Probing many-body noise in a strongly interacting two-dimensional dipolar spin system

The most direct approach for characterizing the quantum dynamics of a strongly-interacting system is to measure the time-evolution of its full many-body state. Despite the conceptual simplicity of this approach, it quickly becomes intractable as the system size grows. An alternate framework is to think of the many-body dynamics as generating noise, which can be measured by the decoherence of a probe qubit. Our work centers on the following question: What can the decoherence dynamics of such a probe tell us about the many-body system? In particular, we utilize optically addressable probe spins to experimentally characterize both static and dynamical properties of strongly-interacting magnetic dipoles. Our experimental platform consists of two types of spin defects in diamond: nitrogen-vacancy (NV) color centers (probe spins) and substitutional nitrogen impurities (many-body system). We demonstrate that signatures of the many-body system's dimensionality, dynamics, and disorder are naturally encoded in the functional form of the NV's decoherence profile. Leveraging these insights, we directly characterize the two-dimensional nature of a nitrogen delta-doped diamond sample. In addition, we explore two distinct facets of the many-body dynamics: First, we address a persistent debate about the microscopic nature of spin dynamics in strongly-interacting dipolar systems. Second, we demonstrate direct control over the spectral properties of the many-body system, including its correlation time. Our work opens the door to new directions in both quantum sensing and simulation.Comment: 10 + 8 + 5 pages; 3 + 5 figure

Sensing the local charge and strain environments surrounding Nitrogen-Vacancy centers in diamond

Nitrogen-Vacancy (NV) centers in diamond have been established as exceptionally versatile probes for quantum technologies from sensing to simulation.Owing to the versatility of diamond fabrication, NVs can be integrated into probes with nanoscale resolution and superb sensitivity. However, because the diamond is host to many other types of defects, the local environment of the NV is unique for each NV, which poses challenges for any devices instrumenting NVs. This thesis contributes to the future of NV technologies along two essential directions. First, we work towards a more complete understanding of the local charge and strain environments of the NV. In addition to permitting the calibration of these effects for NV probes, we suggest potential uses for the local charges and strain that had previously been considered hindrances. Second, we develop new technologies for NV sensing and simulation. Our work integrating NVs into diamond anvil cells opens the door to detecting high pressure phenomena using the NVs as all-in-one sensors. Finally, our study of the coherence regimes of the local defect environment of the NV is a step towards versatile quantum simulation in dimensions lower than three