Engineered Randomness for Ubiquitous Quantum-Enhanced Metrology in Exponential-Dimensional Manifolds
Center for Intelligence and Quantum Science (CIQS)（智能与量子科学中心）；Hubei Key Laboratory of Gravitation and Quantum Physics（引力与量子物理湖北省重点实验室）；Department of Physics, University of California, Berkeley（加州大学伯克利分校物理系）；Challenge Institute for Quantum Computation, University of California, Berkeley（加州大学伯克利分校挑战量子计算研究所）；Theoretical Physics III, Center for Electronic Correlations and Magnetism, Institute of Physics（理论物理III，电子关联与磁学中心，物理研究所）；Centre for Advanced Analytics and Predictive Sciences (CAAPS)（高级分析与预测科学中心）；CENOLI, Université Libre de Bruxelles（布鲁塞尔自由大学CENOLI）；International Solvay Institutes（国际索尔维研究所）；Laboratoire Kastler Brossel, Collège de France, CNRS（法国科学院CNRS卡斯勒-布罗塞尔实验室，法兰西学院）；International Joint Laboratory on Quantum Sensing and Quantum Metrology, School of Physics, Huazhong University of Science and Technology（华中科技大学物理学院量子传感与计量国际联合实验室）；Institute for Quantum Science and Engineering, Huazhong University of Science and Technology（华中科技大学量子科学与工程研究院）；University of Augsburg（奥格斯堡大学）
Yaoming Chu, Baiyi Yu, Hartmut Häffner, Markus Heyl, Nathan Goldman, Jianming Cai
The exponential growth of many-body Hilbert space presents a fundamental barrier to quantum technology, obscuring the search for physically significant states within an astronomically vast landscape. Consequently, resources for quantum-enhanced metrology have been largely confined to the symmetric subspace whose dimensionality scales only polynomially with the particle number-leaving the vast majority of the Hilbert space largely unexplored and poorly understood. Here we challenge this paradigm by demonstrating that metrological advantage can arise as a ubiquitous feature across exponential-dimensional manifolds. By tailoring the first-moment structure of random unitaries, we uncover dense manifolds of engineered random states (ERSs) where Heisenberg-limited scaling emerges as a statistically generic property. This ubiquity endows these resource states with inherent resilience against parameter disorder. We experimentally validate this framework on a trapped-ion processor, achieving a metrological enhancement of $6.98 \pm 0.38$ dB beyond the standard quantum limit. Potential applications extend to diverse platforms, ranging from superconducting circuits and waveguide QED to solid-state spins and polar molecules. Our results establish a powerful paradigm where quantum-enhanced precision can be harvested from the exponential vastness of the Hilbert space.
We introduce the notion of fault-tolerant quantum metrology to overcome noise beyond our control -- associated with sensing the parameter, by reducing the noise in operations under our control -- associated with preparing and measuring probes and ancillae. To that end, we introduce noise thresholds to quantify the noise resilience of parameter estimation schemes. We demonstrate improved noise thresholds over the non-fault-tolerant schemes. We use quantum Reed-Muller codes to retrieve more information about a single phase parameter being estimated in the presence of full-rank Pauli noise. Using…
Heisenberg-limited metrology in the presence of non-Markovian noise with finite control rates
Center for Quantum Information and Control, University of New Mexico（新墨西哥大学量子信息与控制中心）；Department of Physics and Astronomy, University of New Mexico（新墨西哥大学物理与天文学系）
Parameter estimation is of fundamental importance in areas from atomic spectroscopy and atomic clocks to gravitational wave detection. Entangled probes provide a significant precision gain over classical strategies in the absence of noise. However, recent results seem to indicate that any small amount of realistic noise restricts the advantage of quantum strategies to an improvement by at most a multiplicative constant. Here, we identify a relevant scenario in which one can overcome this restriction and attain superclassical precision scaling even in the presence of uncorrelated noise. We show…
In bosonic quantum metrology, the estimate of a loss parameter is typically performed by means of pure states, such as coherent, squeezed or entangled states, while mixed thermal probes are discarded for their inferior performance. Here we show that thermal sources with suitable correlations can be engineered in such a way to approach, or even surpass, the error scaling of coherent states in the presence of general Gaussian decoherence. Our findings pave the way for practical quantum metrology with thermal sources in optical instruments (e.g., photometers) or at different wavelengths (e.g., fa…
Quantum metrology promises high-precision measurements beyond the capability of any classical techniques, and has the potential to be integral to investigative techniques. However, all sensors must tolerate imperfections if they are to be practical. Here we show that photons with perfectly overlapped modes, which are therefore fully indistinguishable, are not required for quantum-enhanced measurement, and that partially-distinguishable photons do not have to be engineered to mitigate the adverse effects of distinguishability. We quantify the effect of distinguishability on quantum metrology ex…
Quantum state transfer in the presence of noise is one of the main challenges in building quantum computers. We compare the quantum state transfer properties for two classes of qubit chains under the influence of static randomness. In fully engineered chains all nearest-neighbor couplings are tuned in such a way that a single-qubit state can be transferred perfectly between the ends of the chain, while in boundary-controlled chains only the two couplings between the transmitting and receiving qubits and the remainder of the chain can be optimized. We study how the noise in the couplings affect…
Integrated optical devices are expected to play a promising role in the field of quantum information science and technology. In this paper, we propose a scheme for the generation of nondegenerate, copolarised, modal, and path- entangled photons using a directional coupler and an asymmetric Y-coupler geometry in type 0 phase-matched domain engineered lithium niobate(LN) waveguide. The nonlinearity in LN is tailored in such a way that quasi phase matching conditions for two different spontaneous parametric down conversion processes are obeyed simultaneously, leading to a modal and path-entangled…
Making use of coherence and entanglement as metrological quantum resources allows to improve the measurement precision from the shot-noise- or quantum limit to the Heisenberg limit. Quantum metrology then relies on the availability of quantum engineered systems that involve controllable quantum degrees of freedom which are sensitive to the measured quantity. Sensors operating in the qubit mode and exploiting their coherence in a phase-sensitive measurement have been shown to approach the Heisenberg scaling in precision. Here, we show that this result can be further improved by operating the qu…
Noise robustness of three outcome Bell certified quantum randomness
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology（光子科学研究所，巴塞罗那科学技术学院）；Center for Theoretical Physics, Polish Academy of Sciences（波兰科学院理论物理中心）；Department of Algorithms and System Modeling, Faculty of Electronics, Telecommunications and Informatics, Gdańsk University of Technology（格但斯克理工大学电子、电信与信息学院算法与系统建模系）；ICREA-Institucio Catalana de Recerca i Estudis Avançats（加泰罗尼亚研究与高级研究学院）
The hybridization of distinct quantum systems is now seen as an effective way to engineer the properties of an entire system leading to applications in quantum metamaterials, quantum simulation, and quantum metrology. One well known example is superconducting circuits coupled to ensembles of microscopic natural atoms. In such cases, the properties of the individual atom are intrinsic, and so are unchangeable. However, current technology allows us to fabricate large ensembles of macroscopic artificial atoms such as superconducting flux qubits, where we can really tailor and control the properti…
Benchmarking weak randomness in Quantum and Natural Sources
University of Gdańsk（格但斯克大学）；University of Malta（马耳他大学）；Jagiellonian University（雅盖隆大学）；EMGG TerraData Limitada（EMGG TerraData有限公司）；Universidad de Concepción（康塞普西翁大学）；Universidad Católica de la Santísima Concepción（康塞普西翁天主教大学）；SeQure Quantum SpA（SeQure量子股份公司）
In quantum metrology, entanglement represents a valuable resource that can be used to overcome the Standard Quantum Limit (SQL) that bounds the precision of sensors that operate with independent particles. Measurements beyond the SQL are typically enabled by relatively simple entangled states (squeezed states with Gaussian probability distributions), where quantum noise is redistributed between different quadratures. However, due to both fundamental limitations and the finite measurement resolution achieved in practice, sensors based on squeezed states typically operate far from the true funda…
Entanglement is the central yet fleeting phenomena of quantum physics. Once being considered a peculiar counter-intuitive property of quantum theory it has developed into the most central element of quantum technology providing speed up to quantum computers, a path towards long distance quantum cryptography and increased sensitivity in quantum metrology. Consequently, there have been a number of experimental demonstration of entanglement between photons, atoms, ions as well as solid state systems like spins or quantum dots, superconducting circuits and macroscopic diamond. Here we experimental…
Tailoring Synthetic Gauge Fields in Ultracold Atoms via Spatially Engineered Vector Beams
State Key Laboratory of Optical Field Manipulation Science and Technology, Chinese Academy of Sciences（中国科学院光学场调控科学与技术重点实验室）；Research Center on Vector Optical Fields, Institute of Optics and Electronics, Chinese Academy of Sciences（中国科学院光电技术研究所矢量光场研究中心）；College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences（中国科学院大学材料科学与光电技术学院）
Joint Attosecond Science Laboratory (JASLab), National Research Council of Canada and University of Ottawa（联合阿秒科学实验室，加拿大国家研究委员会和渥太华大学）；Department of Physics, University of Ottawa（渥太华大学物理系）；Laboratory for Laser Energetics, University of Rochester（罗切斯特大学激光能量学实验室）；Nexus for Quantum Technologies, University of Ottawa（渥太华大学量子技术枢纽）；Department of Physics, University of Windsor（温莎大学物理系）
Nonlinear-enhanced wideband sensing via subharmonic excitation of a quantum harmonic oscillator
University of California Los Angeles（加州大学洛杉矶分校）；Challenge Institute for Quantum Computation, University of California Los Angeles（加州大学洛杉矶分校挑战量子计算研究所）；Center for Quantum Science and Engineering, University of California Los Angeles（加州大学洛杉矶分校量子科学与工程中心）
