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308 results on '"Bedzyk, Michael J"'

1. Systematic improvements in transmon qubit coherence enabled by niobium surface encapsulation

Author

Bal, Mustafa, Murthy, Akshay A., Zhu, Shaojiang, Crisa, Francesco, You, Xinyuan, Huang, Ziwen, Roy, Tanay, Lee, Jaeyel, Zanten, David van, Pilipenko, Roman, Nekrashevich, Ivan, Lunin, Andrei, Bafia, Daniel, Krasnikova, Yulia, Kopas, Cameron J., Lachman, Ella O., Miller, Duncan, Mutus, Josh Y., Reagor, Matthew J., Cansizoglu, Hilal, Marshall, Jayss, Pappas, David P., Vu, Kim, Yadavalli, Kameshwar, Oh, Jin-Su, Zhou, Lin, Kramer, Matthew J., Lecocq, Florent, Goronzy, Dominic P., Torres-Castanedo, Carlos G., Pritchard, P. Graham, Dravid, Vinayak P., Rondinelli, James M., Bedzyk, Michael J., Hersam, Mark C., Zasadzinski, John, Koch, Jens, Sauls, James A., Romanenko, Alexander, and Grassellino, Anna

Published
2024
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5. Thermally conductive ultra-low-k dielectric layers based on two-dimensional covalent organic frameworks

Author

Evans, Austin M., Giri, Ashutosh, Sangwan, Vinod K., Xun, Sangni, Bartnof, Matthew, Torres-Castanedo, Carlos G., Balch, Halleh B., Rahn, Matthew S., Bradshaw, Nathan P., Vitaku, Edon, Burke, David W., Li, Hong, Bedzyk, Michael J., Wang, Feng, Brédas, Jean-Luc, Malen, Jonathan A., McGaughey, Alan J. H., Hersam, Mark C., Dichtel, William R., and Hopkins, Patrick E.

Published
2021
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6. Formation and Microwave Losses of Hydrides in Superconducting Niobium Thin Films Resulting from Fluoride Chemical Processing.

Author

Torres‐Castanedo, Carlos G., Goronzy, Dominic P., Pham, Thang, McFadden, Anthony, Materise, Nicholas, Masih Das, Paul, Cheng, Matthew, Lebedev, Dmitry, Ribet, Stephanie M., Walker, Mitchell J., Garcia‐Wetten, David A., Kopas, Cameron J., Marshall, Jayss, Lachman, Ella, Zhelev, Nikolay, Sauls, James A., Mutus, Joshua Y., McRae, Corey Rae H., Dravid, Vinayak P., and Bedzyk, Michael J.

Subjects
CHEMICAL processes, QUANTUM computing, QUANTUM information science, DIFFUSION barriers, TRANSMISSION electron microscopy
Abstract

Superconducting niobium (Nb) thin films have recently attracted significant attention due to their utility for quantum information technologies. In the processing of Nb thin films, fluoride‐based chemical etchants are commonly used to remove surface oxides that are known to affect superconducting quantum devices adversely. However, these same etchants can also introduce hydrogen to form Nb hydrides, potentially negatively impacting microwave loss performance. Here, comprehensive materials characterization of Nb hydrides formed in Nb thin films as a function of fluoride chemical treatments is presented. In particular, secondary‐ion mass spectrometry, X‐ray scattering, and transmission electron microscopy reveal the spatial distribution and phase transformation of Nb hydrides. The rate of hydride formation is determined by the fluoride solution acidity and the etch rate of Nb2O5, which acts as a diffusion barrier for hydrogen into Nb. The resulting Nb hydrides are detrimental to Nb superconducting properties and lead to increased power‐independent microwave loss in coplanar waveguide resonators. However, Nb hydrides do not correlate with two‐level system loss or device aging mechanisms. Overall, this work provides insight into the formation of Nb hydrides and their role in microwave loss, thus guiding ongoing efforts to maximize coherence time in superconducting quantum devices. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Enhanced imaging of electronic hot spots using quantum squeezed light.

Author

An, Haechan, Najjar Amiri, Ali, Goronzy, Dominic P., Garcia Wetten, David A., Bedzyk, Michael J., Shakouri, Ali, Hersam, Mark C., and Hosseini, Mahdi

Subjects
PHOTONS, SQUEEZED light, QUANTUM correlations, SEMICONDUCTOR devices, SEMICONDUCTOR materials, ELECTRONIC equipment
Abstract

Detecting electronic hot spots is important for understanding the heat dissipation and thermal management of electronic and semiconductor devices. Optical thermoreflective imaging is being used to perform precise temporal and spatial imaging of heat on wires and semiconductor materials. We apply quantum squeezed light to perform thermoreflective imaging on micro-wires, surpassing the shot-noise limit of classical approaches. We obtain a far-field temperature sensing accuracy of 42 mK after 50 ms of averaging and show that a 256 × 256 pixel image can be constructed with such sensitivity in 10 min. We can further obtain single-shot temperature sensing of 1.6 K after only 10 μ s of averaging, enabling a dynamical study of heat dissipation. Not only do the quantum images provide accurate spatiotemporal information about heat distribution but also the measure of quantum correlation provides additional information, inaccessible by classical techniques, which can lead to a better understanding of the dynamics. We apply the technique to both aluminum and niobium microwires and discuss the applications of the technique in studying electron dynamics at low temperatures. [ABSTRACT FROM AUTHOR]

Published
2024
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19. Reexpansion of charged nanoparticle assemblies in concentrated electrolytes.

Author

Reinertsen, Roger J. E., Kewalramani, Sumit, Jiménez-Ángeles, Felipe, Weigand, Steven J., Bedzyk, Michael J., and de la Cruz, Monica Olvera

Subjects
SMALL-angle X-ray scattering, NANOPARTICLES, ION-ion collisions, COLLOIDAL crystals, ELECTROLYTES
Abstract

Electrostatic forces in solutions are highly relevant to a variety of fields, ranging from electrochemical energy storage to biology. However, their manifestation in concentrated electrolytes is not fully understood, as exemplified by counterintuitive observations of colloidal stability and long-ranged repulsions in molten salts. Highly charged biomolecules, such as DNA, respond sensitively to ions in dilute solutions. Here, we use non-base-pairing DNA-coated nanoparticles (DNA-NP) to analyze electrostatic interactions in concentrated salt solutions. Despite their negative charge, these conjugates form colloidal crystals in solutions of sufficient divalent cation concentration. We utilize small-angle X-ray scattering (SAXS) to study such DNA-NP assemblies across the full accessible concentration ranges of aqueous CaCl2, MgCl2, and SrCl2 solutions. SAXS shows that the crystallinity and phases of the assembled structures vary with cation type. For all tested salts, the aggregates contract with added ions at low salinities and then begin expanding above a cation-dependent threshold salt concentration. Wide-angle X-ray scattering (WAXS) reveals enhanced positional correlations between ions in the solution at high salt concentrations. Complementary molecular dynamics simulations show that these ion-ion interactions reduce the favorability of dense ion configurations within the DNA brushes below that of the bulk solution. Measurements in solutions with lowered permittivity demonstrate a simultaneous increase in ion coupling and decrease in the concentration at which aggregate expansion begins, thus confirming the connection between these phenomena. Our work demonstrates that interactions between charged objects continue to evolve considerably into the high-concentration regime, where classical theories project electrostatics to be of negligible consequence. [ABSTRACT FROM AUTHOR]

Published
2024
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21. Systematic Improvements in Transmon Qubit Coherence Enabled by Niobium Surface Encapsulation

Author

Bal, Mustafa, Murthy, Akshay A., Zhu, Shaojiang, Crisa, Francesco, You, Xinyuan, Huang, Ziwen, Roy, Tanay, Lee, Jaeyel, van Zanten, David, Pilipenko, Roman, Nekrashevich, Ivan, Bafia, Daniel, Krasnikova, Yulia, Kopas, Cameron J., Lachman, Ella O., Miller, Duncan, Mutus, Josh Y., Reagor, Matthew J., Cansizoglu, Hilal, Marshall, Jayss, Pappas, David P., Vu, Kim, Yadavalli, Kameshwar, Oh, Jin-Su, Zhou, Lin, Kramer, Matthew J., Lecocq, Florent Q., Goronzy, Dominic P., Torres-Castanedo, Carlos G., Pritchard, Graham, Dravid, Vinayak P., Rondinelli, James M., Bedzyk, Michael J., Hersam, Mark C., Zasadzinski, John, Koch, Jens, Sauls, James A., Romanenko, Alexander, and Grassellino, Anna

Subjects
Quantum Physics, Condensed Matter - Materials Science, Condensed Matter - Superconductivity
Abstract

We present a novel transmon qubit fabrication technique that yields systematic improvements in T$_1$ coherence times. We fabricate devices using an encapsulation strategy that involves passivating the surface of niobium and thereby preventing the formation of its lossy surface oxide. By maintaining the same superconducting metal and only varying the surface structure, this comparative investigation examining different capping materials and film substrates across different qubit foundries definitively demonstrates the detrimental impact that niobium oxides have on the coherence times of superconducting qubits, compared to native oxides of tantalum, aluminum or titanium nitride. Our surface-encapsulated niobium qubit devices exhibit T$_1$ coherence times 2 to 5 times longer than baseline niobium qubit devices with native niobium oxides. When capping niobium with tantalum, we obtain median qubit lifetimes above 200 microseconds. Our comparative structural and chemical analysis suggests that amorphous niobium oxides may induce higher losses compared to other amorphous oxides. These results are in line with high-accuracy measurements of the niobium oxide loss tangent obtained with ultra-high Q superconducting radiofrequency (SRF) cavities. This new surface encapsulation strategy enables even further reduction of dielectric losses via passivation with ambient-stable materials, while preserving fabrication and scalable manufacturability thanks to the compatibility with silicon processes.

Published
2023

29. Impact of charge switching stimuli on supramolecular perylene monoimide assemblies† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c8sc05595e

Author

Dannenhoffer, Adam, Sai, Hiroaki, Huang, Dongxu, Nagasing, Benjamin, Harutyunyan, Boris, Fairfield, Daniel J., Aytun, Taner, Chin, Stacey M., Bedzyk, Michael J., Olvera de la Cruz, Monica, and Stupp, Samuel I.

Subjects
Chemistry, sense organs, skin and connective tissue diseases
Abstract

A switchable perylene monoimide which undergoes reversible morphological and electronic changes controlled by the ionization state of the phenolic oxygen., The development of stimuli-responsive amphiphilic supramolecular nanostructures is an attractive target for systems based on light-absorbing chromophores that can function as photosensitizers in water. We report here on a water soluble supramolecular carboxylated perylene monoimide system in which charge can be switched significantly by a change in pH. This was accomplished by substituting the perylene core with an ionizable hydroxyl group. In acidic environments, crystalline supramolecular nanoribbons with dimensions on the order of 500 × 50 × 2 nm form readily, while in basic solution the additional electrostatic repulsion of the ionized hydroxyl reduces assemblies to very small dimensions on the order of only several nanometers. The HOMO/LUMO levels were also found to be sensitive to pH; in acidic media the HOMO/LUMO levels are –5.65 and –3.70 eV respectively versus vacuum, whereas is in basic conditions they are –4.90 and –3.33 eV, respectively. Utilizing the assemblies as photosensitizers in photocatalytic production of hydrogen with [Mo3S13]2– as a catalyst at a pH of 4, H2 was generated with a turnover number of 125 after 18 hours. Charge switching the assemblies at a pH of 9–10 and using an iron porphyrin catalyst, protons could again be reduced to hydrogen and CO2 was reduced to CO with a turnover number of 30. The system investigated offers an example of dynamic photosensitizing assemblies that can drive reactions in both acidic and basic media.

Published
2019

33. Characterization of Nb films for superconducting qubits using phase boundary measurements.

Author

Ryan, Kevin M., Torres-Castanedo, Carlos G., Goronzy, Dominic P., Wetten, David A. Garcia, Field, Mark, Kopas, Cameron J., Marshall, Jayss, Reagor, Matthew J., Bedzyk, Michael J., Hersam, Mark C., and Chandrasekhar, Venkat

Subjects
SUPERCONDUCTING transition temperature, SUPERCONDUCTING films, QUBITS, X-ray diffraction measurement, CRYSTAL orientation, CRYSTAL grain boundaries
Abstract

Continued advances in superconducting qubit performance require more detailed understandings of the many sources of decoherence. Within these devices, two-level systems arise due to defects, interfaces, and grain boundaries and are thought to be a major source of qubit decoherence at millikelvin temperatures. In addition to Al, Nb is a commonly used metallization layer in superconducting qubits. Consequently, a significant effort is required to develop and qualify processes that mitigate defects in Nb films. As the fabrication of complete superconducting qubits and their characterization at millikelvin temperatures is a time and resource intensive process, it is desirable to have measurement tools that can rapidly characterize the properties of films and evaluate different treatments. Here, we show that measurements of the variation of the superconducting critical temperature Tc with an applied external magnetic field H (of the phase boundary T c − H) performed with very high-resolution show features that are directly correlated with the structure of the Nb films. In combination with x-ray diffraction measurements, we show that one can even distinguish variations in the size and crystal orientation of the grains in a Nb film by small but reproducible changes in the measured superconducting phase boundary. [ABSTRACT FROM AUTHOR]

Published
2022
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47. High-efficiency two-dimensional RuddlesdenPopper perovskite solar cells

Author

Tsai, Hsinhan, Nie, Wanyi, Blancon, Jean-Christophe, Stoumpos, Constantinos C., Asadpour, Reza, Harutyunyan, Boris, Neukirch, Amanda J., Verduzco, Rafael, Crochet, Jared J., Tretiak, Sergei, Pedesseau, Laurent, Even, Jacky, Alam, Muhammad A., Gupta, Gautam, Lou, Jun, Ajayan, Pulickel M., Bedzyk, Michael J., Kanatzidis, Mercouri G., and Mohite, Aditya D.

Subjects
Usage, Analysis, Research, Properties, Crystal structure -- Analysis, Solar cells -- Research -- Properties -- Analysis, Perovskite -- Usage -- Properties
Abstract

Author(s): Hsinhan Tsai [1, 2]; Wanyi Nie [1]; Jean-Christophe Blancon [1]; Constantinos C. Stoumpos [3, 4, 5]; Reza Asadpour [6]; Boris Harutyunyan [4, 5]; Amanda J. Neukirch [1]; Rafael Verduzco [...]

Published
2016
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48. Phase control of Mn-based spinel films via pulsed laser deposition.

Author

Zhenxing Feng, Xiao Chen, Fister, Timothy T., Bedzyk, Michael J., and Fenter, Paul

Subjects
SPINEL, SPINEL group, PULSED laser deposition, COATING processes, ELECTROCHEMICAL analysis
Abstract

Phase transformations in battery cathode materials during electrochemical-insertion reactions lead to capacity fading and low cycle life. One solution is to keep the same phase of cathode materials during cation insertion-extraction processes. Here, we demonstrate a novel strategy to control the phase and composition of Mn-based spinel oxides for magnesium-ion battery applications through the growth of thin films on lattice-matched substrates using pulsed laser deposition. Materials at two extreme conditions are considered: fully discharged cathode MgMn2O4 and fully charged cathode Mn2O4. The tetragonal MgMn2O4 (MMO) phase is obtained on MgAl2O4 substrates, while the cubic MMO phase is obtained on MgO substrates. Similarly, growth of the empty Mn2O4 spinel in the cubic phase is obtained on an MgO substrate. These results demonstrate the ability to control separately the phase of spinel thin films (e.g., tetragonal vs. cubic MMO) at nominally fixed composition, and to maintain a fixed (cubic) phase while varying its composition (MgxMn2O4, for x = 0, 1). This capability provides a novel route to gain insights into the operation of battery electrodes for energy storage applications. [ABSTRACT FROM AUTHOR]

Published
2016
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