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  1. Correlated quantum many-body phenomena in lattice models have been identified as a set of physically interesting problems that cannot be solved classically. Analog quantum simulators, in photonics and microwave superconducting circuits, have emerged as near-term platforms to address these problems. An important ingredient in practical quantum simulation experiments is the tomography of the implemented Hamiltonians—while this can easily be performed if we have individual measurement access to each qubit in the simulator, this could be challenging to implement in many hardware platforms. In this paper, we present a scheme for tomography of quantum simulators which can be described by a Bose-Hubbard Hamiltonian while having measurement access to only some sites on the boundary of the lattice. We present an algorithm that uses the experimentally routine transmission and two-photon correlation functions, measured at the boundary, to extract the Hamiltonian parameters at the standard quantum limit. Furthermore, by building on quantum enhanced spectroscopy protocols that, we show that with the additional ability to switch on and off the on-site repulsion in the simulator, we can sense the Hamiltonian parameters beyond the standard quantum limit.

    <supplementary-material><permissions><copyright-statement>Published by the American Physical Society</copyright-statement><copyright-year>2024</copyright-year></permissions></supplementary-material></sec> </div> <a href='#' class='show open-abstract' style='margin-left:10px;'>more »</a> <a href='#' class='hide close-abstract' style='margin-left:10px;'>« less</a> <div class="actions" style="padding-left:10px;"> <span class="reader-count"> Free, publicly-accessible full text available July 1, 2025</span> </div> </div><div class="clearfix"></div> </div> </li> <li> <div class="article item document" itemscope itemtype="http://schema.org/TechArticle"> <div class="item-info"> <div class="title"> <a href="https://par.nsf.gov/biblio/10517881-realizing-tight-binding-hamiltonians-using-site-controlled-coupled-cavity-arrays" itemprop="url"> <span class='span-link' itemprop="name">Realizing tight-binding Hamiltonians using site-controlled coupled cavity arrays</span> </a> </div> <div> <strong> <a class="misc external-link" href="https://doi.org/10.1038/s41467-023-41034-x" target="_blank" title="Link to document DOI">https://doi.org/10.1038/s41467-023-41034-x  <span class="fas fa-external-link-alt"></span></a> </strong> </div> <div class="metadata"> <span class="authors"> <span class="author" itemprop="author">Saxena, Abhi</span> <span class="sep">; </span><span class="author" itemprop="author">Manna, Arnab</span> <span class="sep">; </span><span class="author" itemprop="author">Trivedi, Rahul</span> <span class="sep">; </span><span class="author" itemprop="author">Majumdar, Arka</span> </span> <span class="year">( <time itemprop="datePublished" datetime="2023-12-01">December 2023</time> , Nature Communications) </span> </div> <div style="cursor: pointer;-webkit-line-clamp: 5;" class="abstract" itemprop="description"> <title>Abstract

    Analog quantum simulators rely on programmable and scalable quantum devices to emulate Hamiltonians describing various physical phenomenon. Photonic coupled cavity arrays are a promising alternative platform for realizing such simulators, due to their potential for scalability, small size, and high-temperature operability. However, programmability and nonlinearity in photonic cavities remain outstanding challenges. Here, using a silicon photonic coupled cavity array made up of$$8$$8high quality factor ($$Q$$Qup to$$\, \sim 7.1\times {10}^{4}$$~7.1×104) resonators and equipped with specially designed thermo-optic island heaters for independent control of cavities, we demonstrate a programmable photonic cavity array in the telecom regime, implementing tight-binding Hamiltonians with access to the full eigenenergy spectrum. We report a$$\sim 50\%$$~50%reduction in the thermal crosstalk between neighboring sites of the cavity array compared to traditional heaters, and then present a control scheme to program the cavity array to a given tight-binding Hamiltonian. The ability to independently program high-Q photonic cavities, along with the compatibility of silicon photonics to high volume manufacturing opens new opportunities for scalable quantum simulation using telecom regime infrared photons.

     
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  2. Abstract

    Scalable programmable photonic integrated circuits (PICs) can potentially transform the current state of classical and quantum optical information processing. However, traditional means of programming, including thermo-optic, free carrier dispersion, and Pockels effect result in either large device footprints or high static energy consumptions, significantly limiting their scalability. While chalcogenide-based non-volatile phase-change materials (PCMs) could mitigate these problems thanks to their strong index modulation and zero static power consumption, they often suffer from large absorptive loss, low cyclability, and lack of multilevel operation. Here, we report a wide-bandgap PCM antimony sulfide (Sb2S3)-clad silicon photonic platform simultaneously achieving low loss (<1.0 dB), high extinction ratio (>10 dB), high cyclability (>1600 switching events), and 5-bit operation. These Sb2S3-based devices are programmed via on-chip silicon PIN diode heaters within sub-ms timescale, with a programming energy density of$$\sim 10\,{fJ}/n{m}^{3}$$~10fJ/nm3. Remarkably, Sb2S3is programmed into fine intermediate states by applying multiple identical pulses, providing controllable multilevel operations. Through dynamic pulse control, we achieve 5-bit (32 levels) operations, rendering 0.50 ± 0.16 dB per step. Using this multilevel behavior, we further trim random phase error in a balanced Mach-Zehnder interferometer.

     
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  3. Increasing the space-bandwidth product of spatial light modulators incurs severe issues in terms of power consumption, mutual crosstalk, and control signal wiring. In this opinion article, we propose a novel system to overcome these challenges by marrying energy-efficient modulators in photonic integrated circuits (PICs) and a meta-optical beam aggregator. This hybrid approach can significantly improve the space-bandwidth product, theoretically up to 1013Hz · pixel, which is several orders of magnitude higher than the state-of-the-art.

     
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  4. We report a hybrid phase-change mateial Sb2S3-silicon photonic tunable directional coupler, which exhibits low insertion loss (< 1.0 dB), large extinction ratio (> 10 dB), high endurance (> 1,600 switching events), and 32 operation levels.

     
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  7. Prototyping of van der Waals materials on dense nanophotonic devices requires high-precision monolayer discrimination to avoid bulk material contamination. We use the glass transition temperature of polycarbonate, used in the standard dry transfer process, to draw an in situ point for the precise pickup of two-dimensional materials. We transfer transition metal dichalcogenide monolayers onto a large-area silicon nitride spiral waveguide and silicon nitride ring resonators to demonstrate the high-precision contamination-free nature of the modified dry transfer method. Our improved local transfer technique is a necessary step for the deterministic integration of high-quality van der Waals materials onto nanocavities for the exploration of few-photon nonlinear optics on a high-throughput, nanofabrication-compatible platform.

     
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