Measuring the Complete Transverse Spatial Mode Spectrum of a Wave Field

Measuring the Chern number of Hofstadter bands with ultracold bosonic atoms

Sixty years ago, Karplus and Luttinger pointed out that quantum particles moving on a lattice could acquire an anomalous transverse velocity in response to a force, providing an explanation for the unusual Hall effect in ferromagnetic metals. A striking manifestation of this transverse transport was then revealed in the quantum Hall effect, where the plateaus depicted by the Hall conductivity were attributed to a topological invariant characterizing Bloch bands: the Chern number. Until now, topological transport associated with non-zero Chern numbers has only been revealed in electronic system…

Measuring complete quantum states with a single observable

Experimental determination of an unknown quantum state usually requires several incompatible measurements. However, it is also possible to determine the full quantum state from a single, repeated measurement. For this purpose, the quantum system whose state is to be determined is first coupled to a second quantum system (the "assistant") in such a way that part of the information in the quantum state is transferred to the assistant. The actual measurement is then performed on the enlarged system including the original system and the assistant. We discuss in detail the requirements of this proc…

Scheme for on-chip verification of transverse mode entanglement using the electro-optic effect

A key ingredient in emerging quantum-enhanced technologies is the ability to coherently manipulate and detect superpositions of basis states. In integrated optics implementations, transverse spatial modes supported by multimode structures offer an attractive carrier of quantum superpositions. Here we propose an integrated dynamic mode converter based on the electro-optic effect in nonlinear channel waveguides for deterministic transformations between mutually non-orthogonal bases of spatial modes. We theoretically show its capability to demonstrate a violation of a Bell-type Clauser-Horne-Shim…

测量纠缠双光子场的完整空间Schmidt模式集

Measuring the complete set of spatial Schmidt modes of entangled two-photon fields

本文提出了一种无需先验知识即可测量纠缠双光子场完整空间Schmidt模式集的技术，实现了最高3000多个模式的测量，信度达98%。

Determination of the Anisotropy of Permittivity of Quantum Paraelectric Strontium Titanate

The dielectric properties of strontium titanate (SrTiO$_3$) have previously been reported from room temperature to low temperatures with conflicting results. In this work, precision measurement of the permittivity is undertaken by simultaneously measuring transverse electric and transverse magnetic resonant modes within a single crystal. It is unequivocally shown that the permittivity is isotropic at room temperature with a permittivity of order $316.3\pm2.2$ by measuring multiple modes of different electric field polarisations. As the crystal is cooled to 5 K and undergoes well known phase tr…

Transverse-Field Ising Dynamics in a Rydberg-Dressed Atomic Gas

We report on the realization of long-range Ising interactions in a cold gas of cesium atoms by Rydberg dressing. The interactions are enhanced by coupling to Rydberg states in the vicinity of a Förster resonance. We characterize the interactions by measuring the mean-field shift of the clock transition via Ramsey spectroscopy, observing one-axis twisting dynamics. We furthermore emulate a transverse-field Ising model by periodic application of a microwave field and detect dynamical signatures of the paramagnetic-ferromagnetic phase transition. Our results highlight the power of optical address…

利用双光子干涉实现超灵敏横向偏转测量

Ultrasensitive Transverse Deflection Measurement with Two-photon Interference

本研究提出并实验演示了一种空间 HOM 干涉技术，通过横向动量采样测量光束横向偏转，利用 Fisher 信息分析确定最佳工作点，规避了衍射极限下的直接成像分辨率要求，实现了高精度空间传感。

Measuring quantum states: an experimental setup for measuring the spatial density matrix

To quantify the effect of decoherence in quantum measurements, it is desirable to measure not merely the square modulus of the spatial wavefunction, but the entire density matrix, whose phases carry information about momentum and how pure the state is. An experimental setup is presented which can measure the density matrix (or equivalently, the Wigner function) of a beam of identically prepared charged particles to an arbitrary accuracy, limited only by count statistics and detector resolution. The particles enter into an electric field causing simple harmonic oscillation in the transverse dir…

通过横向里德伯阻塞相互作用的光子的空间关联

Spatial correlations of photons interacting via transverse Rydberg blockade

该研究建立里德伯非线性介质中相互作用光子的横向空间动力学理论，推导关联函数定量预测，确立横向里德伯阻塞为可测量关联机制，为测量阻塞半径提供直接手段。

测量神经网络量子态中的Renyi熵

Measuring Renyi Entropy in Neural Network Quantum States

该研究通过交换算符和神经网络态计算一维横向场Ising模型的Renyi熵，揭示临界点、共形场论行为及淬火后的振荡和新的长度尺度。