Hardware-efficient quantum error correction via concatenated bosonic qubits.

To solve problems of practical importance, quantum computers probably need to incorporate quantum error correction, in which a logical qubit is redundantly encoded in many noisy physical qubits. The large physical-qubit overhead associated with error correction motivates the search for more hardware-efficient approaches. Here, using a superconducting quantum circuit, we realize a logical qubit memory formed from the concatenation of encoded bosonic cat qubits with an outer repetition code of distance d = 5 (ref.

Manipulating the interfacial structure of nanomaterials to achieve a unique combination of strength and ductility.

The control of interfaces in engineered nanostructured materials has met limited success compared with that which has evolved in natural materials, where hierarchical structures with distinct interfacial states are often found. Such interface control could mitigate common limitations of engineering nanomaterials. For example, nanostructured metals exhibit extremely high strength, but this benefit comes at the expense of other important properties like ductility.

Disruption of thermally-stable nanoscale grain structures by strain localization.

Nanocrystalline metals with average grain sizes of only a few nanometers have recently been observed to fail through the formation of shear bands. Here, we investigate this phenomenon in nanocrystalline Ni which has had its grain structure stabilized by doping with W, with a specific focus on understanding how strain localization drives evolution of the nanoscale grain structure. Shear banding was initiated with both microcompression and nanoindentation experiments, followed by site-specific transmission electron microscopy to characterize the microstructure.