Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences最新文献

Driven optical cavities containing a nonlinear medium support stable dissipative solitons, cavity solitons, in the form of bright or dark spots of light on a uniformly-lit background. Broadening effects due to diffraction or group velocity dispersion are balanced by the nonlinear interaction with the medium while cavity losses balance the input energy. The history, properties, physical interpretation and wide application of cavity solitons are reviewed. Cavity solitons in the plane perpendicular to light propagation find application in optical information processing, while cavity solitons in the longitudinal direction produce high-quality frequency combs with applications in optical communications, frequency standards, optical clocks, future GPS, astronomy and quantum technologies.This article is part of the theme issue 'The quantum theory of light'.

The controlled SWAP test for detecting and quantifying entanglement applied to pure qubit states is robust to small errors in the states and efficient for large multi-qubit states (Foulds et al. 2021 Quantum Sci. Technol. 6, 035002 (doi:10.1088/2058-9565/abe458)). We extend this, and the related measure concentratable entanglement (CE), to enable important practical applications in quantum information processing. We investigate the lower bound of concentratable entanglement given in (Beckey et al. 2023 Phys. Rev. A 107, 062425 (doi:10.1103/physreva.107.062425)) and conjecture an upper bound of the mixed-state concentratable entanglement that is robust to c-SWAP test errors. Since experimental states are always slightly mixed, our work makes the c-SWAP test and CE measure suitable for application in experiments to characterize entanglement. We further present the CE of some key higher-dimensional states such as qudit states and entangled optical states to validate the CE as a higher-dimensional measure of entanglement.This article is part of the theme issue 'The quantum theory of light'.

Quantum retrodiction, in which the state of a quantum system prior to a measurement is assigned based on the results of that measurement, has had a long history and has been used in quantum optics research for decades. Here we summarize the theory and point out some of the more interesting results, before applying the theory to state identification from multiple shots of an experiment. One surprising result is that we show that a photodetector with low quantum efficiency can discriminate between photonic states better than a detector with a higher efficiency.This article is part of the theme issue 'The quantum theory of light'.

We derive a compact expression for the second-order correlation function [Formula: see text] of a quantum state in terms of its Wigner function, thereby establishing a direct link between [Formula: see text] and the state's shape in phase space. We conduct an experiment that simultaneously measures [Formula: see text] through direct photocounting and reconstructs the Wigner function via homodyne tomography. The results confirm our theoretical predictions.This article is part of the theme issue 'The quantum theory of light'.

Towards the end of his life, Rudolf Peierls became interested in photon momentum and radiation pressure. He subsequently published a number of theoretical papers on the subject. Although the work of Peierls has neither been widely adopted nor developed, it did nevertheless have a provoking and fruitful effect on the radiation pressure research undertaken by Alan Gibson and Rodney Loudon at the University of Essex.This article is part of the theme issue, 'The quantum theory of light'.

The quantum theory of light in real media requires attention to a number of physical features. Even in near-transparent dielectrics, we have to incorporate dispersion, losses and the effects of interfaces. Here, we review the quantization of light in a dielectric and see how this affects radiative processes and light propagation. In the second half of the paper, we turn to optical forces and momentum. There we show why there are two rival force densities in a medium and also why there must be two distinct optical momenta. In the process, this resolves the century-old Abraham-Minkowski dilemma.This article is part of the theme issue 'The quantum theory of light'.

This work provides a mathematical derivation of a quasi-stationary (QS) model for multimode parametric down-conversion (PDC), which was presented in Gatti et al. (Gatti et al., Sci. Rep. 13, 16786) with heuristic arguments. Here, the model is derived from the 3D + 1 propagation equation of the quantum fields in a nonlinear crystal, and its approximations are discussed thoroughly. Thanks to its relative simplicity, and to the fact that it is valid in any gain regime, both at a quantum and classical level, it allows a unified description of disparate experimental observations conducted over the last 20 years, often described in the past by means of limited ad hoc models.This article is part of the theme issue 'The quantum theory of light'.

Quantum entanglement describes superposition states in multi-dimensional systems-at least two partite-which cannot be factorized and are thus non-separable. Non-separable states also exist in classical theories involving vector spaces. In both cases, it is possible to violate a Bell-like inequality. This has led to controversial discussions, which we resolve by identifying an operational distinction between the classical and quantum cases.This article is part of the theme issue 'The quantum theory of light'.

It has been shown that measurements involving indefinite causal order can be superior to those in which a sequence of operations occurs in a specified order. In optics, such measurements are realized naturally in a Sagnac interferometer. We show that such an arrangement can measure the solid angle (on the Poincaré sphere) enclosed by a sequence of unitary transformations of the polarization. This is the Pancharatnam-Berry phase. Extension from the classical or single-photon treatment to a fully quantized treatment allows the analysis of the interferometer for arbitrary quantum states of light.This article is part of the theme issue 'The quantum theory of light'.

We present a brief introduction to the quantum theory of light as it is understood in the field of quantum optics. Our aim is not to review the topic, which would require a very extensive article (or even a book of several volumes) but rather to provide sufficient background to set the ideas in the following papers in their correct context.This article is part of the theme issue 'The quantum theory of light'.