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Search Publications by: Neil M. Zimmerman (Assoc)

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Displaying 26 - 50 of 153

Effect of device design on charge offset drift in Si/SiO2 single electron devices

October 9, 2018
Author(s)
Binhui Hu, Erick Ochoa, Daniel Sanchez, Justin K. Perron, Neil M. Zimmerman, Michael Stewart
We have measured the low-frequency time instability known as charge offset drift of Si/SiO2 single electron devices (SEDs) with and without an overall poly-Si top gate. We find that SEDs with a poly-Si top gate have significantly less charge offset drift

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

July 30, 2018
Author(s)
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

AC Signal Characterization for Optimization of a CMOS Single Electron Pump

January 8, 2018
Author(s)
Roy E. Murray, Justin K. Perron, Michael D. Stewart, Neil M. Zimmerman
Pumping single electrons at a set rate is being widely pursued as an electrical current standard. Much work has been done on pumping using a single AC signal, but using multiple coordinated AC signals may help lower error rates. Whether pumping with one or

Valley blockade in a silicon double quantum dot

November 13, 2017
Author(s)
Justin K. Perron, Michael Gullans, Jacob Taylor, Michael Stewart, Neil M. Zimmerman
Electrical transport in double quantum dots (DQD) is useful for illuminating many interesting aspects of the carrier states in quantum dots. Here we show data comparing bias triangles (i.e., regions of allowed current in DQDs) at positive and negative bias

Valley Phase and Voltage Control of Coherent Manipulation in Si Quantum Dots

June 28, 2017
Author(s)
Neil M. Zimmerman, Peihao Huang, Dimitrie Culcer
With any roughness at the interface of an indirect-bandgap semiconducting dot, the phase of the valley-orbit coupling can take on a random value. This random value, in double quantum dots, causes a large change in the exchange splitting. We demonstrate a

An electrically driven spin qubit based on valley mixing

February 2, 2017
Author(s)
wister huang, Neil M. Zimmerman, Andrew S. Dzurak, Dimitrie Culcer
The electrical control of single spin qubits based on semiconductor quantum dots is of great interest for scalable quantum computing since electric elds are much easier to produce and spatially focus than magnetic elds. Here we outline the mechanism for a

Stability of Single Electron Devices: Charge Offset Drift

June 29, 2016
Author(s)
Michael D. Stewart, Neil M. Zimmerman
Abstract: Single electron devices (SEDs) afford the opportunity to isolate and manipulate individual electrons. This ability imbues SEDs with potential applications in a wide array of areas from metrology (current and capacitance) to quantum information

A New Regime of Pauli-Spin Blockade

April 7, 2016
Author(s)
Justin K. Perron, Michael D. Stewart, Neil M. Zimmerman
Pauli-spin blockade is a phenomenon that allows for a type of spin to charge conversion often used to probe fundamental physics such as spin relaxation and singlet-triplet coupling. In this paper we theoretically explore Pauli-spin blockade as a function

Formation of Strain Induced Quantum Dots in Gated Semiconductor Nanostructures

August 5, 2015
Author(s)
Ted C. Thorbeck, Neil M. Zimmerman
Elastic strain changes the energies of the conduction and valence bands in a semiconductor, which will affect transport through a semiconductor nanostructure. We show that the typical strains in a semiconductor nanostructure arising from metal gates or

The Redefinition of the SI: Impact on Calibration Services at NIST

June 1, 2015
Author(s)
Neil M. Zimmerman, Jon R. Pratt, Michael R. Moldover, David B. Newell, Gregory F. Strouse
As most readers are probably at least vaguely aware, it is likely that the SI system of units will be redefied in 2018. This redefinition would fundamentally change the logical structure of the SI, with one result being a substantial change in how mass is

Charge Offset Stability in Si Single Electron Devices with Al Gates

September 19, 2014
Author(s)
Neil M. Zimmerman, Henry Yang, Nai Shyan Lai, Wee Han Lim, Andrew S. Dzurak
We report on the charge offset drift (time stability) in Si quantum dots defined with Al gates. The size of the charge offset drift (0.1 e) is intermediate between that of Al/AlO_x/Al tunnel junctions (greater than 1 e) and Si quantum dots defined with Si

Dephasing of Si singlet-triplet qubits due to charge and spin defects

June 14, 2013
Author(s)
Dimitrie Culcer, Neil M. Zimmerman
We study the effect of charge and spin noise on singlet-triplet qubits in Si quantum dots. We set up a theoretical framework aimed at enabling experiment to efficiently identify the most deleterious defects, and complement it with the knowledge of defects

Determining the Location and Cause of Unintentional Quantum Dots in a Nanowire

March 21, 2012
Author(s)
Ted C. Thorbeck, Neil M. Zimmerman
Unintentional quantum dots are a common problem for single electron devices in both silicon and carbon. To determine the cause of these dots it is helpful to know their size and location. Because each dot is capacitively coupled to multiple gates, we can