Rhenium as a material platform for long-lived transmon qubits

TL;DR

This paper investigates rhenium as a superconducting film material that suppresses native oxide formation, leading to transmon qubits with significantly improved relaxation times, potentially advancing quantum computing performance.

Contribution

The study demonstrates that rhenium can be used as a superconducting film to create transmon qubits with long relaxation times, highlighting its potential to reduce dielectric loss and enhance qubit coherence.

Findings

Achieved transmon relaxation times up to 407 microseconds.

Rhenium suppresses native oxide formation, reducing dielectric loss.

Constructed a loss budget consistent with measured T1 times.

Abstract

Dielectric loss at the interfaces of superconducting films has long been recognized as limiting the performance of state-of-the-art superconducting circuits. Notably, the presence of a native oxide layer on the film is hypothesized to contribute to dielectric loss at the metal-air interface. Here, we explore rhenium as a candidate for the film, motivated by its remarkable property to suppress native oxide formation. We demonstrate rhenium on sapphire as a promising material platform for superconducting circuits through the realization of transmons with mean relaxation times $T_1$ up to 407 microseconds at 5 GHz. Our transmons are supplemented with a loss characterization study, in which we separate the dominant loss mechanisms and construct a loss budget that agrees with our $T_1$ measurements. Further characterization may establish rhenium as a leading candidate for maximizing decoherence time.