Abstract The Derivative Removal by Adiabatic Gate (DRAG) technique is the standard remedy for leakage to non-computational states in transmon-based quantum gates. However, a wide class of platforms—including fluxonium and composite-transmon qubits—cannot benefit from it, since their canonical gate implementations rely on Landau-Majorana-Stückelberg-Zener (LMSZ) protocols. Specifically, the constant Rabi envelope of the LMSZ model does not allow using the DRAG correction, which requires a non-zero first derivative. A complementary obstruction affects hardware that does not support time-dependent Rabi-frequency modulation: such platforms cannot benefit from the Allen-Eberly-Hioe (AEH) model either, an unpleasant fact given its analytical tractability. We resolve both limitations by introducing the concept of isoprobability twin models—distinct pairs of Rabi frequency Ω ( t ) and detuning Δ ( t ) that yield identical post-pulse transition probabilities through the Delos–Thorson transformation. We experimentally demonstrate the equivalence of multiple LMSZ and AEH twin models on IBM’s ibm_kyiv processor. We then show that the framework unlocks the DRAG technique by trading the canonical, constant-Rabi LMSZ pulse for a smooth cosine-Rabi twin, and numerically demonstrate that the resulting DRAG-corrected pulse suppresses leakage to a transmon’s non-computational states by up to six orders of magnitude at moderate chirp slopes and by three orders of magnitude on average over the entire driving landscape, while preserving the LMSZ transition-probability landscape.
Abstract A spectral line intensity ratio technique based on neutral and singly ionized argon (Ar 0 and Ar 1+ ) emissions has been established to diagnose the edge plasma parameter of a tokamak. Here, collisional-radiative modelling implemented in the ADAS database is applied to identify suitable spectral line pairs with distinct sensitivities to electron temperature and density. Several argon line ratios are examined, and their diagnostic capabilities are assessed under relevant plasma conditions, and have been listed for measuring plasma n e and T e . The intensity ratio of Ar 0 lines at 750.38 and 763.51 nm has been applied on ADITYA-U tokamak to measure the plasma edge electron temperature, which comes out to be approximately 6−14 eV. The recommended approach exhibits the effectiveness of the argon spectral line ratio as a non-intrusive diagnostic tool for edge plasma characterization in tokamaks.
Abstract Cold atoms play a crucial role in enabling precision spectroscopy and various quantum technology applications. To fully exploit their potential in emerging technologies, it is essential to characterize atom losses during imaging of atoms. In this work, we systematically investigate atom-number measurement losses in a cold-atom ensemble arising due to light-assisted collisions. We have studied the dynamics of lightassisted collisions by measuring the loss coefficients and the compensated measured atom numbers. We then assess the accuracy of the inferred atom numbers and internalstate readout in the presence of these loss processes. These results present a detailed picture of detection-limited noise and collisional loss in cold atom clouds of quantum sensing and quantum communication applications.
Abstract We present a deterministic, grid-based framework for solving the stationary Schrödinger equation for strongly correlated few-body systems. This formulation leverages a resolvent filter operator ( H − E ) − 1 operating directly in spatial representations, offering an operationally boundary-agnostic approach where edge points act as free dynamical unknowns and physical asymptotic decay emerges spontaneously from internal Hamiltonian dynamics without manual boundary matching. We apply this framework to the helium atom in hyperspherical coordinates as a prototypical benchmark for strong electron correlation, successfully extracting both the ground state and a diverse manifold of low-lying excited states. By systematically analyzing grid configurations, we show that discretization errors follow a strict O ( Δ ρ 2 ) behavior, which is efficiently eliminated via Richardson extrapolation. The resulting grid-extrapolated energies exhibit exceptional agreement with high-precision variational benchmarks, demonstrating that deterministic spectral filtering provides a robust and powerful alternative for complex quantum systems, achieving rapid convergence within only a few iterations.
Abstract Laser-produced xenon (Xe) plasma can emit extreme ultraviolet (EUV) radiation around 11.2 nm, which is regarded as a promising candidate for next EUV lithography due to its debris-free, long-term stable fuel supply and easy operation. However, the inherent free expansion of gas targets in vacuum distorts the gas density distribution, thereby lowering the EUV conversion efficiency (CE). This study simulates the CE of 11.2 nm EUV emitted from laser-produced Xe plasmas at axial positions of 0.50–1.50 mm away from the nozzle exit, under gas pressures ranging from 4–100 bar. The gas density distributions obtained from simulations are experimentally verified with a Nomarski interferometer, while the calculated EUV spectra were validated via EUV experimental spectroscopy. The results indicate that increasing the Xe pressure and positioning the laser focus closer to the nozzle exit improve both the laser absorption fraction and radiative conversion ratio, while slightly degrading the spectral purity. A maximum CE of approximately 7.8% is obtained at 11.2 nm within a 2% bandwidth. Furthermore, it is found that the emission region becomes smaller closer to the nozzle exit , offering a means to control source size. This work establishes, for the first time, a comprehensive theoretical framework for predicting and optimizing the CE of Xe-based EUV sources, and demonstrates its application potential for next-generation high-volume manufacturing lithography.
