Philip R. Hemmer

Low-value fuel-grade petroleum coke (petcoke), an abundant byproduct from petroleum refining operations, is traditionally used in low-value fuel and metallurgical applications owing to its high carbon content and ability to be used in the synthesis of advanced carbon materials. In this paper, we demonstrate a non-oxidation-based route for producing conductive few-layer graphene from petcoke through sequential isopropanol assisted pre-treatment, thermal desulfurization, and CO ₂ assisted liquid phase exfoliation. Unlike conventional graphene synthesis processes using high temperature chemical vapor deposition, oxidation reduction-based Hummer’s type methods, or exfoliation from expensive graphite sources, our approach enables the conversion of inexpensive petcoke into graphene nanosheets using a scalable solvent assisted route. Thermal treatment increased the graphitization degree of petroleum coke to approximately 78%, demonstrating its potential as a precursor for advanced graphitic materials. The optimized CO₂-assisted liquid-phase exfoliation and centrifugation procedure achieved approximately 90% recovery of dispersed exfoliated carbon solids. Combined optical microscopy, Raman, TEM, HRTEM, AFM, and electrical analyses confirmed the formation of well-dispersed, conductive few-layer graphene nanosheets, with thicknesses corresponding to approximately 3–5 layers. The graphene dispersions display stability up to six months and can be transformed into conductive films with a maximum electrical conductivity of 872 S m⁻ ¹ after thermal annealing. This work establishes petcoke as a promising low-cost carbon resource for sustainable graphene production and offers a practical route for transforming refinery waste into value-added materials for energy storage, conductive coatings, composites, and carbon-based technologies.

The Winter Colloquium on the Physics of Quantum Electronics (PQE) has been a seminal force in quantum optics and related areas since 1971. It is rather mindboggling to recognize how the concepts presented at these conferences have transformed scientific understanding and human society. In January, 2017, the participants of PQE were asked to consider the equally important prospects for the future, and to formulate a set of questions representing some of the greatest aspirations in this broad field. The result is this multi-authored paper, in which many of the world's leading experts address the following fundamental questions: (1) What is the future of gravitational wave astronomy? (2) Are there new quantum phases of matter away from equilibrium that can be found and exploited - such as the time crystal? (3) Quantum theory in uncharted territory: What can we learn? (4) What are the ultimate limits for laser photon energies? (5) What are the ultimate limits to temporal, spatial, and optical resolution? (6) What novel roles will atoms play in technology? (7) What applications lie ahead for nitrogen-vacancy centers in diamond? (8) What is the future of quantum coherence, squeezing, and entanglement for enhanced superresolution and sensing? (9) How can we solve (some of) humanity's biggest problems through new quantum technologies? (10) What new understanding of materials and biological molecules will result from their dynamical characterization with free electron lasers? (11) What new technologies and fundamental discoveries might quantum optics achieve by the end of this century? (12) What novel topological structures can be created and employed in quantum optics?

We propose an approach for super-resolution optical lithography which is based on the inverse of magnetic resonance imaging (MRI). The technique uses atomic coherence in an ensemble of spin systems whose final state population can be optically detected. In principle, our method is capable of producing arbitrary one and two dimensional high-resolution patterns with high contrast.

A diamond nanomagnetometer is used to probe conformational changes of a single protein [Also see Report by Shi et al. ]

Use of a diamond-based nanomagnetometer reduces the detection volume of MRI to the level of individual protein molecules. [Also see Reports by Mamin et al. and Staudacher et al. ]

A high-nitrogen-concentration diamond sample was subjected to 200-keV electron irradiation using a transmission electron microscope. The optical and spin-resonance properties of the nitrogen-vacancy (NV) color centers were investigated as a function of the irradiation dose up to 6.4 × 10²¹ e⁻/cm². The microwave transition frequency of the NV⁻ center was found to shift by up to 0.6% (17.1 MHz) and the linewidth broadened with increasing electron-irradiation dose. Unexpectedly, the measured magnetic sensitivity is best at the lowest irradiation dose, even though the NV concentration increases monotonically with increasing dose. This is in large part due to a sharp reduction in optically detected spin contrast at higher doses.