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The investigation of the switching current probability distribution of a Josephson junction is a conventional tool to gain information on the phase slips dynamics as a function of the temperature. Here we adopt this well-established…

Mesoscale and Nanoscale Physics · Physics 2020-05-15 C. Puglia , G. De Simoni , F. Giazotto

Quantum optimal control theory allows to design accurate quantum gates. We employ it to design high-fidelity two-bit gates for Josephson charge qubits in the presence of both leakage and noise. Our protocol considerably increases the…

Quantum Physics · Physics 2009-11-13 Simone Montangero , Tommaso Calarco , Rosario Fazio

We propose to dynamically control the conductivity of a Josephson junction composed of two weakly coupled one dimensional condensates of ultracold atoms. A current is induced by a periodically modulated potential difference between the…

Quantum Gases · Physics 2021-02-10 Beilei Zhu , Vijay Pal Singh , Junichi Okamoto , Ludwig Mathey

The fluxonium qubit has arisen as one of the most promising candidate devices for implementing quantum information in superconducting devices, since it is both insensitive to charge noise (like flux qubits) and insensitive to flux noise…

Mesoscale and Nanoscale Physics · Physics 2015-07-20 Samuele Spilla , Fabian Hassler , Anna Napoli , Janine Splettstoesser

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

We report a theoretical study of the macroscopic quantum dynamics in spatially extended Josephson systems. We focus on a Josephson tunnel junction of finite length placed in an externally applied magnetic field. In such a system,…

Superconductivity · Physics 2009-11-11 M. V. Fistul , A. V. Ustinov

We theoretically study specific schemes for performing a fundamental two-qubit quantum gate via controlled atomic collisions by switching microscopic potentials. In particular we calculate the fidelity of a gate operation for a…

Quantum Physics · Physics 2009-10-31 T. Calarco , E. A. Hinds , D. Jaksch , J. Schmiedmayer , J. I. Cirac , P. Zoller

We propose a hybrid quantum circuit with both charge and flux qubits connected to a large Josephson junction that gives rise to an effective inter-qubit coupling controlled by the external magnetic flux. This switchable inter-qubit coupling…

Superconductivity · Physics 2009-11-13 Xiao-Ling He , J. Q. You , Yu-xi Liu , L. F. Wei , Franco Nori

Aluminum-based Josephson junctions are currently the main sources of nonlinearity for control and manipulation of superconducting qubits. A phase-slip junction, the dual of a Josephson junction, provides an alternative source of…

Superconductivity · Physics 2026-02-09 Cheeranjeev Purmessur , Kaicheung Chow , Bernard van Heck , Angela Kou

Current superconducting quantum processors require strategies for coping with material defects and imperfect parameter targeting in order to scale up while maintaining high performance. To that end, in-situ control of qubit frequencies with…

Quantum Physics · Physics 2021-04-19 Joseph A. Valery , Shoumik Chowdhury , Glenn Jones , Nicolas Didier

We propose an active mechanism for coupling the quantized mode of a nanomechanical resonator to the persistent current in the loop of a superconducting Josephson junction (or phase slip) flux qubit. This coupling is independently controlled…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Fei Xue , Y. D Wang , C. P. Sun , H. Okamoto , H. Yamaguchi , K. Semba

We propose a scheme to clarify the coupling nature between superconducting Josephson qubits andmicroscopic two-level systems. Although dominant interest in studying two-level systems was in phase qubits previously, we find that the…

Quantum Physics · Physics 2012-12-13 Zhen-Tao Zhang , Yang Yu

Van der Waals assembly allows for the creation of Josephson junctions in an atomically sharp interface between two exfoliated Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi-2212) flakes that are twisted relative to each other. In a narrow range of…

Superconductivity · Physics 2024-09-11 Alessandro Coppo , Luca Chirolli , Nicola Poccia , Uri Vool , Valentina Brosco

We consider a specific instance of a superconducting circuit, the so-called charge-qubit, consisting of a capacitor and a Josephson junction. Starting from the microscopic description of the latter in terms of two tunneling BCS models in…

Quantum Physics · Physics 2023-04-27 F. Benatti , F. Carollo , R. Floreanini , H. Narnhofer , F. Valiera

Controlling the energy spectrum of quantum-coherent superconducting circuits, i.e. the energies of excited states, the circuit anharmonicity and the states' charge dispersion, is essential for designing performant qubits. This control is…

We have studied the switching behaviour of a small capacitance Josephson junction both in experiment, and by numerical simulation of a model circuit. The switching is a comples process involving the transition between two dynamical states…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Joachim Sjostrand , Jochen Walter , David Haviland , Hans Hansson , Anders Karlhede

We consider the quantum dynamics of excitations in a system of two capacitively coupled Josephson junctions. Quantum breather states are found in the middle of the energy spectrum of the confined nonescaping states of the system. They are…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 R. A. Pinto , S. Flach

We show that two capacitively-coupled Josephson junctions, in the quantum limit, form a simple coupled qubit system with effective coupling controlled by the junction bias currents. We compute numerically the energy levels and wave…

Currents of the single-electron transistors driven by time-dependent fields via external dissipative circuits are investigated theoretically. By expressing the external circuit in terms of driven harmonic oscillators and using the…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Jung Hyun Oh , D. Ahn , S. W. Hwang

We introduce a technique to control the macroscopic quantum state of an rf SQUID qubit. We propose to employ a stream of single flux quantum (SFQ) pulses magnetically coupled to the qubit junction to momentarily suppresses its critical…

Quantum Physics · Physics 2018-07-04 Xingxiang Zhou , Jonathan L. Habif , Mark F. Bocko , Marc J. Feldman