Related papers: Microscopic Relaxation Channels in Materials for S…
Scalable architectures characterized by quantum bits (qubits) with low error rates are essential to the development of a practical quantum computer. In the superconducting quantum computing implementation, understanding and minimizing…
The interaction between solid-state qubits and their environmental degrees of freedom produces non-unitary effects like decoherence and dissipation. Uncontrolled decoherence is one of the main obstacles that must be overcome in quantum…
We present measurements of coherence and successive decay dynamics of higher energy levels of a superconducting transmon qubit. By applying consecutive $\pi$-pulses for each sequential transition frequency, we excite the qubit from the…
The dominant contribution to the energy relaxation of state-of-the-art superconducting qubits is often attributed to their coupling to an ensemble of material defects which behave as two-level systems. These defects have varying microscopic…
Superconducting qubits are sensitive to a variety of loss mechanisms including dielectric loss from interfaces. By changing the physical footprint of the qubit it is possible to modulate sensitivity to surface loss. Here we show a…
Superconducting qubits are considered as a promising platform for implementing a fault tolerant quantum computing. However, surface defects of superconductors and the substrate leading to qubit state decoherence and fluctuations in qubit…
The performance and scalability of superconducting quantum circuits are fundamentally constrained by non-equilibrium quasiparticles, which induce microwave losses that limit resonator quality factors and qubit coherence times. Understanding…
The temporal stability and reproducibility of qubit parameters are critical for the long-term operation and maintenance of superconducting quantum processors. In this work, we present a comprehensive longitudinal characterization of 27…
We present the results of an industry-grade fabrication of superconducting qubits on 200 mm wafers utilizing CMOS-established processing methods. By automated waferprober resistance measurements at room temperature, we demonstrate a…
Niobium metal occupies nearly 100\% of the volume of a typical 2D transmon device. While the aluminum Josephson junction is of utmost importance, maintaining quantum coherence across the entire device means that pair-breaking in Nb leads,…
Surface dielectric loss of superconducting transmon qubit is believed as one of the dominant sources of decoherence. Reducing surface dielectric loss of superconducting qubit is known to be a great challenge for achieving high quality…
Addressing and mitigating decoherence sources plays an essential role in the development of a scalable quantum computing system, which requires low gate errors to be consistently maintained throughout the circuit execution. While nuclear…
Identifying, quantifying, and suppressing decoherence mechanisms in qubits are important steps towards the goal of engineering a quantum computer or simulator. Superconducting circuits offer flexibility in qubit design; however, their…
Superconducting integrated circuits have demonstrated a tremendous potential to realize integrated quantum computing processors. However, the downside of the solid-state approach is that superconducting qubits suffer strongly from energy…
We report superconducting fluxonium qubits with coherence times largely limited by energy relaxation and reproducibly satisfying T2 > 100 microseconds (T2 > 300 microseconds in one device). Moreover, given the state of the art values of the…
We demonstrate experimentally the creation and measurement of an entangled state between a microscopic two level system and a macroscopic superconducting resonator where their indirect interaction is mediated by an artificial atom, a…
Most quantum error correction (QEC) protocols for superconducting qubits assume spatially and temporally uncorrelated decoherence events; however, recent evidence suggests that cosmic radiation induces spatially correlated errors. We…
Designing the spatial profile of the superconducting gap -- gap engineering -- has long been recognized as an effective way of controlling quasiparticles in superconducting devices. In aluminum films, their thickness modulates the gap;…
We report a comparative study on microwave control lines for a transmon qubit using: (i) flexible stripline transmission lines, and (ii) semi-rigid coaxial cables. During each experiment we performed repeated measurements of the energy…
Decoherence in quantum bit circuits is presently a major limitation to their use for quantum computing purposes. We present experiments, inspired from NMR, that characterise decoherence in a particular superconducting quantum bit circuit,…