A 54.6 GHz Clock Transition in Ho Electron Spin Qubits Assembled into a Metal-Organic Framework.

A high-symmetry assembly of molecular spin qubits has been achieved in the metal-organic framework (MOF) [Ho(pzdo)](ClO) (), where the eight-coordinate Ho nodes are bridged by pyrazine-1,4-dioxide (pzdo) ligands. The approximate square-antiprismatic () coordination of the Ho ion leads to the stabilization of the = ±4 ground-state doublet due to crystal-field splitting of the = 8 total angular momentum state. Mixing of the = +4 and = -4 projection states opens a zero-field energy gap (Δ) resulting in the spin clock transition (SCT) evident in the EPR spectra of .

Block2: A comprehensive open source framework to develop and apply state-of-the-art DMRG algorithms in electronic structure and beyond.

block2 is an open source framework to implement and perform density matrix renormalization group and matrix product state algorithms. Out-of-the-box it supports the eigenstate, time-dependent, response, and finite-temperature algorithms. In addition, it carries special optimizations for ab initio electronic structure Hamiltonians and implements many quantum chemistry extensions to the density matrix renormalization group, such as dynamical correlation theories.

Fermionic Reduced Density Low-Rank Matrix Completion, Noise Filtering, and Measurement Reduction in Quantum Simulations.

Fermionic reduced density matrices summarize the key observables in Fermionic systems. In electronic systems, the two-particle reduced density matrix (2-RDM) is sufficient to determine the energy and most physical observables of interest. Here, we consider the possibility of using matrix completion to reconstruct the two-particle reduced density matrix to chemical accuracy from partial information.

Isolating Clusters of Light Elements in Molecular Sieves with Atom Probe Tomography.

Understanding the 3-D distribution and nature of active sites in heterogeneous catalysts is critical to developing structure-function relationships. However, this is difficult to achieve in microporous materials as there is little relative z-contrast between active and inactive framework elements (e.g.

Nanoscale Chemical Imaging of Zeolites Using Atom Probe Tomography.

Understanding structure-composition-property relationships in zeolite-based materials is critical to engineering improved solid catalysts. However, this can be difficult to realize as even single zeolite crystals can exhibit heterogeneities spanning several orders of magnitude, with consequences for, for example, reactivity, diffusion as well as stability. Great progress has been made in characterizing these porous solids using tomographic techniques, though each method has an ultimate spatial resolution limitation.