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A polarization-insensitive fishnet/spacer/mirror plasmonic absorber for hot electron photodetection application

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Chinese Optics Letters 2020年第5期18卷 63-67页

作者： Zhiqiang Yang Kang Du Wending Zhang Soojin Chua Ting Mei Key Laboratory of Space Applied Physics and Chemistry Ministry of Educationand Shaanxi Key Labora tory of Optical Information TechnologySchool of ScienceNorth Western Polytechnical UniversityXi'an 710072China Department of Electrical and Computer Engineering National University of SingaporeSingapore 117583Singapore LEES Program Singapore-MIT Alliance for Research&Technology(SMART)Singapore 138602Singapore

A polarization-insensitive plasmonic absorber is designed consisting of Au fishnet structures on a TiO2 spacer/Ag mirror. The fishnet structures excite localized surface plasmon and generate hot electrons from the absorbed photons, while the TiO2 layer induces Fabry–Perot resonance, and the Ag mirror acts as a back *** optimizing the TiO2 layer thickness, numerical simulation shows that 97% of the incident light is absorbed in the Au layer. The maximum responsivity and external quantum efficiency of the device can approach 5 mA/W and ~1%, respectively, at the wavelength of 700 nm.

关键词： plasmonic absorber Fabry–Perot resonance internal photoemission surface plasmon

Single photon detection by cavity-assisted all-optical gain

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Physical Review B 2019年第20期99卷 205303-205303页

作者： Christopher Panuski Mihir Pant Mikkel Heuck Ryan Hamerly Dirk Englund Department of Electrical Engineering and Computer Science MIT Cambridge Massachusetts 02139 USA Department of Photonics Engineering Technical University of Denmark 2800 Kgs. Lyngby Denmark

We consider the free-carrier dispersion effect in a semiconductor nanocavity in the limit of discrete photoexcited electron-hole pairs. This analysis reveals the possibility of ultrafast, incoherent transduction and gain from a single photon signal to a strong coherent probe field. Homodyne detection of the displaced probe field enables an all-optical method for room-temperature, photon-number-resolving single photon detection. In particular, we estimate that a single photon absorbed within a silicon nanocavity can, within tens of picoseconds, be detected with ∼99% efficiency and a dark count rate on the order of kilohertz assuming a mode volume Veff∼10−2(λ/nSi)3 for a 4.5-μm probe wavelength and a loaded quality factor Q on the order of 104.

关键词： Optical sources & detectors Photonic crystals Photonics Photorefractive & Kerr effects Cavity resonators

No-signaling proofs with o(√log n) provers are in pspace

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arXiv 2019年

作者： Holden, Dhiraj Kalai, Yael Department of Electrical Engineering and Computer Science MIT United States Microsoft Research United States

No-signaling proofs, motivated by quantum computation, have found applications in cryptography and hardness of approximation. An important open problem is characterizing the power of no-signaling proofs. It is known that 2-prover no-signaling proofs are characterized by PSPACE, and that no-signaling proofs with poly(n)-provers are characterized by EXP. However, the power of k-prover no-signaling proofs, for 2 k2) into a no-signaling one with value at least 2−O(k2). In the first route, we show that the classical prover reduction method for converting k-prover games into 2-prover games carries over to the no-signaling setting with the following loss in soundness: if a k-player game has value less than 2−ck2 (for some constant c > 0), then the corresponding 2-prover game has value at most 1−2dk2 (for some constant d > 0). In the second route we show that the value of a sub-no-signaling game can be approximated in space that is polynomial in the communication complexity and exponential in the number of provers. Copyright © 2019, The Authors. All rights reserved.

关键词： Signaling

Capacities and optimal input distributions for particle-intensity channels

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arXiv 2020年

作者： Farsad, Nariman Chuang, Will Goldsmith, Andrea Komninakis, Christos Médard, Muriel Rose, Christopher Vandenberghe, Lieven Wesel, Emily E. Wesel, Richard D. Department of Electrical Engineering Stanford University StanfordCA94305 United States Qualcomm 6455 Lusk Blvd San DiegoCA92121 United States Department of Electrical Engineering and Computer Science MIT CambridgeMA02139 United States School of Engineering Brown University ProvidenceRI02912 United States Department of Electrical and Computer Engineering UCLA Los AngelesCA90095-1594 United States Stanford University StanfordCA94305 United States

This work introduces the particle-intensity channel (PIC) as a model for molecular communication systems and characterizes the capacity limits as well as properties of the optimal (capacity-achieving) input distributions for such channels. In the PIC, the transmitter encodes information, in symbols of a given duration, based on the probability of particle release, and the receiver detects and decodes the message based on the number of particles detected during the symbol interval. In this channel, the transmitter may be unable to control precisely the probability of particle release, and the receiver may not detect all the particles that arrive. We model this channel using a generalization of the binomial channel and show that the capacity-achieving input distribution for this channel always has mass points at probabilities of particle release of zero and one. To find the capacity-achieving input distributions, we develop an efficient algorithm we call dynamic assignment Blahut-Arimoto (DAB). For diffusive particle transport, we also derive the conditions under which the input with two mass points is capacity-achieving. Copyright © 2020, The Authors. All rights reserved.

关键词： Transmitters

Absorption-based diamond spin microscopy on a plasmonic quantum metasurface

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arXiv 2020年

作者： Kim, Laura Choi, Hyeongrak Trusheim, Matthew E. Englund, Dirk R. Research Laboratory of Electronics MIT CambridgeMA02139 United States Department of Electrical Engineering and Computer Science MIT CambridgeMA02139 United States U.S. Army Research Laboratory Sensors and Electron Devices Directorate AdelphiMD20783 United States

Nitrogen vacancy (NV) centers in diamond have emerged as a leading quantum sensor platform, combining exceptional sensitivity with nanoscale spatial resolution by optically detected magnetic resonance (ODMR). Because fluorescence-based ODMR techniques are limited by low photon collection efficiency and modulation contrast, there has been growing interest in infrared (IR)-absorption-based readout of the NV singlet state transition. IR readout can improve contrast and collection efficiency [1–3], but it has thus far been limited to long-pathlength geometries in bulk samples due to the small absorption cross section of the NV singlet state. Here, we amplify the IR absorption by introducing a resonant diamond metallodielectric metasurface that achieves a quality factor of Q ∼ 1,000. This"plasmonic quantum sensing metasurface" (PQSM) combines localized surface plasmon polariton resonances with long-range Rayleigh-Wood anomaly modes and achieves desired balance between field localization and sensing volume to optimize spin readout sensitivity. From combined electromagnetic and rate-equation modeling, we estimate a sensitivity below 1 nT Hz−21 per µm2 of sensing area using numbers for present-day NV diamond samples and fabrication techniques. The proposed PQSM enables a new form of microscopic ODMR sensing with infrared readout near the spin-projection-noise-limited sensitivity, making it appealing for the most demanding applications such as imaging through scattering tissues and spatially-resolved chemical NMR detection. © 2020, CC-BY.

关键词： Diamonds

Implicit posterior variational inference for deep Gaussian processes

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arXiv 2019年

作者： Yu, Haibin Chen, Yizhou Dai, Zhongxiang Low, Bryan Kian Hsiang Jaillet, Patrick Dept. of Computer Science National University of Singapore Singapore Dept. of Electrical Engineering and Computer Science MIT United States

A multi-layer deep Gaussian process (DGP) model is a hierarchical composition of GP models with a greater expressive power. Exact DGP inference is intractable, which has motivated the recent development of deterministic and stochastic approximation methods. Unfortunately, the deterministic approximation methods yield a biased posterior belief while the stochastic one is computationally costly. This paper presents an implicit posterior variational inference (IPVI) framework for DGPs that can ideally recover an unbiased posterior belief and still preserve time efficiency. Inspired by generative adversarial networks, our IPVI framework achieves this by casting the DGP inference problem as a two-player game in which a Nash equilibrium, interestingly, coincides with an unbiased posterior belief. This consequently inspires us to devise a best-response dynamics algorithm to search for a Nash equilibrium (i.e., an unbiased posterior belief). Empirical evaluation shows that IPVI outperforms the state-of-the-art approximation methods for DGPs. Copyright © 2019, The Authors. All rights reserved.

关键词： Game theory

Characterizing and Optimizing Qubit Coherence Based on SQUID Geometry

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Physical Review Applied 2020年第5期13卷 054079-054079页

作者： Jochen Braumüller Leon Ding Antti P. Vepsäläinen Youngkyu Sung Morten Kjaergaard Tim Menke Roni Winik David Kim Bethany M. Niedzielski Alexander Melville Jonilyn L. Yoder Cyrus F. Hirjibehedin Terry P. Orlando Simon Gustavsson William D. Oliver Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Department of Physics Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA MIT Lincoln Laboratory Lexington Massachusetts 02421 USA Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA

The dominant source of decoherence in contemporary frequency-tunable superconducting qubits is 1/f flux noise. To understand its origin and find ways to minimize its impact, we systematically study flux noise amplitudes in more than 50 flux qubits with varied superconducting quantum interference device (SQUID) geometry parameters and compare our results to a microscopic model of magnetic spin defects located at the interfaces surrounding the SQUID loops. Our data are in agreement with an extension of the previously proposed model, based on numerical simulations of the current distribution in the investigated SQUIDs. Our results and detailed model provide a guide for minimizing the flux noise susceptibility in future circuits.

关键词： Quantum computation Quantum fluctuations & noise Quantum information with solid state qubits SQUID Superconducting qubits

Publisher Correction: Battery-free wireless imaging of underwater environments

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Nature communications 2022年第1期13卷 6011页

作者： Sayed Saad Afzal Waleed Akbar Osvy Rodriguez Mario Doumet Unsoo Ha Reza Ghaffarivardavagh Fadel Adib Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139 USA. MIT Media Lab Massachusetts Institute of Technology Cambridge MA 02139 USA. Program in Media Arts and Sciences Massachusetts Institute of Technology Cambridge MA 02139 USA. Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139 USA. fadel@mit.edu. MIT Media Lab Massachusetts Institute of Technology Cambridge MA 02139 USA. fadel@mit.edu. Program in Media Arts and Sciences Massachusetts Institute of Technology Cambridge MA 02139 USA. fadel@mit.edu. MIT Sea Grant Massachusetts Institute of Technology Cambridge MA 02139 USA. fadel@mit.edu.

eRAKI: Fast robust artificial neural networks for k-space interpolation (RAKI) with coil combination and joint reconstruction

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arXiv 2021年

作者： Yu, Heng Dong, Zijing Arefeen, Yamin Liao, Congyu Setsompop, Kawin Bilgic, Berkin Department of Automation Tsinghua University Beijing China Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA United States Athinoula A. Martinos Center for Biomedical Imaging CharlestownMA United States Radiological Sciences Laboratory Stanford University StanfordCA United States Department of Electrical Engineering Stanford University StanfordCA United States Harvard Medical School BostonMA United States Harvard-MIT Health Sciences and Technology Massachusetts Institute of Technology CambridgeMA United States

RAKI can perform database-free MRI reconstruction by training models using only auto-calibration signal (ACS) from each speciflc scan. As it trains a separate model for each individual coil, learning and inference with RAKI can be computationally prohibitive, particularly for large 3D datasets. In this abstract, we accelerate RAKI by more than 200 times by directly learning a coil-combined target and further improve the reconstruction performance using joint reconstruction across multiple echoes together with an elliptical-CAIPI sampling approach. We further deploy these improvements in quantitative imaging and rapidly obtain T2 and T2* parameter maps from a fast EPTI scan. © 2021, CC0.

关键词： Neural networks