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CircuitQ: An open-source toolbox for superconducting circuits

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arXiv 2021年

作者： Aumann, Philipp Menke, Tim Oliver, William D. Lechner, Wolfgang Institute for Theoretical Physics University of Innsbruck InnsbruckA-6020 Austria Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Harvard University CambridgeMA02138 United States MIT Lincoln Laboratory 244 Wood Street LexingtonMA02420 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Parity Quantum Computing GmbH InnsbruckA-6020 Austria

We introduce CircuitQ, an open-source toolbox for the analysis of superconducting circuits implemented in Python. It features the automated construction of a symbolic Hamiltonian of the input circuit and a dynamic numerical representation of the Hamiltonian with a variable basis choice. The software implementation is capable of choosing the basis in a fully automated fashion based on the potential energy landscape. Additional features include the estimation of the T1 lifetimes of the circuit states under various noise mechanisms. We review previously established circuit quantization methods and formulate them in a way that facilitates the software implementation. The toolbox is then showcased by applying it to practically relevant qubit circuits and comparing it to specialized circuit solvers. Our circuit quantization is applicable to circuit inputs from a large design space, and the software is open-sourced. We thereby add an important resource for the design of new quantum circuits for quantum information processing applications. © 2021, CC BY.

关键词： Hamiltonians

SPECTRAL PARTITIONING OF TIME-VARYING NETWORKS WITH UNOBSERVED EDGES

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arXiv 2019年

作者： Schaub, Michael T. Segarra, Santiago Wai, Hoi-To Inst. for Data Systems and Society MIT & Department of Engineering Science University of Oxford Department of Electrical and Computer Engineering Rice University Department of SEEM Chinese University of Hong Kong NT Hong Kong

We discuss a variant of ‘blind’ community detection, in which we aim to partition an unobserved network from the observation of a (dynamical) graph signal defined on the network. We consider a scenario where our observed graph signals are obtained by filtering white noise input, and the underlying network is different for every observation. In this fashion, the filtered graph signals can be interpreted as defined on a time-varying network. We model each of the underlying network realizations as generated by an independent draw from a latent stochastic blockmodel (SBM). To infer the partition of the latent SBM, we propose a simple spectral algorithm for which we provide a theoretical analysis and establish consistency guarantees for the recovery. We illustrate our results using numerical experiments on synthetic and real data, highlighting the efficacy of our approach. Copyright © 2019, The Authors. All rights reserved.

关键词： Time varying networks

Generating spatially entangled itinerant photons with waveguide quantum electrodynamics

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arXiv 2020年

作者： Kannan, Bharath Campbell, Daniel Vasconcelos, Francisca Winik, Roni Kim, David Kjaergaard, Morten Krantz, Philip Melville, Alexander Niedzielski, Bethany M. Yoder, Jonilyn Orlando, Terry P. Gustavsson, Simon Oliver, William D. Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States MIT Lincoln Laboratory 244 Wood Street LexingtonMA02420 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States

Realizing a fully connected network of quantum processors requires the ability to distribute quantum entanglement. For distant processing nodes, this can be achieved by generating, routing, and capturing spatially entangled itinerant photons. In this work, we demonstrate deterministic generation of such photons using superconducting transmon qubits that are directly coupled to a waveguide. In particular, we generate two-photon N00N states and show that the state and spatial entanglement of the emitted photons can be tuned via the qubit frequencies. Using quadrature amplitude detection, we reconstruct the moments and correlations of the photonic modes and demonstrate state preparation fidelities of 84%. Our results provide a path towards realizing quantum communication and teleportation protocols using non-classical, spatially entangled itinerant photons. Copyright © 2020, The Authors. All rights reserved.

关键词： Quantum entanglement

Multi-level quantum noise spectroscopy

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arXiv 2020年

作者： Sung, Youngkyu Vepsäläinen, Antti Braumüller, Jochen Yan, Fei Wang, Joel I-Jan Kjaergaard, Morten Winik, Roni Krantz, Philip Bengtsson, Andreas Melville, Alexander J. Niedzielski, Bethany M. Schwartz, Mollie E. Kim, David K. Yoder, Jonilyn L. Orlando, Terry P. Gustavsson, Simon Oliver, William D. Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States MIT Lincoln Laboratory 244 Wood Street LexingtonMA02421 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States

System noise identification is crucial to the engineering of robust quantum systems. Although existing quantum noise spectroscopy (QNS) protocols measure an aggregate amount of noise affecting a quantum system, they generally cannot distinguish between the underlying processes that contribute to it. Here, we propose and experimentally validate a spin-locking-based QNS protocol that exploits the multi-level energy structure of a superconducting qubit to achieve two notable advances. First, our protocol extends the spectral range of weakly anharmonic qubit spectrometers beyond the present limitations set by their lack of strong anharmonicity. Second, the additional information gained from probing the higher-excited levels enables us to identify and distinguish contributions from different underlying noise mechanisms. Copyright © 2020, The Authors. All rights reserved.

关键词： Quantum noise

Compact and low loss silicon carbide waveguide with high nonlinearity based on CMOS-compatible platform

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Compact and low loss silicon carbide waveguide with high non...

Nonlinear Optics, NLO 2019

作者： Xing, Peng Ma, Danhao Ooi, Kelvin J. A. Choi, Ju Won Agarwal, Anuradha M. Tan, Dawn T. H. SUTD-MIT International Design Center Singapore University of Technology and Design 8 Somapah Road Singapore Department of Materials Science and Engineering Massachusetts Institute of Technology CambridgeMA United States School of Electrical and Computer Engineering Xiamen University Malaysia Jalan Sunsuria Bandar Sunsuria Sepang Selangor Darul Ehsan43900 Malaysia Materials Research Laboratory Massachusetts Institute of Technology CambridgeMA United States

Silicon carbide ring resonator is demonstrated with intrinsic Q-factor of 160,000. Waveguide with nonlinear parameter 40W-1/m is demonstrated. Material Kerr nonlinearity is measured to be 4.8 ×10-14cm2/W and thre... 详细信息

ISBN: (纸本)9781943580620

关键词： Waveguides

Silicon hard-stop spacers for 3D integration of superconducting qubits

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arXiv 2019年

作者： Niedzielski, Bethany M. Kim, David K. Schwartz, Mollie E. Rosenberg, Danna Calusine, Greg Das, Rabi Melville, Alexander J. Plant, Jason Racz, Livia Yoder, Jonilyn L. Ruth-Yost, Donna Oliver, William D. MIT Lincoln Laboratory 244 Wood Street LexingtonMA02420 United States Department of Electrical Engineering & Computer Science Massachusetts Institute of Technology CambridgeMA United States

As designs for superconducting qubits become more complex, 3D integration of two or more vertically bonded chips will become necessary to enable increased density and connectivity. Precise control of the spacing between these chips is required for accurate prediction of circuit performance. In this paper, we demonstrate an improvement in the planarity of bonded superconducting qubit chips while retaining device performance by utilizing hard-stop silicon spacer posts. These silicon spacers are defined by etching several microns into a silicon substrate and are compatible with 3D-integrated qubit fabrication. This includes fabrication of Josephson junctions, superconducting air-bridge crossovers, underbump metallization and indium bumps. To qualify the integrated process, we demonstrate high-quality factor resonators on the etched surface and measure qubit coherence (T1, T2,echo > 40 µs) in the presence of silicon posts as near as 350µm to the qubit. Copyright © 2019, The Authors. All rights reserved.

关键词： Silicon

IEEE ICCI*CC Series in Year 20: Latest Advances in Cognitive Informatics and Cognitive Computing towards General AI (Plenary Panel Report-I)

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IEEE ICCI*CC Series in Year 20: Latest Advances in Cognitive...

IEEE International Conference on Cognitive Informatics

作者： Yingxu Wang Bernard Widrow Witold Pedrycz Robert C. Berwick Paolo Soda Sam Kwong Okyay Kaynak Carlo S. Regazzoni Christine Chan Marina Gavrilova Guoyin Wang FI2CICC Dept. of ESE University of Calgary AB Canada FAAAS FNAE FI2CICC Dept. of Packard Electrical Engg Stanford Univ. USA FCAS FI2CICC Dept of ECE Univ. of Alberta AB Canada FI2CICC Dept. Electrical Engineering &#x0026 Computer Science MIT Boston MA USA FI2CICC Lab. of PMBDA Universit&#x00E0 Campus Bio-Medico (UCBM) Rome Italy FI2CICC Dept. of Computer Science Hongkong City Univ. Hong Kong FI2CICC Bogazici University Istanbul Turkey FI2CICC Defence Research and Development Canada Toronto Canada DITEN University of Genova Italy FI2CICC FCAE Dept. of ECE Univ. of Regina SA Canada FI2CICC Dept. of Computer Science Univ. of Calgary AB Canada FI2CICC Chongqing Univ. of Posts and Telecommunications Chongqing China

ISBN: (纸本)9781665421201

Cognitive Informatics (CI) and Cognitive Computing (CC) are fundamental intelligence theories and general AI technologies triggered by the transdisciplinary advances in intelligence, computer, brain, knowledge, cognitive, robotic, and cybernetic sciences for engineering implementations. This paper presents a summary of the plenary panel (Part I) on the theoretical foundations of CI/CC as well recent breakthroughs in AI engineering reported in the 20th IEEE International ICCI*CC Conference (ICCI*CC'21). The latest advances in CI and CC towards general AI are presented by twenty-two distinguished panelists. Strategic AI engineering applications in CI, CC, and cognitive systems are elaborated for abstract intelligence, general AI, cognitive robots, autonomous systems, intelligent vehicles, and safety-and-mission-critical systems.

关键词： Knowledge engineering Intelligent vehicles Autonomous systems Conferences Cognitive informatics Cognitive robotics Artificial intelligence

Environmental hotspot identification in limited time with a UAV equipped with a downward-facing camera

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arXiv 2019年

作者： Sung, Yoonchang Dixit, Deeksha Tokekar, Pratap CSAIL MIT CambridgeMA02139 United States Department of Computer Science University of Maryland College ParkMD20742 United States Department of Electrical and Computer Engineering Virginia Tech BlacksburgVA24061 United States

Our work is motivated by environmental monitoring tasks, where finding the global maxima (i.e., hotspot) of a spatially varying field is crucial. We investigate the problem of identifying the hotspot for fields that can be sensed using an Unmanned Aerial Vehicle (UAV) equipped with a downwardfacing camera. The UAV has a limited time budget which it can use for learning the unknown field and identifying the hotspot. Our contribution is to show how this problem can be formulated as a novel multi-fidelity variant of the Gaussian Process (GP) multi-armed bandit problem. The novelty is two-fold: (i) unlike standard multi-armed bandit settings, the rewards of the arms are correlated with each other;and (ii) unlike standard GP regression, the measurements in our problem are images (i.e., vector measurements) whose quality depends on the altitude of the UAV. We present a strategy for finding the sequence of UAV sensing locations and empirically compare it with several baselines. Experimental results using images gathered onboard a UAV are also presented and the scalability of the proposed methodology is assessed in a large-scale simulated environment in Gazebo. © 2019, CC BY.

关键词： Unmanned aerial vehicles (UAV)

Supervised and unsupervised transfer learning for question answering

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Supervised and unsupervised transfer learning for question a...

2018 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies, NAACL HLT 2018

作者： Chung, Yu-An Lee, Hung-Yi Glass, James MIT Computer Science and Artificial Intelligence Laboratory CambridgeMA United States Department of Electrical Engineering National Taiwan University Taipei Taiwan

ISBN: (纸本)9781948087278

Although transfer learning has been shown to be successful for tasks like object and speech recognition, its applicability to question answering (QA) has yet to be well-studied. In this paper, we conduct extensive experiments to investigate the transferability of knowledge learned from a source QA dataset to a target dataset using two QA models. The performance of both models on a TOEFL listening comprehension test (Tseng et al., 2016) and MCTest (Richardson et al., 2013) is significantly improved via a simple transfer learning technique from MovieQA (Tapaswi et al., 2016). In particular, one of the models achieves the state-of-The-Art on all target datasets;for the TOEFL listening comprehension test, it outperforms the previous best model by 7%. Finally, we show that transfer learning is helpful even in unsupervised scenarios when correct answers for target QA dataset examples are not available. © 2018 The Association for Computational Linguistics.

关键词： Speech recognition