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Dive into the research topics where David W. Abraham is active.

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Featured researches published by David W. Abraham.


Nature Communications | 2014

Implementing a strand of a scalable fault-tolerant quantum computing fabric

Jerry M. Chow; Jay Gambetta; Easwar Magesan; David W. Abraham; Andrew W. Cross; Blake Johnson; Nicholas Masluk; Colm A. Ryan; John A. Smolin; Srikanth Srinivasan; Matthias Steffen

With favourable error thresholds and requiring only nearest-neighbour interactions on a lattice, the surface code is an error-correcting code that has garnered considerable attention. At the heart of this code is the ability to perform a low-weight parity measurement of local code qubits. Here we demonstrate high-fidelity parity detection of two code qubits via measurement of a third syndrome qubit. With high-fidelity gates, we generate entanglement distributed across three superconducting qubits in a lattice where each code qubit is coupled to two bus resonators. Via high-fidelity measurement of the syndrome qubit, we deterministically entangle the code qubits in either an even or odd parity Bell state, conditioned on the syndrome qubit state. Finally, to fully characterize this parity readout, we develop a measurement tomography protocol. The lattice presented naturally extends to larger networks of qubits, outlining a path towards fault-tolerant quantum computing.


Applied Physics Letters | 2013

Improved superconducting qubit coherence using titanium nitride

Josephine B. Chang; Michael R. Vissers; Antonio Corcoles; Martin Sandberg; Jiansong Gao; David W. Abraham; Jerry M. Chow; Jay Gambetta; Mary Beth Rothwell; George A. Keefe; Matthias Steffen; David P. Pappas

We demonstrate enhanced relaxation and dephasing times of transmon qubits, up to ∼60u2009μs, by fabricating the interdigitated shunting capacitors using titanium nitride (TiN). Compared to qubits made with lift-off aluminum deposited simultaneously with the Josephson junction, this represents as much as a six-fold improvement and provides evidence that surface losses from two-level system (TLS) defects residing at or near interfaces contribute to decoherence. Concurrently, we observe an anomalous temperature dependent frequency shift of TiN resonators, which is inconsistent with the predicted TLS model.


Review of Scientific Instruments | 1985

Two‐dimensional, remote micropositioner for a scanning tunneling microscope

H. Jonathon Mamin; David W. Abraham; Eric Ganz; John Clarke

A simple walker is described that is suitable as the coarse positioner in a scanning tunneling microscope. The walker is fabricated from a single piece of piezoelectric ceramic and has feet coated with thin metal and insulating films. The walker can move in either of two orthogonal, horizontal directions on an insulated, metallized quartz substrate in steps that can be varied from 25 to 400 nm.


Applied Physics Letters | 1986

Direct imaging of Au and Ag clusters by scanning tunneling microscopy

David W. Abraham; Klaus Sattler; Eric Ganz; H. Jonathon Mamin; Ruth Ellen Thomson; John Clarke

Clusters of Au and Ag deposited on the surface of highly oriented pyrolitic graphite have been imaged in air using a scanning tunneling microscope. An image is shown of a 350‐A silver cluster obtained in the constant‐current (topographic) mode. In the variable‐current mode, clusters of 6–20 atoms have been observed with atomic resolution. The motion and growth of clusters on the support are observed.


Superconductor Science and Technology | 2016

Bulk and surface loss in superconducting transmon qubits

Oliver Dial; Douglas McClure; Stefano Poletto; George A. Keefe; Mary Beth Rothwell; Jay Gambetta; David W. Abraham; Jerry M. Chow; Matthias Steffen

Decoherence of superconducting transmon qubits is purported to be consistent with surface loss from two-level systems on the substrate surface. Here, we present a study of surface loss in transmon devices, explicitly designed to have varying sensitivities to different surface loss contributors. Our experiments also encompass two particular different sapphire substrates, which reveal the onset of a yet unknown additional loss mechanism outside of surface loss for one of the substrates. Tests across different wafers and devices demonstrate substantial variation, and we emphasize the importance of testing large numbers of devices for disentangling different sources of decoherence.


Physical Review B | 1987

Theory and observation of highly asymmetric atomic structure in scanning-tunneling-microscopy images of graphite.

David Tománek; Steven G. Louie; Mamin Hj; David W. Abraham; R. E. Thomson; Eric Ganz; John Clarke


Physical Review B | 1986

Contamination-mediated deformation of graphite by the scanning tunneling microscope

Mamin Hj; Eric Ganz; David W. Abraham; R. E. Thomson; John Clarke


Physical Review B | 2011

Effect of subvolume excitation and spin-torque efficiency on magnetic switching

J. Z. Sun; R. P. Robertazzi; J. Nowak; P. L. Trouilloud; G. Hu; David W. Abraham; M. C. Gaidis; S. L. Brown; E. J. O’Sullivan; W. J. Gallagher; Daniel C. Worledge


Applied Physics Letters | 2016

Erratum: “Spin torque switching of perpendicular Ta|CoFeB|MgO-based magnetic tunnel junctions” [Appl. Phys. Lett. 98, 022501 (2011)]

Daniel C. Worledge; Guohan Hu; David W. Abraham; J. Z. Sun; P. L. Trouilloud; Janusz J. Nowak; Sam Brown; Michael C. Gaidis; Eugene J. O'Sullivan; R. P. Robertazzi


Archive | 2014

Isolation de mode de puce et réduction de diaphonie par l'intermédiaire de couches métalliques enterrées et de trous d'interconnexion traversants

David W. Abraham; George A. Keefe; Christian Lavoie; Mary E. Rothwell

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Srikanth Srinivasan

Indian Institute of Technology Bombay

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Andrew W. Cross

Massachusetts Institute of Technology

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Eric Ganz

University of Minnesota

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