611 research outputs found
Stabilizer formalism for generalized concatenated quantum codes
The concept of generalized concatenated quantum codes (GCQC) provides a
systematic way for constructing good quantum codes from short component codes.
We introduce a stabilizer formalism for GCQCs, which is achieved by defining
quantum coset codes. This formalism offers a new perspective for GCQCs and
enables us to derive a lower bound on the code distance of stabilizer GCQCs
from component codes parameters,for both non-degenerate and degenerate
component codes. Our formalism also shows how to exploit the error-correcting
capacity of component codes to design good GCQCs efficiently.Comment: 5 pages, 2 figures, International Symposium on Information Theory, 7
July - 12 July 2013, Istanbul, Turke
High-Q exterior whispering gallery modes in a metal-coated microresonator
We propose a kind of plasmonic whispering gallery modes highly localized on
the exterior surface of a metal-coated microresonator. This exterior (EX)
surface mode possesses high quality factors at room temperature, and can be
efficiently excited by a tapered fiber. The EX mode can couple to an interior
(IN) mode and this coupling produces a strong anti-crossing behavior, which not
only allows conversion of IN to EX modes, but also forms a long-lived
anti-symmetric mode. As a potential application, the EX mode could be used for
a biosensor with a sensitivity high up to 500 nm per refraction index unit, a
large figure of merit, and a wide detection range
Cavity QED treatment of scattering-induced efficient free-space excitation and collection in high-Q whispering-gallery microcavities
Whispering-gallery microcavity laser possesses ultralow threshold, whereas
convenient free-space optical excitation and collection suffer from low
efficiencies due to its rotational symmetry. Here we analytically study a
three-dimensional microsphere coupled to a nano-sized scatterer in the
framework of quantum optics. It is found that the scatterer is capable of
coupling light in and out of the whispering-gallery modes (WGMs) without
seriously degrading their high-Q properties, while the microsphere itself plays
the role of a lens to focus the input beam on the scatterer and vice versa. Our
analytical results show that (1) the high-Q WGMs can be excited in free space,
and (2) over 50% of the microcavity laser emission can be collected within less
than . This coupling system holds great potential for low
threshold microlasers free of external couplers.Comment: 10 pages, 8 figure
Strongly enhanced light-matter interaction in a hybrid photonic-plasmonic resonator
We propose a hybrid photonic-plasmonic resonant structure which consists of a
metal nanoparticle (MNP) and a whispering gallery mode (WGM) microcavity. It is
found that the hybrid mode enables a strong interaction between the light and
matter, and the single-atom cooperativity is enhanced by more than two orders
of magnitude compared to that in a bare WGM microcavity. This remarkable
improvement originates from two aspects: (1) the MNP offers a highly enhanced
local field in the vicinity of an emitter, and (2), surprisingly, the
high-\textit{Q} property of WGMs can be maintained in the presence of the MNP.
Thus the present system has great advantages over a single microcavity or a
single MNP, and holds great potential in quantum optics, nonlinear optics and
highly sensitive biosening.Comment: 5 pages, 4 figure
Temperature-insensitive detection of low-concentration nanoparticles using a functionalized high-Q microcavity
The ability to detect nanoparticles in extremely dilute solutions in the presence of environmental noise is crucial for biosensing applications. In this paper we propose a scheme for detecting target nanoparticles through their scattering effects in a high-Q whispering gallery microcavity. The detection signal, defined as the total linewidth broadening of the two new split modes that appear upon nanoparticle adsorption, is highly sensitive and proportional to the nanoparticle concentration. Furthermore, this new method of detection eliminates the requirement for strict temperature control and is capable of distinguishing the signal from the biorecognitions (e.g., antibodies) initially attached to the resonator and that from the target nanoparticles (e.g., antigens)
On chip, high-sensitivity thermal sensor based on high-Q polydimethylsiloxane-coated microresonator
A high-sensitivity thermal sensing is demonstrated by coating a layer of
polydimethylsiloxane (PDMS) on the surface of a silica toroidal microresonator
on a silicon wafer. Possessing high-Q whispering gallery modes (WGMs), the
PDMS-coated microresonator is highly sensitive to the temperature change of the
surroundings. We find that, when the PDMS layer becomes thicker, the WGM
experiences a transition from red- to blue-shift with temperature increasing
due to the negative thermal-optic coefficient of PDMS. The measured sensitivity
(0.151 nm/K) is one order of magnitude higher than pure silica microcavity
sensors. The ultra-high resolution of the thermal sensor is also analyzed to
reach 10-4 K
Coupling of a Single Diamond Nanocrystal to a Whispering-Gallery Microcavity: Photon Transportation Benefitting from Rayleigh Scattering
We study the Rayleigh scattering induced by a diamond nanocrystal in a
whispering-gallery-microcavity--waveguide coupling system, and find that it
plays a significant role in the photon transportation. On one hand, this study
provides a new insight into future solid-state cavity quantum electrodynamics
toward strong coupling physics. On the other hand, benefitting from this
Rayleigh scattering, novel photon transportation such as dipole induced
transparency and strong photon antibunching can occur simultaneously. As
potential applications, this system can function as high-efficiency photon
turnstiles. In contrast to [B. Dayan \textit{et al.}, \textrm{Science}
\textbf{319},1062 (2008)], the photon turnstiles proposed here are highly
immune to nanocrystal's azimuthal position.Comment: 4 pages, 4 figure
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