arXiv subjects

Neel Malvania

Publications and source records attributed to Neel Malvania.

8 recordsLinked to original sources

arXiv2026

Static dc electric field orientation effects on two-photon Rydberg EIT

We examine the influence of a static dc electric field on Electromagnetically Induced Transparency (EIT) resonances that involve highly excited Rydberg states. Our focus is on how these resonances are altered when the relative orientation between the laser polarization and the external electric field vectors are varied. We experimentally demonstrate characteristic variations in the amplitude of the Stark-split EIT resonances, which can be explained by the selection rules in various geometries. We also present a simplified semi-analytical model that closely resembles the experimental observations. We use these findings to obtain information about the spatially inhomogeneous electric field, produced by a biased wire, using EIT fluorescence measurements that agrees with the expected angular dependencies. These results suggest that simultaneous analysis of frequency shifts and amplitudes of Rydberg EIT resonances may enable vector electrometry of electrostatic fields, necessary for many quantum sensing applications.

physics.atom-ph↗

arXiv2026

Electron Beam Profiling via Rydberg Electromagnetically Induced Transparency in Rubidium Vapor with Crossed Laser beams

We present an all-optical detection approach to determine the position and spatial profile of an electron beam based on quantum properties of alkali metal atoms. To measure the electric field, produced by an electron beam, we excite thermal rubidium atoms to a highly excited Rydberg state via a two-photon ladder transition and detect Stark shifts of Rydberg states by monitoring frequencies of the corresponding electromagnetically induced transparency (EIT) transmission peaks. We addressed several technical challenges in this approach. First, we use crossed laser beams to obtain spatial information about the electron beam position and geometry. Second, by pulsing the electron beam and using phase-sensitive optical detection, we separate the true electron beam electric signature from the parasitic electric fields due to photoelectric charges on the windows. Finally, we use a principle component analysis to further improve signal quality. We test this method to detect the current and to reconstruct a 2D profile of a 20 keV electron beam with currents ranging from 25 - 100 uA. While this technique provides less spatial resolution than fluorescence-based measurements, thanks to their speed and limited optical access requirements it can be useful for real-time non-invasive diagnostics of charged particle beams at accelerator facilities.

physics.atom-ph↗

arXiv2025

Non-perturbative 2D spatial measurements of electric fields within a plasma sheath

We introduce an all-optical quantum-enhanced diagnostic for electric fields in low-temperature plasmas. Trace amounts of rubidium vapor, added to argon plasma, allow us to produce spectrally narrow electric field-sensitive optical resonances via quantum optical effect of Rydberg electromagnetically induced transparency, and to non-invasively measure electric field in plasma with sensitivity exceeding 1 V/cm. By collecting fluorescence from the illuminated region of interest, we reconstruct a 2D spatial profile of the electric field magnitude with $30~μ$m resolution. As a proof-of-principle demonstration, we measured the changes in electric field within the plasma sheath surrounding a biased Langmuir probe tip. This method holds significant potential for studying sheath structures in low-temperature plasmas.

physics.plasm-ph↗

arXiv2025

Rydberg Atom Electric Field Sensors as Linear Time-invariant Systems

Over the past decade, Rydberg atom electric field sensors have been under investigation as potential alternatives or complements to conventional antenna-based receivers for select applications in RF communications, remote sensing, and precision metrology. To understand the potential utility of these devices for various use cases, it is crucial to develop models that accurately predict key performance metrics such as instantaneous bandwidth and dynamic range. However, existing numerical models require solving a large set of coupled differential equations that is computationally intensive and lengthy to solve. We present an analytic approach that can be used to derive an impulse response function that allows up to two orders-of-magnitude reduction in computation time compared to the full time-dependent integration of the equations of motion. This approach can be used to enable rapid assessments of the Rydberg sensor's response to various waveforms.

quant-ph↗

arXiv2025

Electron beam characterization via fluorescence imaging of Rydberg states in atomic vapor

We demonstrate an all-optical, minimally invasive method for electron beam (e-beam) characterization using Rydberg electrometry. The e-beam passes through a dilute Rb vapor prepared in a quantum superposition of ground and Rydberg states that reduces resonant absorption in a narrow spectral region. Imaging the modifications of Rb fluorescence due to shifts in the Rydberg state from the e-beam electric field allows us to reconstruct e-beam width, centroid position, and current. We experimentally demonstrate this technique using a 20 keV e-beam in the range of currents down to 20 $μ$A, and discuss technical challenges produced by environmental electric potentials in the detection chamber. Overall, we demonstrate the promising potential of such an approach as a minimally invasive diagnostic for charged particle beams.

physics.atom-ph↗

arXiv2020

Generalized hydrodynamics in strongly interacting 1D Bose gases

The dynamics of strongly interacting many-body quantum systems are notoriously complex and difficult to simulate. A new theory, generalized hydrodynamics (GHD), promises to efficiently accomplish such simulations for nearly-integrable systems. It predicts the evolution of the distribution of rapidities, which are the momenta of the quasiparticles in integrable systems. GHD was recently tested experimentally for weakly interacting atoms, but its applicability to strongly interacting systems has not been experimentally established. Here we test GHD with bundles of one-dimensional (1D) Bose gases by performing large trap quenches in both the strong and intermediate coupling regimes. We measure the evolving distribution of rapidities, and find that theory and experiment agree well over dozens of trap oscillations, for average dimensionless coupling strengths that range from 0.3 to 9.3. By also measuring momentum distributions, we gain experimental access to the interaction energy and thus to how the quasiparticles themselves evolve. The accuracy of GHD demonstrated here confirms its wide applicability to the simulation of nearly-integrable quantum dynamical systems. Future experimental studies are needed to explore GHD in spin chains, as well as the crossover between GHD and regular hydrodynamics in the presence of stronger integrability breaking perturbations.

cond-mat.quant-gas↗

arXiv2019

Observation of Dynamical Fermionization

We observe dynamical fermionization, where the momentum distribution of a Tonks-Girardeau (T-G) gas of strongly interacting bosons in 1D evolves from bosonic to fermionic after its axial confinement is removed. The asymptotic momentum distribution after expansion in 1D is the distribution of rapidities, which are the conserved quantities associated with many-body integrable systems. Rapidities have not previously been measured in any interacting many-body quantum system. Our measurements agree well with T-G gas theory. We also study momentum evolution after the trap depth is suddenly changed to a new non-zero value. We observe the predicted bosonic-fermionic oscillations and see deviations from the theory outside of the T-G gas limit.

cond-mat.quant-gas↗

arXiv2018

Energy-dependent 3-body loss in 1D Bose gases

We study the loss of atoms in quantum Newton's cradles (QNCs) with a range of average energies and transverse confinements. We find that the three-body collision rate in one-dimension is strongly energy dependent, as predicted by a strictly 1D theory. We adapt the theory to atoms in waveguides, then using detailed momentum measurements to infer all the collisions that occur, we compare the observed loss to the adapted theory and find that they agree well.

physics.atom-ph↗