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Search Publications by: Mark Keller (Fed)

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Displaying 26 - 50 of 100

Electron Counting Capacitance Standard with an improved five-junction R-pump

November 7, 2011
Author(s)
Benedetta Camarota, Hansjoerg Scherer, Sergey Lotkhov, Gerd-Dietmar Willenberg, Franz Josef Ahlers, Mark W. Keller
The Electron Counting Capacitance Standard currently pursued at PTB, aims at the closure of the Quantum Metrological Triangle with a final precision of a few parts in 10 7. This paper reports the considerable progress recently achieved with a new

Theory for a Dissipative Droplet Soliton Excited by a Spin Torque Nanocontact

August 30, 2010
Author(s)
Mark Hoefer, Thomas J. Silva, Mark W. Keller
A distinct type of solitary wave is predicted to form in spin torque oscillators when the free layer has a sufficiently large perpendicular anisotropy. In this structure, which is a dissipative version of the conservative droplet soliton originally studied

Spin-transfer dynamics in spin valves with out-of-plane magnetized CoNi free layers

January 29, 2010
Author(s)
William H. Rippard, Alina M. Deac, Matthew R. Pufall, Justin M. Shaw, Mark W. Keller, Stephen E. Russek, Gerrit E. Bauer, Claudio Serpico
We have measured spin-transfer-induced dynamics in magnetic nanocontact devices having a perpendicularly magnetized Co/Ni free layer and an in-plane magnetized CoFe fixed layer. The frequencies and powers of the excitations agree well with the predictions

Time domain measurement of phase noise in a spin torque oscillator

May 13, 2009
Author(s)
Mark W. Keller, Anthony B. Kos, Thomas J. Silva, William H. Rippard, Matthew R. Pufall
We measure phase noise from the zero crossings of the voltage vs. time waveform of a spin torque nanocontact oscillating in a vortex mode. The power spectrum of the phase noise varies with Fourier frequency f as 1/f 2, consistent with frequency

Why the long-term charge offset drift in Si single-electron tunneling transistors is much smaller (better) than in metal-based ones: Two-level fluctuator stability

August 7, 2008
Author(s)
Neil M. Zimmerman, W H. Huber, Brian J. Simonds, Emmanouel S. Hourdakis, Fujiwara Fujiwara, Yukinori Ono, Yasuo Takahashi, Hiroshi Inokawa, Miha Furlan, Mark W. Keller
A common observation in metal-based (specifically, those with AlOx tunnel junctions) single- electron tunneling (SET) devices is a time-dependent instability known as the long-term charge offset drift. This drift is not seen in Si-based devices. Our aim is

Current Status of the Quantum Metrology Triangle

January 18, 2008
Author(s)
Mark W. Keller
The quantum metrology triangle is a test of the consistency of three quantum electrical standards: the single-electron tunneling current standard, the Josephson voltage standard, and the quantum Hall resistance standard. This paper considers what is known

Uncertainty budget for the NIST Electron Counting Capacitance Standard, ECCS- 1

November 21, 2007
Author(s)
Mark W. Keller, Neil M. Zimmerman, Ali L. Eichenberger
We measure a cryogenic, vacuum-gap capacitor by two methods: 1) charging it with a known number of electrons and measuring the resulting voltage, and 2) using a capacitance bridge traceable to the SI farad. We report a detailed uncertainty budget for the

A single-photon pump

August 25, 2006
Author(s)
Kevin Osborn, Mark W. Keller
We describe a gated quantum dot device called a single-photon pump that produces single photons on demand through the controlled tunneling of individual electrons and holes. Simulations using an InGaAs/GaAs dot show that two modes of operation are possible

HEMT Amplified SET Measurements of Individual InGaAs Quantum Dots

August 25, 2006
Author(s)
Kevin Osborn, Mark W. Keller, Richard Mirin
A High Electron Mobility Transistor (HEMT) is used with a Single Electron Transistor (SET) to measure single electrons tunnelling into individual InGaAs quantum dots. The SET detects the charge motion as an electron tunnels from an underlying n-doped layer