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Achieving fast gates and long coherence times for superconducting qubits presents challenges, typically requiring either a stronger coupling of the drive line or an excessively strong microwave signal to the qubit. To address this, we…

Quantum Physics · Physics 2024-07-17 Aashish Sah , Suman Kundu , Heikki Suominen , Qiming Chen , Mikko Möttönen

We provide insight into the qubit measurement process involving a switching type of detector. We study the switching-induced decoherence during escape events. We present a simple method to obtain analytical results for the qubit dephasing…

Mesoscale and Nanoscale Physics · Physics 2009-05-20 I. Serban , F. K. Wilhelm

In order to gain a better understanding of the origin of decoherence in superconducting flux qubits, we have measured the magnetic field dependence of the characteristic energy relaxation time ($T_1$) and echo phase relaxation time…

Superconductivity · Physics 2009-11-11 K. Kakuyanagi , T. Meno , S. Saito , H. Nakano , K. Semba , H. Takayanagi , F. Deppe , A. Shnirman

We study non-perturbatively the time evolution of a qubit subject to amplitude-damping noise. We show that at strong coupling the qubit decoherence can be quenched owing to large environment feedbacks, such that the qubit can evolve…

Quantum Physics · Physics 2014-03-11 Shin-Tza Wu

Superconducting qubits are one of the most advanced candidates to realize scalable and fault-tolerant quantum computing. Despite recent significant advancements in the qubit lifetimes, the origin of the loss mechanism for state-of-the-art…

Relaxation and decoherence of a qubit coupled to environment and driven by a resonant ac field are investigated by analytically solving Bloch equation of the qubit. It is found that the decoherence of a driven qubit can be decomposed into…

Other Condensed Matter · Physics 2007-05-23 Zhongyuan Zhou , Shih-I Chu , Siyuan Han

Based on a network graph analysis of the underlying circuit, a quantum theory of arbitrary superconducting charge qubits is derived. Describing the dissipative elements of the circuit with a Caldeira-Leggett model, we calculate the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Guido Burkard

Decoherence in superconducting qubits is dominated by defects that reside at amorphous interfaces. Interaction with discrete defects results in dropouts that complicate qubit operation and lead to nongaussian tails in the distribution of…

Decoherence in superconducting qubits is known to arise because of a variety of environmental degrees of freedom. In this article, we focus on the influence of thermal fluctuations in a weakly damped circuit resonance coupled to the qubit.…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 P. Bertet , I. Chiorescu , C. J. P. M Harmans , J. E. Mooij

We study the decoherence of a superconducting qubit due to the dispersive coupling to a damped harmonic oscillator. We go beyond the weak qubit-oscillator coupling, which we associate with a phase Purcell effect, and enter into a strong…

Mesoscale and Nanoscale Physics · Physics 2007-10-30 I. Serban , E. Solano , F. K. Wilhelm

Dielectric loss from two-level states is shown to be a dominant decoherence source in superconducting quantum bits. Depending on the qubit design, dielectric loss from insulating materials or the tunnel junction can lead to short coherence…

Charge fluctuations from gate bias and background traps severely limit the performance of a charge qubit in a Cooper-pair box (CPB). Here we present an experimentally realizable method to control the decoherence effects of these charge…

Superconductivity · Physics 2009-11-10 J. Q. You , Xuedong Hu , Franco Nori

The long-time maintenance of quantum coherence is crucial for its practical applications. We explore decoherence process of a multiqubit system passing through a correlated channel (phase flip, bit flip, bit-phase flip, and depolarizing).…

Quantum Physics · Physics 2020-02-06 Ming-Liang Hu , Heng Fan

We consider whether quantum coherence in the form of mutual entanglement between a pair of qubits is susceptible to decay that may be more rapid than the decay of the coherence of either qubit individually. An instance of potential…

Quantum Physics · Physics 2009-11-10 Ting Yu , J. H. Eberly

The major contribution to decoherence of a double quantum dot or a Josephson junction charge qubit comes from the electrostatic coupling to fluctuating background charges hybridized with the conduction electrons in the reservoir. However,…

Mesoscale and Nanoscale Physics · Physics 2010-09-07 I. V. Yurkevich , J. Baldwin , I. V. Lerner , B. L. Altshuler

Cooperative effects in the loss (the amplitude damping) and decoherence (the phase damping) of the qubits (two-state quantum systems) due to the inevitable coupling to the same environment are investigated. It is found that the qubits…

Quantum Physics · Physics 2007-05-23 Lu-Ming Duan , Guang-Can Guo

We propose an experimentally realizable method to control the coupling between two flux qubits. In our proposal, the bias fluxes are always fixed for these two inductively-coupled qubits. The detuning of these two qubits can be initially…

Superconductivity · Physics 2009-11-11 Yu-xi Liu , L. F. Wei , J. S. Tsai , Franco Nori

Proposals for scalable quantum computing devices suffer not only from decoherence due to the interaction with their environment, but also from severe engineering constraints. Here we introduce a practical solution to these major concerns,…

Quantum Physics · Physics 2009-11-07 Mark S. Byrd , Daniel A. Lidar

In quantum computation, quantum coherence must be maintained during gate operation. However, in physical implementations, various couplings with the environment are unavoidable and can lead to a dephasing of a quantum bit(qubit). The…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Toshifumi Itakura , Yasuhiro Tokura

We have developed quantitative description of quantum coherent oscillations in the system of two coupled qubits in the presence of weak decoherence that in general can be correlated between the two qubits. It is shown that in the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Kristian Rabenstein , Dmitri V. Averin