On-chip Magnetoresistive Sensors for Detection and Localization of Paramagnetic Particles

This paper presents the work towards miniaturized magnetic biosensor array based on the detection of paramagnetic particles using the giant magnetoresistance (GMR) effect. GMR sensors have been studied for many years, but its application for on-chip integration and in complex configurations, as well as effective localization for Lab-On-Chip and Tissue Engineering applications is not yet explored. This work demonstrates the development of initial prototypes of 5 and 9 sensor GMR arrays of varying geometries and corresponding calibration and localization algorithms to detect and localize paramagnetic materials in 2D. The generation of a uniform magnetic field using a 16 magnet Halbach cylinder was also analyzed and optimized using FEA for different sensor configurations. Results show excellent localization for the fully calibrated 5 sensor arrays, with a mean (SD) error of 2.45 (1.61) mm for the ferrofluid as compared to 1.48 (1.14) mm for a strong ferromagnet for a 25×25mm2 array surface. The 9sensor array similarly showed good results for full calibration

Roadmap on semiconductor-cell biointerfaces.

This roadmap outlines the role semiconductor-based materials play in understanding the complex biophysical dynamics at multiple length scales, as well as the design and implementation of next-generation electronic, optoelectronic, and mechanical devices for biointerfaces. The roadmap emphasizes the advantages of semiconductor building blocks in interfacing, monitoring, and manipulating the activity of biological components, and discusses the possibility of using active semiconductor-cell interfaces for discovering new signaling processes in the biological world

Probing Many-body Localization with a Programmable Superconducting Quantum Processor

In many-body localized (MBL) systems, entanglement propagates throughout the system despite the absence of transport. Early experiments have relied on population measurements to indirectly probe these entanglement dynamics. However, because the entanglement results from phase relationships between localized orbitals, it is more naturally probed with phase sensitive algorithms and measurement. In this thesis, we use an array of nearest neighbor coupled superconducting qubits to introduce phase sensitive protocols to the experimental study of MBL systems. We establish that system is MBL by demonstrating disorder induced ergodicity breaking and the presence of effective nonlocal interactions. We then use density matrix reconstructions to observe the hallmark slow growth of entanglement and provide a site-resolved spatial and temporal map of the developing entanglement. We also inspect the capacity of the MBL phase to preserve quantum correlations by observing the decay of distillable entanglement when Bell pair embedded in an MBL environment and dephased by remote excitation. In superconducting quantum processors, such as that used in the MBL study above, dissipation leads to computational errors and must be minimized. To that end, we also describe coherence engineering experiments in terms of the low power internal quality factor Qi of coplanar waveguide (CPW) resonators, a figure of merit characterizing dissipation in the quantum computing regime. We investigate titanium nitride as a superconducting base metal for quantum circuits. By optimizing the deposition conditions, we achieve a record low-power Qi in CPW resonators. We also characterize the dielectric loss due to flux trapping hole arrays. Since flux traps are commonly used to prevent magnetic vortex formation and dielectric loss is a limiting dissipation mechanism, it is important to estimate the contribution of flux traps to the dielectric dissipation budget. We find that for reasonable hole patterns the dielectric loss can be small while preventing vortex formation