Phys.org February 5, 2024 To scale up superconducting quantum circuits based on transmon qubits, substantial enhancements in qubit coherence time is necessary. Tantalum (Ta) has emerged as a promising candidate in this regard. However, amorphous surface Ta oxide layer may introduce dielectric loss limiting the coherence time. A team of researchers in the US (Brookhaven National Laboratory, Pacific Northwest National Laboratory, Princeton University) developed a new approach for suppressing the formation of tantalum oxide using an ultrathin magnesium (Mg) capping layer. They demonstrated that oxide was confined to an extremely thin region directly beneath the Mg/Ta interface, and that the […]
Tag Archives: Qubit coherence
Researchers Set Record by Preserving Quantum States in Silicon Carbide for More Than Five Seconds
SciTech Daily March 13, 2022 Inability to easily read the information held in qubits, and the short coherence of qubits are impediments to the many technological applications of quantum science such as hacker proof communications networks and quantum computers. An international team of researchers (USA – University of Chicago, Argonne National Laboratory, Japan, Sweden) has demonstrated single-shot readout of single defects in SiC via spin-to-charge conversion, whereby the defect’s spin state was mapped onto a long-lived charge state. With this technique, they achieved over 80% readout fidelity without pre- or post-selection, resulting in a high signal-to-noise ratio that enabled them […]
Scientists strengthen quantum building blocks in milestone critical for scale-up
Phys.org July 20, 2020 Spin-orbit qubits coherence have shown limited coherence times, far too short for quantum technologies. An international team of researchers (Australia, Japan, Germany) has demonstrated that increasing the strength of that spin-orbit coupling lets us achieve significantly longer coherence times. They showed ultra-long coherence times of 10 ms for holes where spin–orbit coupling yields quantized total angular momentum. They focused on holes bound to boron acceptors in bulk silicon 28, whose wavefunction symmetry can be controlled through crystal strain, allowing direct control over the longitudinal electric dipole that causes decoherence. These results open a pathway to develop new […]