@article{Patel2023,
title = {Dynamical Characterization and Room-Temperature Control of an Optically Addressable Single Spin in Hexagonal Boron Nitride},
author = {Raj N. Patel and Rebecca E. K. Fishman and Tzu-Yung Huang and Jordan A. Gusdorff and David A. Fehr and David A. Hopper and S. Alex Breitweiser and Benjamin Porat and Michael E. Flatté and Lee C. Bassett},
url = {https://arxiv.org/abs/2309.05604},
year = {2023},
date = {2023-09-14},
abstract = {Hexagonal boron nitride (h-BN), a wide bandgap, two-dimensional solid-state material, hosts pure single-photon emitters that have shown signatures of optically-addressable electronic spins. Here, we report on a single emitter in h-BN exhibiting optically detected magnetic resonance at room temperature, and we propose a model for its electronic structure and optical dynamics. Using photon emission correlation spectroscopy in conjunction with time-domain optical and microwave experiments, we establish key features of the emitter's electronic structure. Specifically, we propose a model that includes a spinless optical ground and excited state, a metastable spin-1/2 configuration, and an emission modulation mechanism. Using optical and spin dynamics simulations, we constrain and quantify transition rates in the model, and we design protocols that optimize the signal-to-noise ratio for spin readout. This constitutes a necessary step toward quantum control of spin states in h-BN.},
keywords = {},
pubstate = {forthcoming},
tppubtype = {article}
}

@article{vandeStolpe2023,
title = {Mapping a 50-spin-qubit network through correlated sensing},
author = {G.L. van de Stolpe and D. P. Kwiatkowski and C.E. Bradley and J. Randall and S. A. Breitweiser and L. C. Bassett and M. Markham and D.J. Twitchen and T.H. Taminiau},
url = {https://arxiv.org/abs/2307.06939},
year = {2023},
date = {2023-08-10},
abstract = {Spins associated to optically accessible solid-state defects have emerged as a versatile platform for exploring quantum simulation, quantum sensing and quantum communication. Pioneering experiments have shown the sensing, imaging, and control of multiple nuclear spins surrounding a single electron-spin defect. However, the accessible size and complexity of these spin networks has been constrained by the spectral resolution of current methods. Here, we map a network of 50 coupled spins through high-resolution correlated sensing schemes, using a single nitrogen-vacancy center in diamond. We develop concatenated double-resonance sequences that identify spin-chains through the network. These chains reveal the characteristic spin frequencies and their interconnections with high spectral resolution, and can be fused together to map out the network. Our results provide new opportunities for quantum simulations by increasing the number of available spin qubits. Additionally, our methods might find applications in nano-scale imaging of complex spin systems external to the host crystal.},
keywords = {},
pubstate = {forthcoming},
tppubtype = {article}
}

@article{Poteshman2023,
title = {Network structure and dynamics of effective models of nonequilibrium quantum transport},
author = {Abigail N. Poteshman and Mathieu Ouellet and Lee C. Bassett and Dani S. Bassett},
url = {https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.5.023125},
doi = {10.1103/PhysRevResearch.5.023125},
year = {2023},
date = {2023-05-26},
journal = {Physical Review Research},
volume = {5},
pages = {023125},
abstract = {Across all scales of the physical world, dynamical systems can be usefully represented as abstract networks that encode the systems' units and interunit interactions. Understanding how physical rules shape the topological structure of those networks can clarify a system's function and enhance our ability to design, guide, or control its behavior. In the emerging area of quantum network science, a key challenge lies in distinguishing between the topological properties that reflect a system's underlying physics and those that reflect the assumptions of the employed conceptual model. To elucidate and address this challenge, we study networks that represent nonequilibrium quantum-electronic transport through quantum antidot devices—an example of an open, mesoscopic quantum system. The network representations correspond to two different models of internal antidot states: a single-particle, noninteracting model and an effective model for collective excitations including Coulomb interactions. In these networks, nodes represent accessible energy states and edges represent allowed transitions. We find that both models reflect spin conservation rules in the network topology through bipartiteness and the presence of only even-length cycles. The models diverge, however, in the minimum length of cycle basis elements, in a manner that depends on whether electrons are considered to be distinguishable. Furthermore, the two models reflect spin-conserving relaxation effects differently, as evident in both the degree distribution and the cycle-basis length distribution. Collectively, these observations serve to elucidate the relationship between network structure and physical constraints in quantum-mechanical models. More generally, our approach underscores the utility of network science in understanding the dynamics of quantum systems.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Omirzakhov2023,
title = {An Integrated Reconfigurable Spin Control System on 180 nm CMOS for Diamond NV Centers},
author = {Kaisarbek Omirzakhov and Mohamad Hossein Idjadi and Tzu-Yung Huang and S. Alex Breitweiser and David A. Hopper and Lee C. Bassett and Firooz Aflatouni},
url = {https://ieeexplore.ieee.org/document/10079193/keywords#keywords},
doi = {10.1109/TMTT.2023.3254600},
year = {2023},
date = {2023-03-23},
journal = {IEEE Transactions on Microwave Theory and Techniques},
pages = {1-12},
abstract = {Solid-state electron spins are key building blocks for emerging applications in quantum information science, including quantum computers, quantum communication links, and quantum sensors. These solid-state spins are mainly controlled using complex microwave pulse sequences, which are typically generated using benchtop electrical instruments. Integration of the required electronics will enable realization of a scalable low-power and compact optically addressable quantum system. Here, we report an integrated reconfigurable quantum control system, which is used to find electron-spin resonance (ESR) frequency and perform Rabi, Ramsey, and Hahn-echo measurements for a nitrogen-vacancy (NV) center spin qubit in diamond. The chip can be programmed to synthesize an RF signal tunable from 1.6 to 2.6 GHz, which is modulated with a sequence of up to 4098 reconfigurable pulses with a pulse width and pulse-to-pulse delay adjustable from 10 ns to 42 ms and 18 ns to 42 ms, respectively, at a resolution of 2.5 ns. The 180-nm CMOS chip is fabricated within a footprint of 3.02 mm 2 and has a power consumption of 80 mW.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Thompson2023,
title = {Red Emission from Copper-Vacancy Color Centers in Zinc Sulfide Colloidal Nanocrystals},
author = {Sarah M. Thompson and Cüneyt Şahin and Shengsong Yang and Michael E. Flatté and Christopher B. Murray and Lee C. Bassett and Cherie R. Kagan},
url = {https://pubs.acs.org/doi/full/10.1021/acsnano.3c00191
https://arxiv.org/abs/2301.04223},
doi = {10.1021/acsnano.3c00191},
year = {2023},
date = {2023-03-09},
journal = {ACS Nano},
abstract = {Copper-doped zinc sulfide (ZnS:Cu) exhibits down-conversion luminescence in the UV, visible, and IR regions of the electromagnetic spectrum; the visible red, green, and blue emission is referred to as R-Cu, G-Cu, and B-Cu, respectively. The sub-bandgap emission arises from optical transitions between localized electronic states created by point defects, making ZnS:Cu a prolific phosphor material and an intriguing candidate material for quantum information science, where point defects excel as single-photon sources and spin qubits. Colloidal nanocrystals (NCs) of ZnS:Cu are particularly interesting as hosts for the creation, isolation, and measurement of quantum defects, since their size, composition, and surface chemistry can be precisely tailored for bio-sensing and opto-electronic applications. Here, we present a method for synthesizing colloidal ZnS:Cu NCs that emit primarily R-Cu, which has been proposed to arise from the CuZn-VS complex, an impurity-vacancy point defect structure analogous to well-known quantum defects in other materials that produce favorable optical and spin dynamics. First principles calculations confirm the thermodynamic stability and electronic structure of CuZn-VS. Temperature- and time-dependent optical properties of ZnS:Cu NCs show blueshifting luminescence and an anomalous plateau in the intensity dependence as temperature is increased from 19 K to 290 K, for which we propose an empirical dynamical model based on thermally-activated coupling between two manifolds of states inside the ZnS bandgap. Understanding of R-Cu emission dynamics, combined with a controlled synthesis method for obtaining R-Cu centers in colloidal NC hosts, will greatly facilitate the development of CuZn-VS and related complexes as quantum point defects in ZnS.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}