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We propose and study a realistic model for the decoherence of topological qubits, based on Majorana fermions in one-dimensional topological superconductors. The source of decoherence is the fluctuating charge on a capacitively coupled gate,…

Mesoscale and Nanoscale Physics · Physics 2012-08-14 Manuel J. Schmidt , Diego Rainis , Daniel Loss

So far, super quantum discord has been calculated explicitly only for Bell-diagonal states and expressions for more general quantum states are not known. In this paper, we derive explicit expressions for super quantum discord for a larger…

Quantum Physics · Physics 2014-09-16 H. Eftekhari , E. Faizi

We study decoherence effects in qubits coupled to environments that exhibit resonant frequencies in their spectral function. We model the coupling of the qubit to its environment via the Caldeira-Leggett formulation of quantum…

Superconductivity · Physics 2010-06-07 Kaushik Mitra , C. A. R. Sá de Melo

A superconducting qubit implementation is proposed that takes the advantage of both charge and phase degrees of freedom. Superpositions of flux states in a superconducting loop with three Josephson junctions form the states of the qubit.…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 M. H. S. Amin

Recent progress with microfabricated quantum devices has revealed that an ubiquitous source of noise originates in tunneling material defects that give rise to a sparse bath of parasitic two-level systems (TLSs). For superconducting qubits,…

The dominant contribution to the energy relaxation of state-of-the-art superconducting qubits is often attributed to their coupling to an ensemble of material defects which behave as two-level systems. These defects have varying microscopic…

A known source of decoherence in superconducting qubits is the presence of broken Cooper pairs, or quasiparticles. These can be generated by high-energy radiation, either present in the environment or purposefully introduced, as in the case…

The time evolution of a qubit, consisting of two single-level quantum dots, is studied in the presence of telegraph noise. The dots are connected by two tunneling paths, with an Aharonov-Bohm flux enclosed between them. Under special…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 A. Aharony , S. Gurvitz , O. Entin-Wohlman , S. Dattagupta

We reproduce the sub-exponential decoherence of one-dimensional quasicondensates observed in recent experiments. Counter-intuitively, the quasicondensates may decohere even when stongly coupled, if the temperature is large enough or the…

Quantum Gases · Physics 2009-08-21 R. G. Scott , D. A. W. Hutchinson

Critical current fluctuations with a 1/ f spectral density (f is frequency) are potentially a limiting source of intrinsic decoherence in superconducting quantum bits (qubits) based on Josephson tunnel junctions. Prior measurements of this…

Superconductivity · Physics 2007-05-23 Michael Mueck , Matthias Korn , C. G. A. Mugford , J. B. Kycia , John Clarke

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

In systems considered for quantum computing, i.e., for control of quantum dynamics with the goal of processing information coherently, decoherence and deviation from pure quantum states, are the main obstacles to fault-tolerant error…

Mesoscale and Nanoscale Physics · Physics 2010-10-12 Vladimir Privman

One of the key problems facing superconducting qubits and other Josephson junction devices is the decohering effects of bi-stable material defects. Although a variety of phenomenological models exist, the true microscopic origin of these…

Mesoscale and Nanoscale Physics · Physics 2013-03-14 Timothy C. DuBois , Manolo C. Per , Salvy P. Russo , Jared H. Cole

We present a superconducting qubit for the circuit quantum electrodynamics architecture that has a tunable coupling strength g. We show that this coupling strength can be tuned from zero to values that are comparable with other…

Mesoscale and Nanoscale Physics · Physics 2011-01-21 J. M. Gambetta , A. A. Houck , Alexandre Blais

We investigate the decoherence process for a quantum register composed of N qubits coupled to an environment. We consider an environment composed of one common phonon bath and several electronic baths. This environment is relevant to the…

Quantum Physics · Physics 2009-11-10 B. Ischi , M. Hilke , M. Dube

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…

We analyze decoherence of an electron in a double-dot due to the interaction with acoustic phonons. For large tunneling rates between the quantum dots, the main contribution to decoherence comes from the phonon emission relaxation…

Quantum Physics · Physics 2007-05-23 L. Fedichkin , A. Fedorov

Low-frequency noise presents a serious source of decoherence in solid-state qubits. When combined with a continuous weak measurement of the eigenstates, the low-frequency noise induces a second-order relaxation between the qubit states.…

Quantum Physics · Physics 2011-07-26 L. Tian

Solid state quantum bits are a promising candidate for the realization of a scalable quantum computer, however, they are usually strongly limited by decoherence. We consider a double quantum dot charge qubit, whose basis states are defined…

Mesoscale and Nanoscale Physics · Physics 2015-06-24 Udo Hartmann , Frank K. Wilhelm

It is believed that classical behavior emerges in a quantum system due to decoherence. It has also been proposed that gravity can be a source of this decoherence. We examine this in detail by studying a number of quantum systems, including…

General Relativity and Quantum Cosmology · Physics 2017-10-31 Saurya Das , Matthew P. G. Robbins , Elias C. Vagenas