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Josephson weak links made of two-dimensional topological insulators (TIs) exhibit magnetic oscillations of the supercurrent that are reminiscent of those in superconducting quantum interference devices (SQUIDs). We propose a microscopic…

Mesoscale and Nanoscale Physics · Physics 2015-07-13 G. Tkachov , P. Burset , B. Trauzettel , E. M. Hankiewicz

Quasiparticle - a key concept to describe interacting particles - characterizes electron-electron interaction in metals (Fermi liquid) and electron pairing in superconductors. While this concept essentially relies on the simplification of…

Mesoscale and Nanoscale Physics · Physics 2021-07-30 Satoru Tokuda , Seigo Souma , Kouji Segawa , Takashi Takahashi , Yoichi Ando , Takeshi Nakanishi , Takafumi Sato

We study the quantum dynamics of a Bose Josephson junction(BJJ) made up of two coupled Bose-Einstein condensates. Apart from the usual ac Josephson oscillations, two different dynamical states of BJJ can be observed by tuning the…

Quantum Gases · Physics 2015-06-11 René John Kerkdyk , S. Sinha

We study the macroscopic quantum tunneling of two weakly-linked superfluids made of interacting fermionic atoms. We derive atomic Josephson junction equations and find that zero-mode and pi-mode frequencies of coherent atomic oscillations…

Statistical Mechanics · Physics 2008-04-09 L. Salasnich , N. Manini , F. Toigo

Starting from the reduced dynamical model of a two-junction quantum interference device, a quantum analog of the system has been exhibited, in order to extend the well known properties of this device to the quantum regime. By finding…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 F. Romeo , R. De Luca

The influence of low to moderate frequency environments on Macroscopic Quantum Tunneling (MQT) in superconducting circuits is studied within the Im-F approach to evaluate tunneling rates. Particular attention is paid to two model…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 M. Duckheim , J. Ankerhold

We propose a new qubit consisting of a superconducting ring with two ordinary zero junctions and one ferromagnetic pi junction. In the system, two degenerate stable states appear in the phase space without an external magnetic field because…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 T. Yamashita , S. Takahashi , S. Maekawa

The design for an inductive superconducting quantum interference proximity transistor with enhanced performance, the L-SQUIPT, is presented and analyzed. The interferometer is based on a double-loop structure, where each ring comprises a…

Mesoscale and Nanoscale Physics · Physics 2022-11-18 F. Paolucci , P. Solinas , F. Giazotto

We study macroscopic quantum coherence (MQC) in small ferrimagnets. Through semi-classical calculations we show that even a small uncompensated moment has a drastic effect on MQC. In particular, there is a rapid crossover to a regime where…

Mesoscale and Nanoscale Physics · Physics 2009-10-30 Alain Chiolero , Daniel Loss

Collective excitations reveal fundamental properties and potential applications of superconducting states. We theoretically study macroscopic quantum tunneling (MQT) in a Josephson junction composed of multi-band superconductors, focusing…

Superconductivity · Physics 2014-07-14 Hidehiro Asai , Yukihiro Ota , Shiro Kawabata , Masahiko Machida , Franco Nori

We examine the macroscopic quantum tunneling (MQT) in high-Tc superconductor Josephson junctions with a d-wave order parameter. Using microscopic Hamiltonian and the functional integral method, we analytically obtain the MQT rate (the…

Superconductivity · Physics 2009-11-10 Shiro Kawabata , Satoshi Kashiwaya , Yasuhiro Asano , Yukio Tanaka

We develop a theory for two quasiparticle-induced decoherence mechanisms of a driven superconducting qubit. In the first mechanism, an existing quasiparticle (QP) tunnels across the qubit's Josephson junction while simultaneously absorbing…

We theoretically study the macroscopic quantum tunneling (MQT) in a hetero Josephson junction formed by a conventional single-gap superconductor and a multi-gap one such as ${MgB}_{2}$ and iron-based superconductors. In such a Josephson…

Quantum Physics · Physics 2011-02-11 Yukihiro Ota , Masahiko Machida , Tomio Koyama

Low-temperature characters of superconducting devices yield definite probes for different superconducting phenomena. We study the macroscopic quantum tunneling (MQT) in a Josephson junction, composed of a single-gap superconductor and a…

Superconductivity · Physics 2014-12-19 Hidehiro Asai , Shiro Kawabata , Yukihiro Ota , Masahiko Machida

Mesoscopic multi-terminal Josephson junctions are novel devices that provide weak coupling between several bulk superconductors through a common normal layer. Because of the nonlocal coupling of the superconducting banks, a current flow…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 M. H. S. Amin , A. N. Omelyanchouk , A. Blais , A. Maassen van den Brink , G. Rose , T. Duty , A. M. Zagoskin

We have carried out systematic Macroscopic Quantum Tunneling (MQT) experiments on Nb/Al-AlO_x/Nb Josephson junctions (JJs) of different areas. Employing on-chip lumped element inductors, we have decoupled the JJs from their environmental…

Superconductivity · Physics 2010-11-19 Christoph Kaiser , Roland Schäfer , Michael Siegel

The integration of semiconductor Josephson junctions (JJs) in superconducting quantum circuits provides a versatile platform for hybrid qubits and offers a powerful way to probe exotic quasiparticle excitations. Recent proposals for using…

Prototype Josephson-junction based qubit coherence times are too short for quantum computing. Recent experiments probing superconducting phase qubits have revealed previously unseen fine splittings in the transition energy spectra. These…

The non-dissipative non-linearity of a Josephson junction converts macroscopic superconducting circuits into artificial atoms, enabling some of the best controlled quantum bits (qubits) today. Three fundamental types of superconducting…

The superconducting phase qubit combines Josephson junctions into superconducting loops and defines one of the promising solid state device implementations for quantum computing. While conventional designs are based on magnetically…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 G. Blatter , V. B. Geshkenbein , L. Ioffe