Quantum and classical correlations of intense beams of light via joint photodetection

Quantum Trajectories for Realistic Photodetection I: General Formalism

Quantum trajectories describe the stochastic evolution of an open quantum system conditioned on continuous monitoring of its output, such as by an ideal photodetector. In practice an experimenter has access to an output filtered through various electronic devices, rather than the microscopic states of the detector. This introduces several imperfections into the measurement process, of which only inefficiency has previously been incorporated into quantum trajectory theory. However, all electronic devices have finite bandwidths, and the consequent delay in conveying the output signal to the obse…

Quantum state engineering assisted by entanglement

We suggest a general scheme for quantum state engineering based on conditional measurements carried out on entangled twin-beam of radiation. Realistic detection schemes such as {\sc on/off} photodetection, homodyne detection and joint measurement of two-mode quadratures are analyzed in details. Imperfections of the apparatuses, such as nonunit quantum efficiency and finite resolution, are taken into account. We show that conditional {\sc on/off} photodetection provides a reliable scheme to verify nonclassicality, whereas conditional homodyning represents a tunable and robust source of squeezed…

Observation of Anti-correlation of Classical Chaotic Light

We wish to report an experimental observation of anti-correlation from first-order incoherent classical chaotic light. We explain why the classical statistical theory does not apply and provide a quantum interpretation. In quantum theory, either correlation or anti-correlation is a two-photon interference phenomenon, which involves the superposition of two-photon amplitudes, a nonclassical entity corresponding to different yet indistinguishable alternative ways of producing a joint-photodetection event.

Entanglement of a pair of quantum emitters via continuous fluorescence measurements: a tutorial

We discuss recent developments in measurement protocols that generate quantum entanglement between two remote qubits, focusing on the theory of joint continuous detection of their spontaneous emission. We consider a device geometry similar to that used in well-known Bell-state measurements, which we analyze using a conceptually transparent model of stochastic quantum trajectories; we use this to review photodetection, the most straightforward case, and then generalize to the diffusive trajectories from homodyne and heterodyne detection as well. Such quadrature measurement schemes are a realist…

适用于联合光子数与光谱自由度的物理现实光探测的完整量子过程模型

A complete quantum process model for physically realistic photo-detection in the joint photon-number and spectral degrees of freedom

该研究针对光探测理论模型忽略光谱自由度的问题，提出结合光子数效应与频率依赖探测器响应的完整量子过程模型，可用于优化探测窗口以最大化量子效应可观测性。

纠缠激光束与量子鬼频率梳

Entangled laser beams and quantum ghost frequency comb

本文研究纠缠激光束在连续波运转下产生的量子鬼频率梳，揭示其100%对比度的周期性关联，并展示其在非局域精密测量中优于纠缠光子对的性能。