arXiv subjects

T. Dyson

Publications and source records attributed to T. Dyson.

4 recordsLinked to original sources

arXiv2026

A First Demonstration of the SQUAT Detector Architecture: Direct Measurement of Resonator-Free Charge-Sensitive Transmons

The Superconducting Quasiparticle-Amplifying Transmon (SQUAT) is a new sensor architecture for THz (meV) detection based on a weakly charge-sensitive transmon directly coupled to a transmission line. In such devices, energy depositions break Cooper pairs in the qubit capacitor islands, generating quasiparticles. Quasiparticles that tunnel across the Josephson junction change the transmon qubit parity, generating a measurable signal. In this paper, we present the design of first-generation SQUATs and demonstrate an architecture validation. We summarize initial characterization measurements made with prototype devices, comment on background sources that influence the observed parity-switching rate, and present experimental results showing simultaneous detection of charge and quasiparticle signals using aluminum-based SQUATs.

physics.ins-det↗

arXiv2024

First Measurement of Correlated Charge Noise in Superconducting Qubits at an Underground Facility

We measure space- and time-correlated charge jumps on a four-qubit device, operating 107 meters below the Earth's surface in a low-radiation, cryogenic facility designed for the characterization of low-threshold particle detectors. The rock overburden of this facility reduces the cosmic ray muon flux by over 99% compared to laboratories at sea level. Combined with 4$\pi$ coverage of a movable lead shield, this facility enables quantifiable control over the flux of ionizing radiation on the qubit device. Long-time-series charge tomography measurements on these weakly charge-sensitive qubits capture discontinuous jumps in the induced charge on the qubit islands, corresponding to the interaction of ionizing radiation with the qubit substrate. The rate of these charge jumps scales with the flux of ionizing radiation on the qubit package, as characterized by a series of independent measurements on another energy-resolving detector operating simultaneously in the same cryostat with the qubits. Using lead shielding, we achieve a minimum charge jump rate of 0.19$^{+0.04}_{-0.03}$ mHz, almost an order of magnitude lower than that measured in surface tests, but a factor of roughly eight higher than expected based on reduction of ambient gammas alone. We operate four qubits for over 22 consecutive hours with zero correlated charge jumps at length scales above three millimeters.

quant-ph↗

arXiv2020

Radio-Frequency Interference at the McGill Arctic Research Station

The frequencies of interest for redshifted 21 cm observations are heavily affected by terrestrial radio-frequency interference (RFI). We identify the McGill Arctic Research Station (MARS) as a new RFI-quiet site and report its RFI occupancy using 122 hours of data taken with a prototype antenna station developed for the Array of Long-Baseline Antennas for Taking Radio Observations from the Sub-Antarctic. Using an RFI flagging process tailored to the MARS data, we find an overall RFI occupancy of 1.8% averaged over 20-125 MHz. In particular, the FM broadcast band (88-108 MHz) is found to have an RFI occupancy of at most 1.6%. The data were taken during the Arctic summer, when degraded ionospheric conditions and an active research base contributed to increased RFI. The results quoted here therefore represent the maximum-level RFI environment at MARS.

astro-ph.IM↗

arXiv2020

The Array of Long Baseline Antennas for Taking Radio Observations from the Sub-Antarctic

Measurements of redshifted 21-cm emission of neutral hydrogen at <30 MHz have the potential to probe the cosmic "dark ages," a period of the universe's history that remains unobserved to date. Observations at these frequencies are exceptionally challenging because of bright Galactic foregrounds, ionospheric contamination, and terrestrial radio-frequency interference. Very few sky maps exist at <30 MHz, and most have modest resolution. We introduce the Array of Long Baseline Antennas for Taking Radio Observations from the Sub-Antarctic (ALBATROS), a new experiment that aims to image low-frequency Galactic emission with an order-of-magnitude improvement in resolution over existing data. The ALBATROS array will consist of antenna stations that operate autonomously, each recording baseband data that will be interferometrically combined offline. The array will be installed on Marion Island and will ultimately comprise 10 stations, with an operating frequency range of 1.2-125 MHz and maximum baseline lengths of ~20 km. We present the ALBATROS instrument design and discuss pathfinder observations that were taken from Marion Island during 2018-2019.

astro-ph.IM↗