We study how the behavior of quantum noise, presenting the fundamental limit on the sensitivity of interferometric gravitational-wave detectors, depends on properties of input states of light. We analyze the situation with specially prepared nonclassical input states which reduce the photon-counting noise to the Heisenberg limit. This results in a great reduction of the optimum light power needed to achieve the standard quantum limit, compared to the usual configuration.
Quantum entanglement is the quintessence of quantum information processing mostly limited to the microscopic regime governed by Heisenberg uncertainty principle. For practical applications, however, macroscopic entanglement gives great benefits in both photon loss and sensitivity. Recently, a novel method of macroscopic entanglement generation has been proposed and demonstrated in a coupled interferometric system using classical laser light, where superposition between binary bases in each interferometric system plays a key role. Here, the function of path superposition applied to independent …
Recent experiments have demonstrated the generation of entanglement by quasi-adiabatically driving through quantum phase transitions of a ferromagnetic spin-1 Bose-Einstein condensate in the presence of a tunable quadratic Zeeman shift. We analyze, in terms of the Fisher information, the interferometric value of the entanglement accessible by this approach. In addition to the Twin-Fock phase studied experimentally, we unveil a second regime, in the broken axisymmetry phase, which provides Heisenberg scaling of the quantum Fisher information and can be reached on shorter time scales. We identif…
We propose an interferometric scheme for the estimation of a linear combination with non-negative weights of an arbitrary number $M>1$ of unknown phase delays, distributed across an $M$-channel linear optical network, with Heisenberg-limited sensitivity. This is achieved without the need of any sources of photon-number or entangled states, photon-number resolving detectors or auxiliary interferometric channels. Indeed, the proposed protocol remarkably relys upon a single squeezed state source, an antisqueezing operation at the interferometer output, and on-off photodetectors.
Demonstrating Heisenberg-limited unambiguous phase estimation without adaptive measurements
我们推导出，并通过实验证明，一个明确的相位估计与精确缩放的海森堡限制，不需要自适应测量的干涉计划。也就是说，在没有相位的先验知识的情况下，我们可以获得具有标准偏差的相位的估计，该标准偏差仅是比最小物理允许值大的小常数因子。我们的计划解决了相位模糊时存在的多个通过相移，或NOON状态，用于获得改善的相位分辨率。像最近引入的自适应技术[Higgins et al 2007 Nature 450 393]一样，我们的实验在单个光子上使用相移的多个应用。通过不需要自适应测量，而是使用预定的测量序列，本方案在概念上更简单并且明显更容易实现。此外，我们展示了一个简化的自适应方案，也超过了标准的单次量子限制。
High sensitivity quantum interferometry requires more than just access to entangled states. It is achieved through deep understanding of quantum correlations in a system. Integrable models offer the framework to develop this understanding. We communicate the design of interferometric protocols for an integrable model that describes the interaction of bosons in a four-site configuration. Analytic formulae for the quantum dynamics of certain observables are computed. These expose the system's functionality as both an interferometric identifier, and producer, of NOON states. Being equivalent to a…
The estimation of physical parameters with Heisenberg sensitivity and beyond is one of the crucial problems for current quantum metrology. However, unavoidable lossy effect is commonly believed to be the main obstacle when applying fragile quantum states. To utilize the lossy quantum metrology, we offer an interferometric procedure for phase parameters estimation at the Heisenberg (up to 1/N) and super-Heisenberg (up to 1/N^3) scaling levels in the framework of the linear and nonlinear metrology approaches, respectively. The heart of our setup is the novel soliton Josephson Junction (SJJ) syst…
In a Mach-Zenhder interferometer (MZI), the highest precision for a measurement error is given by vacuum fluctuations of quantum mechanics, resulting in a shot noise limit1,2,3,4,5. Because the intensity measurement in an MZI is correlated with the phase difference, the precision measurement (Δn) is coupled with the phase resolution (Δϕ) by the Heisenberg uncertainty principle. Quantum metrology offers a different solution to this precision measurement using nonclassical light such as squeezed light or higher-order entangled-photon pairs, resulting in a smaller Δϕ for the same Δn3,4,5,6,7,8. H…
Implications and applications of the variance-based uncertainty equalities
在量子力学中，基于方差的海森堡型不确定性关系是一系列数学不等式，它们对状态准备的可实现精度构成了基本限制。与此相反，我们构造并公式化了两个量子测不准等式，它们对所有的不相容观测量对都成立，并表明了L. Maccone和A. K. Pati [Phys. Rev. Lett. 113，260401（2014）]。此外，我们提出了一个明确的解释背后的推导，并将这些关系到所谓的智能状态。作为例子，我们研究了量子比特系统中这些不确定性不等式的性质，得到了方差和的一个与状态无关的界。最后，我们将这些不等式应用于自旋压缩情形，并讨论了它在干涉灵敏度中的意义。
Implementation of the quantum interferometry concept to spin-1 atomic Bose-Einstein condensates is analyzed by employing a polar state evolved in time. In order to identify the best interferometric configurations, the quantum Fisher information is maximized. Three optimal configurations are identified, among which one was not reported in the literature yet, although it gives the highest value of the quantum Fisher information in experimentally achievable short time dynamics. Details of the most optimal configurations are investigated based on the error-propagation formula which includes the in…
Quantum-Enhanced Phase Estimation with Photon-Added Even and Odd Coherent States in an SU(1,1) Interferometer
University of Ibn Tofail（伊本·图费勒大学）；Abdus Salam International Centre for Theoretical Physics (ICTP)（阿卜杜斯·萨拉姆理论物理国际中心）；Institute for Research in Fundamental Sciences (IPM)（基础科学研究所）
Distributed quantum phase sensing using an SU(1,1) Perelomov coherent state in a Mach-Zehnder interferometer network
Mohammed V University in Rabat（拉巴特穆罕默德五世大学）；Faculty of Sciences, Mohammed V University in Rabat（拉巴特穆罕默德五世大学理学院）；LPHE-Modeling and Simulation, Faculty of Sciences, Mohammed V University in Rabat（拉巴特穆罕默德五世大学理学院LPHE建模与模拟）；Centre of Physics and Mathematics, CPM, Faculty of Sciences, Mohammed V University in Rabat（拉巴特穆罕默德五世大学理学院物理与数学中心CPM）
The use of special quantum states to achieve sensitivities below the limits established by classically behaving states has enjoyed immense success since its inception. In bosonic interferometers, squeezed states, number states and cat states have been implemented on various platforms and have demonstrated improved measurement precision over interferometers based on coherent states. Another metrologically useful state is an equal superposition of two eigenstates with maximally different energies; this state ideally reaches the full interferometric sensitivity allowed by quantum mechanics. By le…
Optimal initial states for quantum Fisher information in linearized cavity optomechanics
School of Information Science and Engineering, Hunan Institute of Engineering（湖南工程学院信息科学与工程学院）；Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Synergetic Innovation Center for Quantum Effects and Applications, XJ-Laboratory and Department of Physics, Hunan Normal University（湖南师范大学物理与电子科学学院）；Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials, and Department of Physics, Hunan University of Science and Technology（湖南科技大学物理与电子科学学院）；College of Physics and Electronic Engineering, Hengyang Normal University（衡阳师范学院物理与电子工程学院）
