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1. Variational Simulation of the Lipkin-Meshkov-Glick Model on a Neutral Atom Quantum Computer

   https://doi.org/10.1103/PRXQuantum.6.020350  

   Chinnarasu, R; Poole, C; Phuttitarn, L; Noori, A; Graham, T M; Coppersmith, S N; Balantekin, A B; Saffman, M (June 2025, PRX Quantum)

   We simulate the Lipkin-Meshkov-Glick model using the variational-quantum-eigensolver algorithm on a neutral atom quantum computer. We test the ground-state energy of spin systems with up to 15 spins. Two different encoding schemes are used: an individual spin encoding where each spin is represented by one qubit, and an efficient Gray code encoding scheme that only requires a number of qubits that scales with the logarithm of the number of spins. This more efficient encoding, together with zero-noise extrapolation techniques, is shown to improve the fidelity of the simulated energies with respect to exact solutions. Published by the American Physical Society2025 

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2. Extended interaction length laser-driven acceleration in a tunable dielectric structure

   https://doi.org/10.1103/PhysRevAccelBeams.27.051303  

   Crisp, Sophie; Ody, Alexander; England, Joel; Musumeci, Pietro (May 2024, Physical Review Accelerators and Beams)

   The development of long, tunable structures is critical to increasing energy gain in laser-driven dielectric accelerators (DLAs). Here we combine pulse-front-tilt illumination with slab-geometry structures assembled by precisely aligning off-the-shelf 4 mm long transmission gratings to achieve up to 200 keV energy modulation for 6 MeV injected electrons. The effective interaction length is longer than 1 mm, limited by the dephasing of the accelerated particles in the structure. The piezo-based independent mounting system for the gratings allows tuning of the gap and field distribution inside the structure. Published by the American Physical Society2024 

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3. Random coordinate descent: A simple alternative for optimizing parameterized quantum circuits

   https://doi.org/10.1103/PhysRevResearch.6.033029  

   Ding, Zhiyan; Ko, Taehee; Yao, Jiahao; Lin, Lin; Li, Xiantao (July 2024, Physical Review Research)

   Variational quantum algorithms rely on the optimization of parameterized quantum circuits in noisy settings. The commonly used back-propagation procedure in classical machine learning is not directly applicable in this setting due to the collapse of quantum states after measurements. Thus, gradient estimations constitute a significant overhead in a gradient-based optimization of such quantum circuits. This paper introduces a random coordinate descent algorithm as a practical and easy-to-implement alternative to the full gradient descent algorithm. This algorithm only requires one partial derivative at each iteration. Motivated by the behavior of measurement noise in the practical optimization of parameterized quantum circuits, this paper presents an optimization problem setting that is amenable to analysis. Under this setting, the random coordinate descent algorithm exhibits the same level of stochastic stability as the full gradient approach, making it as resilient to noise. The complexity of the random coordinate descent method is generally no worse than that of the gradient descent and can be much better for various quantum optimization problems with anisotropic Lipschitz constants. Theoretical analysis and extensive numerical experiments validate our findings. Published by the American Physical Society2024 

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4. Impact of nanometer-thin stiff layer on adhesion to rough surfaces

   https://doi.org/10.1103/PhysRevResearch.6.033015  

   Kumar, Shubhendu; Gaire, Babu; Persson, B_N J; Dhinojwala, Ali (July 2024, Physical Review Research)

   Adhesives require molecular contact, which is governed by roughness, modulus, and load. Here, we measured adhesion for stiff glassy polymer layers of varying thickness on top of a soft elastomer with rough substrates. We found that a 90-nm-thick PMMA layer on a softer elastic block was sufficient to drop macroscopic adhesion to almost zero during the loading cycle. This drop in adhesion for bilayers follows the modified Persson-Tosatti model, where the elastic energy for conformal contact depends on the thickness and modulus of the bilayer. In contrast, we observed no dependence on thickness of the PMMA layer on the work of adhesion calculated using the pull-off forces. Understanding how mechanical gradients (like bilayers) affect adhesion is critical for areas such as adhesion, friction, and colloidal and granular physics. Published by the American Physical Society2024 

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5. Candidate de Sitter vacua

   https://doi.org/10.1103/PhysRevD.111.086015  

   McAllister, Liam; Moritz, Jakob; Nally, Richard; Schachner, Andreas (April 2025, Physical Review D)

   We construct compactifications of type IIB string theory that yield, at leading order in the ${\alpha }^{\prime }$and $g_s$expansions, de Sitter vacua of the form envisioned by Kachru We specify explicit Calabi-Yau orientifolds and quantized fluxes for which we derive the four-dimensional effective supergravity theories, incorporating the exact flux superpotential, the nonperturbative superpotential from Euclidean D3-branes, and the Kähler potential at tree level in the string loop expansion but to all orders in ${\alpha }^{\prime }$. Each example includes a Klebanov-Strassler throat region containing a single anti-D3-brane, whose supersymmetry-breaking energy, computed at leading order in ${\alpha }^{\prime }$, causes an uplift to a metastable de Sitter vacuum in which all moduli are stabilized. Finding vacua that demonstrably survive subleading corrections, and in which the quantization conditions are completely understood, is an important open problem for which this work has prepared the foundations. Published by the American Physical Society2025 

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