arXiv subjects

Noah Van Horne

Publications and source records attributed to Noah Van Horne.

3 recordsLinked to original sources

arXiv2021

Improved description of trapped ions as an electro-mechanical system

Trapped ions are among the leading candidates for quantum computing technologies. Interfacing ion qubits in separate traps and interfacing ion qubits with superconducting qubits are two of the many challenges to scale up quantum computers. One approach to overcome both problems is to use a conducting wire to mediate the Coulomb interaction between ions in different traps, or between ions and superconducting qubits. To this end, a trapped charged particle inducing charge on a conductor has long been modeled as a system of equivalent lumped element electronic components. Careful consideration reveals two assumptions in the derivation of this model which are unjustified in many situations of interest. We identify these assumptions and explain their implications. In addition, we introduce an improved way to use linear relationships to describe the interaction of trapped ions with nearby conductors. The new method is based on realistic assumptions and reproduces results from other works that are not based on the circuit element model. It is targeted for trouble-shooting experimental designs and allows experiments to test and compare the accuracy of different theoretical models.

quant-ph↗

arXiv2020

Making large overhangs in micrometer and nanometer-sized structures

We describe two general procedures for fabricating microstructures with large overhangs and high aspect-ratio support pillars. The first method uses a static angled dry etch on micro- or nano-pillars to create an initial overhang, followed by wet etching for further erosion. The second method uses a time-dependent angled etch on a flat plane patterned with protective resin, to reduce the number of lithography steps needed to make these objects. The time-dependent dry etch is again followed by a wet etch. For the second method we derive a formula that provides the rate at which the attack angle must evolve, given a known etch rate within the target material, the depth of the desired overhang (undercut), and the instantaneous attack angle.

cond-mat.mtrl-sci↗

arXiv2018

Single atom energy-conversion device with a quantum load

This work reports the functioning of a single atom energy-conversion device, operating either as a quantum engine or a refrigerator, coupled to a quantum load. The "working fluid" is comprised of two optical levels of a single ion, and the load is one vibrational mode of the same ion cooled down to the quantum regime. The energy scales of these two modes differ by 9 orders of magnitude. We realize cyclic energy transfers between the working fluid and the quantum load, either increasing or decreasing the population of the vibrational mode. This is achieved albeit the interaction between the load and the working fluid leads to a significant population redistribution and quantum correlations between them. The performance of the engine cycles as a function of several parameters is examined, and found to be in agreement with theory. We specifically look at the ergotropy of the load, which indicates the amount of energy stored in the load that can be extracted with a unitary process. We show that ergotropy rises with the number of engine cycles despite an increase in the entropy of the load. Our experiment represents the first fully quantum 4-stroke energy-conversion device operating with a generic coupling to a quantum load.

quant-ph↗