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: Quantum circuits
New cooling technology developed for quantum computing circuits
Phys.org June 16, 2023 Quantum circuits interact with the environment via several temperature-dependent degrees of freedom. Multiple experiments to-date have shown that most properties of superconducting devices appear to plateau out at T ≈ 50 mK – far above the refrigerator base temperature. This is reflected in the thermal state population of qubits and polarisation of surface spins. An international team of researchers (UK, Sweden, USA – industry) demonstrated how to remove this thermal constraint by operating a circuit immersed in liquid 3He. This allowed cooling tof he decohering environment of a superconducting resonator. They saw a continuous change in measured physical […]