DQMP Forum - Samudra Sur - Valeria Vento

02.06.2026 13:00 – 14:00

Interplay of Noise and Reservoir-induced Decoherence in Persistent Currents
Samudra Sur (group of prof. Giamarchi)

Persistent current is one of the striking signatures of quantum phase coherence, arising when electronic wavefunctions remain coherent around a mesoscopic ring threaded by magnetic flux, producing the Aharonov–Bohm effect. Consequently, a suppression of the current indicates that one or several mechanisms of decoherence are at play. In this presentation, I will describe the fate of the persistent current in a non-equilibrium setting, where a tight-binding ring is subjected to stochastic disorder as well as a fermionic reservoir attached to each site. Using the Keldysh formalism, we find that noise and reservoir effects compete rather than add, giving rise to two distinct decoherence mechanisms that exhibit unusual current decay. Remarkably, the reservoirs play a dual role; weak coupling supports the current, while strong coupling suppresses it.
Ref.: Sur and Giamarchi, arXiv:2510.17982 (2025)


Super-resolution Localization and Control of 2D Quantum Emitters
Valeria Vento (group of prof. Srivastava)

In transition-metal dichalcogenide (TMD) heterobilayers, lattice mismatch and reconstruction create localized traps for interlayer excitons, forming quantum emitters with potential as nanoscale sensors of correlated phases of matter[1]. These emitters are electrically tunable and inherit spin–valley selection rules and strong light–matter coupling, yet deterministic spatial control remains challenging due to subwavelength confinement and disorder. In this talk, I will present a platform that combines cryogenic optical spectroscopy with scanning probe microscopy to investigate trapped interlayer excitons in WSe2/MoSe2 bilayers[2]. By exploiting AFM-based local Stark shift, we achieve super-resolution localization of emitters separated by only a few tens of nanometers and demonstrate deterministic control of individual charge states, including trion formation. Time-resolved measurements further allow us to resolve radiative and non-radiative decay channels, revealing controlled manipulation of individual exciton dynamics and opening a path toward coherent inter-dot coupling. These results establish a platform for sensing and trapping
anyons in semiconducting FCIs[3].
Ref.: [1] W. Li, et al., arXiv:2111.09440 (2024). [2] B. Lyu*, V. Vento*, et al., in preparation (2026). [3] W. Li, et al., Nature 651, 48 (2026).

Lieu

Bâtiment: Ecole de Physique

Auditoire Stückelberg

entrée libre