arXiv subjects

E. P. Ruddy

Publications and source records attributed to E. P. Ruddy.

5 recordsLinked to original sources

arXiv2026

Search for Dark Photons between 16.96--19.52 $μ$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 Additionally, we present an analysis of an unpublished dataset covering a region between 19.46--19.52 $μ$eV. This region overlaps with a recently reported dark photon signal at 19.5 $μ$eV with a kinetic coupling strength of $|χ_{\text{rand}}| \simeq 6.5 \times 10^{-15}$ 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 $17.1σ$ excess above the noise. However, no such signal was observed. We thus exclude couplings $|χ_{\text{rand}}|\geq 4.90\times10^{-15}$ at the 90\% confidence level over the newly reported region. In addition, using our previously reported axion data, we exclude couplings $|χ_{\text{rand}}|\geq2.90\times 10^{-15}$ between 16.96--19.46 $μ$eV at the 90\% confidence level.

hep-ex↗

arXiv2025

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 $μ$eV of newly scanned parameter space in the mass ranges 17.28-18.44 $μ$eV and 18.71-19.46 $μ$eV. No statistically significant evidence of an axion signal was observed, excluding couplings $|g_γ|\geq$ 2.75$\times$$|g_γ^{\text{KSVZ}}|$ and $|g_γ|\geq$ 2.96$\times$$|g_γ^{\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 $μ$eV of parameter space has now been scanned between 16.96-19.46 $μ$eV, excluding $|g_γ|\geq$ 2.86$\times$$|g_γ^{\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↗

arXiv2024

Protecting backaction-evading measurements from parametric instability

Noiseless measurement of a single quadrature in systems of parametrically coupled oscillators is theoretically possible by pumping at the sum and difference frequencies of the two oscillators, realizing a backaction-evading (BAE) scheme. Although this would hold true in the simplest scenario for a system with pure three-wave mixing, implementations of this scheme are hindered by unwanted higher-order parametric processes that destabilize the system and add noise. We show analytically that detuning the two pumps from the sum and difference frequencies can stabilize the system and fully recover the BAE performance, enabling operation at otherwise inaccessible cooperativities. We also show that the acceleration demonstrated in a weak signal detection experiment [PRX QUANTUM 4, 020302 (2023)] was only achievable because of this detuning technique.

quant-ph↗

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

A cavity entanglement and state swapping method to accelerate the search for axion dark matter

In cavity-based axion dark matter detectors, quantum noise remains a primary barrier to achieving the scan rate necessary for a comprehensive search of axion parameter space. Here we introduce a method of scan rate enhancement in which an axion-sensitive cavity is coupled to an auxiliary resonant circuit through simultaneous two-mode squeezing (entangling) and state swapping interactions. We show analytically that when combined, these interactions can amplify an axion signal before it becomes polluted by vacuum noise introduced by measurement. This internal amplification yields a wider bandwidth of axion sensitivity, increasing the rate at which the detector can search through frequency space. With interaction rates predicted by circuit simulations of this system, we show that this technique can increase the scan rate up to 15-fold relative to the scan rate of a detector limited by vacuum noise.

quant-ph↗