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Topical Collection "Quantum Information"

A topical collection in Entropy (ISSN 1099-4300). This collection belongs to the section "Quantum Information".

Editor

Collection Editor
Prof. Dr. Jay Lawrence

The James Franck Institite, University of Chicago, Chicago, IL 60637, USA; and Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755, USA
Website | E-Mail
Interests: condensed matter and many-body theory; quantum information and quantum foundations; entanglement, measurement and decoherence

Topical Collection Information

Dear Colleagues,

Entropy is eager to launch a special collection on quantum information, which will build on the success of the recent Special Issue on this topic. We expect that the journal will provide a niche for investigators working at the interface of quantum information with other subjects in which information and entropy are of particular interest. Such subjects are found within broader disciplines ranging from biology, through quantum chemistry and many-body physics, to general relativity. In addition to the many fascinating ways in which quantum coherence and quantum entanglement are manifested in material systems, there are also compelling foundational issues involving the relationships among quantum mechanics, information, thermodynamics, statistical mechanics, relativity, and space-time itself. What principles are primary, and what is derived? Does one have a choice? What are the most interesting open questions?

Prof. Dr. Jay Lawrence
Collection Editor

Manuscript Submission Information

Manuscripts for the topical collection can be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on this website. The topical collection considers regular research articles, short communications and review articles. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page.

Please visit the Instructions for Authors page before submitting a manuscript. The article processing charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs).


Published Papers (4 papers)

2017

Jump to: 2016

Open AccessArticle Optomechanical Analogy for Toy Cosmology with Quantized Scale Factor
Entropy 2017, 19(9), 485; doi:10.3390/e19090485
Received: 30 June 2017 / Revised: 23 August 2017 / Accepted: 8 September 2017 / Published: 12 September 2017
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Abstract
The simplest cosmology—the Friedmann–Robertson–Walker–Lemaître (FRW) model— describes a spatially homogeneous and isotropic universe where the scale factor is the only dynamical parameter. Here we consider how quantized electromagnetic fields become entangled with the scale factor in a toy version of the FRW model.
[...] Read more.
The simplest cosmology—the Friedmann–Robertson–Walker–Lemaître (FRW) model— describes a spatially homogeneous and isotropic universe where the scale factor is the only dynamical parameter. Here we consider how quantized electromagnetic fields become entangled with the scale factor in a toy version of the FRW model. A system consisting of a photon, source, and detector is described in such a universe, and we find that the detection of a redshifted photon by the detector system constrains possible scale factor superpositions. Thus, measuring the redshift of the photon is equivalent to a weak measurement of the underlying cosmology. We also consider a potential optomechanical analogy system that would enable experimental exploration of these concepts. The analogy focuses on the effects of photon redshift measurement as a quantum back-action on metric variables, where the position of a movable mirror plays the role of the scale factor. By working in the rotating frame, an effective Hubble equation can be simulated with a simple free moving mirror. Full article
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Open AccessArticle Dynamics of Entanglement in Jaynes–Cummings Nodes with Nonidentical Qubit-Field Coupling Strengths
Entropy 2017, 19(7), 331; doi:10.3390/e19070331
Received: 2 June 2017 / Revised: 18 June 2017 / Accepted: 29 June 2017 / Published: 3 July 2017
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Abstract
How to analytically deal with the general entanglement dynamics of separate Jaynes–Cummings nodes with continuous-variable fields is still an open question, and few analytical approaches can be used to solve their general entanglement dynamics. Entanglement dynamics between two separate Jaynes–Cummings nodes are examined
[...] Read more.
How to analytically deal with the general entanglement dynamics of separate Jaynes–Cummings nodes with continuous-variable fields is still an open question, and few analytical approaches can be used to solve their general entanglement dynamics. Entanglement dynamics between two separate Jaynes–Cummings nodes are examined in this article. Both vacuum state and coherent state in the initial fields are considered through the numerical and analytical methods. The gap between two nonidentical qubit-field coupling strengths shifts the revival period and changes the revival amplitude of two-qubit entanglement. For vacuum-state fields, the maximal entanglement is fully revived after a gap-dependence period, within which the entanglement nonsmoothly decreases to zero and partly recovers without exhibiting sudden death phenomenon. For strong coherent-state fields, the two-qubit entanglement decays exponentially as the evolution time increases, exhibiting sudden death phenomenon, and the increasing gap accelerates the revival period and amplitude decay of the entanglement, where the numerical and analytical results have an excellent coincidence. Full article
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2016

Jump to: 2017

Open AccessArticle Boltzmann Sampling by Degenerate Optical Parametric Oscillator Network for Structure-Based Virtual Screening
Entropy 2016, 18(10), 365; doi:10.3390/e18100365
Received: 3 September 2016 / Revised: 10 October 2016 / Accepted: 11 October 2016 / Published: 13 October 2016
Cited by 3 | PDF Full-text (984 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A structure-based lead optimization procedure is an essential step to finding appropriate ligand molecules binding to a target protein structure in order to identify drug candidates. This procedure takes a known structure of a protein-ligand complex as input, and structurally similar compounds with
[...] Read more.
A structure-based lead optimization procedure is an essential step to finding appropriate ligand molecules binding to a target protein structure in order to identify drug candidates. This procedure takes a known structure of a protein-ligand complex as input, and structurally similar compounds with the query ligand are designed in consideration with all possible combinations of atomic species. This task is, however, computationally hard since such combinatorial optimization problems belong to the non-deterministic nonpolynomial-time hard (NP-hard) class. In this paper, we propose the structure-based lead generation and optimization procedures by a degenerate optical parametric oscillator (DOPO) network. Results of numerical simulation demonstrate that the DOPO network efficiently identifies a set of appropriate ligand molecules according to the Boltzmann sampling law. Full article
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Open AccessArticle Metric for Estimating Congruity between Quantum Images
Entropy 2016, 18(10), 360; doi:10.3390/e18100360
Received: 20 July 2016 / Revised: 29 September 2016 / Accepted: 29 September 2016 / Published: 9 October 2016
Cited by 2 | PDF Full-text (3548 KB) | HTML Full-text | XML Full-text
Abstract
An enhanced quantum-based image fidelity metric, the QIFM metric, is proposed as a tool to assess the “congruity” between two or more quantum images. The often confounding contrariety that distinguishes between classical and quantum information processing makes the widely accepted peak-signal-to-noise-ratio (PSNR) ill-suited
[...] Read more.
An enhanced quantum-based image fidelity metric, the QIFM metric, is proposed as a tool to assess the “congruity” between two or more quantum images. The often confounding contrariety that distinguishes between classical and quantum information processing makes the widely accepted peak-signal-to-noise-ratio (PSNR) ill-suited for use in the quantum computing framework, whereas the prohibitive cost of the probability-based similarity score makes it imprudent for use as an effective image quality metric. Unlike the aforementioned image quality measures, the proposed QIFM metric is calibrated as a pixel difference-based image quality measure that is sensitive to the intricacies inherent to quantum image processing (QIP). As proposed, the QIFM is configured with in-built non-destructive measurement units that preserve the coherence necessary for quantum computation. This design moderates the cost of executing the QIFM in order to estimate congruity between two or more quantum images. A statistical analysis also shows that our proposed QIFM metric has a better correlation with digital expectation of likeness between images than other available quantum image quality measures. Therefore, the QIFM offers a competent substitute for the PSNR as an image quality measure in the quantum computing framework thereby providing a tool to effectively assess fidelity between images in quantum watermarking, quantum movie aggregation and other applications in QIP. Full article
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