Two-dimensional atom localization via Raman-driven coherence

Rahmatullah Rahmatullah, Sajid Qamar

Ren-Gang Wan, Jun Kou, Jiang Li +2 more

Jiahua Li, Rong Yu, Min Liu +2 more

Sayari Majumder, Bhagyashri Bidwai, Bernadette Varsha +1 more

We demonstrate a minimally perturbative detection method—Raman driven spin noise spectroscopy (RDSNS)—to directly probe the local density of a cloud of cold 39K atoms in real time. The technique relies on detecting the polarization fluctuations of a far-off resonant focused probe light passing through the atoms, driven by two coherent Raman lasers connecting adjacent Zeeman spin states. This is an easily implementable scheme with a wide-ranging applicability in detecting cold atoms. Unlike traditional fluorescence and absorption imaging techniques, this approach does not require stochastic photon scattering from trapped atoms, thereby leaving the cold cloud unperturbed. The data can be collected in MHz refresh rate, allowing for near real-time detection. We validated this technique by monitoring the strength of the RDSNS signal by varying the key parameters of the three-dimensional magneto-optical trap (MOT) and the cold atom source (two-dimensional MOT). We performed experiments to probe local densities across the cold atom cloud using our technique and compared it with the inverse Abel-transformed density profiles extracted from the fluorescence of a spherically symmetric atomic cloud and found excellent agreement. This detection protocol is particularly advantageous for probing systems that lack inherent symmetry, where the Abel transformation is inapplicable. Moreover, RDSNS imaging is suitable for extracting the dynamical properties of systems in real time.

Haowei Li, Wei Yi

We show that a dissipative two-dimensional Raman lattice can be engineered in a two-component ultracold atomic gas, where the interplay of the two-dimensional spin-orbit coupling and light-induced atom loss gives rise to a density flow diagonal to the underlying square lattice. The flow is driven by the non-Hermitian corner skin effect, under which eigenstates localize toward one corner of the system. We illustrate that the topological edge states of the system can only be accounted for by the non-Bloch band theory where the deformation of the bulk eigenstates are explicitly considered. The directional flow can be detected through the dynamic evolution of an initially localized condensate in the lattice, or by introducing an immobile impurity species that interact spin selectively with a condensate in the ground state of the Raman lattice.

Forough Bozorgzadeh, Mohammad Reza Ghorbani Fard, Mostafa Sahrai