Radiation impacts are a leading cause of information degradation in superconducting quantum devices due to their frequency in occurrence and instigation of widespread correlated errors. Recent developments [1] have built Monte-Carlo models using Geant4 and G4CMP to track the generation of e/h pairs, phonons, and superconducting quasiparticles. Building upon this work, we have developed...
Calibrating ultra-sensitive THz/meV detectors in cryogenic environments is a challenging pursuit, as conventional fiber optics suffer greatly from loss and tunable sources are limited. A system composed of a high-frequency photomixer coupled to a hollow cylindrical waveguide is being developed to deliver tunable frequency THz photons to cryogenic sensors. This work is motivated by the need to...
The Quantum Underground Instrumentation Experimental Testbed (QUIET) is a laboratory 100 meters underground at Fermilab designed to support advanced research in quantum computing and cryogenic detectors. Equipped with a 10 mK dilution refrigerator, QUIET enables the low-background characterization of superconducting qubits and detectors in a controlled environment. Over a series of cooldowns,...
In order to understand the effects of cosmic rays on superconducting qubits we have developed a that system correlates cosmic ray events with decoherence in qubits. This system consists of a qubit chip sandwiched between two arrays of MKIDs. We recent showed that both $T_1$ and $T_2$ times decreased when events were detected on our MKIDs. Now we look to expand the capabilities of our system...
Understanding the energy transport in low-temperature detectors is essential for rare-event searches, quantum sensing applications, and studies of radiation-induced effects in matter. In this work, we extend the G4CMP framework to describe charge transport in sapphire and the collective excitations in superfluid helium as phonons and rotons. For sapphire, a material of growing interest in...
Temporal fluctuations in the energy relaxation time ($T_1$) of superconducting qubits can occur on fast and irregular timescales. A quantitative understanding of these nonstationary relaxation dynamics is important for improving qubit stability and advancing fault-tolerant quantum processors. Here, we employ a new method for continuous monitoring of qubit relaxation based on an input–output...
The impact of ionizing radiation, such as gamma rays and cosmic ray muons, on superconducting qubit chips results in the generation of electron-hole pairs in the substrate, as well as a cascade of pair-breaking phonons. These energetic phonons spread efficiently throughout the chip and create excess quasiparticles in the junction electrodes of any qubits present on the device layer. This...
Phonon-mediated detectors have emerged as a promising technology for detecting low-energy particles, such as dark matter and neutrinos. Coupling phonons with qubit technology enables the realization of highly sensitive detectors for such particles. We have incorporated phonon transport in G4CMP for several novel materials. Similarly, we have now extended this simulation to model...
The fabrication efforts of the COSMIQ group are focused on creating superconducting aluminum doped with manganese (Al/Mn) gap engineered films/circuits to utilize their low-band gap for both quantum sensing and computing purposes. Environmental radiation and cosmic rays produce phonons in substrates that can then cause Cooper pairs to break producing quasiparticles (QPs). With precise gap...
There are growing efforts to use substrate-coupled kinetic inductance detectors as athermal phonon detectors for particle detection. One challenge encountered is the significant position-dependence these detectors can exhibit, destroying energy resolution of non-collimated sources. We show this position dependence can be overcome by operating the detectors to be sensitive to thermalized...
In recent years superconducting qubits have made huge strides in performance and quality. With improved qubit quality comes increasingly strict environmental requirements. One background of concern comes from black body radiation from higher temperature stages of the dilution refrigerator. IR photons are particularly challenging to shield from as many common RF materials are transparent to...
Superconducting quantum devices (SQDs) are at the forefront of technologies to investigate scientific phenomena such as dark matter and application spaces such as quantum computing. The performance of SQDs is affected by correlated events that are produced by naturally occurring radiation. These events deposit energy into materials, including substrates, which produce secondary particles from...
The interaction between superconducting qubits and quasiparticles that tunnel across the Josephson junction can be used to detect quasiparticle-generating particle scattering events, making them promising platforms for sub-eV phonon/photon sensing. Each tunneling event can flip the qubit charge parity and may also result in energy transfer between the qubit and the quasiparticle. We present a...
Both cosmogenic and terrestrial radiation are known to contribute to errors in superconducting qubits. There are multiple types and sources of ionizing radiation that can be relevant to these qubits, such as particle showers from cosmic rays, gamma radiation from surrounding earth and building materials, and radioactivity internal to the dilution fridge or qubit package itself. To investigate...
We experimentally investigated the prospect for using superconducting transmon qubits as cryogenic quantum sensors of ionizing radiation. We interrogated a six-qubit chip with resonators inductively coupled on both sides of a central transmission line in a hanger geometry. Measurements were performed without and with a source of ionizing radiation applied, external to the cryostat at room...
The SONIQ (Sensing of Neutrinos In Qubits) collaboration aims to build arrays of superconducting qubits capable of detecting meV-scale energy deposits arising from neutrino-nucleus scattering interactions within a bulk target. We outline development of these sensors, targeting sub-eV resolution on a kg-scale germanium target. We discuss current work, touching on qubit design, the use of low Tc...
The interaction of ionizing radiation with superconducting qubits can lead to large-scale correlated errors that are problematic, as they cannot be fixed by conventional error correction techniques. These radiation induced upset events have mostly been studied using the natural radiation in the environment and manmade radioactive sources, making it difficult to directly correlate the observed...
