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Reducing materials and processing-induced decoherence is critical to the development of utility-scale quantum processors based on superconducting qubits. Here we report on the impact of two fluorine-based wet etches, which we use to treat…

Scalability in the fabrication and operation of quantum computers is key to move beyond the NISQ era. So far, superconducting transmon qubits based on aluminum Josephson tunnel junctions have demonstrated the most advanced results, though…

Applied Physics · Physics 2022-09-08 Tom Doekle Vethaak

We have fabricated and characterized asymmetric gap-engineered junctions and transmon devices. To create Josephson junctions with asymmetric gaps, Ti was used to proximitize and lower the superconducting gap of the Al counter-electrode. DC…

We realize a single-Josephson-junction transmon qubit shunted by a simple geometric inductor. We couple it capacitively to a conventional transmon and show that the ZZ interaction between the two qubits is completely suppressed when they…

We introduce a simplified fabrication technique for Josephson junctions and demonstrate superconducting Xmon qubits with $T_1$ relaxation times averaging above 50$~\mu$s ($Q>$1.5$\times$ 10$^6$). Current shadow-evaporation techniques for…

Superconductivity · Physics 2021-02-24 A. Osman , J. Simon , A. Bengtsson , S. Kosen , P. Krantz , D. Perez , M. Scigliuzzo , Jonas Bylander , A. Fadavi Roudsari

Josephson junctions (JJs) are ubiquitous superconducting devices, enabling high sensitivity magnetometers and voltage amplifiers, as well as forming the basis of high performance cryogenic computer and superconducting quantum computers.…

Superconductor qubits typically use aluminum-aluminum oxide tunnel junctions to provide the non-linear inductance. Junctions with semiconductor barriers make it possible to vary the superconductor material and explore beyond aluminum. We…

Graphene-based Josephson junctions played an important role in various quantum devices from their inception. Magnetic tunnel junctions or vertical devices were also made out of graphene by exposing the graphene layer to localised pattern of…

Mesoscale and Nanoscale Physics · Physics 2024-12-25 Partha Sarathi Banerjee , Rahul Marathe , Sankalpa Ghosh

Josephson junction (JJ) is a key nonlinear element in superconducting devices such as qubits, amplifiers, and bolometers. Recently, gate-tunable JJs based on graphene and semiconductors have gained interest due to their rich Andreev physics…

Josephson junctions (JJ) and their tunable properties, including their nonlinearities, form the core of superconducting circuit quantum electrodynamics (cQED). In quantum circuits, low-noise amplification of feeble microwave signals is…

Gatemons are superconducting qubits resembling transmons, with a gate-tunable semiconducting weak link as the Josephson element. Here, we report a gatemon device featuring an aluminum microwave circuit on a Ge/SiGe heterostructure embedding…

Stochastic switching-current distribution in a graphene-based Josephson junction exhibits a crossover from the classical to quantum regime, revealing the macroscopic quantum tunneling (MQT) of a Josephson phase particle at low temperatures.…

Mesoscale and Nanoscale Physics · Physics 2012-11-15 Gil-Ho Lee , Dongchan Jeong , Jae-Hyun Choi , Yong-Joo Doh , Hu-Jong Lee

This review discusses the electronic properties and the prospective research directions of superconductor-graphene heterostructures. The basic electronic properties of graphene are introduced to highlight the unique possibility of combining…

Mesoscale and Nanoscale Physics · Physics 2018-04-18 Gil-Ho Lee , Hu-Jong Lee

Short ballistic graphene Josephson junctions sustain superconducting current with a non-sinusoidal current-phase relation up to a critical current threshold. The current-phase relation, arising from proximitized superconductivity, is…

Mesoscale and Nanoscale Physics · Physics 2020-01-09 Francesco M. D. Pellegrino , Giuseppe Falci , Elisabetta Paladino

Hybrid graphene-superconductor devices have attracted much attention since the early days of graphene research. So far, these studies have been limited to the case of diffusive transport through graphene with poorly defined and modest…

We propose to combine the advantages of graphene, such as easy tunability and long coherence times, with Josephson physics to manufacture qubits. If these qubits are built around a 0 and $\pi$ junction they can be controlled by an external…

Mesoscale and Nanoscale Physics · Physics 2009-10-06 Colin Benjamin , Jiannis K. Pachos

We report on realization and quantum transport study of a twisted bilayer graphene (tBLG) Josephson junction device. High-quality tBLG employed in the device fabrication is obtained via chemical vapour deposition and the device is…

Mesoscale and Nanoscale Physics · Physics 2020-03-06 Dingran Rui , Luzhao Sun , N. Kang , Hailin Peng , Zhongfan Liu , H. Q. Xu

The high kinetic inductance offered by granular aluminum (grAl) has recently been employed for linear inductors in superconducting high-impedance qubits and kinetic inductance detectors. Due to its large critical current density compared to…

We show that a system of Josephson junctions coupled via low-resistance tunneling contacts to graphene substrate(s) may effectively operate as a current switching device. The effect is based on the dissipation-driven…

Superconductivity · Physics 2009-11-13 Roman M. Lutchyn , Victor Galitski , Gil Refael , S. Das Sarma

We report on a ballistic and fully tunable Josephson junction system consisting of two parallel ribbons of graphene in contact with superconducting MoRe. By electrostatic gating of the two individual graphene ribbons we gain control over…