arXiv subjects

Binayyak Roy

Publications and source records attributed to Binayyak Roy.

3 recordsLinked to original sources

arXiv2026

Flat-band systems: A platform to realize the moments of Quantum Metric

The quantum metric is a fundamental geometric property of Bloch bands that governs a wide range of physical phenomena, yet experimentally accessing it remains challenging. We show that the momentum-space variation of the quantum metric can be probed through the real-space dynamics of a Gaussian wave packet prepared in an isolated flat band. Following the application of a weak constant force, we demonstrate analytically that the leading order change in the wave-packet variance is linear in time and contains a contribution proportional to the wave-packet averaged gradient of the quantum-metric trace. This geometric contribution remains finite despite the absence of band dispersion. We illustrate the effect using a gapped Lieb lattice with an exactly flat middle band and vanishing Berry curvature, allowing the quantum-metric contribution to the spreading to be isolated. The numerical results agree with the analytical prediction and confirm the quantum-metric contribution to the wave-packet spreading. The required lattice preparation, tunable hopping amplitudes, applied force, and density measurements are compatible with established ultracold-atom techniques, providing a possible platform for observing the predicted response. Our results establish wave-packet spreading as a dynamical probe of quantum geometry in flat-band systems.

cond-mat.quant-gas↗

arXiv2026

MEDA: Measurement-Efficient Disorder-Aware Majorana Zero Mode Detection in Realistic Devices

Fault-tolerant topological quantum computing relies on identifying Majorana zero modes (MZMs), but reliable detection in realistic devices remains challenging. Conventional topological indicators are inherently biased in finite, disordered systems, blurring the distinction between true MZMs and trivial states. Furthermore, attempts to map these indicators to real observables via machine learning require dense, expensive conductance measurements, creating a severe scaling bottleneck. To simultaneously address topological bias and measurement limitations, we present MEDA: a Measurement-Efficient, Disorder-Aware framework for MZM detection in realistic devices. MEDA maps sparse, practically obtainable observables directly to the robust periodic disorder invariant (PDI). Using a novel sparse parameter regime, MEDA reduces measurement volume by 10x while maintaining predictive quality, even in moderate to strong disorder regimes that limit conventional methods. Furthermore, MEDA naturally prioritizes input features consistent with the topological gap protocol, demonstrating strong physical interpretability.

cs.ET↗

arXiv2026

Floquet-Engineered Parity Anomaly Staircase in a Cold Atom Dirac Lattice

We propose a Floquet-engineered cold atom realization of a parity anomaly inspired anomalous Hall staircase in a two dimensional $π$-flux lattice. The effective model hosts massive Dirac fermions generated by the combined action of a time reversal symmetry breaking Floquet mass and a static inversion breaking mass offset. An additional momentum dependent scalar displacement term shifts different Dirac sectors in opposite energy directions without modifying their Bloch eigenvectors. As a result, the Berry curvature contribution associated with individual massive Dirac sectors can be selectively occupied, allowing the anomalous Hall response to evolve stepwise as a function of chemical potential or scalar displacement term. Evaluating the full lattice Berry curvature integral, we find plateau-like responses near $0$, $e^2/2h$, and $e^2/h$, corresponding respectively to the activation of zero, one, and two effective massive Dirac sector contributions. We analyze the associated low energy Dirac theory, band topology, Berry curvature structure, and two parameter response maps, and discuss a possible realization using Raman-assisted tunneling, off-resonant Floquet driving, and auxiliary AC-Stark dressing in ultracold atomic optical lattices.

cond-mat.quant-gas↗