9,986 research outputs found
Photonic Crystal Microcavities for Classical and Quantum Information Processing
Photonic crystal (PC) cavities enable localization of light into volumes (V) below a cubic optical wavelength (smaller than any other types of optical resonators) with high quality (Q) factors. This permits a strong interaction of light and matter, which is relevant for construction of classical light sources with improved properties (e.g., low threshold lasers) and of nonclassical light sources (such as single and entangled photon sources), which are crucial pieces of hardware of quantum information processing systems. This talk will cover some of our recent experimental results on quantum and classical devices enabled by such interaction, as well as our work on designing such devices and circuits efficiently. We have demonstrated a spontaneous emission rate enhancement by a factor of 8 and suppression by a factor of 5 for a single self-assembled InAs/GaAs quantum dot (QD) embedded in a GaAs photonic crystal cavity and on- and off-resonance with the cavity mode, respectively. A strong localization of optical field in such a nanocavity (experimental Q-factor of 5000 and mode volume below a cubic optical wavelength) with a quantum dot embedded inside is of importance for building single photon sources with improved efficiency, photon indistinguishability, and repetition rate. We have demonstrated a single photon source on demand based on the pulsed excitation of a single quantum dot in such a nanocavity, with pulse duration between 200 ps and 8 ns and with a small multi-photon probability (as small as 5% compared to an attenuated laser of the same intensity). In addition, we have shown that colloidal PbS quantum dots coupled to AlGaAs photonic crystal cavities can be used as an alternative to self-assembled InAs/GaAs quantum dots for construction of cheap and reusable quantum and classical light emitters. We have also demonstrated an improved classical light source-laser, based on coupling of a large number (81) of photonic crystal nanocavities inside a two dimension- - al array. Such a laser exhibits a low lasing threshold (~2.5 mW), operates in a single mode, produces large output powers (greater than 12 muW, which two orders of magnitude larger than a single nanocavity laser), and can be directly modulated as speeds greater than 100 GHz. An inverse problem approach to designing photonic crystal cavities that we have developed enables their rapid optimization in a single step, thereby reducing the cavity optimization time from weeks to hours. We are also pursuing theoretical and experimental work on integration of a number of photonic crystal components (cavities and waveguides) into functional circuits for classical and quantum information processing, including nontrivial two-qubit quantum gates
Enhanced indistinguishability of in-plane single photons by resonance fluorescence on an integrated quantum dot
Integrated quantum light sources in photonic circuits are envisaged as the building blocks of future on-chip architectures for quantum logic operations. While semiconductor quantum dots have been proven to be the highly efficient emitters of quantum light, their interaction with the host material induces spectral decoherence, which decreases the indistinguishability of the emitted photons and limits their functionality. Here, we show that the indistinguishability of in-plane photons can be greatly enhanced by performing resonance fluorescence on a quantum dot coupled to a photonic crystal waveguide. We find that the resonant optical excitation of an exciton state induces an increase in the emitted single-photon coherence by a factor of 15. Two-photon interference experiments reveal a visibility of 0.80 ± 0.03, which is in good agreement with our theoretical model. Combined with the high in-plane light-injection efficiency of photonic crystal waveguides, our results pave the way for the use of this system for the on-chip generation and transmission of highly indistinguishable photons
Electrically injected quantum dot photonic crystal microcavity light emitters and microcavity arrays
Progress in the design, fabrication and characterization of electrically injected photonic-crystal quantum-dot microcavity light sources is described. In the devices investigated in this study, the carriers are injected directly into the photonic crystal microcavity, avoiding the surface state recombination in the photonic crystal pattern. A novel and robust air-bridge contact technology is demonstrated. Spectral linewidths ∼2–3 nm are observed from hexagonal microcavities of varying sizes in the output spectra of oxide-clad microcavity devices. Narrower linewidths ∼1.3 nm are observed from air-clad devices. Results on arrays of densely packed oxide-clad photonic crystal microcavities are also presented. Spectral characteristics of oxide-clad and air-clad devices are compared.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58142/2/d7_9_S09.pd
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Chip-scale Photonic Devices for Light-matter Interactions and Quantum Information Processing
Chip-scale photonic devices such as microdisks, photonic crystal cavities and slow-light photonic crystal waveguides possess strong light localization and long photon lifetime, which will significantly enhance the light-matter interactions and can be used to implement new functionalities for both classical and quantum information processing, optical computation and optical communication in integrated nanophotonic circuits.
This thesis will focus on three topics about light matter interactions and quantum information processing with chip-scale photonic devices, including 1) Design and characterization of asymmetric resonate cavity with radiation directionality and air-slot photonic crystal cavity with ultrasmall effective mode volume, 2) Exciton-photon interactions between quantum dots and photonic crystal devices and non-classical photon source from a single quantum dot, and 3) Quantum controlled phase gate and phase switching based on quantum dots and photonic crystal waveguide.
The first topic is engineered control of radiation directionality and effective mode volume for optical mode in chip-scale silicon micro-/nano-cavities. High quality factor (Q), subwavelength mode volume (V) and controllable radiation directionality are the major properties for optical cavities designs. In Chapter 2, asymmetric resonant cavities with rational caustics are proposed and interior whispering gallery modes in monolithic silicon mesoscopic microcavities are experimentally demonstrated. These microcavities possess unique robustness of cavity quality factor against roughness Rayleigh scattering. In Chapter 3, air-slot mode-gap photonic crystal cavities with quality factor of 10^4 and effective mode volume ~ 0.02 cubic wavelengths are experimentally demonstrated. The origin of the high Q air-slot cavity mode is the mode-gap effect from the slotted photonic crystal waveguide mode with negative dispersion.
The second topic is exciton-photon coupling between quantum dots and twodimensional photonic crystal nanocavities and waveguide localized modes, including Purcell effect in weak coupling regime and vacuum Rabi splitting in strong coupling regime. In Chapter 4, micro-photoluminescence measurements of PbS quantum dots coupled to air-slot mode-gap photonic crystal cavities with potentially high qualify factor and small effective mode volume are presented. Purcell factor due to ultrahigh Q/V ratios are critical for applications in non-classical photon sources, cavity QED, nonlinear optics and sensing. In Chapter 5, the observation of subpoisson photon statistics from a single InAs quantum dot emission is presented from both continuous wave and pulsed Hanbury Brown and Twiss measurement. Furthermore, strong coupling between single quantum dot exciton line and photonic crystal waveguide localized mode is demonstrated experimentally and theoretically analyzed with master equations, which can be used as a great implementation platform for realizing future solid-state quantum computation.
The third topic is quantum controlled phase gate and phase switching operations based on quantum dots and photonic crystal slow-light waveguide. In Chapter 6, we propose a scheme to realize controlled phase gate between two single photons through a single quantum dot embedded in a photonic crystal waveguide. Enhanced Purcell factor and large β factor lead to high gate fidelity over broadband frequencies compared to cavity-assisted system. The excellent physical integration of this photonic crystal waveguide system provides tremendous potential for large-scale quantum information processing. In Chapter 7, dipole induced transparency can be achieved in a system which consists of two quantum dots properly located in silicon photonic crystal waveguide. Furthermore, we describe how this effect can be useful for designing full Ï€ phase switching in a hetero-photonic crystal waveguide structure just by a small amount of photons
Monolithically Integrated Microcavity Lasers on Silicon
In recent years, due to the limitation of Moore's Law, traditional electronic integrated circuits have been unable to meet the requirements of exponential growth of data traffic. An optical interconnect paradigm with higher density of processing units and lower energy consumption is urgently needed. Highly integrated III-V lasers on silicon are promising candidates for ultra-compact light sources of the next generation on-chip optical interconnect. Here, we present various InAs/GaAs quantum dot microcavity lasers monolithically grown on silicon, including micro-disk lasers, 2D Photonic Crystal lasers with L3 defects, 1D Photonic Crystal nanobeam lasers, Photonic Crystal bandedge lasers, topological corner state lasers, Dirac-vortex topological lasers and vortex lasers based on bound states in the continuum (BIC)
Solid-state quantum optics with quantum dots in photonic nanostructures
Quantum nanophotonics has become a new research frontier where quantum optics
is combined with nanophotonics in order to enhance and control the interaction
between strongly confined light and quantum emitters. Such progress provides a
promising pathway towards quantum-information processing on an all-solid-state
platform. Here we review recent progress on experiments with single quantum
dots in nanophotonic structures. Embedding the quantum dots in photonic
band-gap structures offers a way of controlling spontaneous emission of single
photons to a degree that is determined by the local light-matter coupling
strength. Introducing defects in photonic crystals implies new functionalities.
For instance, efficient and strongly confined cavities can be constructed
enabling cavity-quantum-electrodynamics experiments. Furthermore, the speed of
light can be tailored in a photonic-crystal waveguide forming the basis for
highly efficient single-photon sources where the photons are channeled into the
slowly propagating mode of the waveguide. Finally, we will discuss some of the
surprises that arise in solid-state implementations of quantum-optics
experiments in comparison to their atomic counterparts. In particular, it will
be shown that the celebrated point-dipole description of light-matter
interaction can break down when quantum dots are coupled to plasmon
nanostructures.Comment: Review. 15 pages, 9 figure
Interfacing single photons and single quantum dots with photonic nanostructures
Photonic nanostructures provide means of tailoring the interaction between
light and matter and the past decade has witnessed a tremendous experimental
and theoretical progress in this subject. In particular, the combination with
semiconductor quantum dots has proven successful. This manuscript reviews
quantum optics with excitons in single quantum dots embedded in photonic
nanostructures. The ability to engineer the light-matter interaction strength
in integrated photonic nanostructures enables a range of fundamental
quantum-electrodynamics experiments on, e.g., spontaneous-emission control,
modified Lamb shifts, and enhanced dipole-dipole interaction. Furthermore,
highly efficient single-photon sources and giant photon nonlinearities may be
implemented with immediate applications for photonic quantum-information
processing. The review summarizes the general theoretical framework of photon
emission including the role of dephasing processes, and applies it to photonic
nanostructures of current interest, such as photonic-crystal cavities and
waveguides, dielectric nanowires, and plasmonic waveguides. The introduced
concepts are generally applicable in quantum nanophotonics and apply to a large
extent also to other quantum emitters, such as molecules, nitrogen vacancy
ceters, or atoms. Finally, the progress and future prospects of applications in
quantum-information processing are considered.Comment: Updated version resubmitted to Reviews of Modern Physic
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