source by unconventional photon blockade
The lack of suitable quantum emitters in silicon and silicon-based materials
has prevented the realization of room temperature, compact, stable, and
integrated sources of single photons in a scalable on-chip architecture, so
far. Current approaches rely on exploiting the enhanced optical nonlinearity of
silicon through light confinement or slow-light propagation, and are based on
parametric processes that typically require substantial input energy and
spatial footprint to reach a reasonable output yield. Here we propose an
alternative all-silicon device that employs a different paradigm, namely the
interplay between quantum interference and the third-order intrinsic
nonlinearity in a system of two coupled optical cavities. This unconventional
photon blockade allows to produce antibunched radiation at extremely low input
powers. We demonstrate a reliable protocol to operate this mechanism under
pulsed optical excitation, as required for device applications, thus
implementing a true single-photon source. We finally propose a state-of-art
implementation in a standard silicon-based photonic crystal integrated circuit
that outperforms existing parametric devices either in input power or footprint
area.Comment: 5 pages, 3 figures + Supplementary information (3 pages, 2 figures
Quantum theory of photonic crystal polaritons
We formulate a full quantum mechanical theory of the interaction between
electromagnetic modes in photonic crystal slabs and quantum well excitons
embedded in the photonic structure. We apply the formalism to a high index
dielectric layer with a periodic patterning suspended in air. The strong
coupling between electromagnetic modes lying above the cladding light line and
exciton center of mass eigenfunctions manifests itself with the typical
anticrossing behavior. The resulting band dispersion corresponds to the
quasi-particles coming from the mixing of electromagnetic and material
excitations, which we call photonic crystal polaritons. We compare the results
obtained by using the quantum theory to variable angle reflectance spectra
coming from a scattering matrix approach, and we find very good quantitative
agreement.Comment: Proceedings of the "8th Conference on Optics of Excitons in Confined
Systems" (OECS-8), 15-17 September 2003, Lecce (Italy
A proposed study of multiple scattering through clouds up to 1 THz
A rigorous computation of the electromagnetic field scattered from an atmospheric liquid water cloud is proposed. The recent development of a fast recursive algorithm (Chew algorithm) for computing the fields scattered from numerous scatterers now makes a rigorous computation feasible. A method is presented for adapting this algorithm to a general case where there are an extremely large number of scatterers. It is also proposed to extend a new binary PAM channel coding technique (El-Khamy coding) to multiple levels with non-square pulse shapes. The Chew algorithm can be used to compute the transfer function of a cloud channel. Then the transfer function can be used to design an optimum El-Khamy code. In principle, these concepts can be applied directly to the realistic case of a time-varying cloud (adaptive channel coding and adaptive equalization). A brief review is included of some preliminary work on cloud dispersive effects on digital communication signals and on cloud liquid water spectra and correlations
Visible quantum plasmonics from metallic nanodimers
We report theoretical evidence that bulk nonlinear materials weakly
interacting with highly localized plasmonic modes in ultra-sub-wavelength
metallic nanostructures can lead to nonlinear effects at the single plasmon
level in the visible range. In particular, the two-plasmon interaction energy
in such systems is numerically estimated to be comparable with the typical
plasmon linewidths. Localized surface plasmons are thus predicted to exhibit a
purely nonclassical behavior, which can be clearly identified by a
sub-Poissonian second-order correlation in the signal scattered from the
quantized plasmonic field under coherent electromagnetic excitation. We
explicitly show that systems sensitive to single-plasmon scattering can be
experimentally realized by combining electromagnetic confinement in the
interstitial region of gold nanodimers with local infiltration or deposition of
ordinary nonlinear materials. We also propose configurations that could allow
to realistically detect such an effect with state-of-the-art technology,
overcoming the limitations imposed by the short plasmonic lifetime
- …