Browsing by Author "León-Montiel, Roberto de J."

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    Exceptional points of any order in a single, lossy waveguide beam splitter by photon-number-resolved detection
    (OSA, 2019-08) Quiroz-Juárez, Mario A.; Perez-Leija, Armando; Tschernig, Konrad; Rodriguez-Lara, Blas M.; Magaña-Loaiza, Omar S.; Busch, Kurt; Joglekar, Yogesh N.; León-Montiel, Roberto de J.; Physics, School of Science
    Exceptional points (EPs) are degeneracies of non-Hermitian operators where, in addition to the eigenvalues, the corresponding eigenmodes become degenerate. Classical and quantum photonic systems with EPs have attracted tremendous attention due to their unusual properties, topological features, and an enhanced sensitivity that depends on the order of the EP, i.e., the number of degenerate eigenmodes. Yet, experimentally engineering higher-order EPs in classical or quantum domains remain an open challenge due to the stringent symmetry constraints that are required for the coalescence of multiple eigenmodes. Here, we analytically show that the number-resolved dynamics of a single, lossy waveguide beam splitter, excited by 𝑁 indistinguishable photons and post-selected to the 𝑁-photon subspace, will exhibit an EP of order 𝑁+1. By using the well-established mapping between a beam splitter Hamiltonian and the perfect state transfer model in the photon-number space, we analytically obtain the time evolution of a general 𝑁-photon state and numerically simulate the system’s evolution in the post-selected manifold. Our results pave the way toward realizing robust, arbitrary-order EPs on demand in a single device.
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    Observation of slowly decaying eigenmodes without exceptional points in Floquet dissipative synthetic circuits
    (Springer Nature, 2018-12-03) León-Montiel, Roberto de J.; Quiroz-Juárez, Mario A.; Domínguez-Juárez, Jorge L.; Quintero-Torres, Rafael; Aragón, José L.; Harter, Andrew K.; Joglekar, Yogesh N.; Physics, School of Science
    Parity-time symmetric systems allow one to study new types of Hamiltonians which could have potential impact on our understanding of nonlinear physics. The authors investigate the energy stored in an electronic Floquet system and demonstrate that such a setup can be used to study the dynamics of dissipative parity-time symmetric systems.
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    On-Demand Parity-Time Symmetry in a Lone Oscillator through Complex Synthetic Gauge Fields
    (APS, 2022-11-14) Quiroz-Juárez, Mario A.; Agarwal, Kaustubh S.; Cochran , Zachary A.; Aragón, José L.; Joglekar, Yogesh N.; León-Montiel, Roberto de J.; Physics, School of Science
    What is the fate of an oscillator when its inductance and capacitance are varied while its frequency is kept constant? Inspired by this question, we propose a protocol to implement parity-time (PT ) symmetry in a lone oscillator. Different forms of constrained variations lead to static, periodic, or arbitrary balanced gain and loss profiles, that can be interpreted as purely imaginary gauge fields. With a state-of-the-art, dynamically tunable LC oscillator comprising synthetic circuit elements, we demonstrate static and Floquet PT breaking transitions, including those at vanishingly small gain and loss, by tracking the circuit energy. Concurrently, we derive and observe conserved quantities in this open, balanced gain-loss system, both in the static and Floquet cases. Lastly, by measuring the circuit energy, we unveil a giant dynamical asymmetry along exceptional-point contours that emerge symmetrically from the Hermitian degeneracies at Floquet resonances. Distinct from material or parametric gain and loss mechanisms, our protocol enables on-demand parity-time symmetry in a minimal classical system—a single oscillator—and may be ported to other realizations including metamaterials and optomechanical systems.