AVS 72 Session QS-ThP: Quantum Science and Technology Poster Session

The Issue:
Emerging quantum-enabled devices, including quantum computers, photonic devices, neuromorphic, superconducting, spin, and advanced microelectronic platforms, are increasingly presented as peer elements in heterogeneous computing scientific workflows. However, the boundary between experimental device output and runtime compute continuation remains creates isolation. Device configuration, execution conditions, telemetry, logs, uncertainty, AI/ML probability interpretation, and returned results are often handled through separate files, scripts, instruments, schedulers, or manual processes, limiting reproducibility and cross-platform comparison. Quantum computers are treated as stand-alone devices.

Presenting a solution:
This poster conceptually presents ACGEOS, a governed runtime orchestration architecture for integrating quantum-enabled devices into auditable heterogeneous workflows. The model treats each task, device, configuration, telemetry record, result, and continuation state as an identifiable object. A portable governed container, the .polyp , preserves the original request, device setup, execution context, telemetry, logs, error state, and returned data. A Binding Object Layer record links expected execution to actual returned state, allowing the workflow to continue without losing provenance.

Innovation:

A central feature is a triplet return model from the quantum-device integration:

1. un-edited quantum result preserved as a .polyp , the original evidence package,
2. a BOL-bound result returned to the compute runtime for deterministic workflow continuation, and
3. an AI/ML evaluation sidecar used for confidence scoring, anomaly detection, repeatability assessment, or interpretation of probabilistic device behavior. In this model, AI/ML does not replace the governed result of record; it becomes an attached evaluation layer.

The proposed architecture is intended for future testbeds where quantum, photonic, neuromorphic, GPU, CPU, and instrument-class devices must participate in reproducible scientific workflows. The goal is to provide a systems-level bridge between device performance, experimental evidence, and compute continuation, supporting scalability, reliability, and translation of emerging quantum technologies into practical research and engineering environments.

Using a low temperature scanning tunneling microscope (STM) with a superconducting tip and sample, it can be investigated at the atomic scale. In this work, we report high resolution STM measurements with a microwave source at the SIS junction. We have achieved an energy resolution of 9 μeV at 1.09 K, representing the lowest benchmark value reported at this temperature so far and on par with state-of-the-art mK systems.

The reliable scaling of superconducting quantum processors depends heavily on the reproducibility and yield of the underlying micro- and nanofabrication processes. As quantum computing research expands, open user facilities play a critical role in providing standardized, high-quality fabrication baselines that democratize hardware developmentand prototyping. In this work, we present a user-facility-compatible fabrication flow for coplanar waveguide (CPW) resonators and planar transmon qubits, developed using the equipment at the Cornell NanoScale Facility (CNF).

This baseline methodology focuses on process optimization to maximize device yield, establish a reliable foundation for quantum coherence, and improve overall fabrication efficiency. A primary challenge in planar qubit fabrication is mitigating Two-Level System (TLS) losses arising from interfacial defects and fabrication residues, a step that traditionally relies on labor-intensive processing. To address this, our process flow incorporates a streamlined wet chemical treatment protocol. This optimized approach significantly reduces hands-on effort while effectively minimizing polymer and oxide residues at critical material interfaces, providing an easier fabrication route that ensures no degradation of feature resolution or device quality.

We characterize the efficiency of this baseline flow through comprehensive room-temperature metrology, followed by cryogenic microwave measurements. The presentation details the step-by-step cleanroom recipe, emphasizing the correlation between our refined wet processing and the resulting quantum metrics. This baseline provides the broader materials for quantum information science community with a reliable approach to consistently achieve high-yield quantum hardware.

Superconducting qubits rely on the controlled dynamics of the Josephson phase across weak links, yet the microscopic relationship between junction structure, dissipation, electromagnetic environment, and phase coherence remains difficult to access directly. Scanning tunneling microscopy provides an unusual route to this problem: the tunnel junction itself can act as a local, continuously tunable Josephson junction between superconducting electrodes. Unlike lithographically defined devices, an STM-defined junction allows the critical current, normal-state resistance, capacitance, and local atomic environment to be varied in situ while preserving cryogenic operation and microwave access.

Here we develop STM-defined Josephson junctions as a platform for exploring qubit-relevant superconducting phase dynamics. Using superconducting tips and samples, we characterize Josephson coupling as a function of junction conductance, material parameters, and engineered microwave environment. We examine signatures associated with phase fluctuations, junction switching, and the crossover toward regimes where the junction potential becomes sufficiently nonlinear and isolated to support phase-qubit-like dynamics. Even when operated below the threshold for a fully realized qubit, this approach provides direct access to the ingredients that govern superconducting weak-link behavior: local structure, dissipation, impedance, and noise. The resulting platform bridges atomic-scale superconducting spectroscopy and circuit-level Josephson physics, offering a flexible route toward local studies of superconducting quantum devices.

The high tunability of semiconductor platforms has enabled them to be leveraged for various technologies and applications. The aspects of superconductivity can also be engineered to have specific targets. Recent efforts surrounding superconducting films for quantum systems have largely focused on achieving higher critical temperatures. However, as consensus is reached surrounding the importance of defects in quantum systems there is increasing interest in elucidating and controlling other mechanisms and resulting parameters. Understanding how synthesis parameters influence structural disorder at various length scales and their impact on the physical properties is a complex problem. This work will look into aspects of disorder ranging from the atomic scale to longer range inhomogeneities in the crystalline lattice and the relationships with electrical transport.

We will discuss the deposition of epitaxial superconducting ZrN by molecular beam epitaxy, the separate roles of atomic and crystalline disorder, and relationships between synthesis parameters and resulting structural and physical properties. The use of various substrates and orientations allows for insight into the effects of lattice mismatch and the preferential growth directions. Under the conditions investigated, rocksalt ZrN appears to prefer formation along the (001) direction but (111) oriented inclusions are observed when the temperature is too low. There is a complex relationship between synthesis parameters and resulting short range (atomic scale) and long range (crystalline lattice) order, as measured by detailed X-ray diffraction. The resulting structure shows tunability of electrical transport and optical properties, which can both range from metallic to dielectric. A broad generalization shows that samples deposited at elevated temperatures were more metallic and have higher superconducting transitions. However, other properties change in unintuitive ways, which can be explained by the non-monotonic changes in the atomic scale disorder. This work integrating superconducting films with known semiconductor platforms provides an avenue for the pursuit of (001) oriented heterostructures for superconducting or optical quantum applications.

Computational studies predict CaO as a promising host crystal suitable to sustain optically addressable QuBits with long coherence times due to low natural abundance of calcium isotopes with nuclei with net spin and low spin orbit coupling, allowing defect states to be well isolated from magnetic noise. In this work we experimentally engineer bismuth and rare earth lanthanide dopants in varying concentration levels in an ultra-high purity, low defect CaO thin film to experimentally verify defect structure and coherence times. Reactive RF Sputtering is selected as a desirable physical vapor deposition method allowing tunable deposition rates through changes in magnetron power and cathode working distance to the substrate. Relaxed (001) oriented CaO films are grown on r-plane sapphire single crystal substrates achieving film heteroepitaxy. Host crystal purity is paramount to achieving long spin coherence times, as any magnetic impurities may interact with defect states. To minimize chemical impurity, we develop an ultra-high purity calcium sputtering source by hydrothermal sintering. 1- and 2-inch calcium hydroxide (99.999% pure) to above 95 % theoretical density. Sintering temperatures below 150°C inhibit solid state diffusion of contaminants into the source target, maintaining exceptionally high target purity throughout all processing stages. Calcium oxide thin films and dopants are co-sputtered via an off-axis geometry to mitigate anion bombardment, allowing for increased deposition rates, smooth film morphology, high density, and low film mosaicity as quantified via XRD and XRR. High deposition temperatures (875°) allow for film deposition with high crystallinity. Dopant concentration down to the single part-per-million level is quantified by induction coupled plasma optical emission spectroscopy via film dissolution in aqueous solution. Dopant concentration is coupled with deposition rate from the calcium and dopant source magnetrons and is experimentally tuned by changing dopant magnetron working distance and power, in turn modifying calcium and dopant source flux to the substrate. Oxygen vacancy defects that scale with Er are identified in the CaO lattice via deep UV photoluminescence measurements performed with a 248 nm laser excitation at room temperature – these provide an interesting pathway to infer dopant concentrations. Finally STEM analysis, including electron ptychography, that shows film microstructure, lattice strains, and defects will be presented.

CeO₂ is a well-known host for defect-generated qubits that offers high relaxation and coherence times desirable in quantum computing applications. Scalable and reproducible qubit performance with large spin coherence lifetimes requires materials with high crystallinity, low point defect concentrations, and excellent surface quality. In this work, we investigate structural and electronic properties of erbium doped CeO₂ to better understand how the crystalline quality and the defect chemistry affect its performance in quantum information technology. Utilizing RF magnetron sputtering from CeO₂ ceramics, we can tune the crystalline quality by methodically adjusting the deposition parameters such as substrate temperature, total pressure, gas ratio, and stage bias. We find that high deposition temperatures and low oxygen flows yield films with smooth surfaces (<1nm RMS), outstanding crystallinity, and low mosaicity (<0.2° FWHM rocking curve) but also create oxygen vacancies. We demonstrate that a subsequent thermal anneal in oxygen atmosphere heals the films and improves electrical properties. By dilute-doping CeO₂ with optically-active erbium, we can introduce defect qubits without altering the overall crystalline quality. During the erbium co-sputtering, we can modulate dopant levels from tens to hundreds parts per million throughout the CeO₂ thickness, as confirmed by inductively coupled plasma atomic emission spectroscopy. Photoluminescence spectroscopy results show a strong erbium emission at ~1510 nm with a 3.7 ms lifetime in agreement with theoretical calculations. Transmission electron microscopy confirms homogenous erbium doping within the film, coherent film-substrate interface, dense and continuous growth, and a smooth surface. Ultimately, we use a rich combination of characterization probes to better understand the connection between thin film structure and electronic properties that give rise to high-performing defect qubits.