Conveners
Oral Presentations: Kick-Off
- Britton Plourde
Oral Presentations: Industry
- Vladislav Kurilovich (Google Quantum AI)
Oral Presentations: Afternoon Session
- Brent VanDevender (Pacific Northwest National Laboratory)
Oral Presentations: Backgrounds
- Daniel Baxter (Fermi National Accelerator Laboratory)
Oral Presentations: Theory Primer
- Vladislav Kurilovich (Google Quantum AI)
Oral Presentations: Co-located Sensors
- Brent VanDevender (Pacific Northwest National Laboratory)
Oral Presentations: Chip Response - Calibration & Modeling
- Noah Kurinsky (SLAC)
Oral Presentations: Spin Qubits - Overlapping Communities
- Jonathan Cripe (Laboratory for Physical Sciences)
Oral Presentations: Chip Response - Event Reconstruction
- Daniel Baxter (Fermi National Accelerator Laboratory)
Oral Presentations: Wrap-Up
- Britton Plourde
One of the roadblocks towards the implementation of a fault-tolerant superconducting quantum processor is impacts of ionizing radiation with the qubit substrate. Such impacts temporarily elevate the density of quasiparticles (QPs) across the device, leading to correlated qubit error bursts. The most damaging errorsโT1 errorsโstem from QP tunneling across the qubit Josephson junctions (JJs)....
We will discuss devices that have microwave kinetic inductance detectors (MKIDs) fabricated on the same substrate as qubits to assessing the impact of ionizing radiation. We will present our results using the MKIDs as a radiation sensor to look for correlations between detected events and two-level system dynamics: we observe no correlation in our data. We will also compare the recovery time...
Ionizing radiation impacts create bursts of quasiparticle density in superconducting qubits. These bursts temporarily degrade qubit coherence, which can be detrimental for quantum error correction. Here, we experimentally resolve quasiparticle bursts in 3D gap-engineered transmon qubits by continuously monitoring qubit transitions. Gap engineering allows us to reduce the burst detection rate...
Spatiotemporally correlated error bursts, arising from quasiparticles generated by ionizing radiation and mechanical noise, pose significant challenges to implementing quantum error correction in superconducting quantum processors. In this work, we explore methods for detecting these errors in two superconducting circuits: offset charge sensitive (OCS) transmons and Fluxonium. In OCS...
In addition to radiation impacts, superconducting qubit arrays can be subject to correlated quasiparticle poisoning from nonionizing sources that also result in bursts of pair-breaking phonons. We observe elevated correlated and single-qubit poisoning rates in superconducting qubit arrays at the start of a cooldown followed by power-law reductions in time, while the rate of offset charge...
In the last decade, the sensitivity of superconducting athermal phonon detectors has improved by nearly two orders of magnitude, driven largely by the scientific need to search for dark matter with smaller masses and thus smaller energy depositions. Though these detectors are fabricated using nearly identical materials and fabrication techniques as those used for superconducting qubits, they...
We investigate qubit error bursts in 5- and 7-transmon processors of similar design, fabrication and packaging, but with different types of qubit Josephson junctions. The duration and rate of bursts are device specific but within the range of prior experiments and consistent with ionizing radiation. We observe two unforeseen signatures specifically in the processor with Dolan junctions. First,...
The QUAntum LImited PHotons In the Dark Experiment (QUALIPHIDE) is a cryogenic broadband search for light dark matter candidates, primarily looking for signatures of massive hidden photons kinetically mixing with Standard Model photons. We report results from an experimental campaign coupling a focusing metallic dish to a pixelated array of energy-resolving $\sim$3 to $\sim$120THz sensitive...
We evaluate the quasiparticle contribution to the frequency shift and relaxation rates of a transmon with the Josephson junctions connecting superconductors that have unequal energy gaps. The gap difference substantially affects the transmon characteristics. We investigate their dependence on the density and effective temperature of the quasiparticles, and on the nominal (unperturbed by the...
Quantum error correction fundamentally requires that physical errors are sufficiently uncorrelated in time and space. In superconducting qubit processors, impacts from ionizing radiation violate this assumption by elevating quasiparticle density across the substrate, triggering correlated qubit error bursts. Previously, we demonstrated that the most damaging of theseโcorrelated T1 errors...
The CLIQUE (Controlled Linac Irradiation of Quantum Experiments) Facility at Johns Hopkins Applied Physics Laboratory is an experimental user facility that contains an electron linear accelerator (linac) used as an on-demand high-energy particle source to study deleterious effects on quantum systems. The linac provides a pulsed, microsecond burst of ~20 MeV electrons that are redirected at a...
Correlated error bursts causing decoherence in superconducting qubits have been detrimental to quantum error correction schemes, with recent work by Google showing approximately once per hour correlated bursts in their qubits. Over the past decade, it has been shown that ionizing radiation contributes to this effect, with cosmic rays being commonly identified. However, with advent of...
In this talk we report the observation of offset charge jumps induced by external radiation in Si/SiGe quantum dots that serve as spin qubits. Such charge jumps are important for quantum dot qubits, because they directly alter the operating point of the qubit in gate voltage space, and such uncontrolled shifts can induce errors in qubit initialization, readout, and manipulation. Using the...
Spin qubits have seen much progress over recent years, proving to be an appealing candidate for scalable quantum computing with small footprints, electrical control, promising coherence times, and the industry-compatible silicon material platform. As advances are made in the spaces of control and scaling, addressing noise from various origins becomes increasingly pertinent. It has been shown...
Superconducting qubits are susceptible to transient energy deposition arising from cosmic rays and environmental radioactivity. High-energy phonons generated by particle interactions in the qubit chip substrate can create quasiparticles that temporarily degrade qubit coherence.
We investigate the qubit response under controlled irradiation using a proximal Radium-224 source. To identify...
When an ionizing particle interacts with the substrate of a superconducting qubit chip, it generates high-energy athermal phonons that propagate through the material, breaking Cooper pairs in the superconducting films and inducing quasiparticle poisoning. These non-equilibrium quasiparticles limit qubit coherence times and introduce correlated errors across large qubit arrays, posing a major...
The Superconducting Quasiparticle-Amplifying Transmon (SQUAT) is a sensor architecture targeting meV (THz) detection based on a weakly charge-sensitive transmon qubit directly coupled to a transmission line.ย Energy depositions in the qubit capacitor generate quasiparticles that tunnel across the Josephson junction.ย Each tunnel changes the qubit parity and produces a measurable signal in CW...
