scholarly journals Quantum Entanglement in Time

2021 ◽  
Author(s):  
◽  
Del Rajan
Keyword(s):  
Quantum Information ◽  
Quantum Physics ◽  
Information Science ◽  
Quantum Effect ◽  
Relativistic Quantum ◽  
Theoretical Aspect ◽  
Quantum Systems ◽  
Quantum Communications ◽  
Information Encoding ◽  
Classical Systems

<p>This thesis is in the field of quantum information science, which is an area that reconceptualizes quantum physics in terms of information.  Central to this area is the quantum effect of entanglement in space.  It is an interdependence among two or more spatially separated quantum systems that would be impossible to replicate by classical systems.  Alternatively, an entanglement in space can also be viewed as a resource in quantum information in that it allows the ability to perform information tasks that would be impossible or very difficult to do with only classical information.  Two such astonishing applications are quantum communications which can be harnessed for teleportation, and quantum computers which can drastically outperform the best classical supercomputers.   In this thesis our focus is on the theoretical aspect of the field, and we provide one of the first expositions on an analogous quantum effect known as entanglement in time.  It can be viewed as an interdependence of quantum systems across time, which is stronger than could ever exist between classical systems.  We explore this temporal effect within the study of quantum information and its foundations as well as through relativistic quantum information.  An original contribution of this thesis is the design of one of the first quantum information applications of entanglement in time, namely a quantum blockchain.  We describe how the entanglement in time provides the quantum advantage over a classical blockchain.  Furthermore, the information encoding procedure of this quantum blockchain can be interpreted as non-classically influencing the past, and hence the system can be viewed as a `quantum time machine.'</p>

scholarly journals Quantum Entanglement in Time

2021 ◽  
Author(s):  
◽  
Del Rajan
Keyword(s):  
Quantum Information ◽  
Quantum Physics ◽  
Information Science ◽  
Quantum Effect ◽  
Relativistic Quantum ◽  
Theoretical Aspect ◽  
Quantum Systems ◽  
Quantum Communications ◽  
Information Encoding ◽  
Classical Systems

<p>This thesis is in the field of quantum information science, which is an area that reconceptualizes quantum physics in terms of information.  Central to this area is the quantum effect of entanglement in space.  It is an interdependence among two or more spatially separated quantum systems that would be impossible to replicate by classical systems.  Alternatively, an entanglement in space can also be viewed as a resource in quantum information in that it allows the ability to perform information tasks that would be impossible or very difficult to do with only classical information.  Two such astonishing applications are quantum communications which can be harnessed for teleportation, and quantum computers which can drastically outperform the best classical supercomputers.   In this thesis our focus is on the theoretical aspect of the field, and we provide one of the first expositions on an analogous quantum effect known as entanglement in time.  It can be viewed as an interdependence of quantum systems across time, which is stronger than could ever exist between classical systems.  We explore this temporal effect within the study of quantum information and its foundations as well as through relativistic quantum information.  An original contribution of this thesis is the design of one of the first quantum information applications of entanglement in time, namely a quantum blockchain.  We describe how the entanglement in time provides the quantum advantage over a classical blockchain.  Furthermore, the information encoding procedure of this quantum blockchain can be interpreted as non-classically influencing the past, and hence the system can be viewed as a `quantum time machine.'</p>

scholarly journals From quantum foundations to applications and back

2018 ◽  
Vol 376 (2123) ◽  
pp. 20170326 ◽  
Author(s):  
Nicolas Gisin ◽  
Florian Fröwis
Keyword(s):  
Quantum Information ◽  
Quantum Physics ◽  
Information Science ◽  
Quantum Information Processing ◽  
Measurement Problem ◽  
Foundations Of Quantum Mechanics ◽  
Applied Physics ◽  
Open Problems ◽  
Quantum Non Locality ◽  
Non Locality

Quantum non-locality has been an extremely fruitful subject of research, leading the scientific revolution towards quantum information science, in particular, to device-independent quantum information processing. We argue that the time is ripe to work on another basic problem in the foundations of quantum physics, the quantum measurement problem, which should produce good physics in theoretical, mathematical, experimental and applied physics. We briefly review how quantum non-locality contributed to physics (including some outstanding open problems) and suggest ways in which questions around macroscopic quantumness could equally contribute to all aspects of physics. This article is part of a discussion meeting issue ‘Foundations of quantum mechanics and their impact on contemporary society’.

Quantum Information Science Vis-à-Vis Information Schools

2019 ◽  
pp. 199-211
Author(s):  
P. K. Paul ◽  
D. Chatterjee ◽  
A. Bhuimali
Keyword(s):  
Information Theory ◽  
Quantum Information ◽  
Computer Science ◽  
Quantum Physics ◽  
Information Science ◽  
New Paradigm ◽  
Quantum Information Science ◽  
Information Studies ◽  
Quantum Science ◽  
Science Information

Quantum information science (QIS) is a combination of quantum science (which combines radio physics, condensed physics, and electronics) and information science (which combines computer science, information technology, mathematics, information studies, and documentation studies). Quantum information science (QIS) is actually an extension of quantum computing. Quantum information science (QIS) is mistakenly taken as quantum information theory, but it has several differences with this. Quantum information science (QIS) is mainly responsible for improved and faster acquisition, transmission, and processing of information. The 20th century is marked by three monumental achievements, namely, computer science, quantum physics, and information theory, which have not only stunned the civilized world but also ushered into a new world – a new paradigm of science and technology.

Dissipation, Entropy, Chaos in Quantum Physics

1998 ◽  
Vol 07 (01) ◽  
pp. 107-119
Author(s):  
Michael Danos
Keyword(s):  
Probability Measure ◽  
Thermal Equilibrium ◽  
Quantum Physics ◽  
Measure Zero ◽  
Chaotic Behavior ◽  
Quantum Systems ◽  
Classical Systems ◽  
Heisenberg Uncertainty ◽  
The Difference ◽  
The Impact

As a consequence of the Heisenberg uncertainty any quantum physics system inescapably undergoes relaxation towards thermal equilibrium, thus towards maximum entropy. The non-dissipative states have probability measure zero and cannot exist in nature. The impact these results have on chaotic behavior of quantum systems will be discussed, as well as the difference between quantum and classical systems, which have vanishing uncertainty.

scholarly journals An introductory review on resource theories of generalized nonclassical light

2021 ◽  
Vol 2038 (1) ◽  
pp. 012008
Author(s):  
Sanjib Dey
Keyword(s):  
Quantum Information ◽  
Quantum Physics ◽  
Quantum Effect ◽  
Resource Theory ◽  
Standard Quantum ◽  
Quantum Operations ◽  
Quantum Phenomena ◽  
Quantum Optical ◽  
Oscillator Quantum ◽  
Free Set

Abstract Quantum resource theory is perhaps the most revolutionary framework that quantum physics has ever experienced. It plays vigorous roles in unifying the quantification methods of a requisite quantum effect as wells as in identifying protocols that optimize its usefulness in a given application in areas ranging from quantum information to computation. Moreover, the resource theories have transmuted radical quantum phenomena like coherence, nonclassicality and entanglement from being just intriguing to being helpful in executing realistic thoughts. A general quantum resource theoretical framework relies on the method of categorization of all possible quantum states into two sets, namely, the free set and the resource set. Associated with the set of free states there is a number of free quantum operations emerging from the natural constraints attributed to the corresponding physical system. Then, the task of quantum resource theory is to discover possible aspects arising from the restricted set of operations as resources. Along with the rapid growth of various resource theories corresponding to standard harmonic oscillator quantum optical states, significant advancement has been expedited along the same direction for generalized quantum optical states. Generalized quantum optical framework strives to bring in several prosperous contemporary ideas including nonlinearity, PT -symmetric non-Hermitian theories, q-deformed bosonic systems, etc., to accomplish similar but elevated objectives of the standard quantum optics and information theories. In this article, we review the developments of nonclassical resource theories of different generalized quantum optical states and their usefulness in the context of quantum information theories.

scholarly journals Observers of quantum systems cannot agree to disagree

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Patricia Contreras-Tejada ◽  
Giannicola Scarpa ◽  
Aleksander M. Kubicki ◽  
Adam Brandenburger ◽  
Pierfrancesco La Mura
Keyword(s):  
Quantum Information ◽  
Quantum Systems ◽  
Physical Principle ◽  
Quantum Foundations ◽  
Classical Systems ◽  
The World ◽  
No Signaling ◽  
Active Research ◽  
Rule Out

AbstractIs the world quantum? An active research line in quantum foundations is devoted to exploring what constraints can rule out the postquantum theories that are consistent with experimentally observed results. We explore this question in the context of epistemics, and ask whether agreement between observers can serve as a physical principle that must hold for any theory of the world. Aumann’s seminal Agreement Theorem states that two observers (of classical systems) cannot agree to disagree. We propose an extension of this theorem to no-signaling settings. In particular, we establish an Agreement Theorem for observers of quantum systems, while we construct examples of (postquantum) no-signaling boxes where observers can agree to disagree. The PR box is an extremal instance of this phenomenon. These results make it plausible that agreement between observers might be a physical principle, while they also establish links between the fields of epistemics and quantum information that seem worthy of further exploration.

QUANTUMNESS OF ENSEMBLE FROM NO-BROADCASTING PRINCIPLE

2006 ◽  
Vol 04 (01) ◽  
pp. 105-118 ◽  
Author(s):  
MICHAł HORODECKI ◽  
PAWEł HORODECKI ◽  
RYSZARD HORODECKI ◽  
MARCO PIANI
Keyword(s):  
Quantum Information ◽  
Information Content ◽  
Quantum Physics ◽  
Single Copy ◽  
Quantum Systems ◽  
Quantum States ◽  
New Approach ◽  
Permanence Property ◽  
The Status ◽  
The Difference

Quantum information, though not precisely defined, is a fundamental concept of quantum information theory which predicts many fascinating phenomena and provides new physical resources. A basic problem is to recognize the features of quantum systems responsible for those phenomena. One of these important features is that non-commuting quantum states cannot be broadcast: two copies cannot be obtained out of a single copy, not even reproduced marginally on separate systems. We focus on the difference in information content between one copy and two copies, which is a basic manifestation of the gap between quantum and classical information. We show that if the chosen information measure is the Holevo quantity, the difference between the information content of one copy and two copies is zero if and only if the states can be broadcast. We propose a new approach in defining measures of quantumness of ensembles based on the difference in information content between the original ensemble and the ensemble of duplicated states. We comment on the permanence property of quantum states and the recently introduced superbroadcasting operation. We also provide an appendix where we discuss the status of quantum information in quantum physics, based on the so-called isomorphism principle.

scholarly journals Some Foundational Issues in Quantum Information Science

2021 ◽  
Author(s):  
Amitabha Gupta
Keyword(s):  
Quantum Information ◽  
Bayesian Approach ◽  
Quantum Physics ◽  
Information Science ◽  
Quantum Information Science ◽  
Quantum Bit ◽  
Physical Approach ◽  
Processing Information

This chapter has three Parts. Part 1 attempts to analyze the concept “information” (in some selected contexts where it has been used) in order to understand the consequences of representing and processing information, quantum mechanically. There are at least three views on ‘Information’ viz., ‘Semantic Naturalism’, ‘the Quantum Bayesian Approach’ and ‘Information is Physical’ approach. They are then critically examined and at last one is given preference. Part 2 of the chapter then goes on to discuss the manner in which the study and quantification of “Qubit” (Quantum bit), Superposition and Entanglement, comprise the three pillars of Quantum Information Science and enable the discipline to develop the theory behind applications of quantum physics to the transmission and processing of information. In Part 3 we take up the issue that although it might appear bewildering, the physical approach to Quantum Information Science is equally proficient in dealing with its impact on the questions of “consciousness,” “freewill” and biological questions in the area known as “bioinformatics.”

scholarly journals Quantum tomography protocols with positivity are compressed sensing protocols

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
Amir Kalev ◽  
Robert L Kosut ◽  
Ivan H Deutsch
Keyword(s):  
Quantum Mechanics ◽  
Quantum Information ◽  
Compressed Sensing ◽  
Information Science ◽  
Signal Reconstruction ◽  
Special Property ◽  
Quantum Tomography ◽  
Quantum Systems ◽  
Reconstruction Technique ◽  
Quantum Information Science

AbstractCharacterising complex quantum systems is a vital task in quantum information science. Quantum tomography, the standard tool used for this purpose, uses a well-designed measurement record to reconstruct quantum states and processes. It is, however, notoriously inefficient. Recently, the classical signal reconstruction technique known as ‘compressed sensing’ has been ported to quantum information science to overcome this challenge: accurate tomography can be achieved with substantially fewer measurement settings, thereby greatly enhancing the efficiency of quantum tomography. Here we show that compressed sensing tomography of quantum systems is essentially guaranteed by a special property of quantum mechanics itself—that the mathematical objects that describe the system in quantum mechanics are matrices with non-negative eigenvalues. This result has an impact on the way quantum tomography is understood and implemented. In particular, it implies that the information obtained about a quantum system through compressed sensing methods exhibits a new sense of ‘informational completeness.’ This has important consequences on the efficiency of the data taking for quantum tomography, and enables us to construct informationally complete measurements that are robust to noise and modelling errors. Moreover, our result shows that one can expand the numerical tool-box used in quantum tomography and employ highly efficient algorithms developed to handle large dimensional matrices on a large dimensional Hilbert space. Although we mainly present our results in the context of quantum tomography, they apply to the general case of positive semidefinite matrix recovery.

scholarly journals Optically addressable molecular spins for quantum information processing

Science ◽  
2020 ◽  
Vol 370 (6522) ◽  
pp. 1309-1312 ◽  
Author(s):  
S. L. Bayliss ◽  
D. W. Laorenza ◽  
P. J. Mintun ◽  
B. D. Kovos ◽  
D. E. Freedman ◽  
...  
Keyword(s):  
Quantum Information ◽  
Ground State ◽  
Information Science ◽  
Quantum Information Processing ◽  
Building Blocks ◽  
Quantum Systems ◽  
Quantum Information Science ◽  
Molecular Systems ◽  
Wide Range ◽  
State Spin

Spin-bearing molecules are promising building blocks for quantum technologies as they can be chemically tuned, assembled into scalable arrays, and readily incorporated into diverse device architectures. In molecular systems, optically addressing ground-state spins would enable a wide range of applications in quantum information science, as has been demonstrated for solid-state defects. However, this important functionality has remained elusive for molecules. Here, we demonstrate such optical addressability in a series of synthesized organometallic, chromium(IV) molecules. These compounds display a ground-state spin that can be initialized and read out using light and coherently manipulated with microwaves. In addition, through atomistic modification of the molecular structure, we vary the spin and optical properties of these compounds, indicating promise for designer quantum systems synthesized from the bottom-up.

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