Distributed Quantum Computation Architecture Using Semiconductor Nanophotonics

In a large-scale quantum computer, the cost of communications will dominate the performance and resource requirements, place many severe demands on the technology, and constrain the architecture. Unfortunately, fault-tolerant computers based entirely on photons with probabilistic gates, though equipped with "built-in" communication, have very large resource overheads; likewise, computers with reliable probabilistic gates between photons or quantum memories may lack sufficient communication resources in the presence of realistic optical losses. Here, we consider a compromise architecture, in which semiconductor spin qubits are coupled by bright laser pulses through nanophotonic waveguides and cavities using a combination of frequent probabilistic and sparse determinstic entanglement mechanisms. The large photonic resource requirements incurred by the use of probabilistic gates for quantum communication are mitigated in part by the potential high-speed operation of the semiconductor nanophotonic hardware. The system employs topological cluster-state quantum error correction for achieving fault-tolerance. Our results suggest that such an architecture/technology combination has the potential to scale to a system capable of attacking classically intractable computational problems.Comment: 29 pages, 7 figures; v2: heavily revised figures improve architecture presentation, additional detail on physical parameters, a few new reference

Grating couplers with an integrated power splitter for high-intensity optical power distribution

In this letter, we present a fiber grating coupler with an integrated 16-way power splitter. The incoming light from the fiber is split immediately over 16 channels, and therefore, the total optical power is never confined in a single waveguide. This is of particular interest for silicon photonics platforms, because, here, high optical intensities can cause significant non-linear losses. The device has a total coupling efficiency that is similar to standard focusing grating couplers. Furthermore, a channel non-uniformity below 1.1 dB has been obtained. By studying the alignment sensitivity, we found that for high splitting uniformity, a careful positioning of the fiber is necessary. We also experimentally demonstrate that this device is indeed capable of handling high optical powers without introducing additional non-linear losses

TOWARDS RELIABLE NANOPHOTONIC INTERCONNECTION NETWORK DESIGNS

As technology scales into deep submicron domains, electrical wires start to face critical challenges in latency and power since they do not scale well as compared to transistors. Many recent researches have shifted focus to optical on-chip interconnection because of its promises of high bandwidth density, low propagation delay, distance-independent power consumption (compared to metal), and natural support for multicast and broadcast. Unfortunately, while optical interconnect provides many attractive and promising features, there are also fundamental challenges in fabrication of those devices to providing robust and reliable on-chip communication. Microrings resonators, the basic components of nanophotonic interconnect, may not resonate at the designated wavelength under fabrication errors (a.k.a. process variations PV) or thermal fluctuation (TF), leading to communication errors and bandwidth loss. In addition, the power overhead required to correct the drift can overturn the benefits promised by this new technology. Hence, the objective of the thesis is to maximize network bandwidth through proper arrangement among microrings and wavelengths with minimum tuning power requirement. I propose the following techniques to achieve my goals. First, I will present a series of solutions, called ``MinTrim'', to address the wavelength drifting problem of microrings and subsequent bandwidth loss problem of an optical network, due to the PV. Next, to mitigate bandwidth loss and performance degradation caused by PV and TF, I will propose an architecture-level approach, ``BandArb'', which allocates the bandwidth at runtime according to network demands and temperature with low computation overhead. Finally, I will conclude the thesis and discuss the future works in this field

Monolithic integration of erbium-doped amplifiers with silicon-on-insulator waveguides

Monolithic integration of Al2O3:Er3+ amplifier technology with passive silicon-on-insulator waveguides is demonstrated. A signal enhancement of >7 dB at 1533 nm wavelength is obtained. The straightforward wafer-scale fabrication process, which includes reactive co-sputtering and subsequent reactive ion etching, allows for parallel integration of multiple amplifier and laser sections with silicon or other photonic circuits on a chip

Metamateriales sub-longitud de onda para microdispositivos fotónicos de altas prestaciones

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, leída el 28-04-2020Photonics has become of paramount importance in many areas of our everyday life owing to its inherent potential to develop not only telecom and datacom solutions, but also many other applications such as metrology [DeMiguel’18], energy generation and saving [Polman’12, Miller’17], spectrometry [Velasco’13a], sensing [Rodríguez-Barrios’10], medicine [Morgner’00] and industrial manufacturing [Malinauskas’16], to name a few. Particularly, integrated optics has attracted increasing industrial attention and scientific efforts to implement photonic integrated circuits (PICs) capable of tackling all abovementioned tasks in compact and efficient systems.Among all the available materials, silicon photonics leverages the maturity of the fabrication techniques reached by the microelectronics industry, enabling cost-effective mass production [Chen’18]. Different material platforms with a high refractive index contrast have been proposed for silicon photonics to achieve higher integration levels and perform more complex functions in a single chip, such as silicon-on-insulator (SOI) and silicon nitride (Si3N4, commonly simplified to SiN). The increased integration capacity of silicon photonics has enabled to tackle one of our greatest technological challenges: global data traffic inside data centers. Besides short-range optical interconnects for telecom and datacom applications, the progress in silicon photonics also encompasses many other untapped applications that are being explored by academia and industry: absorption spectroscopy and bio-sensing [Herrero-Bermello’17, Wangüemert-Pérez’19], light detection and ranging (LIDAR) [Poulton’17a], quantum computing [Harris’16], microwave and terahertz photonics [Marpaung’19, Harter’18], nonlinear optics [Leuthold’10], and many others...La fotónica ha adquirido una importancia fundamental en muchos ámbitos de nuestra vida cotidiana debido a su potencial intrínseco para desarrollar soluciones no sólo en el campo de las telecomunicaciones y las interconexiones de corto alcance, sino también en otras muchas áreas como la metrología [DeMiguel’18], la generación de energía [Polman’12, Miller’17], la espectrometría [Velasco’13a], la detección [Rodríguez-Barrios’10], la medicina [Morgner’00] y la fabricación industrial [Malinauskas’16]. En particular, la óptica integrada ha atraído tanto la atención de la industria como los esfuerzos científicos para implementar circuitos fotónicos integrados (PICs, Photonic Integrated Circuits) capaces de abordar todas las tareas mencionadas anteriormente en sistemas compactos y eficientes. Entre todos los materiales disponibles, la fotónica de silicio aprovecha la madurez de las técnicas de fabricación alcanzadas por la industria de la microelectrónica, permitiendo una producción en masa rentable [Chen’18]. Para maximizar su densidad de integración y poder realizar funciones más complejas en un único chip, diferentes plataformas materiales con un alto contraste de índice de refracción se han propuesto, como por ejemplo las plataformas de silicio sobre aislante (SOI, Silicon-On-Insulator) y de nitruro de silicio (Si3N4, comúnmente simplificada a SiN, Silicon Nitride). Esta mayor densidad de integración ha permitido abordar uno de nuestros mayores desafíos tecnológicos hasta la fecha: el tráfico de datos global dentro de los centros de datos. Además de las interconexiones ópticas de corto alcance, el progreso de la fotónica de silicio también comprende muchas otras aplicaciones inexploradas que están siendo estudiadas en el ámbito académico e industrial como, por ejemplo, la espectroscopía de absorción y biodetección [Herrero-Bermello’17, Wangüemert-Pérez’19], LIDAR (Light Detection And Ranging) [Poulton’17a], computación cuántica [Harris’16], fotónica de microondas y terahercios [Marpaung’19, Harter’18], óptica no lineal [Leuthold’10], y muchas otras...Fac. de Ciencias FísicasTRUEunpu