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We study a carbon nanotube quantum dot embedded into a SQUID loop in order to investigate the competition of strong electron correlations with proximity effect. Depending whether local pairing or local magnetism prevails, a superconducting…

Mesoscale and Nanoscale Physics · Physics 2012-02-16 Romain Maurand , Tobias Meng , Edgar Bonet , Serge Florens , Laëtitia Marty , Wolfgang Wernsdorfer

We have observed the Josephson effect in junctions formed between single crystals of SrFe1.74Co0.26As2 and Ba0.23K0.77Fe2As2. I-V curves showed resistively-shunted junction characteristics, and the ac Josephson effect was observed under…

We study the Josephson coupling between two superconductors through a single correlated molecular level, including Coulomb interaction on the level and coupling to a bosonic environment. All calculations are done to the lowest, i.e., the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Tomas Novotny , Alessandra Rossini , Karsten Flensberg

A double quantum dot coupled to an s-wave superconductor and subject to an inhomogeneous magnetic field can host a pair of zero-energy Majorana fermions when the dot properties are tuned appropriately. Here, we demonstrate the possibility…

Mesoscale and Nanoscale Physics · Physics 2013-08-26 Björn Sothmann , Jian Li , Markus Büttiker

The Josephson effect is a prominent phenomenon of quantum supercurrents that has been widely studied in superconductors and superfluids. Typical Josephson junctions consist of two real-space superconductors (superfluids) coupled through a…

We study a phase-tunable four-terminal Josephson junction formed in an InSbAs two-dimensional electron gas proximitized by aluminum. By embedding the two pairs of junction terminals in asymmetric DC SQUIDs we can control the superconducting…

Mesoscale and Nanoscale Physics · Physics 2024-09-12 Christian G. Prosko , Wietze D. Huisman , Ivan Kulesh , Di Xiao , Candice Thomas , Michael J. Manfra , Srijit Goswami

With the help of the numerical renormalization group method, we theoretically investigate the Josephson phase transition in a parallel junction with one quantum dot embedded in each arm. It is found that in the cases of uniform dot levels…

Mesoscale and Nanoscale Physics · Physics 2018-08-08 Guang-Yu Yi , Xiao-Qi Wang , Cui Jiang , Wei-Jiang Gong

We investigate electronic transport in Josephson junctions formed by single-walled carbon nanotubes coupled to superconducting electrodes. We observe enhanced zero-bias conductance (up to 10e^2/h) and pronounced sub-harmonic gap structures…

Mesoscale and Nanoscale Physics · Physics 2007-08-24 Y. Zhang , G. Liu , C. N. Lau

We investigate the supercurrent through a quantum dot for the whole range of couplings using the numerical renormalization group method. We find that the Josephson current switches abruptly from a $\pi$- to a 0-phase as the coupling…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Mahn-Soo Choi , Minchul Lee , Kicheon Kang , W. Belzig

We introduce a new approach to the Josephson effect in SIS tunnel junctions. The Josephson coupling energy is calculated from the overlap of real space Cooper pair wavefunctions in two superconductors through an insulating barrier. It is…

Superconductivity · Physics 2007-05-23 Yong-Jihn Kim

We apply a Gutzwiller-like variational technique to study Josephson conduction across a quantum dot with an odd number of electrons connected to two superconducting leads. We show that, for small values of the superconducting gap, Kondo…

Strongly Correlated Electrons · Physics 2007-05-23 G. Campagnano , D. Giuliano , A. Tagliacozzo

In typical Josephson junctions, the Josephson current is an odd function of the superconducting phase difference. Recently, diode effect in Josephson junctions is observed in experiments wherein the maximum and the minimum values of the…

Superconductivity · Physics 2023-05-08 Abhiram Soori

We present a technique for integrating ultraclean carbon nanotubes into superconducting circuits, aiming to realize Josephson junctions based on one-dimensional elementary quantum conductors. This technique primarily involves depositing the…

Mesoscale and Nanoscale Physics · Physics 2024-12-13 S. Annabi , E. Arrighi , A. Peugeot , H. Riechert , J. Griesmar , K. Watanabe , T. Taniguchi , L. Bretheau , J. -D. Pillet

A semiconducting nanowire proximitized by an $s$-wave superconductor can be tuned into a topological state by an applied magnetic field. This quantum phase transition is marked by the emergence of Majorana zero modes at the ends of the…

Mesoscale and Nanoscale Physics · Physics 2020-07-01 Chaitanya Murthy , Vladislav D. Kurilovich , Pavel D. Kurilovich , Bernard van Heck , Leonid I. Glazman , Chetan Nayak

The Josephson effect provides a direct method to probe the strength of the pairing interaction in superconductors. By measuring the phase fluctuating Josephson current between a superconducting tip of a scanning tunneling microscope (STM)…

Superconductivity · Physics 2016-05-25 Mallika T. Randeria , Benjamin E. Feldman , Ilya K. Drozdov , Ali Yazdani

We derive, via fourth order perturbation theory, an expression for the Josephson current through a gated interacting quantum dot. We analyze our expression for two different models of the superconductor-dot-superconductor (SDS) system. When…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 A. V. Rozhkov , D. P. Arovas , F. Guinea

We investigate the Josephson effects in the junction formed by \emph{DIII}-class topological and $s$-wave superconductors, by embedding a quantum dot in the junction. Three dot-superconductor coupling manners are considered, respectively.…

Mesoscale and Nanoscale Physics · Physics 2015-06-23 Zhen Gao , Wan-Fei Shan , Wei-Jiang Gong

We study the Josephson effect through a one-dimensional system of interacting electrons, connected to two superconductors by tunnel junctions. The interactions are treated in the framework of the one-channel Luttinger model. At zero…

Condensed Matter · Physics 2009-10-22 Rosario Fazio , F. W. J. Hekking , A. A. Odintsov

We investigate the Josephson effect between two coupled superconductors, coupled by the tunneling of pairs of electrons, in the regime that their energy level spacing is comparable to the bulk superconducting gap, but neglecting any…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Dominique Gobert , Ulrich Schollwock , Jan von Delft

Using the pseudospin representation and the SU(2) phase operators we introduce a complex parameter to characterize both infinite and finite superconducting systems. While in the bulk limit the parameter becomes identical to the conventional…

Superconductivity · Physics 2007-05-23 Zafer Gedik