scholarly journals Experimental quantum reading with photon counting

2021 ◽  
Vol 7 (4) ◽  
pp. eabc7796
Author(s):  
Giuseppe Ortolano ◽  
Elena Losero ◽  
Stefano Pirandola ◽  
Marco Genovese ◽  
Ivano Ruo-Berchera
Keyword(s):  
Maximum Likelihood ◽  
Coherent States ◽  
Photon Counting ◽  
Optical Memory ◽  
Digital Data ◽  
Quantum Hypothesis ◽  
Squeezed Vacuum ◽  
Potential Applications ◽  
Experimental Findings ◽  
Quantum Hypothesis Testing

The final goal of quantum hypothesis testing is to achieve quantum advantage over all possible classical strategies. In the protocol of quantum reading, this is achieved for information retrieval from an optical memory, whose generic cell stores a bit of information in two possible lossy channels. We show, theoretically and experimentally, that quantum advantage is obtained by practical photon-counting measurements combined with a simple maximum-likelihood decision. In particular, we show that this receiver combined with an entangled two-mode squeezed vacuum source is able to outperform any strategy based on statistical mixtures of coherent states for the same mean number of input photons. Our experimental findings demonstrate that quantum entanglement and simple optics are able to enhance the readout of digital data, paving the way to real applications of quantum reading and with potential applications for any other model that is based on the binary discrimination of bosonic loss.

scholarly journals Coherent preorder of quantum states

2020 ◽  
Vol 20 (13&14) ◽  
pp. 1124-1137
Author(s):  
Zhaofang Bai ◽  
Shuanping Shuanping Du
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Coherent States ◽  
Quantum Coherence ◽  
Quantum Information Processing ◽  
Quantum States ◽  
Mixed States ◽  
Quantum Hypothesis ◽  
Quantum Hypothesis Testing

As an important quantum resource, quantum coherence play key role in quantum information processing. It is often concerned with manipulation of families of quantum states rather than individual states in isolation. Given two pairs of coherent states $(\rho_1,\rho_2)$ and $(\sigma_1,\sigma_2)$, we are aimed to study how can we determine if there exists a strictly incoherent operation $\Phi$ such that $\Phi(\rho_i) =\sigma_i,i = 1,2$. This is also a classic question in quantum hypothesis testing. In this note, structural characterization of coherent preorder under strongly incoherent operations is provided. Basing on the characterization, we propose an approach to realize coherence distillation from rank-two mixed coherent states to $q$-level maximally coherent states. In addition, one scheme of coherence manipulation between rank-two mixed states is also presented.

Microcavities

2017 ◽  
Author(s):  
Alexey V. Kavokin ◽  
Jeremy J. Baumberg ◽  
Guillaume Malpuech ◽  
Fabrice P. Laussy
Keyword(s):  
Quantum Wells ◽  
Strong Light ◽  
Fundamental Physics ◽  
Postgraduate Students ◽  
Optical Cavities ◽  
Semiconductor Quantum Wells ◽  
Exciton Polaritons ◽  
Different Types ◽  
Potential Applications ◽  
Experimental Findings

Both rich fundamental physics of microcavities and their intriguing potential applications are addressed in this book, oriented to undergraduate and postgraduate students as well as to physicists and engineers. We describe the essential steps of development of the physics of microcavities in their chronological order. We show how different types of structures combining optical and electronic confinement have come into play and were used to realize first weak and later strong light–matter coupling regimes. We discuss photonic crystals, microspheres, pillars and other types of artificial optical cavities with embedded semiconductor quantum wells, wires and dots. We present the most striking experimental findings of the recent two decades in the optics of semiconductor quantum structures. We address the fundamental physics and applications of superposition light-matter quasiparticles: exciton-polaritons and describe the most essential phenomena of modern Polaritonics: Physics of the Liquid Light. The book is intended as a working manual for advanced or graduate students and new researchers in the field.

Photo-induced variation of magnetism in coordination polymers with ligand-based electron transfer

2021 ◽  
Author(s):  
Yan-Lei Lu ◽  
Wen-Long Lan ◽  
Wei Shi ◽  
Qionghua Jin ◽  
Peng Cheng
Keyword(s):  
Electron Transfer ◽  
Coordination Polymers ◽  
Optical Memory ◽  
High Density ◽  
Information Storage ◽  
Memory Devices ◽  
Storage Materials ◽  
Potential Applications ◽  
Induced Variation

Photo-induced variation of magnetism from ligand-based electron transfer have been extensively studied because of their potential applications in magneto-optical memory devices, light-responsive switches, and high-density information storage materials. In this...

scholarly journals Quantum Filtering Equations for a System Driven by Nonclassical Fields

2018 ◽  
Vol 25 (02) ◽  
pp. 1850007 ◽  
Author(s):  
Anita Da̧browska
Keyword(s):  
Quantum System ◽  
Coherent States ◽  
Single Photon ◽  
Photon Counting ◽  
Stochastic Evolution ◽  
Input Output ◽  
Nonclassical States ◽  
Cascade System ◽  
Unitary Evolution ◽  
Photon States

Using Gardiner and Collet’s input-output model and the concept of cascade system, we determine the filtering equation for a quantum system driven by light in some specific nonclassical states. The quantum system and electromagnetic field are described by making use of quantum stochastic unitary evolution. We consider two examples of the nonclassical states of field: a combination of vacuum and single photon states and a mixture of two coherent states. The stochastic evolution conditioned on the results of the photon counting and quadrature measurements is described.

Photochromism and photoswitchable luminescence in a Zn7 cluster-based metal-organic framework with organic guest

2021 ◽  
Author(s):  
Jian-Jun Liu ◽  
Jia-Jia Fu ◽  
Teng Liu ◽  
Chixian He ◽  
Feixiang Cheng
Keyword(s):  
Metal Organic Framework ◽  
Optical Memory ◽  
Memory Devices ◽  
Potential Applications ◽  
Metal Organic ◽  
Photochromic Materials ◽  
Organic Framework

Photochromic materials coupled with the photoswitchable luminescence functionalities are of particular interest due to their potential applications in switches and optical memory devices. However, construct such materials, especially those with...

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