Towards practical quantum computers: transmon qubit with a lifetime approaching 0.5 milliseconds

Here we report a breakthrough in the fabrication of a long lifetime transmon qubit. We use tantalum films as the base superconductor. By using a dry etching process, we obtained transmon qubits with a best T-1 lifetime of 503 mu s. As a comparison, we also fabricated transmon qubits with other popular materials, including niobium and aluminum, under the same design and fabrication processes. After characterizing their coherence properties, we found that qubits prepared with tantalum films have the best performance. Since the dry etching process is stable and highly anisotropic, it is much more suitable for fabricating complex scalable quantum circuits, when compared to wet etching. As a result, the current breakthrough indicates that the dry etching process of tantalum film is a promising approach to fabricate medium- or large-scale superconducting quantum circuits with a much longer lifetime, meeting the requirements for building practical quantum computers.

Automated summary

A breakthrough in fabricating a long lifetime transmon qubit was reported, using tantalum films as the base superconductor with a dry etching process. The transmon qubits achieved a best T-1 lifetime of 503 μs, outperforming those fabricated with niobium and aluminum. The stable and highly anisotropic dry etching process of tantalum film shows promise for fabricating medium- or large-scale superconducting quantum circuits with longer lifetimes, meeting the requirements for practical quantum computers.