Publications
Compact, inexpensive coaxial terminations and wiring for low temperature RF applications
We have examined a promising family of radio frequency coaxial connectors (the SSMCX range) suitable for use at low temperatures. We describe the measured characteristics of these connectors in typical arrangements using lossy Cooner stainless steel inner and outer (braided) coaxial cable and other specialty low temperature coaxial cables including Beryllium Copper (BeCu) outer and inner conductors, Copper Nickel (CuNi) outer and Niobium–Titanium (NbTi) superconducting inner conductors, and Nb outer/NbTi inner conductor (homemade) cables.
Pareto evolution of gene networks: An algorithm to optimize multiple fitness objectives
The computational evolution of gene networks functions like a forward genetic screen to generate, without preconceptions, all networks that can be assembled from a defined list of parts to implement a given function. Frequently networks are subject to multiple design criteria that cannot all be optimized simultaneously. To explore how these tradeoffs interact with evolution, we implement Pareto optimization in the context of gene network evolution.
Quantum many-body interactions in digital oxide superlattices
Controlling the electronic properties of interfaces has enormous scientific and technological implications and has been recently extended from semiconductors to complex oxides that host emergent ground states not present in the parent materials. These oxide interfaces present a fundamentally new opportunity where, instead of conventional bandgap engineering, the electronic and magnetic properties can be optimized by engineering quantum many-body interactions.
Signaling dynamics and embryonic development
Strong enhancement of graphene-light interaction in a photonic crystal nanocavity
We demonstrate enhanced light-matter interaction in graphene coupled with a photonic crystal nanocavity, exhibiting strongly enhanced optical absorption and spontaneous emission in graphene. © OSA 2012.
Carrier dynamics in Si nanowires fabricated by metal-assisted chemical etching
Silicon nanowire arrays fabricated by metal-assisted wet chemical etching have emerged as a promising architecture for solar energy harvesting applications. Here we investigate the dynamics and transport properties of photoexcited carriers in nanowires derived from an intrinsic silicon wafer using the terahertz (THz) time-domain spectroscopy. Both the dynamics and the pump fluence dependence of the photoinduced complex conductivity spectra up to several THz were measured.
Critical casimir forces in cellular membranes
Recent experiments suggest that membranes of living cells are tuned close to a miscibility critical point in the two-dimensional Ising universality class. We propose that one role for this proximity to criticality in live cells is to provide a conduit for relatively long-range critical Casimir forces. Using techniques from conformal field theory we calculate potentials of mean force between membrane bound inclusions mediated by their local interactions with the composition order parameter.
Electro-optofluidics: Achieving dynamic control on-chip
A vital element in integrated optofluidics is dynamic tuning and precise control of photonic devices, especially when employing electronic techniques which are challenging to utilize in an aqueous environment. We overcome this challenge by introducing a new platform in which the photonic device is controlled using electro-optical phase tuning. The phase tuning is generated by the thermo-optic effect using an on-chip electric microheater located outside the fluidic channel, and is transmitted to the optofluidic device through optical waveguides.
Spectroscopic Imaging STM Studies of Electronic Structure in Both the Superconducting and Pseudogap Phases of Underdoped Cuprates
A motivation for the development of atomically resolved spectroscopic imaging STM (SISTM) has been to study the broken symmetries in the electronic structure of cuprate high temperature superconductors. Both the d-wave superconducting (dSC) and the pseudogap (PG) phases of underdoped cuprates exhibit two distinct classes of electronic states when studied using SI-STM. The class consists of the dispersive Bogoliubov quasiparticles of a homogeneous d-wave superconductor.
Approaching intrinsic performance in ultra-thin silicon nitride drum resonators
We have fabricated circular silicon nitride drums of varying diameter (20 μm to 1 mm) and thickness (15 nm-75 nm) using electron beam lithography and measured the dissipation (Q -1) of these amorphous silicon nitride resonators using optical interferometric detection. We observe that the dissipation is strongly dependent on mode type for relatively large, thick membranes as predicted by the current models of dissipation due to clamping loss.