Optical microcavity

About: Optical microcavity is a research topic. Over the lifetime, 2599 publications have been published within this topic receiving 72125 citations. The topic is also known as: optical microcavities.

Heralded high-fidelity quantum hyper-CNOT gates assisted by charged quantum dots inside single-sided optical microcavities

Abstract: Photonic hyper-parallel quantum information processing (QIP) can simplify the quantum circuit and improve the information-processing speed, as well as reduce the quantum resource consumption and suppress the photonic dissipation noise. Here, utilizing the singly charged semiconductor quantum dot (QD) inside single-sided optical microcavity as the potentially experimental platform, we propose five schemes for heralded four-qubit hyper-controlled-not (hyper-CNOT) gates, covering all cases of four-qubit hyper-CNOT gates operated on both the polarization and spatial-mode degrees of freedom (DoFs) of a two-photon system. The novel heralding mechanism improves the fidelity of each hyper-CNOT gate to unity in principle without the strict restriction of strong coupling. The adaptability and scalability of the schemes make the hyper-CNOT gates more accessible under current experimental technologies. These heralded high-fidelity photonic hyper-CNOT gates can therefore have immense utilization potentials in high-capacity quantum communication and fast quantum computing, which are of far-reaching significance for QIP.

Narrowband thermal radiation from closed-end microcavities

Abstract: High spectral selectivity of thermal radiation is important for achieving high-efficiency energy systems. In this study, intense, narrowband, and low directional absorption/radiation were observed in closed-end microcavity which is a conventional open-end microcavity covered by a semi-transparent thin metal film. The quality factor (Q factor) of optical absorption band strongly depended on the film electrical conductivity. Asymmetric and narrow absorption band with a Q factor of 25 at 1.28 μm was obtained for a 6-nm-thick Au film. Numerical simulations suggest that the formation of a fixed-end mode at the cavity aperture contributes to the narrowband optical absorption. The closed-end microcavity filled with SiO2 exhibits intense and isotropic thermal radiation over a wide solid angle according to numerical simulation. The narrow and asymmetric absorption spectrum was experimentally confirmed in a model of closed-end microcavity.

Semiconductor optical microcavities for chip-based cavity QED

Abstract: Optical microcavities can be characterized by two key quantities: an effective mode volume Veff, which describes the per photon electric field strength within the cavity, and a quality factor Q, which describes the photon lifetime within the cavity. Cavities with a small Veff and a high Q offer the promise for applications in nonlinear optics, sensing, and cavity quantum electrodynamics (cavity QED). Chip-based devices are particularly appealing, as planar fabrication technology can be used to make optical structures on a semiconductor chip that confine light to wavelength-scale dimensions, thereby creating strong enough electric fields that even a single photon can have an appreciable interaction with matter. When combined with the potential for integration and scalability inherent to microphotonic structures created by planar fabrication techniques, these devices have enormous potential for future generations of experiments in cavity QED and quantum networks. This thesis is largely focused on the development of ultrasmall Veff, high-Q semiconductor optical microcavities. In particular, we present work that addresses two major topics of relevance when trying to observe coherent quantum interactions within these semiconductor-based systems: (1) the demonstration of low optical losses in a wavelength-scale microcavity, and (2) the development of an efficient optical channel through which the sub-micron-scale optical field in the microcavity can be accessed. The two microcavities of specific interest are planar photonic crystal defect resonators and microdisk resonators. The first part of this thesis details the development of photonic crystal defect microcavities. A momentum space analysis is used to design structures in graded square and hexagonal lattice photonic crystals that not only sustain high Qs and small Veffs, but are also relatively robust to imperfections. These designs are then implemented in a number of experiments, starting with device fabrication in an InAsP/InGaAsP multi-quantum-well material to create low-threshold lasers with Qs of 1.3x10^4, and followed by fabrication in a silicon-on-insulator system to create passive resonators with Qs as high as 4.0x10^4. In the latter experiments, an optical fiber taper waveguide is used to couple light into and out of the cavities, and we demonstrate its utility as an optical probe that provides spectral and spatial information about the cavity modes. For a cavity mode with Q ~ 4x10^4, we demonstrate mode localization data consistent with Veff ~ 0.9(λ/n)^3. In the second part of this thesis, we describe experiments in a GaAs/AlGaAs material containing self-assembled InAs quantum dots. Small diameter microdisk cavities are fabricated with Q ~ 3.6x10^5 and Veff ~ 6(λ/n)^3, and with Q ~ 1.2x10^5 and Veff ~ 2(λ/n)^3. These devices are used to create room-temperature, continuous-wave, optically pumped lasers with thresholds as low as 1μW of absorbed pump power. Optical fiber tapers are used to efficiently collect emitted light from the devices, and a laser differential efficiency as high as 16% is demonstrated. Furthermore, these microdisk cavities have the requisite combination of high Q and small Veff to enable strong coupling to a single InAs quantum dot, in that the achievable coupling rate between the quantum dot and a single photon in the cavity is predicted to exceed the decay rates within the system. Quantum master equation simulations of the expected behavior of such fiber-coupled devices are presented, and progress towards such cavity QED experiments is described.

Integrated vertical microcavity using a nano-scale deformation for strong lateral confinement

Abstract: We report on the realization of a solid state Fabry-Perot-like microcavity that uses a small Gaussian-shaped deformation inside the cavity to achieve strong lateral photon confinement on the order of the wavelength. Cavities with a mode volume V 1000 are fabricated by means of focused ion beam milling, removing the necessity for etched sidewalls as required for micropillar cavities. Perylene-diimide dye doped polystyrene was embedded in the microcavity and probed by time-resolved microphotoluminescence. A Purcell enhancement of the spontaneous emission rate by a factor of 3.5 has been observed at room temperature.

Electron injection-controlled microcavity plasma device and arrays

Abstract: An embodiment of the invention is a microcavity plasma device that can be controlled by a low voltage electron emitter. The microcavity plasma device includes driving electrodes disposed proximate to a microcavity and arranged to contribute to generation of plasma in the microcavity upon application of a driving voltage. An electron emitter is arranged to emit electrons into the microcavity upon application of a control voltage. The electron emitter is an electron source having an insulator layer defining a tunneling region. The microplasma itself can serve as a second electrode necessary to energize the electron emitter. While a voltage comparable to previous microcavity plasma devices is still imposed across the microcavity plasma devices, control of the devices can be accomplished at high speeds and with a small voltage, e.g., about 5V to 30V in preferred embodiments.