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In this work we study One Axis Twisting (OAT) spin squeezing for metrology in the presence of decoherence. We study Linbladian evolution in the presence of both T_1 and T_2 (longitudinal and transverse relaxation processes). We show that…

Quantum Physics · Physics 2024-03-22 Garry Goldstein

Displacement sensing is a fundamental task in metrology. However, the development of quantum-enhanced sensors that fully utilize the available degrees of freedom in many-body quantum systems remains an outstanding challenge. We propose…

Spin squeezing serves as both a fundamental witness of quantum entanglement and a critical resource for quantum-enhanced metrology. While generating substantial spin squeezing in finite-range interacting systems remains challenging, such…

Quantum Physics · Physics 2026-04-01 Ang Li , Ling-Na Wu , Li You

The control over quantum states in atomic systems has led to the most precise optical atomic clocks to date. Their sensitivity is currently bounded by the standard quantum limit, a fundamental floor set by quantum mechanics for uncorrelated…

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

Quantum optimal control theory (QOCT) can be used to design the shape of electromagnetic pulses that implement operations on quantum devices. By using non-trivially shaped waveforms, gates can be made significantly faster than those built…

Quantum Physics · Physics 2026-02-27 Alonso Hernández-Antón , Fernando Luis , Alberto Castro

This study investigates spin squeezed states in nuclear magnetic resonance (NMR) quadrupolar systems with spins $I=3/2$ and $I=7/2$ at room temperature, taking into account the effects of relaxation on the dynamics. The origin of spin…

We report successful manipulation of non-classical atomic spin states. We generate squeezed spin states by a spin quantum nondemolition measurement, and apply an off-resonant circularly-polarized light pulse to the atoms. By changing the…

Quantum Physics · Physics 2015-05-14 Tetsushi Takano , Shin-Ichi-Ro Tanaka , Ryo Namiki , Yoshiro Takahashi

One of the most important tasks in modern quantum science is to coherently control and entangle many-body systems, and to subsequently use these systems to realize powerful quantum technologies such as quantum-enhanced sensors. However,…

Quantum metrology enables estimation of optical phase shifts with precision beyond the shot-noise limit. One way to exceed this limit is to use squeezed states, where the quantum noise of one observable is reduced at the expense of…

Nuclear magnetic resonance (NMR) experiments can reveal local properties in materials, but are often limited by the low signal-to-noise ratio. Spin squeezed states have an improved resolution below the Heisenberg limit in one of the spin…

Spin-squeezing is a well-established "quantum technology", where well-designed correlations in an ensemble of two-level systems reduce the statistical uncertainty of spectroscopic experiments. This paper reviews some important advances in…

Quantum Gases · Physics 2022-03-31 Alice Sinatra

We study the spin squeezing in a spin-1/2 Bose-Einstein condensates (BEC) with Raman induced spin-orbit coupling (SOC). Under the condition of two-photon resonance and weak Raman coupling strength, the system possesses two degenerate ground…

Quantum Gases · Physics 2020-08-26 Li Chen , Yunbo Zhang , Han Pu

The generation and storage of spin squeezing is an attracting topic in quantum metrology and the foundations of quantum mechanics. The major models to realize the spin squeezing are the one- and two-axis twisting models. Here, we consider a…

Quantum Physics · Physics 2021-03-10 Qing-Shou Tan , Mao Zhang , Yu Chen , Jie-Qiao Liao , Jing Liu

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…

A major challenge in quantum metrology is the generation of entangled states with macroscopic atom number. Here, we demonstrate experimentally that atomic squeezing generated via non-linear dynamics in Bose Einstein condensates, combined…

Quantum Physics · Physics 2015-06-19 W. Muessel , H. Strobel , D. Linnemann , D. B. Hume , M. K. Oberthaler

Entanglement in a many-particle system can enable measurement sensitivities beyond that achievable by only classical correlations. For an ensemble of spins, all-to-all interactions are known to reshape the quantum projection noise, leading…

We investigate the process of spin squeezing in a ferromagnetic dipolar spin-1 Bose-Einstein condensate under the driven oneaxis twisting scheme, with emphasis on the detrimental effect of noisy environments (stray magnetic fields) which…

Quantum Gases · Physics 2017-11-15 Peng Xu , Huanying Sun , S. Yi , Wenxian Zhang

Spin noise spectroscopy is emerging as a powerful technique for studying the dynamics of various spin systems also beyond their thermal equilibrium and linear response. Here, we study spin fluctuations of room-temperature neutral atoms in a…

Atomic Physics · Physics 2021-07-21 V. Guarrera , R. Gartman , G. Bevilacqua , W. Chalupczak

The coherent population trapping (CPT) effect is used for making compact atomic clocks. There are two types of CPT clocks: the one in which the Raman beams are applied continuously and the one in which two CPT pulses separated by a dark…