New material platform for superconducting transmon qubits with coherence times exceeding 0.3 milliseconds

By A. Place, L. Rodgers, Pranav S. Mundada, Basil M Smitham, Mattias Fitzpatrick, Z. Leng, Anjali Premkumar, J. Bryon, A. Vrajitoarea, S. Sussman and 11 more. Nature Communications, 2020

597 citations recorded by the source corpus.

The superconducting transmon qubit is a leading platform for quantum computing and quantum science. Building large, useful quantum systems based on transmon qubits will require significant improvements in qubit relaxation and coherence times, which are orders of magnitude shorter than limits imposed by bulk properties of the constituent materials. This indicates that relaxation likely originates from uncontrolled surfaces, interfaces, and contaminants. Previous efforts to improve qubit lifetimes have focused primarily on designs that minimize contributions from surfaces. However, significant improvements in the lifetime of two-dimensional transmon qubits have remained elusive for several years. Here, we fabricate two-dimensional transmon qubits that have both lifetimes and coherence times with dynamical decoupling exceeding 0.3 milliseconds by replacing niobium with tantalum in the device. We have observed increased lifetimes for seventeen devices, indicating that these material improvements are robust, paving the way for higher gate fidelities in multi-qubit processors. Quantum computers based on superconducting transmon qubits are limited by single qubit lifetimes and coherence times, which are orders of magnitude shorter than limits imposed by bulk material properties. Here, the authors fabricate two-dimensional transmon qubits with both lifetimes and coherence times longer than 0.3 milliseconds by replacing niobium with tantalum in the device.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics

View Paper: https://www.semanticscholar.org/paper/fe6a5ecce382e9484fc68e2549d682a760d5293c

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In Atomic and Molecular Physics, and Optics

Citations in the corpus

Systematic improvements in transmon qubit coherence enabled by niobium surface encapsulation (2023, unknown): “Therefore, our ﬁ ndings help explain why previous experimental studies with qubits prepared from Ta metal exhibited improved T 1 values 13,14 .”
Materials challenges and opportunities for quantum computing hardware (2021, background): “The coherence times can drift or change suddenly over hours and days, even while the device is held at cryogenic temperatures (89, 95, 126, 127).”
High fidelity two-qubit gates on fluxoniums using a tunable coupler (2022, methodology): “If a target gate is inserted after each single-qubit operation, the average fidelity of the gate is determined by the formula (5) with p= p2/p1, where p2 and p1 are the depolarizing parameters corresponding to the gate sequences with and without (reference sequences) the interleaved gate.”