Miniaturizing transmon qubits using van der Waals materials

Abstract

Quantum computers can potentially achieve an exponential speedup versus classical computers on certain computational tasks, as recently demonstrated in systems of superconducting qubits. However, these qubits have large footprints due to their large capacitor electrodes needed to suppress losses by avoiding dielectric materials. This tactic hinders scaling by increasing parasitic coupling among circuit components, degrading individual qubit addressability, and limiting the spatial density of qubits. Here, we take advantage of the unique properties of the van der Waals (vdW) materials to reduce the qubit area by a factor of $>1000$ while preserving the required capacitance without increasing substantial loss. Our qubits combine conventional aluminum-based Josephson junctions with parallel-plate capacitors composed of crystalline layers of superconducting niobium diselenide (NbSe${}_2$) and insulating hexagonal-boron nitride (hBN). We measure a vdW transmon $T_1$ relaxation time of 1.06 $\mu$s, which demonstrates a path to achieve high-qubit-density quantum processors with long coherence times, and illustrates the broad utility of layered heterostructures in low-loss, high-coherence quantum devices.

arXiv comment6 pages, 5 figures, and 1 table

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Cited by in corpus (13)

• Hexagonal Boron Nitride (hBN) as a Low-loss Dielectric for Superconducting Quantum Circuits and Qubits
• A gate-tunable graphene Josephson parametric amplifier
• Percolating Superconductivity in Air-Stable Organic-Ion Intercalated MoS2
• Compact superconducting microwave resonators based on Al-AlOx-Al capacitor
• Compact vacuum gap transmon qubits: Selective and sensitive probes for superconductor surface losses
• Effect of dilute impurities on short graphene Josephson junctions
• 1/f noise in quantum nanoscience
• Dipole coupling of a bilayer graphene quantum dot to a high-impedance microwave resonator
• Making high-quality quantum microwave devices with van der Waals superconductors
• Flux pinning in superconducting multilayer 2H-NbSe${}_2$ nano-step junction
• Local analysis of a single impurity on a graphene Josephson Junction
• Optimal quantum resource generation in coupled transmons immersed in Markovian baths
• Encapsulation epitaxy of air-stable monolayer superconducting films for quantum circuits and qubits