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Realizing useful quantum operations with high fidelity is a two-task quantum control problem wherein decoherence is to be suppressed and desired unitary evolution is to be executed. The dynamical decoupling (DD) approach to decoherence…

Quantum Physics · Physics 2012-07-17 Adam Zaman Chaudhry , Jiangbin Gong

Quantum state control is a fundamental tool for quantum technologies. In this work, we propose and analyze the use of quantum optimal control to exploit the dipolar interaction of ultracold atoms on a lattice ring, focusing on the…

Spin squeezing generated via inter-atom entanglement in multilevel atomic ensembles provides a powerful resource for quantum-enhanced metrology. Existing schemes that harness internal atomic degrees of freedom to boost squeezing typically…

Quantum Physics · Physics 2026-05-18 Zhiwei Hu , Youwei Zhang , Junlei Duan , Mingfeng Wang , Yanhong Xiao

We study the effect of dipolar interactions on the level of squeezing in spin-1 Bose-Einstein condensates by using the single mode approximation. We limit our consideration to the $\mathfrak{su}(2)$ Lie subalgebra spanned by spin operators.…

Quantum Gases · Physics 2016-02-24 Dariusz Kajtoch , Emilia Witkowska

Spin squeezing is vitally important in quantum metrology and quantum information science. The noise reduction resulting from spin squeezing can surpass the standard quantum limit and even reach the Heisenberg Limit (HL) in some special…

Quantum Physics · Physics 2023-08-25 Zhiyao Hu , Qixian Li , Xuanchen Zhang , Long-Gang Huang , He-bin Zhang , Yong-Chun Liu

We apply innovative mathematical tools coming from optimal control theory to improve theoretical and experimental techniques in Magnetic Resonance Imaging (MRI). This approach allows us to explore and to experimentally reach the physical…

Quantum Physics · Physics 2017-09-11 E. Van-Reeth , H. Ratiney , M. Lapert , S. J. Glaser , D. Sugny

We propose a new protocol for preparing spin squeezed states in controllable atomic, molecular, and optical systems, with particular relevance to emerging optical clock platforms compatible with Rydberg interactions. By combining a…

Quantum Physics · Physics 2022-08-04 Jeremy T. Young , Sean R. Muleady , Michael A. Perlin , Adam M. Kaufman , Ana Maria Rey

The advent of quantum devices, which exploit the two essential elements of quantum physics, coherence and entanglement, has sparked renewed interest in the control of open quantum systems. Successful implementations face the challenge to…

Quantum Physics · Physics 2016-05-05 Christiane P. Koch

We establish the conditions under which scalable spin squeezing can be achieved in interacting spin ensembles embedded in arbitrary, inhomogeneous graph geometries. We identify two different forms of squeezing: OAT-like scalable squeezing…

Quantum Physics · Physics 2026-05-26 Andrea Solfanelli , Augusto Smerzi , Peter Zoller , Nicolò Defenu

We analyze the collective spin noise in interacting spin systems. General expressions are derived for the short time behaviour of spin systems with general spin-spin interactions, and we suggest optimum experimental conditions for the…

Quantum Physics · Physics 2009-11-07 Xiaoguang Wang , Anders S. Sorensen , Klaus Molmer

Squeezing currently represents the leading strategy for quantum enhanced precision measurements of a single parameter in a variety of continuous- and discrete-variable settings and technological applications. However, many important…

Quantum Physics · Physics 2020-07-31 Manuel Gessner , Augusto Smerzi , Luca Pezzè

Spin squeezing is a form of entanglement that reshapes the quantum projection noise to improve measurement precision. Here, we provide numerical and analytic evidence for the following conjecture: any Hamiltonian exhibiting finite…

Optimal control is a central problem in quantum thermodynamics. When minimizing dissipated work and work fluctuations defined via the two-point measurement scheme in open quantum systems, existing approaches largely focus on the rapid- and…

Quantum Physics · Physics 2026-04-08 Yuki Kurokawa , Yoshihiko Hasegawa

This dissertation studies spin squeezing, entanglement and decoherence in large ensembles of cold, trapped alkali atoms with hyperfine spin f interacting with optical fields. Restricting the state of each atom to a qutrit embedded in the…

Quantum Physics · Physics 2014-10-02 Leigh M. Norris

We apply optimal control techniques to an inhomogeneous spin ensemble coupled to a cavity. A general procedure is proposed for designing the control strategies. We numerically show the extent to which optimal control fields robust against…

Quantum Physics · Physics 2018-09-12 Q. Ansel , S. Probst , P. Bertet , S. J. Glaser , D. Sugny

Quantum entanglement, in the form of spin squeezing, is known to improve the sensitivity of atomic sensors to static or slowly varying fields. Sensing transient events presents a distinct challenge, requires different analysis tools, and…

Quantum Physics · Physics 2025-12-08 Julia Amoros-Binefa

Useful quantum metrology requires nonclassical states with a high particle number and (close to) the optimal exploitation of the state's quantum correlations. Unfortunately, the single-particle detection resolution demanded by conventional…

Quantum Physics · Physics 2017-11-08 Samuel P. Nolan , Stuart S. Szigeti , Simon A. Haine

Robust quantum control can achieve noise-resilience of quantum systems and quantum technological devices. While the need for noise-resilience grows with the number of fluctuating quantities, and thus typically with the number of qubits,…

We study the generation of metrologically useful entanglement in a three-level (spin-1) system naturally realized in arrays of dipole-interacting Rydberg atoms confined in optical tweezers. In the spin-quadrupolar operator basis, the…

Quantum Physics · Physics 2026-05-04 Sakshi Bahamnia , Thomas Bilitewski

Spin squeezing protocols successfully generate entangled many-body quantum states, the key pillars of the second quantum revolution. In our recent work [Phys. Rev. Lett. 129, 090403 (2022)] we showed that spin squeezing described by the…