We constrain the coupling between axionlike particles (ALPs) and photons, measured with the superconducting resonant detection circuit of a cryogenic Penning trap. By searching the noise spectrum of ...our fixed-frequency resonant circuit for peaks caused by dark matter ALPs converting into photons in the strong magnetic field of the Penning-trap magnet, we are able to constrain the coupling of ALPs with masses around \(2.7906-2.7914\,\textrm{neV/c}^2\) to \(g_{a\gamma}< 1 \times 10^{-11}\,\textrm{GeV}^{-1}\). This is more than one order of magnitude lower than the best laboratory haloscope and approximately 5 times lower than the CERN axion solar telescope (CAST), setting limits in a mass and coupling range which is not constrained by astrophysical observations. Our approach can be extended to many other Penning-trap experiments and has the potential to provide broad limits in the low ALP mass range.
The Cosmology Large Angular Scale Surveyor (CLASS) is a four-telescope array observing the largest angular scales (\(2 \lesssim \ell \lesssim 200\)) of the cosmic microwave background (CMB) ...polarization. These scales encode information about reionization and inflation during the early universe. The instrument stability necessary to observe these angular scales from the ground is achieved through the use of a variable-delay polarization modulator (VPM) as the first optical element in each of the CLASS telescopes. Here we develop a demodulation scheme used to extract the polarization timestreams from the CLASS data and apply this method to selected data from the first two years of observations by the 40 GHz CLASS telescope. These timestreams are used to measure the \(1/f\) noise and temperature-to-polarization (\(T\rightarrow P\)) leakage present in the CLASS data. We find a median knee frequency for the pair-differenced demodulated linear polarization of 15.12 mHz and a \(T\rightarrow P\) leakage of \(<3.8\times10^{-4}\) (95\% confidence) across the focal plane. We examine the sources of \(1/f\) noise present in the data and find the component of \(1/f\) due to atmospheric precipitable water vapor (PWV) has an amplitude of \(203 \pm 12 \mathrm{\mu K_{RJ}\sqrt{s}}\) for 1 mm of PWV when evaluated at 10 mHz; accounting for \(\sim32\%\) of the \(1/f\) noise in the central pixels of the focal plane. The low level of \(T\rightarrow P\) leakage and \(1/f\) noise achieved through the use of a front-end polarization modulator enables the observation of the largest scales of the CMB polarization from the ground by the CLASS telescopes.
Using the Cosmology Large Angular Scale Surveyor, we measure the disk-averaged absolute Venus brightness temperature to be 432.3 \(\pm\) 2.8 K and 355.6 \(\pm\) 1.3 K in the Q and W frequency bands ...centered at 38.8 and 93.7 GHz, respectively. At both frequency bands, these are the most precise measurements to date. Furthermore, we observe no phase dependence of the measured temperature in either band. Our measurements are consistent with a CO\(_2\)-dominant atmospheric model that includes trace amounts of additional absorbers like SO\(_2\) and H\(_2\)SO\(_4\).
The Cosmology Large Angular Scale Surveyor (CLASS) is a telescope array that observes the cosmic microwave background (CMB) over 75% of the sky from the Atacama Desert, Chile, at frequency bands ...centered near 40, 90, 150, and 220 GHz. CLASS measures the large angular scale (\(1^\circ\lesssim\theta\leqslant 90^\circ\)) CMB polarization to constrain the tensor-to-scalar ratio at the \(r\sim0.01\) level and the optical depth to last scattering to the sample variance limit. This paper presents the optical characterization of the 40 GHz telescope during its first observation era, from 2016 September to 2018 February. High signal-to-noise observations of the Moon establish the pointing and beam calibration. The telescope boresight pointing variation is \(<0.023^\circ\) (\(<1.6\)% of the beam's full width at half maximum (FWHM)). We estimate beam parameters per detector and in aggregate, as in the CMB survey maps. The aggregate beam has an FWHM of \(1.579^\circ\pm.001^\circ\) and a solid angle of \(838 \pm 6\ \mu{\rm sr}\), consistent with physical optics simulations. The corresponding beam window function has a sub-percent error per multipole at \(\ell < 200\). An extended \(90^\circ\) beam map reveals no significant far sidelobes. The observed Moon polarization shows that the instrument polarization angles are consistent with the optical model and that the temperature-to-polarization leakage fraction is \(<10^{-4}\) (95% C.L.). We find that the Moon-based results are consistent with measurements of M42, RCW 38, and Tau A from CLASS's CMB survey data. In particular, Tau A measurements establish degree-level precision for instrument polarization angles.
Scalable quantum computing can become a reality with error correction, provided coherent qubits can be constructed in large arrays. The key premise is that physical errors can remain both small and ...sufficiently uncorrelated as devices scale, so that logical error rates can be exponentially suppressed. However, energetic impacts from cosmic rays and latent radioactivity violate both of these assumptions. An impinging particle ionizes the substrate, radiating high energy phonons that induce a burst of quasiparticles, destroying qubit coherence throughout the device. High-energy radiation has been identified as a source of error in pilot superconducting quantum devices, but lacking a measurement technique able to resolve a single event in detail, the effect on large scale algorithms and error correction in particular remains an open question. Elucidating the physics involved requires operating large numbers of qubits at the same rapid timescales as in error correction, exposing the event's evolution in time and spread in space. Here, we directly observe high-energy rays impacting a large-scale quantum processor. We introduce a rapid space and time-multiplexed measurement method and identify large bursts of quasiparticles that simultaneously and severely limit the energy coherence of all qubits, causing chip-wide failure. We track the events from their initial localised impact to high error rates across the chip. Our results provide direct insights into the scale and dynamics of these damaging error bursts in large-scale devices, and highlight the necessity of mitigation to enable quantum computing to scale.
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