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Probing dielectric breakdown in Mott insulators through current oscillations
by Joan Triadú-Galí, Artur Garcia-Saez, Bruno Juliá-Díaz, Axel Pérez-Obiol
Submission summary
| Authors (as registered SciPost users): | Joan Triadú |
| Submission information | |
|---|---|
| Preprint Link: | https://arxiv.org/abs/2502.12702v1 (pdf) |
| Date submitted: | 2025-02-25 16:31 |
| Submitted by: | Triadú, Joan |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Computational |
Abstract
We investigate the dielectric breakdown of mesoscopic Mott insulators, a phenomenon where a strong electric field destabilizes the insulating state, resulting in a transition to a metallic phase. Using the Landau-Zener formalism, which models the excitation of a two-level system, we derive a theoretical expression for the threshold value of the field. To validate our predictions, we present an efficient protocol for estimating the charge gap and threshold field via non-equilibrium current oscillations, overcoming the computational limitations of exact diagonalization. Our simulations demonstrate the accuracy of our theoretical formula for systems with small gaps. Moreover, our findings are directly testable in ultracold atomic experiments with ring geometries and artificial gauge fields, as our method uses measurable quantities and relies on already available technologies. This work aims to bridge the gap between theoretical models and experimentally realizable protocols, providing tools to explore non-equilibrium mesoscopic phenomena in strongly correlated quantum systems.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Current status:
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Report
This study investigates the threshold electric field strength at which dielectric breakdown occurs when a magnetic flux is applied to a Hubbard model on a ring, thereby generating an electric field along the ring. Employing the Landau-Zener model, the authors clarify the relationship between the charge gap and the breakdown threshold. Furthermore, they point out that the charge gap and the breakdown threshold can be estimated from the frequency and amplitude of the current induced by the flux, respectively. These two approaches to assess the threshold are numerically validated to demonstrate their reliability.
The novelty of this paper lies in its elucidation of how the threshold behavior is affected in finite systems, in contrast to previous studies that mainly focused on the one-dimensional Hubbard model in the thermodynamic limit. I believe that this study is suitable for publication. However, I request the authors to address the following comments.
Requested changes
1- Equation (17) relates the charge gap to the threshold field. Could the authors quantitatively clarify the parameter range (regarding the interaction strength $U$ and the system size $L$) over which this relation remains valid?
2- Equation (24) is an expansion in terms of $E_{th}/E$. Could the authors clarify the range of electric field strength $E$ over which this approximation is quantitatively reliable?
3- While the present study focuses on Mott insulators, the approach may be extendable to other gapped systems such as semiconductors. Could the authors comment on whether there are qualitative differences in the threshold behavior due to many-body effects that would not appear in single-particle gapped systems?
4- In Fig. 2(a), the part of the energy spectrum with $E \gtrsim -3$ appears to be omitted. Including the full spectrum within the displayed range might improve clarity unless there is a specific reason for excluding it.
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