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Non-vanishing fluctuations of the vacuum state are a salient feature of quantum theory. These fluctuations fundamentally limit the precision of quantum sensors. Nowadays, several systems such as optical clocks, gravitational wave detectors,…

Quantum spin dephasing is caused by inhomogeneous coupling to the environment, with resulting limits to the measurement time and precision of spin-based sensors. The effects of spin dephasing can be especially pernicious for dense ensembles…

Nitrogen vacancy (NV) centers in diamond are widely deployed as local magnetic sensors, using coherent, single qubit control to measure both time-averaged fields and noise with nanoscale spatial resolution. Moving beyond single qubits to…

Quantum Physics · Physics 2025-04-18 Jared Rovny , Shimon Kolkowitz , Nathalie P. de Leon

High-sensitivity quantum sensors are a promising tool for experimental searches for beyond-Standard-Model interactions. Here, we demonstrate an atomic comagnetometer operating under a resonantly-coupled hybrid spin-resonance (HSR) regime to…

Quantum Physics · Physics 2025-05-02 Xing Heng , Zitong Xu , Xiaofei Huang , Dinghui Gong , Guoqing Tian , Wei Ji , Jiancheng Fang , Dmitry Budker , Kai Wei

Recent advances in the engineering of diamond surfaces make it possible to stabilize the charge state of 7-30 nanometers deep nitrogen-vacancy (NV) quantum sensors in diamond and to remove the charge noise at the surface principally.…

Quantum Physics · Physics 2025-01-23 Anton Pershin , András Tárkányi , Vladimir Verkhovlyuk , Viktor Ivády , Adam Gali

Spin-squeezed states constitute a valuable entanglement resource capable of surpassing the standard quantum limit (SQL). However, spin-squeezed states only enable sub-SQL uncertainty within a narrow parametric window near some specific…

Quantum Physics · Physics 2025-10-10 Jinye Wei , Jungeng Zhou , Yi Shen , Jiahao Huang , Chaohong Lee

Measurement underpins all quantitative science. A key example is the measurement of optical phase, used in length metrology and many other applications. Advances in precision measurement have consistently led to important scientific…

Quantum Physics · Physics 2008-11-26 B. L. Higgins , D. W. Berry , S. D. Bartlett , H. M. Wiseman , G. J. Pryde

As a crucial resource in the field of quantum metrology, spin squeezing can facilitate highly precise measurements that surpass the limitations imposed by classical physics. However, the quantum advantage of spin squeezing is significantly…

Quantum Physics · Physics 2026-05-13 Lin Jiao , Han Pu , Jun-Hong An

Spin squeezing can improve atomic precision measurements beyond the standard quantum limit (SQL), and unitary spin squeezing is essential for improving atomic clocks. We report substantial and nearly unitary spin squeezing in $^{171}$Yb, an…

Entanglement plays a crucial role in proposals for quantum metrology, yet demonstrating quantum enhancement in sensing with sustained spin entanglement remains a challenging endeavor. Here, we combine optical pumping and continuous quantum…

Quantum Physics · Physics 2025-04-09 Junlei Duan , Zhiwei Hu , Xingda Lu , Liantuan Xiao , Suotang Jia , Klaus Mølmer , Yanhong Xiao

Motivated by the recent experimental progress in exploring the use of a nitrogen-vacancy (NV) center in diamond as a quantum computing platform, we propose schemes for fast and high-fidelity entangling gates on this platform. Using both…

Quantum Physics · Physics 2025-08-07 Regina Finsterhoelzl , Wolf-Rüdiger Hannes , Guido Burkard

Quantum technologies use entanglement to outperform classical technologies, and often employ strong cooling and isolation to protect entangled entities from decoherence by random interactions. Here we show that the opposite strategy -…

Coherent coupling between single quantum objects is at the heart of modern quantum physics. When coupling is strong enough to prevail over decoherence, it can be used for the engineering of correlated quantum states. Especially for…

Quantum metrology allows for a huge boost in the precision of parameters estimation. However, it seems to be extremely sensitive on the noise. Bound entangled states are states with large amount of noise what makes them unusable for almost…

Quantum Physics · Physics 2015-12-09 L. Czekaj , A. Przysiezna , M. Horodecki , P. Horodecki

Entanglement, as a key resource for modern quantum technologies, is extremely fragile due to the decoherence. Here, we show that a quantum autoencoder, which is trained to compress a particular set of quantum entangled states into a…

Quantum Physics · Physics 2022-10-12 Feifei Zhou , Yu Tian , Yumeng Song , Chudan Qiu , Xiangyu Wang , Mingti Zhou , Bing Chen , Nanyang Xu , Dawei Lu

In this paper, we investigate spin squeezing in a hybrid quantum system consisting of a Silicon-Vacancy (SiV) center ensemble coupled to a diamond acoustic waveguide via the strain interaction. Two sets of non-overlapping driving fields,…

Quantum Physics · Physics 2023-08-11 Zhen-Qiang Ren , Xian-Liang Lu , Ze-Liang Xiang

We use multi-pulse dynamical decoupling to increase the coherence lifetime (T2) of large numbers of nitrogen-vacancy (NV) electronic spins in room temperature diamond, thus enabling scalable applications of multi-spin quantum information…

Mesoscale and Nanoscale Physics · Physics 2015-06-03 L. M. Pham , N. Bar-Gill , C. Belthangady , D. Le Sage , P. Cappellaro , M. D. Lukin , A. Yacoby , R. L. Walsworth

Quantum sensors, such as the Nitrogen Vacancy (NV) color center in diamond, are known for their exquisite sensitivity, but their performance over time are subject to degradation by environmental noise. To improve the long-term robustness of…

Developing the isolation and control of ultracold atomic systems to the level of single quanta has led to significant advances in quantum sensing, yet demonstrating a quantum advantage in real world applications by harnessing entanglement…

Interferometric phase estimation is an essential tool for precise measurements of quantities such as displacement, velocity and material properties. The lower bound on measurement uncertainty achievable with classical resources is set by…

Quantum Physics · Physics 2024-07-23 Shakib Daryanoosh , Geoff J. Pryde , Howard M. Wiseman , Sergei Slussarenko