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The decoherence of a localized electron spin in a lattice of nuclear spins is an important problem for potential solid-state implementations of a quantum computer. We demonstrate that even at high fields, virtual electron spin-flip…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Neil Shenvi , Rogerio de Sousa , K. Birgitta Whaley

We describe a method for improving coherent control through the use of detailed knowledge of the system's Hamiltonian. Precise unitary transformations were obtained by strongly modulating the system's dynamics to average out unwanted…

We define a quantity, the so-called purity fidelity, which measures the rate of dynamical irreversibility due to decoherence, observed e.g in echo experiments, in the presence of an arbitrary small perturbation of the total (system +…

Chaotic Dynamics · Physics 2009-11-07 Tomaz Prosen , Thomas H. Seligman

The validity of optimized dynamical decoupling (DD) is extended to analytically time dependent Hamiltonians. As long as an expansion in time is possible the time dependence of the initial Hamiltonian does not affect the efficiency of…

Quantum Physics · Physics 2010-03-17 Stefano Pasini , Götz S. Uhrig

Many coherence transfer experiments in Nuclear Magnetic Resonance Spectroscopy, involving network of coupled spins, use temporary spin-decoupling to produce desired effective Hamiltonians. In this paper, we show that significant time can be…

Quantum Physics · Physics 2009-11-07 Navin Khaneja , Steffen J. Glaser , Roger Brockett

We investigate the validity of quantum regression for a family of quantum Hamiltonians on a multipartite system leading to phase-damping reduced dynamics. After finding necessary and sufficient conditions for the CP-divisibility of the…

Quantum Physics · Physics 2022-05-17 Davide Lonigro , Dariusz Chruściński

We study the suppression of qubit dephasing through Uhrig dynamical decoupling (UDD) in nontrivial environments modeled within the spin-boson formalism. In particular, we address the case of (i) a qubit coupled to a bosonic bath with…

Quantum Physics · Physics 2017-01-06 W. S. Teixeira , K. T. Kapale , M. Paternostro , F. L. Semião

Molecular nanomagnets are quantum spin systems potentially serving as qudits for future quantum technologies thanks to their many accessible low-energy states. At low temperatures, the primary source of error in these systems is pure…

We examine the question of survival of quantum entanglement between the bipartite states and multiparticle states like GHZ states under the action of a dephasing bath by the application of sequence of $\pi$ pulses. We show the great…

Quantum Physics · Physics 2015-05-14 G. S. Agarwal

Decoherence largely limits the physical realization of qubits and its mitigation is critical to quantum science. Here, we construct a robust qubit embedded in a decoherence-protected subspace, obtained by hybridizing an applied microwave…

The Hamiltonian control of n qubits requires precision control of both the strength and timing of interactions. Compensation pulses relax the precision requirements by reducing unknown but systematic errors. Using composite pulse techniques…

Quantum Physics · Physics 2015-05-13 Yu Tomita , J. True Merrill , Kenneth R. Brown

We introduce a method to rotate arbitrarily the excitation profile of universal broadband composite pulse sequences for robust high-fidelity population inversion. These pulses compensate deviations in any experimental parameter (e.g. pulse…

Quantum Physics · Physics 2020-02-20 Genko T. Genov , Marcel Hain , Nikolay V. Vitanov , Thomas Halfmann

Aperiodic dynamical decoupling (DD) sequences of $\pi$ pulses are of great interest to decoherence control and have been recently extended from single-qubit to two-qubit systems. If the environmental noise power spectrum is made available,…

Quantum Physics · Physics 2011-10-25 Yu Pan , Zai-Rong Xi , Jiangbin Gong

In the burgeoning field of quantum computing, the precise design and optimization of quantum pulses are essential for enhancing qubit operation fidelity. This study focuses on refining the pulse engineering techniques for superconducting…

Quantum Physics · Physics 2024-09-13 Annika S. Wiening , Joern Bergendahl , Vicente Leyton-Ortega , Peter Nalbach

Identifying and controlling decoherence in single electron sources (SES) is important for their applications in quantum information processing. The recent experiments with ultrashort electron pulses [J. D. Fletcher et al., Nat. Commun. 10,…

Mesoscale and Nanoscale Physics · Physics 2024-04-18 Sungguen Ryu , Rosa López , Llorenç Serra , David Sanchez , Michael Moskalets

Simple constructions and protocols are demonstrated to allow the implementation of universal quantum computation on an arbitrarily large quantum system by controlling a fixed number of spins, vastly reducing the engineering requirements in…

Quantum Physics · Physics 2009-04-23 Alastair Kay

One of the most significant hurdles to be overcome on the path to practical quantum information processors is dealing with quantum errors. Dynamical decoupling is a particularly promising approach that complements conventional quantum error…

Motion-induced dephasing is a dominant decoherence mechanism for atom-gas quantum memories. In this paper, we develop a new coherent manipulation technique which enables arbitrary engineering of the spin-wave momentum with neglectable…

Quantum Physics · Physics 2018-09-05 Yan Jiang , Jun Rui , Xiao-Hui Bao , Jian-Wei Pan

The central spin decoherence problem has been researched for over 50 years in the context of both nuclear magnetic resonance and electron spin resonance. Until recently, theoretical models have employed phenomenological stochastic…

Mesoscale and Nanoscale Physics · Physics 2012-08-03 Wayne M. Witzel , Malcolm S. Carroll , Lukasz Cywinski , S. Das Sarma

Maintaining quantum coherence is a crucial requirement for quantum computation; hence protecting quantum systems against their irreversible corruption due to environmental noise is an important open problem. Dynamical decoupling (DD) is an…

Quantum Physics · Physics 2011-03-24 Ashok Ajoy , Gonzalo A. Alvarez , Dieter Suter