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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Disruption of Commercial Solar Inverter System by TLS Proxy Man-in-the-Middle Attack

Transport Layer Security (TLS) is a cryptographic protocol that encrypts communication data, providing end-to-end communication encryption and authentication. Currently, TLS is widely adopted for securing communication between servers and end devices, including solar inverter systems. Therefore, users/operators can securely access the solar inverters through a web user interface (WebUI) application programmable interface (API) on a PC or server over TLS-enabled Wi-Fi or Ethernet. However, the security of the TLS-based network becomes compromised if it is breached by a TLS proxy man-in-the-middle (MITM) exploit. This report explores potential vulnerabilities in a commercial solar inverter system that leverages a TLS proxy MITM and discusses the impacts through assume-breached penetration testing. Furthermore, the paper explores recommended mitigation methods against the TLS proxy MITM exploit in solar inverters.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

Materials Data on TlS by Materials Project

TlS is I4/mcm structured and crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. there are two inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded in a 10-coordinate geometry to eight equivalent S1- atoms. All Tl–S bond lengths are 3.43 Å. In the second Tl1+ site, Tl1+ is bonded to four equivalent S1- atoms to form distorted edge-sharing TlS4 tetrahedra. All Tl–S bond lengths are 2.60 Å. S1- is bonded in a distorted L-shaped geometry to six Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlS by Materials Project

TlS crystallizes in the tetragonal P4_12_12 space group. The structure is three-dimensional. there are four inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded in a 7-coordinate geometry to seven S1- atoms. There are a spread of Tl–S bond distances ranging from 3.22–3.59 Å. In the second Tl1+ site, Tl1+ is bonded to four S1- atoms to form TlS4 tetrahedra that share corners with three equivalent TlS7 pentagonal bipyramids, corners with four TlS4 tetrahedra, and edges with two equivalent TlS7 pentagonal bipyramids. There are a spread of Tl–S bond distances ranging from 2.56–2.63 Å. In the third Tl1+ site, Tl1+ is bonded to seven S1- atoms to form distorted TlS7 pentagonal bipyramids that share corners with six equivalent TlS7 pentagonal bipyramids, corners with four TlS4 tetrahedra, and edges with five TlS4 tetrahedra. There are a spread of Tl–S bond distances ranging from 3.27–3.60 Å. In the fourth Tl1+ site, Tl1+ is bonded to four S1- atoms to form TlS4 tetrahedra that share a cornercorner with one TlS7 pentagonal bipyramid, corners with four TlS4 tetrahedra, and edges with three equivalent TlS7 pentagonal bipyramids. There are a spread of Tl–S bond distances ranging from 2.54–2.61 Å. There are five inequivalent S1- sites. In the first S1- site, S1- is bonded in a 6-coordinate geometry to six Tl1+ atoms. In the second S1- site, S1- is bonded in a 5-coordinate geometry to five Tl1+ atoms. In the third S1- site, S1- is bonded in a 2-coordinate geometry to six Tl1+ atoms. In the fourth S1- site, S1- is bonded in a distorted water-like geometry to six Tl1+ atoms. In the fifth S1- site, S1- is bonded in a 5-coordinate geometry to five Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlS by Materials Project

TlS is Molybdenum Carbide MAX Phase-like structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded to six equivalent S1- atoms to form a mixture of corner and edge-sharing TlS6 octahedra. The corner-sharing octahedral tilt angles are 10°. All Tl–S bond lengths are 2.78 Å. In the second Tl1+ site, Tl1+ is bonded to six equivalent S1- atoms to form a mixture of corner and edge-sharing TlS6 octahedra. The corner-sharing octahedral tilt angles are 10°. All Tl–S bond lengths are 3.17 Å. S1- is bonded to six Tl1+ atoms to form a mixture of corner and edge-sharing STl6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zr(TlS)4 by Materials Project

Zr(TlS)4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Zr4+ sites. In the first Zr4+ site, Zr4+ is bonded to six S2- atoms to form ZrS6 octahedra that share corners with three TlS5 square pyramids, edges with two ZrS6 octahedra, and edges with six TlS5 square pyramids. There are a spread of Zr–S bond distances ranging from 2.54–2.68 Å. In the second Zr4+ site, Zr4+ is bonded to six S2- atoms to form ZrS6 octahedra that share corners with four TlS5 square pyramids, edges with two ZrS6 octahedra, and edges with four TlS5 square pyramids. There are a spread of Zr–S bond distances ranging from 2.54–2.70 Å. In the third Zr4+ site, Zr4+ is bonded to six S2- atoms to form ZrS6 octahedra that share corners with two equivalent TlS5 square pyramids, edges with two equivalent ZrS6 octahedra, and edges with four TlS5 square pyramids. There are a spread of Zr–S bond distances ranging from 2.59–2.63 Å. There are ten inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded to five S2- atoms to form distorted TlS5 square pyramids that share corners with two equivalent ZrS6 octahedra, corners with two equivalent TlS5 square pyramids, edges with three ZrS6 octahedra, and an edgeedge with one TlS5 square pyramid. The corner-sharing octahedra tilt angles range from 15–18°. There are a spread of Tl–S bond distances ranging from 2.88–3.40 Å. In the second Tl1+ site, Tl1+ is bonded to five S2- atoms to form distorted TlS5 square pyramids that share corners with two ZrS6 octahedra, corners with two equivalent TlS5 square pyramids, edges with three ZrS6 octahedra, and edges with three TlS5 square pyramids. The corner-sharing octahedral tilt angles are 7°. There are a spread of Tl–S bond distances ranging from 2.94–3.43 Å. In the third Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.88–3.24 Å. In the fourth Tl1+ site, Tl1+ is bonded to five S2- atoms to form distorted TlS5 square pyramids that share corners with two ZrS6 octahedra, corners with two equivalent TlS5 square pyramids, edges with three ZrS6 octahedra, and edges with two TlS5 square pyramids. The corner-sharing octahedra tilt angles range from 9–10°. There are a spread of Tl–S bond distances ranging from 2.92–3.48 Å. In the fifth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.92–3.42 Å. In the sixth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.90–3.46 Å. In the seventh Tl1+ site, Tl1+ is bonded to five S2- atoms to form distorted TlS5 square pyramids that share corners with two ZrS6 octahedra, corners with two equivalent TlS5 square pyramids, edges with three ZrS6 octahedra, and edges with three TlS5 square pyramids. The corner-sharing octahedra tilt angles range from 11–15°. There are a spread of Tl–S bond distances ranging from 2.89–3.37 Å. In the eighth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.88–3.26 Å. In the ninth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.89–3.43 Å. In the tenth Tl1+ site, Tl1+ is bonded in a 5-coordinate geometry to five S2- atoms. There are a spread of Tl–S bond distances ranging from 2.91–3.41 Å. There are ten inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to one Zr4+ and five Tl1+ atoms. In the second S2- site, S2- is bonded to two equivalent Zr4+ and four Tl1+ atoms to form distorted SZr2Tl4 octahedra that share a cornercorner with one SZrTl5 octahedra and edges with two SZr2Tl4 octahedra. The corner-sharing octahedral tilt angles are 19°. In the third S2- site, S2- is bonded in a 6-coordinate geometry to two Zr4+ and four Tl1+ atoms. In the fourth S2- site, S2- is bonded to two Zr4+ and four Tl1+ atoms to form distorted SZr2Tl4 octahedra that share a cornercorner with one SZr2Tl4 octahedra and edges with three SZrTl5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth S2- site, S2- is bonded in a 6-coordinate geometry to one Zr4+ and five Tl1+ atoms. In the sixth S2- site, S2- is bonded in a 6-coordinate geometry to two Zr4+ and four Tl1+ atoms. In the seventh S2- site, S2- is bonded in a 6-coordinate geometry to one Zr4+ and five Tl1+ atoms. In the eighth S2- site, S2- is bonded in a 6-coordinate geometry to one Zr4+ and five Tl1+ atoms. In the ninth S2- site, S2- is bonded to one Zr4+ and five Tl1+ atoms to form a mixture of distorted corner and edge-sharing SZrTl5 octahedra. The corner-sharing octahedra tilt angles range from 0–19°. In the tenth S2- site, S2- is bonded in a 6-coordinate geometry to two Zr4+ and four Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf(TlS)4 by Materials Project

Hf(TlS)4 is Orthorhombic Perovskite-like structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to six S2- atoms to form HfS6 octahedra that share corners with two TlS5 square pyramids, edges with two HfS6 octahedra, and edges with five TlS5 square pyramids. There are a spread of Hf–S bond distances ranging from 2.52–2.63 Å. In the second Hf4+ site, Hf4+ is bonded to six S2- atoms to form HfS6 octahedra that share corners with three TlS5 square pyramids, edges with two HfS6 octahedra, and edges with three TlS5 square pyramids. There are a spread of Hf–S bond distances ranging from 2.51–2.66 Å. In the third Hf4+ site, Hf4+ is bonded to six S2- atoms to form HfS6 octahedra that share corners with two equivalent TlS5 square pyramids, edges with two equivalent HfS6 octahedra, and edges with two equivalent TlS5 square pyramids. There are two shorter (2.57 Å) and four longer (2.59 Å) Hf–S bond lengths. There are ten inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded to five S2- atoms to form distorted TlS5 square pyramids that share corners with two equivalent HfS6 octahedra, edges with three HfS6 octahedra, and an edgeedge with one TlS5 square pyramid. The corner-sharing octahedra tilt angles range from 15–19°. There are a spread of Tl–S bond distances ranging from 2.88–3.41 Å. In the second Tl1+ site, Tl1+ is bonded to five S2- atoms to form distorted TlS5 square pyramids that share corners with two HfS6 octahedra, corners with two equivalent TlS5 square pyramids, edges with three HfS6 octahedra, and edges with two TlS5 square pyramids. The corner-sharing octahedra tilt angles range from 7–8°. There are a spread of Tl–S bond distances ranging from 2.96–3.45 Å. In the third Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.89–3.25 Å. In the fourth Tl1+ site, Tl1+ is bonded in a 5-coordinate geometry to five S2- atoms. There are a spread of Tl–S bond distances ranging from 2.92–3.50 Å. In the fifth Tl1+ site, Tl1+ is bonded in a 4-coordinate geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.92–3.46 Å. In the sixth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.92–3.49 Å. In the seventh Tl1+ site, Tl1+ is bonded to five S2- atoms to form distorted TlS5 square pyramids that share corners with two HfS6 octahedra, corners with two equivalent TlS5 square pyramids, edges with three HfS6 octahedra, and edges with two TlS5 square pyramids. The corner-sharing octahedra tilt angles range from 12–16°. There are a spread of Tl–S bond distances ranging from 2.88–3.37 Å. In the eighth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.89–3.28 Å. In the ninth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.89–3.45 Å. In the tenth Tl1+ site, Tl1+ is bonded in a 5-coordinate geometry to five S2- atoms. There are a spread of Tl–S bond distances ranging from 2.93–3.43 Å. There are ten inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to one Hf4+ and five Tl1+ atoms. In the second S2- site, S2- is bonded in a 6-coordinate geometry to two equivalent Hf4+ and four Tl1+ atoms. In the third S2- site, S2- is bonded in a 6-coordinate geometry to two Hf4+ and four Tl1+ atoms. In the fourth S2- site, S2- is bonded to two Hf4+ and four Tl1+ atoms to form distorted corner-sharing SHf2Tl4 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth S2- site, S2- is bonded in a 6-coordinate geometry to one Hf4+ and five Tl1+ atoms. In the sixth S2- site, S2- is bonded in a 6-coordinate geometry to two Hf4+ and four Tl1+ atoms. In the seventh S2- site, S2- is bonded in a 6-coordinate geometry to one Hf4+ and five Tl1+ atoms. In the eighth S2- site, S2- is bonded in a 6-coordinate geometry to one Hf4+ and five Tl1+ atoms. In the ninth S2- site, S2- is bonded in a 6-coordinate geometry to one Hf4+ and five Tl1+ atoms. In the tenth S2- site, S2- is bonded in a 6-coordinate geometry to two Hf4+ and four Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Evolution of Rev7 interactions in eukaryotic TLS DNA polymerase Polζ

Translesion synthesis (TLS) DNA polymerase Polζ is crucial for the bypass replication over sites of DNA damage. The Rev7 subunit of Polζ is a HORMA (Hop1, Rev7, Mad2) protein that facilitates recruitment of Polζ to the replication fork via interactions with the catalytic subunit Rev3 and the translesion synthesis scaffold protein Rev1. Human Rev7 (hRev7) interacts with two Rev7-binding motifs (RBMs) of hRev3 by a mechanism conserved among HORMA proteins whereby the safety-belt loop of hRev7 closes on the top of the ligand. The two copies of hRev7 tethered by the two hRev3-RBMs form a symmetric head-to-head dimer through the canonical HORMA dimerization interface. Recent cryo-EM structures reveal that Saccharomyces cerevisiae Polζ (scPolζ) also includes two copies of scRev7 bound to distinct regions of scRev3. Surprisingly, the HORMA dimerization interface is not conserved in scRev7, with the two scRev7 protomers forming an asymmetric head-to-tail dimer with a much smaller interface than the hRev7 dimer. Here, we validated the two adjacent RBM motifs in scRev3, which bind scRev7 with affinities that differ by two orders of magnitude and confirmed the 2:1 stoichiometry of the scRev7:Rev3 complex in solution. However, our biophysical studies reveal that scRev7 does not form dimers in solution either on its own accord or when tethered by the two RBMs in scRev3. These findings imply that the scRev7 dimer observed in the cryo-EM structures is induced by scRev7 interactions with other Polζ subunits and that Rev7 homodimerization via the HORMA interface is a mechanism that emerged later in evolution.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

TLS characterization using multilevel decay of a fixed-frequency transmon

Transmon qubits are a cornerstone of superconducting quantum computing platforms, yet their coherence times often exhibit temporal fluctuations that degrade processor performance. These variations are commonly attributed to shifts in the resonance frequencies of individual two-level systems (TLSs) near the qubit transition. In this study, we monitor the lifetimes of multiple energy levels of a fixed-frequency transmon and examine their temporal correlations. Our measurements reveal that one or more TLSs—detuned by more than 100 MHz from the qubit transition—can still significantly influence coherence. The proposed method provides a powerful tool for TLS spectroscopy without the need to tune the transmon frequency, either via a flux-tunable inductor or AC-Stark shifts.

Roy, Tanay [Fermilab] (ORCID:000000019442862X)↗
DOE OSTI2026

TLS characterization using multilevel decay of a fixed-frequency transmon

Transmon qubits are a cornerstone of superconducting quantum computing platforms, yet their coherence times often exhibit temporal fluctuations that degrade processor performance. These variations are commonly attributed to shifts in the resonance frequencies of individual two-level systems (TLSs) near the qubit transition. In this study, we monitor the lifetimes of multiple energy levels of a fixed-frequency transmon and examine their temporal correlations. Our measurements reveal that one or more TLSs—detuned by more than 100 MHz from the qubit transition—can still significantly influence coherence. The proposed method provides a powerful tool for TLS spectroscopy without the need to tune the transmon frequency, either via a flux-tunable inductor or AC-Stark shifts.

Roy, Tanay [Fermilab] (ORCID:000000019442862X)↗
DOE OSTI2020

Materials Data on Ti(TlS)4 by Materials Project

Tl4TiS4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ti4+ is bonded in a tetrahedral geometry to four S2- atoms. There are a spread of Ti–S bond distances ranging from 2.26–2.29 Å. There are four inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded in a 6-coordinate geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.98–3.37 Å. In the second Tl1+ site, Tl1+ is bonded in a 5-coordinate geometry to five S2- atoms. There are a spread of Tl–S bond distances ranging from 3.02–3.86 Å. In the third Tl1+ site, Tl1+ is bonded in a 5-coordinate geometry to five S2- atoms. There are a spread of Tl–S bond distances ranging from 2.97–3.77 Å. In the fourth Tl1+ site, Tl1+ is bonded in a 4-coordinate geometry to four S2- atoms. There are a spread of Tl–S bond distances ranging from 2.99–3.46 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to one Ti4+ and four Tl1+ atoms to form distorted corner-sharing STiTl4 trigonal bipyramids. In the second S2- site, S2- is bonded in a 1-coordinate geometry to one Ti4+ and four Tl1+ atoms. In the third S2- site, S2- is bonded in a 1-coordinate geometry to one Ti4+ and five Tl1+ atoms. In the fourth S2- site, S2- is bonded in a 1-coordinate geometry to one Ti4+ and five Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Terrestrial laser scanning data (Levels 0 and 1) from Urban Biogeochemistry Pilot Project sites, Knoxville, Tennessee, Jul 2024 - Jul 2025

This data package contains data from terrestrial laser scanning (TLS) at five urban park sites in Knoxville, Tennessee, USA. All parks include open-grown and/or closed-canopy trees and mixed nearby land use. These study sites were established as part of the Urban Biogeochemistry Pilot Project, which has an overall goal of better understanding how hydrobiogeochemical cycling is altered within the human environment. These five sites represent a gradient of urbanization, and were instrumented to understand hydrological and biogeochemical cycling (e.g., soil moisture, soil physical properties and biogeochemistry, tree transpiration, species type). The TLS data archived here were collected to provide detailed, three-dimensional information about forest structure. Specifically, data were collected to allow tree- and stand-level characterization of woody structure and leaf area. TLS scans were placed to capture the area around trees with sap flow sensors, and as much of a 50 m radius area around the meteorological station as possible given site property limits. Derived products will allow upscaling of water content and transpiration data. This data package contains the following data: - High-level files document further details of the campaign and data package: 1_CampaignSummary.csv provides details about the campaign and study site, 2_ScanAreasDetail.csv provides details about each separate scan area (groups of scans post-processed into a single point cloud), 3_TerrestrialLidarSensor.csv provides further technical details about the Riegl VZ-400i TLS sensor, TLS_CSV_dd.csv is a CSV Data Dictionary providing information about the fields in CSV files following the ESS-DIVE CSV File Formatting Guidelines Reporting Format, TLS_flmd.csv is a File Level Metadata file providing information about each file in the data package following the ESS-DIVE File Level Metadata Reporting Format, and README.txt is a text file describing the overall project and file structure. - Level 0 data are the raw data (.PROJ folders) as recorded by the Riegl VZ-400i TLS instrument before scan co-registration and post-processing with the Riegl's proprietary RiSCAN PRO software, which requires a license. - Level 1 data contain post-processed, co-registered data from each scan area. The "PointClouds" folder for each scan area contains a .las file with 1 cm resolution point cloud data exported from RiSCAN PRO. These are the main files likely to be of interest to most users and can be further processed with any software capable of manipulating .las files (e.g. Python, R CloudCompare). The "Project Information" folder contains log files from post-processing in RiSCAN PRO that may be of interest to users who want to see detailed records of post-processing, including all PDF reports generated by RiSCAN PRO. The "ScanPositions" folder contains information about the final position of all TLS scans, after post-processing, in multiple formats. The file ScanPositions_*.csv provides final geo-referenced scan positions, and the file SOP_backup_*.csv can be used in RiSCAN PRO to restore the co-registered scan positions if users wish to re-process raw data (Level 0 .PROJ folders) with RiSCAN PRO software (e.g., subsample to a different resolution, exclude a certain scan position, or apply different filters on reflectance or deviation values) without redoing time-consuming co-registration steps.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

Terrestrial laser scanning data (Levels 0 and 1) for Pasoh, Malaysia, Sep 2024

This data package contains data from terrestrial laser scanning (TLS) at the Pasoh Forest Reserve, Malaysia. The Pasoh Forest Reserve is a facility of the Forest Research Institute Malaysia, and contains evergreen lowland dipterocarp forest. The Next-Generation Ecosystem Experiments Tropics (NGEE-Tropics) study areas at Pasoh were established to study how different species respond to climatic variation and soil water availability. Two study areas were chosen representing different topography and species. The TLS data archived here were collected to provide detailed, three-dimensional information about forest structure. Specifically, data were collected to allow tree-level characterization of woody structure and leaf area for 12 focal trees with FloraPulse and sap flux sensors, facilitating estimation of woody biomass and leaf area to allow upscaling of water content and transpiration data to the tree-level. Scan positions were not selected to provide consistent data for non-focal trees with the study areas. This data package contains the following data: - High-level files document further details of the campaign and data package: 1_CampaignSummary.csv provides details about the campaign and study site, 2_ScanAreasDetail.csv provides details about each separate scan area (groups of scans post-processed into a single point cloud), 3_TerrestrialLidarSensor.csv provides further technical details about the Riegl VZ-400i TLS sensor, TLS_CSV_dd.csv is a CSV Data Dictionary providing information about the fields in CSV files following the ESS-DIVE CSV File Formatting Guidelines Reporting Format, TLS_flmd.csv is a File Level Metadata file providing information about each file in the data package following the ESS-DIVE File Level Metadata Reporting Format, and README.txt is a text file describing the overall project and file structure. - Level 0 data are the raw data (.PROJ folders) as recorded by the Riegl VZ-400i TLS instrument before scan co-registration and post-processing with the Riegl's proprietary RiSCAN PRO software, which requires a license. - Level 1 data contain post-processed, co-registered data from each scan area. The "PointClouds" folder for each scan area contains a .las file with 1 cm resolution point cloud data exported from RiSCAN PRO. These are the main files likely to be of interest to most users and can be further processed with any software capable of manipulating .las files (e.g. Python, R CloudCompare). The "Project Information" folder contains log files from post-processing in RiSCAN PRO that may be of interest to users who want to see detailed records of post-processing, including all PDF reports generated by RiSCAN PRO. The "ScanPositions" folder contains information about the final position of all TLS scans, after post-processing, in multiple formats. The file ScanPositions_*.csv provides final geo-referenced scan positions, and the file SOP_backup_*.csv can be used in RiSCAN PRO to restore the co-registered scan positions if users wish to re-process raw data (Level 0 .PROJ folders) with RiSCAN PRO software (e.g., subsample to a different resolution, exclude a certain scan position, or apply different filters on reflectance or deviation values) without redoing time-consuming co-registration steps.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Anomalous Loss Reduction Below Two‐Level System Saturation in Aluminum Superconducting Resonators

Superconducting resonators are widely used in many applications such as qubit readout for quantum computing, and kinetic inductance detectors. These resonators are susceptible to numerous loss and noise mechanisms, especially the dissipation due to two-level systems (TLS) which become the dominant source of loss in the few-photon and low temperature regime. In this study, capacitively-coupled aluminum half-wavelength coplanar waveguide resonators are investigated. Surprisingly, the loss of the resonators is observed to decrease with a lowering temperature at low excitation powers and temperatures below the TLS saturation. This behavior is attributed to the reduction of the TLS resonant response bandwidth with decreasing temperature and power to below the detuning between the TLS and the resonant photon frequency in a discrete ensemble of TLS. When response bandwidths of TLS are smaller than their detunings from the resonance, the resonant response and thus the loss is reduced. At higher excitation powers, the loss follows a logarithmic power dependence, consistent with predictions from the generalized tunneling model (GTM). A model combining the discrete TLS ensemble with the GTM is proposed and matches the temperature and power dependence of the measured internal loss of the resonator with reasonable parameters.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Localization and reduction of superconducting quantum coherent circuit losses

Quantum sensing and computation can be realized with superconducting microwave circuits. Qubits are engineered quantum systems of capacitors and inductors with non-linear Josephson junctions. They operate in the single-excitation quantum regime, photons of $27 \mu$eV at 6.5 GHz. Quantum coherence is fundamentally limited by materials defects, in particular atomic-scale parasitic two-level systems (TLS) in amorphous dielectrics at circuit interfaces.[1] The electric fields driving oscillating charges in quantum circuits resonantly couple to TLS, producing phase noise and dissipation. We use coplanar niobium-on-silicon superconducting resonators to probe decoherence in quantum circuits. By selectively modifying interface dielectrics, we show that most TLS losses come from the silicon surface oxide, and most non-TLS losses are distributed throughout the niobium surface oxide. Through post-fabrication interface modification we reduced TLS losses by 85% and non-TLS losses by 72%, obtaining record single-photon resonator quality factors above 5 million and approaching a regime where non-TLS losses are dominant. [1]M\"uller, C., Cole, J. H. & Lisenfeld, J. Towards understanding two-level-systems in amorphous solids: insights from quantum circuits. Rep. Prog. Phys. 82, 124501 (2019)

Altoé, M Virginia P↗
DOE OSTI2023

Simulating noise on a quantum processor: interactions between a qubit and resonant two-level system bath

Material defects fundamentally limit the coherence times of superconducting qubits, and manufacturing completely defect-free devices is not yet possible. Therefore, understanding the interactions between defects and a qubit in a real quantum processor design is essential. We build a model that incorporates the standard tunneling model, the electric field distributions in the qubit, and open quantum system dynamics, and draws from the current understanding of two-level system (TLS) theory. Specifically, we start with one million TLSs distributed on the surface of a qubit and pick the 200 systems that are most strongly coupled to the qubit. We then perform a full Lindbladian simulation that explicitly includes the coherent coupling between the qubit and the TLS bath to model the time dependent density matrix of resonant TLS defects and the qubit. We find that the 200 most strongly coupled TLSs can accurately describe the qubit energy relaxation time. This work confirms that resonant TLSs located in areas where the electric field is strong can significantly affect the qubit relaxation time, even if they are located far from the Josephson junction (JJ). Similarly, a strongly-coupled resonant TLS located in the JJ does not guarantee a reduced qubit relaxation time if a more strongly coupled TLS is far from the JJ. In addition to the coupling strengths between TLSs and the qubit, the model predicts that the geometry of the device and the TLS relaxation time play a significant role in qubit dynamics. Our work can provide guidance for future quantum processor designs with improved qubit coherence times.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Theory of Two-Level Tunneling Systems in Superconductors

We develop a field theory formulation for the interaction of an ensemble of two-level tunneling systems (TLSs) with the electronic states of a superconductor. Predictions for the impact of two-level tunneling systems on superconductivity are presented, including T c and the spectrum of quasiparticle states for conventional BCS superconductors. We show that nonmagnetic TLS impurities in conventional s-wave superconductors can act as pair-breaking or pair-enhancing defects depending on the level population of the distribution of TLS impurities. We present calculations of the enhancement of superconductivity, both T c and the order parameter, for TLS defects in thermal equilibrium with the electrons and lattice. The scattering of quasiparticles by TLS impurities leads to subgap states below the bulk excitation gap, Δ, as well as resonances in the continuum above Δ. The energies and spectral weights of these states depend on the distribution of tunnel splittings, while the spectral weights are particularly sensitive to the level occupation of the TLS impurities. Under microwave excitation, or decoupling from the thermal bath, a nonequilibrium level population of the TLS distribution generates subgap quasiparticle states near the Fermi level that contribute to dissipation and thus degrade the performance of superconducting devices at low temperatures.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Two-Tone Spectroscopy of 3D SRF Cavities to Understand Two-Level System Loss

So-called two-level system (TLS) defects are among the most detrimental sources of loss and decoherence in superconducting quantum devices, and their microscopic nature still poorly understood. We develop a two-tone spectroscopy technique to characterize the spectral line width of TLS. This knowledge will help to distinguishes various types of TLS defects. In our experiments we use the fundamental TM010 pass band modes of 9-cell elliptical SRF cavities to probe spectral properties of TLS in native niobium oxide formed on the inside walls of the resonator. We pump one of the modes (4¿/9 through 8¿/9) with continuous high-power to saturate TLSs that couple to this frequency, and we probe the Q-factor of the ¿-mode. We observe increase of the quality factor of the probed ¿-mode when one of the neighboring modes is pumped. Extremely high quality factors of the pass band modes and their relative proximity in the frequency space allow us to estimate the width of the spectral hole burned in the TLS bath absorption spectrum which is related to the line spectral width of the TLS defects.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗