Quadrupolar Resonance Spectroscopy of Individual Nuclei Using a Room-Temperature Quantum Sensor.

Nuclear quadrupolar resonance (NQR) spectroscopy reveals chemical bonding patterns in materials and molecules through the unique coupling between nuclear spins and local fields. However, traditional NQR techniques require macroscopic ensembles of nuclei to yield a detectable signal, which obscures molecule-to-molecule variations. Solid-state spin qubits, such as the nitrogen-vacancy (NV) center in diamond, facilitate the detection and control of individual nuclei through their local magnetic couplings.

A tale of two transfers: characterizing polydimethylsiloxane viscoelastic stamping and heated poly bis-A carbonate transfer of hexagonal boron nitride.

Two-dimensional (2D) materials have many applications ranging from heterostructure electronics to nanofluidics and quantum technology. In order to effectively utilize 2D materials towards these ends, they must be transferred and integrated into complex device geometries. In this report, we investigate two conventional methods for the transfer of 2D materials: viscoelastic stamping with polydimethylsiloxane (PDMS) and a heated transfer with poly bis-A carbonate (PC).

Designing metasurface optical interfaces for solid-state qubits using many-body adjoint shape optimization.

We present a general strategy for the inverse design of metasurfaces composed of elementary shapes. We use it to design a structure that collects and collimates light from nitrogen-vacancy centers in diamond. Such metasurfaces constitute scalable optical interfaces for solid-state qubits, enabling efficient photon coupling into optical fibers and eliminating free-space collection optics.

Room Temperature Dynamics of an Optically Addressable Single Spin in Hexagonal Boron Nitride.

Hexagonal boron nitride (h-BN) hosts pure single-photon emitters that have shown evidence of optically detected electronic spin dynamics. However, the electrical and chemical structures of these optically addressable spins are unknown, and the nature of their spin-optical interactions remains mysterious. Here, we use time-domain optical and microwave experiments to characterize a single emitter in h-BN exhibiting room temperature optically detected magnetic resonance.

Breaking reflection symmetry: evolving long dynamical cycles in Boolean systems.

In interacting dynamical systems, specific local interaction rules for system components give rise to diverse and complex global dynamics. Long dynamical cycles are a key feature of many natural interacting systems, especially in biology. Examples of dynamical cycles range from circadian rhythms regulating sleep to cell cycles regulating reproductive behavior.

Red Emission from Copper-Vacancy Color Centers in Zinc Sulfide Colloidal Nanocrystals.

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 biosensing and optoelectronic applications.

Template-Assisted Self-Assembly of Fluorescent Nanodiamonds for Scalable Quantum Technologies.

Milled nanodiamonds containing nitrogen-vacancy (NV) centers are nanoscale quantum sensors that form colloidal dispersions. However, variations in their size, shape, and surface chemistry limit the ability to position individual nanodiamonds and statistically study properties that affect their optical and quantum characteristics. Here, we present a scalable strategy to form ordered arrays of nanodiamonds using capillary-driven, template-assisted self-assembly.

Direct Imaging of Antiferromagnetic Domains and Anomalous Layer-Dependent Mirror Symmetry Breaking in Atomically Thin MnPS_{3}.

We have developed a sensitive cryogenic second-harmonic generation microscopy to study a van der Waals antiferromagnet MnPS_{3}. We find that long-range Néel antiferromagnetic order develops from the bulk crystal down to the bilayer, while it is absent in the monolayer. Before entering the long-range antiferromagnetic ordered phase in all samples, an upturn of the second harmonic generation below 200 K indicates the formation of the short-range order and magnetoelastic coupling.

Colloidal Quantum Dots as Platforms for Quantum Information Science.

Colloidal quantum dots (QDs) are nanoscale semiconductor crystals with surface ligands that enable their dispersion in solvents. Quantum confinement effects facilitate wave function engineering to sculpt the spatial distribution of charge and spin states and thus the energy and dynamics of QD optical transitions. Colloidal QDs can be integrated in devices using solution-based assembly methods to position single QDs and to create ordered QD arrays.

A monolithic immersion metalens for imaging solid-state quantum emitters.

Quantum emitters such as the diamond nitrogen-vacancy (NV) center are the basis for a wide range of quantum technologies. However, refraction and reflections at material interfaces impede photon collection, and the emitters' atomic scale necessitates the use of free space optical measurement setups that prevent packaging of quantum devices. To overcome these limitations, we design and fabricate a metasurface composed of nanoscale diamond pillars that acts as an immersion lens to collect and collimate the emission of an individual NV center.

Spin Readout Techniques of the Nitrogen-Vacancy Center in Diamond.

The diamond nitrogen-vacancy (NV) center is a leading platform for quantum information science due to its optical addressability and room-temperature spin coherence. However, measurements of the NV center's spin state typically require averaging over many cycles to overcome noise. Here, we review several approaches to improve the readout performance and highlight future avenues of research that could enable single-shot electron-spin readout at room temperature.

Amplified Sensitivity of Nitrogen-Vacancy Spins in Nanodiamonds Using All-Optical Charge Readout.

Nanodiamonds containing nitrogen-vacancy (NV) centers offer a versatile platform for sensing applications spanning from nanomagnetism to in vivo monitoring of cellular processes. In many cases, however, weak optical signals and poor contrast demand long acquisition times that prevent the measurement of environmental dynamics. Here, we demonstrate the ability to perform fast, high-contrast optical measurements of charge distributions in ensembles of NV centers in nanodiamonds and use the technique to improve the spin-readout signal-to-noise ratio through spin-to-charge conversion.

Dietary choice for a balanced nutrient intake increases the mean and reduces the variance in the reproductive performance of male and female cockroaches.

Sexual selection may cause dietary requirements for reproduction to diverge across the sexes and promote the evolution of different foraging strategies in males and females. However, our understanding of how the sexes regulate their nutrition and the effects that this has on sex-specific fitness is limited. We quantified how protein (P) and carbohydrate (C) intakes affect reproductive traits in male (pheromone expression) and female (clutch size and gestation time) cockroaches (Nauphoeta cinerea).

Ultrafast optical control of orbital and spin dynamics in a solid-state defect.

Atom-scale defects in semiconductors are promising building blocks for quantum devices, but our understanding of their material-dependent electronic structure, optical interactions, and dissipation mechanisms is lacking. Using picosecond resonant pulses of light, we study the coherent orbital and spin dynamics of a single nitrogen-vacancy center in diamond over time scales spanning six orders of magnitude. We develop a time-domain quantum tomography technique to precisely map the defect's excited-state Hamiltonian and exploit the excited-state dynamics to control its ground-state spin with optical pulses alone.

All-optical control of a solid-state spin using coherent dark states.

The study of individual quantum systems in solids, for use as quantum bits (qubits) and probes of decoherence, requires protocols for their initialization, unitary manipulation, and readout. In many solid-state quantum systems, these operations rely on disparate techniques that can vary widely depending on the particular qubit structure. One such qubit, the nitrogen-vacancy (NV) center spin in diamond, can be initialized and read out through its special spin-selective intersystem crossing, while microwave electron spin resonance techniques provide unitary spin rotations.

Quantum spintronics: engineering and manipulating atom-like spins in semiconductors.

The past decade has seen remarkable progress in isolating and controlling quantum coherence using charges and spins in semiconductors. Quantum control has been established at room temperature, and electron spin coherence times now exceed several seconds, a nine-order-of-magnitude increase in coherence compared with the first semiconductor qubits. These coherence times rival those traditionally found only in atomic systems, ushering in a new era of ultracoherent spintronics.