ICFO – The Institute of Photonic Sciences

About: ICFO – The Institute of Photonic Sciences is a facility organization based out in Barcelona, Spain. It is known for research contribution in the topics: Quantum & Quantum entanglement. The organization has 872 authors who have published 1965 publications receiving 56273 citations.

Graphene-Based Active Random Metamaterials for Cavity-Free Lasing.

Abstract: Manipulating and controlling the optical energy flow inside random media is a research frontier of photonics and the basis of novel laser designs. Here, we show that a metamaterial consisting of randomly dispersed graphene nanoflakes embedded within an optically pumped gain medium (rhodamine 6G) can operate as a cavity-free laser thanks to its extraordinarily low threshold for saturable absorption. The emitted light is self-organized into a well-determined spatial pattern, which depends on the graphene flake density and can be externally controlled through the optical pump. We provide different examples of tunable laser operation ranging from stable single-mode to chaoticlike behavior. Our metamaterial design holds great potential for the optical control of light amplification, as well as for the development of single-mode beam-engineered cavity-free lasers.

Two-dimensional topological quantum walks in the momentum space of structured light

Abstract: Quantum walks are powerful tools for quantum applications and for designing topological systems. Although they are simulated in a variety of platforms, genuine two-dimensional realizations are still challenging. Here we present an innovative approach to the photonic simulation of a quantum walk in two dimensions, where walker positions are encoded in the transverse-wavevector component of a single light beam. The desired dynamics is obtained by means of a sequence of liquid-crystal devices, which apply polarization-dependent transverse “kicks” to the photons in the beam. We engineer our quantum walk so that it realizes a periodically driven Chern insulator, and we probe its topological features by detecting the anomalous displacement of the photonic wavepacket under the effect of a constant force. Our compact, versatile platform offers exciting prospects for the photonic simulation of two-dimensional quantum dynamics and topological systems.

Simulating quantum light propagation through atomic ensembles using matrix product states

Abstract: A powerful method to interface quantum light with matter is to propagate the light through an ensemble of atoms. Recently, a number of such interfaces have emerged, most prominently Rydberg ensembles, that enable strong nonlinear interactions between propagating photons. A largely open problem is whether these systems produce exotic many-body states of light and developing new tools to study propagation in the large photon number limit is highly desirable. Here we provide a method based on a "spin model" that maps quasi one-dimensional (1D) light propagation to the dynamics of an open 1D interacting spin system, where all photon correlations are obtained from those of the spins. The spin dynamics in turn are numerically solved using the toolbox of matrix product states. We apply this formalism to investigate vacuum induced transparency, wherein the different photon number components of a pulse propagate with number-dependent group velocity and separate at output.

Geometry of Work Fluctuations versus Efficiency in Microscopic Thermal Machines

Abstract: When engineering microscopic machines, increasing efficiency can often come at a price of reduced reliability due to the impact of stochastic fluctuations. Here we develop a general method for performing multiobjective optimization of efficiency and work fluctuations in thermal machines operating close to equilibrium in either the classical or quantum regime. Our method utilizes techniques from thermodynamic geometry, whereby we match optimal solutions to protocols parametrized by their thermodynamic length. We characterize the optimal protocols for continuous-variable Gaussian machines, which form a crucial class in the study of thermodynamics for microscopic systems.

Thermometry in the quantum regime: Recent theoretical progress

Abstract: Controlling and measuring the temperature in different devices and platforms that operate in the quantum regime is, without any doubt, essential for any potential application. In this review, we report the most recent theoretical developments dealing with accurate estimation of very low temperatures in quantum systems. Together with the emerging experimental techniques and developments of measurement protocols, the theory of quantum thermometry will decisively impinge and shape the forthcoming quantum technologies. While current quantum thermometric methods differ greatly depending on the experimental platform, the achievable precision, and the temperature range of interest, the theory of quantum thermometry is built under a unifying framework at the crossroads of quantum metrology, open quantum systems, and quantum many-body physics. At a fundamental level, theoretical quantum thermometry is concerned with finding the ultimate bounds and scaling laws that limit the precision of temperature estimation for systems in and out-of-thermal equilibrium. At a more practical level, it provides tools to formulate precise, yet feasible, thermometric protocols for relevant experimental architectures. Last but not least, the theory of quantum thermometry examines genuine quantum features, like entanglement and coherence, for their exploitation in enhanced-resolution thermometry.