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Long qubit coherence and efficient atom-photon coupling are essential for advanced applications in quantum communication. One technique to maintain coherence is dynamical decoupling, where a periodic sequence of refocusing pulses is…

Quantum Physics · Physics 2021-02-02 Chang Hoong Chow , Boon Long Ng , Christian Kurtsiefer

The coherence time of an electron spin decohered by the nuclear spin environment in a quantum dot can be substantially increased by subjecting the electron to suitable dynamical decoupling sequences. We analyze the performance of high-level…

Mesoscale and Nanoscale Physics · Physics 2008-03-27 Wenxian Zhang , N. P. Konstantinidis , V. V. Dobrovitski , B. N. Harmon , Lea F. Santos , Lorenza Viola

Dynamical decoupling techniques constitute an integral part of many quantum sensing platforms, often leading to orders-of-magnitude improvements in coherence time and sensitivity. Most AC sensing sequences involve a periodic echo-like…

We investigate the dynamics of key quantum correlations - Negativity (NG), Quantum Discord (QD), and Quantum-Memory-Assisted Entropic Uncertainty (QM-EUR) - in a bipartite two-qubit system under the influence of external pulses and various…

Quantum Physics · Physics 2025-11-17 Aqsa Mushtaq , Chaimae Banouni , Mahboob Ul Haq , S. M. Zangi

We explore the physical limits of pulsed dynamical decoupling methods for decoherence control as determined by finite timing resources. By focusing on a decohering qubit controlled by arbitrary sequences of $\pi$-pulses, we establish a…

Quantum Physics · Physics 2011-04-11 Kaveh Khodjasteh , Tamás Erdélyi , Lorenza Viola

Dynamical decoupling has been actively investigated since Viola first suggested using a pulse sequence to protect a qubit from decoherence. Since then, many schemes of dynamical decoupling have been proposed to achieve high-order…

Quantum Physics · Physics 2015-09-09 Haoyu Qi , Jonathan P. Dowling

We study the doubly nonnegative (DNN) relaxation of the standard quadratic optimization problem \[ \min\{x^\top Qx:\ x\in\Delta^{n-1}\},\qquad \Delta^{n-1}:=\{x\in\mathbb{R}_+^n:\ \mathbb{1}^\top x=1\}, \] for random symmetric matrices with…

Optimization and Control · Mathematics 2026-05-14 Xin Chen

Quantum non-demolition (QND) measurement of collective variables by off-resonant optical probing has the ability to create entanglement and squeezing in atomic ensembles. Until now, this technique has been applied to real or effective spin…

Quantum Physics · Physics 2015-05-19 M. Koschorreck , M. Napolitano , B. Dubost , M. W. Mitchell

The interaction of a quantum system with its environment limits its coherence time. This, in particular, restricts the utility of qubits in quantum information processing applications. In this paper, we show that the decoherence of a…

Mesoscale and Nanoscale Physics · Physics 2025-08-25 L. M. J. Hall , L. S. Sirkina , A. Morreau , W. Langbein , E. A. Muljarov

We study the pairwise quantum discord (QD) for a symmetric multi-qubit system in different types of noisy channels, such as phase-flip, amplitude damping, phase-damping, and depolarizing channels. Using the QD and geometric measure of…

Quantum Physics · Physics 2016-02-17 You-neng Guo , Mao-fa Fang , Zeng Ke , Guo-you Wang

The dynamics of a decohering two-level system driven by a suitable control Hamiltonian is studied. The control procedure is implemented as a sequence of radiofrequency pulses that repetitively flip the state of the system, a technique that…

Quantum Physics · Physics 2009-10-31 Lorenza Viola , Seth Lloyd

We investigate the usefulness and viability of the scheme developed by Viola and Lloyd [Phys. Rev. A 58, 2733 (1998)] to control dephasing in the context of exciton-based quantum computation with self-assembled quantum dots. We demonstrate…

Mesoscale and Nanoscale Physics · Physics 2008-03-31 Thomas E. Hodgson , Lorenza Viola , Irene D'Amico

We analyze the robust character against non-static noise of clock transitions implemented via a method of continuous dynamical decoupling (CDD) in a hyperfine Zeeman multiplet in ^{87}\textrm{Rb}. The emergence of features specific to the…

Quantum Physics · Physics 2023-11-16 J. M. Gomez Llorente , I. Gomez-Ojeda , J. Plata

We present a unified scheme for generating high-fidelity entangling gates in superconducting platforms by continuous dynamical decoupling (CDD) combined with variational minimal-energy optimal control. During the CDD stage, we suppress…

The application of dynamical decoupling pulses to a single qubit interacting with a linear harmonic oscillator bath with $1/f$ spectral density is studied, and compared to the Ohmic case. Decoupling pulses that are slower than the fastest…

Quantum Physics · Physics 2009-11-07 K. Shiokawa , D. A. Lidar

In this work, we investigate the dynamics of quantum correlations captured by entropic and geometric measures of discord under the influence of dissipative channels for widely used two qubit X state with maximally mixed marginals.…

Quantum Physics · Physics 2022-05-31 Nitish Kumar Chandra , Sarang S. Bhosale , Prasanta K. Panigrahi

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 study charge detection and controlled dephasing of a mesoscopic system via a quantum dot detector (QDD), where the mesoscopic system and the QDD are capacitively coupled. The QDD is considered to have coherent resonant tunnelling via a…

Mesoscale and Nanoscale Physics · Physics 2015-06-25 Gyong Luck Khym , Youngnae Lee , Kicheon Kang

A fundamental challenge for quantum information processing is reducing the impact of environmentally-induced errors. Quantum error detection (QED) provides one approach to handling such errors, in which errors are rejected when they are…

Quantum Physics · Physics 2014-01-28 Y. P. Zhong , Z. L. Wang , John M. Martinis , A. N. Cleland , A. N. Korotkov , H. Wang

As quantum computers mature, quantum error correcting codes (QECs) will be adopted in order to suppress errors to any desired level $E$ at a cost in qubit-count $n$ that is merely poly-logarithmic in $1/E$. However in the NISQ era, the…

Quantum Physics · Physics 2021-09-17 Bálint Koczor