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Dangka Shylla

Publications and source records attributed to Dangka Shylla.

12 recordsLinked to original sources
arXiv2025

Sensitivity Comparison of Rydberg Atom-Based Radio-Frequency Electric Field Detection: Ionization Current Versus Optical Readout

We investigate a technique for detecting radio-frequency (RF) electric fields in a Cesium (Cs) vapor cell at room temperature by collecting charge from ionized Rydberg atoms and compare its performance with the established method of electromagnetically induced transparency (EIT). By applying a known RF field, we measure the response from both the electrical (ionization current-based) and optical (EIT-based) readouts. The ionization current-based method yields a sensitivity of 22~$μ$Vm$^{-1}$Hz$^{-1/2}$, while the EIT-based method achieves 3.7~$μ$Vm$^{-1}$Hz$^{-1/2}$. The sensitivity of the ionization current-based method is limited by thermal noise arising from a 2.2~k$Ω$ resistance between the collection electrodes, attributed to a thin Cs film on the inner surfaces of the vapor cell. Controlling or eliminating the Cs layer can significantly improve the sensitivity of this ionization approach.

physics.atom-ph↗
arXiv2024

Primary quantum thermometry of mm-wave blackbody radiation via induced state transfer in Rydberg states of cold atoms

Rydberg states of alkali atoms are highly sensitive to electromagnetic radiation in the GHz-to-THz regime because their transitions have large electric dipole moments. Consequently, environmental blackbody radiation (BBR) can couple Rydberg states together at $μ$s timescales. Here, we track the BBR-induced transfer of a prepared Rydberg state to its neighbors and use the evolution of these state populations to characterize the BBR field at the relevant wavelengths, primarily at 130 GHz. We use selective field ionization readout of Rydberg states with principal quantum number $n\sim30$ in $^{85}$Rb and substantiate our ionization signal with a theoretical model. With this detection method, we measure the associated blackbody-radiation-induced time dynamics of these states, reproduce the results with a simple semi-classical population transfer model, and demonstrate that this measurement is temperature sensitive with a statistical sensitivity to the fractional temperature uncertainty of 0.09 Hz$^{-1/2}$, corresponding to 26 K$\cdot$Hz$^{-1/2}$ at room temperature. This represents a calibration-free SI-traceable temperature measurement, for which we calculate a systematic fractional temperature uncertainty of 0.006, corresponding to 2 K at room temperature when used as a primary temperature standard.

physics.atom-ph↗
arXiv2024

Observation of Asymmetric Sideband Generation in Strongly-driven Rydberg Atoms

Improving the bandwidth of Rydberg atom-based receivers is an ongoing challenge owing to the long-lived Rydberg state lifetimes that limit the refresh rate of ground state atoms. In particular, the LO-based Rydberg mixer approach allows for bandwidths into the few-MHz range. Here, we use heterodyne detection of the Rydberg atom receiver probe laser to separate the negative and positive sidebands that originate from distinct six wave mixing processes, in order to investigate their individual bandwidths. We experimentally confirm the prediction that the negative sideband exhibits a higher bandwidth than the positive sideband. We further explore the effect of coupling and probe laser Rabi frequency on the bandwidth, which we find to be in good agreement with our model. We achieved a maximum experimental (and theoretical) bandwidth of about 11 (11) MHz and 3.5 (5) MHz for the negative and positive sidebands, respectively, from the -3dB roll-off point for optimized field parameters. This work provides insight into the bandwidth-limiting features of Rydberg atom receivers and points the way towards further optimization of their response.

physics.atom-ph↗
arXiv2024

Independent Rydberg Atom Sensing using a Dual-Ladder Scheme

Rydberg atom-based electric field sensing can provide all-optical readout of radio frequency fields in a dielectric environment. However, because a single set of optical fields is typically used to prepare the Rydberg state and read out its response to RF fields, it is challenging to perform simultaneous and independent measurements of the RF field(s). Here we show that using two independent schemes to prepare and read out the same Rydberg state can be used to perform independent measurements in general, which we demonstrate specifically by resolving the the RF polarization. We expect this work will be useful for fiber-coupled sensor heads where spatial multiplexing is challenging, as well as for complex multi-level sensing schemes.

physics.atom-ph↗
arXiv2024

Investigation of fluorescence versus transmission readout for three-photon Rydberg excitation used in electrometry

We present a three-photon based fluorescence readout method where the strength of the fluorescence scales with the strength of the radio-frequency (RF) field being applied. We compare this method to conventional three-photon electromagnetically-induced transparency (EIT) and electromagnetically-induced absorption (EIA). Our demonstrated EIA/EIT sensitivity in the collinear three-photon Cesium system is the best reported to date at roughly 30 uVm^{-1}Hz^{-1/2}. The fluorescence is nearly 4 fold better in sensitivity compared to EIA/EIT readout.

quant-ph↗
arXiv2023

Zeeman-resolved Autler-Townes splitting in Rydberg atoms with tunable resonances and a single transition dipole moment

Applying a magnetic field as a method for tuning the frequency of Autler-Townes splitting for Rydberg electrometry has recently been demonstrated. In this paper we provide a theoretical understanding of EIT signals in the presence of a large magnetic field, as well as demonstrate some advantages of this technique over traditional Autler-Townes based electrometry. We show that a strong magnetic field provides a well-defined quantization axis regardless of the optical field polarizations, we demonstrate that by separating the $m_J$ levels of the Rydberg state we can perform an Autler-Townes splitting with a single participating dipole moment, and we demonstrate recovery of signal strength by populating a single $m_J$ level using circularly polarized light.

physics.atom-ph↗
arXiv2022

Narrow-line cooling of $^{87}$Rb using 5S$_{1/2} \rightarrow$ 6P$_{3/2}$ open transition at 420 nm

Magneto-optical trap (MOT) at narrow (weak) transition offers lower temperature and hence is the key for production of high phase density atomic cloud and subsequently quantum degeneracy with high number of atoms for many elements. In this paper, we describe loading of $^{87}$Rb atoms in the MOT using a narrow open transition at 420 nm from the routinely implemented MOT using broad cyclic transition at 780 nm (IR). The total linewidth of the blue transition, 5S$_{1/2} \rightarrow $ 6P$_{3/2}$ is 1.4 MHz, which is around 4 times narrower than the standard 5S$_{1/2} \rightarrow$ 5P$_{3/2}$ cyclic transition. Using this narrow transition, we have trapped around $10^{8}$ atoms in the MOT with a typical temperature of around $54~μ$K. We have also studied the behavior of the blue MOT with various parameters such as hold time, detuning and power of trapping and repumper beams.

physics.atom-ph↗
arXiv2021

Nature of interference between Autler-Townes peaks in multi-level system

In this work we present a theoretical frame work to identify the role and the nature of interference between Autler-Townes (AT) peaks (or dressed states) in generic multi-level system. The destructive interference between the AT peaks, gives rise to sharp transparency window known as electromagnetically induced transparency (EIT). In the three-level system, the two AT peaks interferes pair-wise with each other, almost similar to the two-slit interference. In the four-level system, the interference between the three AT peaks is also pair-wise analogous to three-slit interference but has a bit more complicated nature of interference. However, in many practical situations in atomic systems only the simple form of interference similar to three-level system dominates. In the three-level system, the nature of interference (i.e. constructive, destructive or zero/no interference) between the two AT peaks is purely determined by the natural decay rate of the states coupled by the control laser. However, in four-level system the nature of interference between the two extreme AT peaks can be tuned from constructive to destructive by tuning the power of the control laser.

physics.atom-ph↗
arXiv2021

Hyperfine measurement of $6\text{P}_{1/2}$ state in $^{87}\text{Rb}$ using double resonance on blue and IR transition

In this paper, we present the spectroscopy of 6P$_{1/2}$ state in $^{87}$Rb using double resonance technique at $780~\text{nm}$ and $421~\text{nm}$. The double resonance technique is implemented using electromagnetically induced transparency (EIT) and optical pumping methods. Using these spectroscopy methods, we have measured the hyperfine splitting of 6P$_{1/2}$ state with precision of $<$400~kHz which agrees well with other spectroscopy methods such as electrical discharge and saturated absorption spectroscopy at $421~\text{nm}$.

physics.atom-ph↗
arXiv2018

Single reference atomic based MW interferometry using EIT

Recently atomic based MW electrometry is experimentally demonstrated and interferometry has been proposed. The proposed interferometry bypasses the conventional, electrical circuit based MW interferometry in much superior fashion. However, this scheme requires three different references for characterizing the unknown MW field. In this work we theoretically study a scheme to develop an atomic based MW interferometry having only one referenced MW field. This scheme involves magnetic sublevels in the Rydberg states and hence will be suitable in even isotope of Yb or alkaline earth element where there is no complicacy due to absence of the hyperfine levels. Further, the wavelengths to excite the Rydberg states, are very close and hence cancels the Doppler shift more effectively which increases the amplitude sensitivity. We characterize this system for the phase and the amplitude of the unknown MW field w.r.t to the known field and compare it to the previously studied systems.

physics.atom-ph↗
arXiv2017

Highly sensitive atomic based MW interferometry

We theoretically study a scheme to develop an atomic based MW interferometry using the Rydberg states in Rb. Unlike the traditional MW interferometry, this scheme is not based upon the electrical circuits, hence the sensitivity of the phase and the amplitude/strength of the MW field is not limited by the Nyquist thermal noise. Further this system has great advantage due to its very high bandwidth, ranging from radio frequency (RF), micro wave (MW) to terahertz regime. In addition, this is \textbf{orders of magnitude} more sensitive to field strength as compared to the prior demonstrations on the MW electrometry using the Rydberg atomic states. However previously studied atomic systems are only sensitive to the field strength but not to the phase and hence this scheme provides a great opportunity to characterize the MW completely including the propagation direction and the wavefront. This study opens up a new dimension in the Radar technology such as in synthetic aperture radar interferometry. The MW interferometry is based upon a six-level loopy ladder system involving the Rydberg states in which two sub-systems interfere constructively or destructively depending upon the phase between the MW electric fields closing the loop.

physics.atom-ph↗