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Search Publications by

Joshua M. Pomeroy (Fed)

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Displaying 1 - 25 of 69

Alternatives to aluminum gates for silicon quantum devices: Defects and strain

September 15, 2021
Ryan Stein, Zachary Barcikowski, Sujitra Pookpanratana, Joshua M. Pomeroy, Michael Stewart
Gate-defined quantum dots (QD) benefit from the use of small grain size metals for gates materials because it aids in shrinking the device dimensions. However, it is not clear what differences arise with respect to process-induced defect densities and

Developing Single Layer MOS Quantum Dots for Diagnostic Qubits

December 28, 2020
Yanxue Hong, Aruna Ramanayaka, Ryan Stein, Joshua M. Pomeroy
The design, fabrication and characterization of single metal gate layer, metal-oxide- semiconductor (MOS) quantum dot devices robust against dielectric breakdown are presented as prototypes for future diagnostic qubits. These devices were developed as a

Reduction of charge offset drift using plasma oxidized aluminum in SETs

October 26, 2020
Yanxue Hong, Ryan Stein, Michael Stewart, Neil M. Zimmerman, Joshua M. Pomeroy
Aluminum oxide (AlOx)-based single-electron transistors (SETs) fabricated in ultra-high vacuum (UHV) chambers using in situ plasma oxidation show excellent stabilities over more than a week, enabling applications as tunnel barriers, capacitor dielectrics

Targeted enrichment of 28Si thin films for quantum computing

March 9, 2020
Ke Tang, Hyun S. Kim, Aruna N. Ramanayaka, David S. Simons, Joshua M. Pomeroy
We report on the growth of isotopically enriched 28Si epitaxial films with precisely controlled enrichment levels, ranging from natural abundance ratio of 92.2% all the way to 99.99987 % (0.832 × 10-6 mol/mol 29Si). Isotopically enriched 28Si is regarded

Linking mass measured by the quartz crystal microbalance to the SI

February 12, 2020
Corey A. Stambaugh, Hamza Shakeel, Maritoni A. Litorja, Joshua M. Pomeroy
The quartz crystal microbalance has been deployed across industry and academy for the monitoring of the film thickness during depositions. Over a half-a-century of academic and industrial research has gone into understanding the relation between film

Use of quantum effects as potential qualifying metrics for "quantum grade silicon"

December 30, 2019
Aruna N. Ramanayaka, Ke Tang, Joseph A. Hagmann, Hyun S. Kim, David S. Simons, Curt A. Richter, Joshua M. Pomeroy
Across solid state quantum information, material deficiencies limit performance through enhanced relaxation, charge defect motion, or isotopic spin noise. While classical measurements of device performance provide cursory guidance, specific qualifying

A compact, UHV ion source for enriching 28Si and depositing epitaxial thin films

August 22, 2019
Ke Tang, Hyun S. Kim, Aruna N. Ramanayaka, David S. Simons, Joshua M. Pomeroy
An ultra-high-vacuum (UHV) compatible Penning ion source for growing pure, highly enriched 28Si epitaxial thin films is presented. Enriched 28Si is a critical material for quantum information due to the elimination of nuclear spins and, in some cases, must

Magnetotransport in highly enriched 28Si for quantum information processing devices

November 25, 2018
Aruna N. Ramanayaka, Ke Tang, Joseph Hagmann, Hyun S. Kim, Curt A. Richter, Joshua M. Pomeroy
Elimination of unpaired nuclear spins can result in low error rates for quantum computation; therefore, isotopically enriched 28Si is regarded as an ideal environment for quantum information processing devices. Using mass selected ion beam deposition

Towards superconductivity in p-type delta-doped Si/Al/Si heterostructures

July 30, 2018
Aruna N. Ramanayaka, Hyun Soo Kim, Joseph A. Hagmann, Roy E. Murray, Ke Tang, Neil M. Zimmerman, Curt A. Richter, Joshua M. Pomeroy, Frederick Meisenkothen, Huairuo Zhang, Albert Davydov, Leonid A. Bendersky
In pursuit of superconductivity in p-type silicon (Si), we are using a single atomic layer of aluminum (Al) sandwiched between a Si substrate and a thin Si epi-layer. The delta layer was fabricated starting from an ultra high vacuum (UHV) flash anneal of

STM patterned nanowire measurements using photolithographically defined implants in Si(100)

January 29, 2018
Aruna N. Ramanayaka, Hyun Soo Kim, Ke Tang, Xiqiao Wang, Richard M. Silver, Michael D. Stewart, Joshua M. Pomeroy
Using photolithographically defined implant wires for electrical connections, we demonstrate measurement of a scanning tunneling microscope (STM) patterned nanoscale electronic device on Si(100), eliminating the onerous alignment procedures and electron

Enriching and purifying silicon epilayers for quantum information

December 7, 2016
Joshua M. Pomeroy, Kevin J. Dwyer, Ke Tang, Hyun Soo Kim, Aruna N. Ramanayaka, David S. Simons
High quality, enriched silicon contains an exceptionally low density of defects and unpaired electron and nuclear spins that allow candidate qubits (single donors or quantum dots) to exhibit very long dephasing times compared to silicon with a natural

Enriching 28Si beyond 99.9998 % for semiconductor quantum computing

August 5, 2014
Kevin J. Dwyer, Joshua M. Pomeroy, David S. Simons, June W. Lau, Kristen L. Steffens
Using a laboratory-scale apparatus, we enrich 28Si and produce material with 40 times less residual 29Si than previously reported. Starting from natural abundance silane gas, we offer an alternative to industrial gas centrifuges for providing materials

99.996% 12C films enriched and deposited in situ

June 28, 2013
Kevin J. Dwyer, Joshua M. Pomeroy, David S. Simons
A mass selected ion beam system is used to isotopically enrich and deposit thin films, which are measured to be 99.9961(4)% 12C. In solid state quantum information, isotopic enrichment of materials has allowed significant improvements in the coherence time

Reply to “Comment on "Testing Three-body Quantum Electrodynamics with Trapped Ti20+ Ions: Evidence for a Z-Dependent Divergence between Experiment and Calculation"

April 12, 2013
Lawrence T. Hudson, C T. Chantler, M N. Kinnane, John D. Gillaspy, A.T. Payne, L F. Smale, Albert Henins, Joshua M. Pomeroy, J A. Kimpton, E Takacs, K Makonyi
We find that Epp’s [1] hypothesis - namely that the current experimental data set is well represented by a small constant or zero offset from the predictions of Artemyev et al. [2] - is not supported by standard statistical analysis. We find that adding

Tunnel junction sensors for HCI-surface measurements at low kinetic energies

January 25, 2013
Joshua M. Pomeroy, Russell E. Lake
In recent years, we have developed and deployed the capability to make and use tunnel junctions sensors (TJS) as extremely sensitive tools for the measurement of surface nanofeatures created by particle surface interactions. Highly charged ion (HCI)

Testing Three-body Quantum Electrodynamics with Trapped Ti-20 Ions: Evidence for a Z-Dependent Divergence between Experiment and Calculation

October 10, 2012
Lawrence T. Hudson, C T. Chantler, Mark N. Kinnane, John D. Gillaspy, A.T. Payne, L F. Smale, Albert Henins, Joseph N. Tan, J A. Kimpton, E Takacs, K Makonyi, Joshua M. Pomeroy
We report the measurement of the w (1s2p 1P1 ! 1s2 1S0) resonance line transition energy in helium-like titanium. Our result, 4749.85(7) eV, deviates from the most recent ab initio prediction by three times our experimental uncertainty and by many times

Charge state dependent energy deposition by ion impacts

August 5, 2011
Russell E. Lake, Joshua M. Pomeroy, Holger Grube, C E. Sosolik
We report on a measurement of craters in thin dielectric films formed by XeQ+ (26 Q 44) projectiles. Tunnel junction devices with ion-irradiated barriers were used to amplify the effect of charge-dependent cratering through the exponential dependence of