arXiv subjects

Sumita Ghosh

Publications and source records attributed to Sumita Ghosh.

11 recordsLinked to original sources

arXiv2025

Search for Dark Photons between 16.96--19.52 $\mu$eV with the HAYSTAC Experiment

We report dark photon results from HAYSTAC Phase II using data from previously reported axion searches. Additionally, we present an analysis of an unpublished dataset covering a region between 19.46--19.52 $\mu$eV. This region overlaps with a recently reported dark photon signal at 19.5 $\mu$eV with a kinetic coupling strength of $|\chi_{\text{rand}}| \simeq 6.5 \times 10^{-15}$ resulting from a reanalysis of previously published data from the TASEH collaboration. Given HAYSTAC's sensitivity, if such a signal were present, it would have appeared as a large $17.1\sigma$ excess above the noise. However, no such signal was observed. We thus exclude couplings $|\chi_{\text{rand}}|\geq 4.90\times10^{-15}$ at the 90\% confidence level over the newly reported region. In addition, using our previously reported axion data, we exclude couplings $|\chi_{\text{rand}}|\geq2.90\times 10^{-15}$ between 16.96--19.46 $\mu$eV at the 90\% confidence level.

hep-ex↗

arXiv2024

Dark Matter Axion Search with HAYSTAC Phase II

This Letter reports new results from the HAYSTAC experiment's search for dark matter axions in our galactic halo. It represents the widest search to date that utilizes squeezing to realize sub-quantum limited noise. The new results cover 1.71 $\mu$eV of newly scanned parameter space in the mass ranges 17.28-18.44 $\mu$eV and 18.71-19.46 $\mu$eV. No statistically significant evidence of an axion signal was observed, excluding couplings $|g_\gamma|\geq$ 2.75$\times$$|g_{\gamma}^{\text{KSVZ}}|$ and $|g_\gamma|\geq$ 2.96$\times$$|g_{\gamma}^{\text{KSVZ}}|$ at the 90$\%$ confidence level over the respective region. By combining this data with previously published results using HAYSTAC's squeezed state receiver, a total of 2.27 $\mu$eV of parameter space has now been scanned between 16.96-19.46 $\mu$eV, excluding $|g_\gamma|\geq$ 2.86$\times$$|g_{\gamma}^{\text{KSVZ}}|$ at the 90$\%$ confidence level. These results demonstrate the squeezed state receiver's ability to probe axion models over a significant mass range while achieving a scan rate enhancement relative to a quantum-limited experiment.

hep-ex↗

arXiv2023

Rydberg-atom-based single-photon detection for haloscope axion searches

We propose a Rydberg-atom-based single-photon detector for signal readout in dark matter haloscope experiments between 40 ${\mu}$eV and 200 ${\mu}$eV (10 GHz and 50 GHz). At these frequencies, standard haloscope readout using linear amplifiers is limited by quantum measurement noise, which can be avoided by using a single-photon detector. Our single-photon detection scheme can offer scan rate enhancements up to a factor of $10^4$ over traditional linear amplifier readout, and is compatible with many different haloscope cavities. We identify multiple haloscope designs that could use our Rydberg-atom-based single-photon detector to search for QCD axions with masses above 40 ${\mu}$eV (10 GHz), currently a minimally explored parameter space.

hep-ex↗

arXiv2023

An improved synthetic signal injection routine for the Haloscope At Yale Sensitive To Axion Cold dark matter (HAYSTAC)

Microwave cavity haloscopes are among the most sensitive direct detection experiments searching for dark matter axions via their coupling to photons. When the power of the expected microwave signal due to axion-photon conversion is on the order of $10^{-24}$~W, having the ability to validate the detector response and analysis procedure by injecting realistic synthetic axion signals becomes helpful. Here we present a method based on frequency hopping spread spectrum for synthesizing axion signals in a microwave cavity haloscope experiment. It allows us to generate a narrow and asymmetric shape in frequency space that mimics an axion's spectral distribution, which is derived from a Maxwell-Boltzmann distribution. In addition, we show that the synthetic axion's power can be calibrated with reference to the system noise. Compared to the synthetic axion injection in HAYSTAC phase I, we demonstrated synthetic signal injection with a more realistic lineshape and calibrated power.

physics.ins-det↗

arXiv2023

New Results from HAYSTAC's Phase II Operation with a Squeezed State Receiver

A search for dark matter axions with masses $>10 μeV/c^{2}$ has been performed using the HAYSTAC experiment's squeezed state receiver to achieve sub-quantum limited noise. This report includes details of the design and operation of the experiment previously used to search for axions in the mass ranges $16.96-17.12$ and $17.14-17.28 μeV/c^{2}$($4.100-4.140$GHz) and $4.145-4.178$GHz) as well as upgrades to facilitate an extended search at higher masses. These upgrades include improvements to the data acquisition routine which have reduced the effective dead time by a factor of 5, allowing for the new region to be scanned $\sim$1.6 times faster with comparable sensitivity. No statistically significant evidence of an axion signal is found in the range $18.44-18.71μeV/c^{2}$($4.459-4.523$GHz), leading to an aggregate upper limit exclusion at the $90\%$ level on the axion-photon coupling of $2.06\times g_γ^{KSVZ}$.

hep-ex↗

arXiv2022

EIT spectroscopy of high-lying Rydberg states in $^{39}K$

We present a study of the Rydberg spectrum in $^{39}K$ for $nS$ and $nD_{3/2}$ series connected to $5^2P_{1/2}$ using two-photon spectroscopy based on EIT in a heated vapor cell. We observed some 80 transitions from $5P_{1/2}$ to Rydberg states with principal quantum numbers $n\sim50-90$, and determined their transition frequencies and state energies with sub-GHz precision. Our spectroscopy results lay the groundwork for using Rydberg atoms as sensitive microwave photon detectors in searches for dark matter axions in the $\sim40-200$ $μ$eV mass range, which is a prime range for future axion searches suggested by theory studies.

physics.atom-ph↗

arXiv2021

Searching for Dark Photons with Existing Haloscope Data

The dark (or hidden) photon is a massive U(1) gauge boson theorized as a dark force mediator and as a dark matter candidate. Dark photons can be detected with axion cavity haloscopes by probing for a power excess caused by the dark photon's kinetic mixing with Standard Model photons. Haloscope axion exclusion limits may therefore be converted into competitive dark photon parameter limits via the calculation of a corresponding dark photon to photon coupling factor. This calculation allows for an improvement in sensitivity of around four orders of magnitude relative to other dark photon exclusions and may be attained using existing data. We present how one converts haloscope axion search limits and a summary of relevant experimental parameters from published searches. In addition, we have included the code that can be used to generate our dark photon exclusion limits for the cases described in this paper. Finally, we present limits on the kinetic mixing coefficient between dark photons and the Standard Model photons based on existing haloscope axion searches.

hep-ph↗

arXiv2021

Limits on the abundance of millicharged particles bound to matter

Millicharged particles (mCPs) are hypothesized particles possessing an electric charge that is a fraction of the charge of the electron. We report a search for mCPs with charges $\gtrsim 10^{-4}~e$ that improves sensitivity to their abundance in matter by roughly two orders of magnitude relative to previous searches. This search is sensitive to such particles over a wide range of masses and charges for which they can form stable bound states with matter, corresponding to a gap in parameter space that is beyond the reach of previous searches from accelerators, colliders, cosmic-ray experiments, and cosmological constraints.

hep-ex↗

arXiv2020

A quantum-enhanced search for dark matter axions

In dark matter axion searches, quantum uncertainty manifests as a fundamental noise source, limiting the measurement of the quadrature observables used for detection. We use vacuum squeezing to circumvent the quantum limit in a search for a new particle. By preparing a microwave-frequency electromagnetic field in a squeezed state and near-noiselessly reading out only the squeezed quadrature, we double the search rate for axions over a mass range favored by recent theoretical projections. We observe no signature of dark matter axions in the combined $16.96-17.12$ and $17.14-17.28\spaceμ\text{eV}/c^2$ mass window for axion-photon couplings above $g_γ = 1.38\times g_γ^\text{KSVZ}$, reporting exclusion at the 90% level.

quant-ph↗

arXiv2018

Optical levitation of 10 nanogram spheres with nano-$g$ acceleration sensitivity

We demonstrate optical levitation of SiO$_2$ spheres with masses ranging from 0.1 to 30 nanograms. In high vacuum, we observe that the measured acceleration sensitivity improves for larger masses and obtain a sensitivity of $0.4 \times 10^{-6}\ g/\sqrt{\mathrm{Hz}}$ for a 12 ng sphere, more than an order of magnitude better than previously reported for optically levitated masses. In addition, these techniques permit long integration times and a mean acceleration of $(-0.7\pm2.4\,[stat] \pm 0.2\,[syst])\times ~ 10^{-9}\,g$ is measured in $1.4\times 10^4$~s. Spheres larger than 10~ng are found to lose mass in high vacuum where heating due to absorption of the trapping laser dominates radiative cooling. This absorption constrains the maximum size of spheres that can be levitated and allows a measurement of the absorption of the trapping light for the commercially available spheres tested here. Spheres consisting of material with lower absorption may allow larger objects to be optically levitated in high vacuum.

physics.optics↗

arXiv2018

Optical Rotation of Levitated Spheres in High Vacuum

A circularly polarized laser beam is used to levitate and control the rotation of microspheres in high vacuum. At low pressure, rotation frequencies as high as 6 MHz are observed for birefringent vaterite spheres, limited by centrifugal stresses. Due to the extremely low damping in high vacuum, controlled optical rotation of amorphous SiO$_2$ spheres is also observed at rates above several MHz. At $10^{-7}$ mbar, a damping time of $6\times10^4$ s is measured for a $10\ μ$m diameter SiO$_2$ sphere. No additional damping mechanisms are observed above gas damping, indicating that even longer damping times may be possible with operation at lower pressure. The controlled optical rotation of microspheres at MHz frequencies with low damping, including for materials that are not intrinsically birefringent, provides a new tool for performing precision measurements using optically levitated systems.

physics.optics↗