Publications

    Joshua Yao-Yu Lin, Dominic W. Pesce, George N. Wong, Ajay Uppili Arasanipalai, Ben S. Prather, and Charles F. Gammie. Submitted. “VLBInet: Radio Interferometry Data Classification for EHT with Neural Networks ”. Publisher's VersionAbstract

    The Event Horizon Telescope (EHT) recently released the first horizon-scale images of the black hole in M87. Combined with other astronomical data, these images constrain the mass and spin of the hole as well as the accretion rate and magnetic flux trapped on the hole. An important question for the EHT is how well key parameters, such as trapped magnetic flux and the associated disk models, can be extracted from present and future EHT VLBI data products. The process of modeling visibilities and analyzing them is complicated by the fact that the data are sparsely sampled in the Fourier domain while most of the theory/simulation is constructed in the image domain. Here we propose a data-driven approach to analyze complex visibilities and closure quantities for radio interferometric data with neural networks. Using mock interferometric data, we show that our neural networks are able to infer the accretion state as either high magnetic flux (MAD) or low magnetic flux (SANE), suggesting that it is possible to perform parameter extraction directly in the visibility domain without image reconstruction. We have applied VLBInet to real M87 EHT data taken on four different days in 2017 (April 5, 6, 10, 11), and our neural networks give a score prediction 0.52, 0.4, 0.43, 0.76 for each day, with an average score 0.53, which shows no significant indication for the data to lean toward either the MAD or SANE state.

    Hana K Warner, Jeffrey Holzgrafe, Beatriz Yankelevich, David Barton, Stefano Poletto, CJ Xin, Neil Sinclair, Di Zhu, Eyob Sete, Brandon Langley, Emma Batson, Marco Colangelo, Amirhassan Shams-Ansari, Graham Joe, Karl K Berggren, Liang Jiang, Matthew Reagor, and Marko Loncar. Submitted. “Coherent control of a superconducting qubit using light.” https://arxiv.org/abs/2310.16155. Publisher's VersionAbstract
    [PDF]
    Quantum science and technology promise the realization of a powerful computational resource that relies on a network of quantum processors connected with low loss and low noise communication channels capable of distributing entangled states [1,2]. While superconducting microwave qubits (3-8 GHz) operating in cryogenic environments have emerged as promising candidates for quantum processor nodes due to their strong Josephson nonlinearity and low loss [3], the information between spatially separated processor nodes will likely be carried at room temperature via telecommunication photons (200 THz) propagating in low loss optical fibers. Transduction of quantum information [4-10] between these disparate frequencies is therefore critical to leverage the advantages of each platform by interfacing quantum resources. Here, we demonstrate coherent optical control of a superconducting qubit. We achieve this by developing a microwave-optical quantum transducer that operates with up to 1.18% conversion efficiency (1.16% cooperativity) and demonstrate optically-driven Rabi oscillations (2.27 MHz) in a superconducting qubit without impacting qubit coherence times (800 ns). Finally, we discuss outlooks towards using the transducer to network quantum processor nodes.
    Yunxiang Song, Yaowen Hu, Marko Loncar, and Ki Youl Yang. Submitted. “Hybrid Kerr-electro-optic frequency combs on thin-film lithium niobate.” arXiv:2402.11669. Publisher's VersionAbstract
    Optical frequency combs are indispensable links between the optical and microwave domains, enabling a wide range of applications including precision spectroscopy, ultrastable frequency generation, and timekeeping. Chip-scale integration miniaturizes bulk implementations onto photonic chips, offering highly compact, stable, and power-efficient frequency comb sources. State of the art integrated frequency comb sources are based on resonantly-enhanced Kerr effect and, more recently, on electro-optic effect. While the former can routinely reach octave-spanning bandwidths and the latter feature microwave-rate spacings, achieving both in the same material platform has been challenging. Here, we leverage both strong Kerr nonlinearity and efficient electro-optic phase modulation available in the ultralow-loss thin-film lithium niobate photonic platform, to demonstrate a hybrid Kerr-electro-optic frequency comb with stabilized spacing. In our approach, a dissipative Kerr soliton is first generated, and then electro-optic division is used to realize a frequency comb with 2,589 comb lines spaced by 29.308 GHz and spanning 75.9 THz (588 nm) end-to-end. Further, we demonstrate electronic stabilization and control of the soliton spacing, naturally facilitated by our approach. The broadband, microwave-rate comb in this work overcomes the spacing-span tradeoff that exists in all integrated frequency comb sources, and paves the way towards chip-scale solutions for complex tasks such as laser spectroscopy covering multiple bands, micro- and millimeter-wave generation, and massively parallel optical communications.
    Damon J. Clark. Submitted. “Diné Entrepreneurship: Indigenous Contemporary Entrepreneurship.” Social Studies.Abstract
    Dine_Entrepreneurship_Clark_Thesis_Abstract.pdf

     

    This qualitative study researches the concept of entrepreneurship in an indigenous population by assessing the external and internal challenges faced, discusses the various types of support offered, and compiles recommendations for partners to understand the Diné individual with a business. This research interviewed nine formal entrepreneurs who are enrolled members of the Navajo Nation tribe who have either created businesses on the reservations, manage nonprofits aimed at supporting entrepreneurs, or possess a wealth of entrepreneurial experiences working both on or off the Navajo Nation Reservation. Entering a specific academic field, the research is a contemporary addition to previous economic research conducted on the Navajo Nation. Utilizing the frameworks of “Nation Building” as the foundational methodology, the text builds upon the themes of economic development, cultural-match, and indigenous sovereignty by analyzing the concept, action, and future of Diné entrepreneurship. Research finds a high degree of miscommunication between key groups, misinterpretation of the term “entrepreneurship” and expectations of each role, and missed opportunities for each sector to benefit from cross-sector partnerships. Additionally, while addressing many of the standard themes of business creation and management, Diné entrepreneurs are simultaneously presented with the twin challenges of embodying Diné values (i.e., a commitment to their community and family) and overcoming specific technical, economic, and social hurdles within the Navajo Nation Reservation. As individuals, various internal factors like private aspirations and academic, personal, and professional experiences work to shape the interviewed entrepreneurs into figures who accept risk, promote innovation, and are audacious. Similarly, a series of external factors were noted as influencing the entrepreneurs, including the role of the nuclear and extended family, actions by the federal, state, and tribal governments, and the concerns of their specific communities, all of which combine to create an environment that either supported or challenged the Diné Entrepreneur.

     

    Kazuhiro Kuruma, Benjamin Pingault, Cleaven Chia, Michael Haas, Graham D Joe, Daniel Rimoli Assumpcao, Sophie Weiyi Ding, Chang Jin, CJ Xin, Matthew Yeh, Neil Sinclair, and Marko Lončar. Submitted. “Engineering Phonon-Qubit Interactions using Phononic Crystals.” https://arxiv.org/abs/2310.06236v1. Publisher's VersionAbstract
    [PDF]
    The ability to control phonons in solids is key for diverse quantum applications, ranging from quantum information processing to sensing. Often, phonons are sources of noise and decoherence, since they can interact with a variety of solid-state quantum systems. To mitigate this, quantum systems typically operate at milli-Kelvin temperatures to reduce the number of thermal phonons. Here we demonstrate an alternative approach that relies on engineering phononic density of states, drawing inspiration from photonic bandgap structures that have been used to control the spontaneous emission of quantum emitters. We design and fabricate diamond phononic crystals with a complete phononic bandgap spanning 50 - 70 gigahertz, tailored to suppress interactions of a single silicon-vacancy color center with resonant phonons of the thermal bath. At 4 Kelvin, we demonstrate a reduction of the phonon-induced orbital relaxation rate of the color center by a factor of 18 compared to bulk. Furthermore, we show that the phononic bandgap can efficiently suppress phonon-color center interactions up to 20 Kelvin. In addition to enabling operation of quantum memories at higher temperatures, the ability to engineer qubit-phonon interactions may enable new functionalities for quantum science and technology, where phonons are used as carriers of quantum information.
    Gal Orenstein, Viktor Krapivin, Yijing Huang, Zhuquan Zhan, Gilberto Pena de la Munoz, Ryan A. Duncan, Quynh Nguyen, Jade Stanton, Samuel Teitelbaum, Hasan Yavas, Takahiro Sato, Matthias C. Hoffmann, Patrick Kramer, Jiahao Zhang, Andrea Cavalleri, Riccardo Comin, Mark P. M. Dean, Ankit S. Disa, Michael Forst, Steven L. Johnson, Matteo Mitrano, Andrew M. Rappe, David Reis, Diling Zhu, Keith A. Nelson, and Mariano Trigo. Submitted. “Observation of polarization density waves in SrTiO3”. Publisher's Version
    Graham D Joe, Cleaven Chia, Benjamin Pingault, Michael Haas, Michelle Chalupnik, Eliza Cornell, Kazuhiro Kuruma, Bartholomeus Machielse, Neil Sinclair, Srujan Meesala, and Marko Lončar. Submitted. “High Q-factor diamond optomechanical resonators with silicon vacancy centers at millikelvin temperatures.” https://arxiv.org/abs/2310.18838. Publisher's VersionAbstract
    [PDF]
    Phonons are envisioned as coherent intermediaries between different types of quantum systems. Engineered nanoscale devices such as optomechanical crystals (OMCs) provide a platform to utilize phonons as quantum information carriers. Here we demonstrate OMCs in diamond designed for strong interactions between phonons and a silicon vacancy (SiV) spin. Using optical measurements at millikelvin temperatures, we measure a linewidth of 13 kHz (Q-factor of ~440,000) for 6 GHz acoustic modes, a record for diamond in the GHz frequency range and within an order of magnitude of state-of-the-art linewidths for OMCs in silicon. We investigate SiV optical and spin properties in these devices and outline a path towards a coherent spin-phonon interface.
    Orhan Eren Akgün, Arif Kerem Dayı, Stephanie Gil, and Angelia Nedić. Submitted. “Learning Trust Over Directed Graphs in Multiagent Systems (extended version)”. Publisher's VersionAbstract
    learning_trust_over_directed_graphs_in_multiagent_systems.pdf
    We address the problem of learning the legitimacy of other agents in a multiagent network when an unknown subset is comprised of malicious actors. We specifically derive results for the case of directed graphs and where stochastic side information, or observations of trust, is available. We refer to this as ``learning trust'' since agents must identify which neighbors in the network are reliable, and we derive a protocol to achieve this. We also provide analytical results showing that under this protocol i) agents can learn the legitimacy of all other agents almost surely, and that ii) the opinions of the agents converge in mean to the true legitimacy of all other agents in the network. Lastly, we provide numerical studies showing that our convergence results hold in practice for various network topologies and variations in the number of malicious agents in the network.
    Orhan Eren Akgun, Arif Kerem Dayı, Stephanie Gil, and Angelia Nedic ́. Submitted. “Learning Trust Over Directed Graphs in Multiagent Systems.” In 5th Annual Conference on Learning for Dynamics and Control, 211: Pp. 1-13.Abstract
    learning_trust_over_directed_graphs.pdf
    We address the problem of learning the legitimacy of other agents in a multiagent network when an unknown subset is comprised of malicious actors. We specifically derive results for the case of directed graphs and where stochastic side information, or observations of trust, is available. We refer to this as “learning trust” since agents must identify which neighbors in the network are reliable, and we derive a protocol to achieve this. We also provide analytical results showing that under this protocol i) agents can learn the legitimacy of all other agents almost surely, and that ii) the opinions of the agents converge in mean to the true legitimacy of all other agents in the network. Lastly, we provide numerical studies showing that our convergence results hold in practice for various network topologies and variations in the number of malicious agents in the network.
    Yaowen Hu, Di Zhu, Shengyuan Lu, Xinrui Zhu, Yunxiang Song, Dylan Renaud, Daniel Assumpcao, Rebecca Cheng, CJ Xin, Matthew Yeh, Hana Warner, Xiangwen Guo, Amirhassan Shams-Ansari, David Barton, Neil Sinclair, and Marko Loncar. Submitted. “Integrated electro-optics on thin-film lithium niobate.” arXiv. Publisher's VersionAbstract
    2404.06398.pdf
    Electro-optics serves as the crucial bridge between electronics and photonics, unlocking a wide array of applications ranging from communications and computing to sensing and quantum information. Integrated electro-optics approaches in particular enable essential electronic high-speed control for photonics while offering substantial photonic parallelism for electronics. Recent strides in thin-film lithium niobate photonics have ushered revolutionary advancements in electro-optics. This technology not only offers the requisite strong electro-optic coupling but also boasts ultra-low optical loss and high microwave bandwidth. Further, its tight confinement and compatibility with nanofabrication allow for unprecedented reconfigurability and scalability, facilitating the creation of novel and intricate devices and systems that were once deemed nearly impossible in bulk systems. Building upon this platform, the field has witnessed the emergence of various groundbreaking electro-optic devices surpassing the current state of the art, and introducing functionalities that were previously non-existent. This technological leap forward provides a unique framework to explore various realms of physics as well, including photonic non-Hermitian synthetic dimensions, active topological physics, and quantum electro-optics. In this review, we present the fundamental principles of electro-optics, drawing connections between fundamental science and the forefront of technology. We discuss the accomplishments and future prospects of integrated electro-optics, enabled by thin-film lithium niobate platform.
    Can M Knaut, Aziza Suleymanzade, Yan-Cheng Wei, Daniel R Assumpcao, Pieter-Jan Stas, Yan Qi Huan, Bartholomeus Machielse, Erik N Knall, Madison Sutula, Gefen Baranes, Neil Sinclair, Chawina De-Eknamkul, David S Levonian, Mihir K Bhaskar, Hongkun Park, Marko Lončar, and Mikhail D Lukin. Submitted. “Entanglement of Nanophotonic Quantum Memory Nodes in a Telecommunication Network.” https://arxiv.org/abs/2310.01316. Publisher's VersionAbstract
    [PDF]
    A key challenge in realizing practical quantum networks for long-distance quantum communication involves robust entanglement between quantum memory nodes connected via fiber optical infrastructure. Here, we demonstrate a two-node quantum network composed of multi-qubit registers based on silicon-vacancy (SiV) centers in nanophotonic diamond cavities integrated with a telecommunication fiber network. Remote entanglement is generated via the cavity-enhanced interactions between the SiV's electron spin qubits and optical photons. Serial, heralded spin-photon entangling gate operations with time-bin qubits are used for robust entanglement of separated nodes. Long-lived nuclear spin qubits are used to provide second-long entanglement storage and integrated error detection. By integrating efficient bi-directional quantum frequency conversion of photonic communication qubits to telecommunication frequencies (1350 nm), we demonstrate entanglement of two nuclear spin memories through 40 km spools of low-loss fiber and a 35 km long fiber loop deployed in the Boston area urban environment, representing an enabling step towards practical quantum repeaters and large-scale quantum networks.
    Jesse Daas, Kolja Kuijpers, Frank Saueressig, Michael F. Wondrak, and Heino Falcke. Submitted. “Probing Quadratic Gravity with the Event Horizon Telescope ”. Publisher's VersionAbstract
    Quadratic gravity constitutes a prototypical example of a perturbatively renormalizable quantum theory of the gravitational interactions. In this work, we construct the associated phase space of static, spherically symmetric, and asymptotically flat spacetimes. It is found that the Schwarzschild geometry is embedded in a rich solution space comprising horizonless, naked singularities and wormhole solutions. Characteristically, the deformed solutions follow the Schwarzschild solution up outside of the photon sphere while they differ substantially close to the center of gravity. We then carry out an analytic analysis of observable signatures accessible to the Event Horizon Telescope, comprising the size of the black hole shadow as well as the radiation emitted by infalling matter. On this basis, we argue that it is the brightness within the shadow region which constrains the phase space of solutions. Our work constitutes the first step towards bounding the phase space of black hole type solutions with a clear quantum gravity interpretation based on observational data.

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