Quantum discord May 28, 2024 · Explore quantum discord, a key concept in quantum information theory, its detection, applications in computing, cryptography, and the future of quantum tech. It has been proposed as the key resource present in certain quantum communication tasks and quantum computational models without containing much entanglement. Experimental validations confirm discord's existence and its potential in quantum technologies. Dec 21, 2017 · We review concepts and methods associated with quantum discord and related topics. , the pointer states. In this article I show how quantum discord is different from quantum entanglement from a pedagogical point of view. In both holographic systems and Haar random states, discord exceeds entanglement, revealing an Mar 12, 2024 · Quantum discord is a measure of nonclassical correla-tions between two subsystems of a quantum system used in quantum information theory. #QuantumSociety # Mar 7, 2012 · Here we show that quantum discord is the optimal resource for the remote quantum state preparation, a variant of the quantum teleportation protocol. Posting academic questions, news, and resources is highly welcome. Our meme channel (#global) is the perfect place to share lighthearted laughs and connect with like-minded individuals. In particular, quantum discord in a separable quantum state is expected to be detected with high-statistical significance. The quantum discord is of the most famous quantum correlations proposed by Ollivier and Zurek [3] and Hen-derson and Vedral [4], which quantifies the quantum cor-relations in bipartite systems without quantum entangle-ment. Quantum discord is an indicator of quantumness of correlations in a composite system, usually revealed via the state disturbance induced by local measurements [9–12]; re-cent results suggested that discord might enable quantum ad-vantages in specific computation or communication settings [13–19]. However, recent results suggest that various applications in quantum information theory do not require entanglement, and that their performance can be captured by Mar 30, 2017 · We review concepts and methods associated with quantum discord and related topics. Theor. Unitary Foundation is a 501 (c) (3) non-profit helping create a quantum technology ecosystem that benefits the most people Mar 23, 2022 · Quantum coherence and quantum correlations like quantum discord are valuable resources in quantum information processing 1, 2, 3. Experimentally, however, it is not easy to perform a reliable Apr 9, 2025 · This article comprehensively explores matrices and their prerequisites for achieving positive semi-definiteness. In this article, we will delve into the world of Quantum Discord and its impact on quantum computing, communication, and metrology. It is interesting to note that the quantum discord of three-qubits and five-qubits is the same, as is the quantum discord of two-qubits and six-qubits. In this contribution, we experimentally realize a form of quantum correlation that exists even in the absence of entanglement and discord. Phys. QKD (FRFI-QKD) protocol to solve this question. Among the many different quantum correlations, in this work we focus on quantum Abstract Quantum discord represents a correlation beyond classicality that could be useful for many quantum information tasks, and therefore is viewed as a valuable quantum resource. It captures all types of quantum correlations, making it a broader metric than entanglement. It captures a broader range of correlations than entanglement and can be present even in states that are separable, meaning they do not exhibit entanglement. May 31, 2023 · Top quarks have been recently shown to be a promising system to study quantum information at the highest-energy scale available. These results Apr 26, 2012 · As quantum technologies move from the issues of principle to those of practice, it is important to understand the limitations on attaining tangible quantum advantages. Quantum discord measures allow an alternative way to extend the idea A recent result by Eastin on the role of this boundary in the efficient classical simulation of quantum computation is discussed. In this paper, we firstly proposed a zero-discord criterion for two-qubit system based on the partial transposition of density matrix, and then extended it to the qubit-qudit system. Stemming from the superposition rule of quantum mechanics, quantum A measure of correlations—quantum discord—has been defined as the mismatch between two quantum analogues of classically equivalent expression of the mutual information. It can be used as a measure of Jun 13, 2025 · Introduction Quantum Discord is a fundamental concept in quantum information theory that has garnered significant attention in recent years due to its potential to revolutionize various aspects of quantum information processing. The Official Quantum League Discord community | 2987 members Nov 2, 2010 · Quantum discord characterizes ``nonclassicality'' of correlations in quantum mechanics. A 81, 042105 (2010)] with minimization taken over only a Quantum discord goes beyond entanglement and exists in a wide range of quantum states that may be separable, playing a crucial role in quantum information tasks. If you're currently researching, working to support, or studying quantum computing, this is the place for you. We will explore its role in quantum Jul 18, 2025 · This research investigates the role of quantum discord and classical correlation of two-coupled double quantum dots (DQDs). The first formula is the original entropic definition and the second is a recently proposed geometric distance measure which leads to an analytical formulation. We also show that quantum discord can be used for describing the selection of the preferred, effectively classical, pointer states. Quantum discord, a key indicator of non-classical correlations in bipartite systems, has been recently extended to multipartite scenarios [Phys. Almost all squeezed-thermal states have nonzero Oct 24, 2018 · We evaluate the quantum discord dynamics of two qubits in independent and common non-Markovian environments. While for pure states, quantum discord, entanglement, and Bell nonlocality all probe the same correlations, for mixed states they probe Quantum discord is an indicator of quantumness of correlations in a composite system, usually revealed via the state disturbance induced by local measurements [9–12]; re-cent results suggested that discord might enable quantum ad-vantages in specific computation or communication settings [13–19]. Geometric quantum discord (GQD) can be defined as the closest distance from a given quantum state to the set of classical–quantum states, reflecting the amount of quantum correlation present in the state. We characterize these modes Quantum discord is the minimal bipartite resource which is needed for a secure quantum key distribution, being a cryptographic primitive equivalent to non-orthogonality. We also describe their possible connections with other aspects of quantum information and beyond, including quantum communication, quantum computation, many-body physics, and open quantum dynamics. g. This is a consequence of quantum discord quantifying the advantage of quantum coherence in quantum communication May 31, 2023 · Here, we provide the full picture of quantum correlations in top quarks by studying also quantum discord and steering. Our formulations span 2, 3, 4n, $$4n+1$$ 4 n + 1 , $$4n+2$$ 4 n + 2 , and $$4n+3 Mar 21, 2014 · We study the computational complexity of quantum discord (a measure of quantum correlation beyond entanglement), and prove that computing quantum discord is NP-complete. The main objective of this study is to establish a graph-theoretic framework for the study of quantum discord and to identify the necessary and sufficient conditions for zero quantum Aug 5, 2016 · Entanglement is a central feature of quantum theory. Quantum discord in the multiparty regime and its applications are also discussed. Perceived drawbacks in the interpretation of quantum discord as a relevant certificate of quantum enhancements are addressed. This raises the intriguing question of Gaussian extremality—whether the quantum discord of a reference Gaussian state can provide a Jul 18, 2025 · This research investigates the role of quantum discord and classical correlation of two-coupled double quantum dots (DQDs). This condition is Dec 29, 2011 · Here we review different notions of classical and quantum correlations quantified by quantum discord and other related measures. e. We present exact analytic formulas for the quantum discord of special families of N-qubit states, including generalized class of GHZ states. By detailed examples we demonstrate the Dec 14, 2001 · We relate this to the quantum superposition principle, and consider the vanishing of discord as a criterion for the preferred effectively classical states of a system, i. However, quantum discord can be different from zero also for some (mixed) separable Sep 10, 2024 · The geometric quantum discord of a two-qudit state has been studied in many papers; however, its exact analytical value in the explicit form is known only for a general two-qubit state, a general qubit-qudit state, and some special families of two-qudit states. It's where most of the fun stuff is happening. We show that for realistic experimental parameters, the conditions for the existence of quantum discord are less demanding than the previously considered for quantum entanglement or nonclassicality. We investigate this difference -- quantum discord -- and show that it can be used as a criterion for the classicality of the correlations. Moreover, we inspect the dynamic behavior of the quantum discord for the three-qubit states under the phase damping channel. We construct gravity duals of quantum discord and classical correlation. Oct 15, 2024 · Global quantum discord (GQD) refers to the number of quantum correlations present in the entire quantum many-body system, rather than just between two subsystems. Based on the general Bloch vectors formalism [E. For pure entangled states, quantum discord coincides with the en-tropy of entanglement. Upvoting indicates when questions and answers are useful. The space of quantum correlations is much richer and more diverse than just quantum entanglement and Bell nonlocality. In quantum information theory, quantum discord is a measure of nonclassical correlations between two subsystems of a quantum system. After reviewing its different versions and properties, we apply it to the questions of quantum information processing. Feb 20, 2012 · Abstract We present two formulae to calculate quantum discord, a kind of quantum correlation, between a qubit and a second party of arbitrary dimension d. We also present a series of general properties of the quantum discord fraction: e. Emphasis is placed on the ‘power of one qubit Apr 30, 2021 · Dissimilar notions of quantum correlations have been established, each being motivated through particular applications in quantum information science and each competing for being recognized as the most relevant measure of quantumness. Welcome to Quantum Society 🌌, the ultimate destination for deep discussions and comfy vibes. Using photonic quantum systems, we explicitly show that the geometric measure of quantum discord is related to the fidelity of this task, which provides an operational meaning. Two measures of quantum discord by the amount of non-commutativity via the trace norm . Oct 24, 2018 · We evaluate the quantum discord dynamics of two qubits in independent and common non-Markovian environments. By mimicking the original protocol of quantum teleportation, we demonstrate that the non-zero quantum discord can be utilized to transmit a high-dimensional OAM state at the single-photon level. We certify the Still, we reveal the hidden quantum correlations in terms of geometric measures of discord. This difference defines the quantum discord. It also contains corre-lations resulting from quantum physical phenomena but not necessarily from quantum entanglement. Quantum Project Community | 9420 members Nov 7, 2014 · Quantum discord is the minimal bipartite resource which is needed for a secure quantum key distribution, being a cryptographic primitive equivalent to non-orthogonality. Sep 5, 2024 · Quantum Discord measures non-classical correlations in quantum systems beyond entanglement. They are also corne… Quantum discord has received a great deal of attention in studies involving quantum computation, metrology, dynamics, many-body physics, and thermodynamics. In this article I show how quantum discord is di erent from quantum entanglement from a pedagogical point of view. These modes are prepared through the incoherent superposition of different intense laser beams, encoding a two-qubit system in both polarization and the first-order Hermite-Gaussian modes [as proposed in Phys. Jan 15, 2025 · We investigate the quantum correlation between light and matter in bipartite quantum systems, drawing on the Jaynes–Cummings model and the Tavis–Cummings model, which are well-established in cavity quantum electrodynamics. While for pure states, quantum discord, entanglement, and Bell nonlocality all probe the same correlations, for mixed states they probe Jun 18, 2025 · Explore the uncharted territories of Quantum Discord and its far-reaching implications in Quantum Simulation and quantum technologies. Aug 11, 2024 · Quantum discord goes beyond entanglement and exists in a wide range of quantum states that may be separable, playing a crucial role in quantum information tasks. It can be used as a measure of Apr 30, 2025 · Quantum discord is a fascinating concept in quantum mechanics that goes beyond traditional entanglement. org Jun 25, 2025 · Quantum discord refers to a measure of the total Quantum Correlations between two systems. Jun 2, 2025 · While entanglement is a cornerstone of quantum theory and holography, quantum correlations arising from superposition, such as quantum discord, offer a broader perspective that has remained largely unexplored in holography. It is interesting to note that the quantum discord of three qubits and five qubits is the same, as is the quantum discord of two qubits and six qubits. The level surfaces of the quantum discord in the three Quantum is a multi-purpose Discord bot, it has over 100 commands to help, moderating and entertaining your server. The current lines of research mostly discuss topics such as entanglement, Bell nonlocality or quantum tomography. The three discord measures vanish simultaneously. Since the first expositions of this concept more than a decade ago [1, 2], a substantial amount of research effort has been devoted to understanding the mathematical properties and physical meanings of discord and similar quantities Mar 28, 2013 · Quantum discord (QD) is one of the main quantum correlations in quantum information theory. It is shown You'll need to complete a few actions and gain 15 reputation points before being able to upvote. Sep 3, 2024 · We perform an experimental study of quantum discord on spin-orbit modes of an intense laser beam, analogous to different X states. They are also cornerstones of quantum computation and quantum communication theory. A: Math. Find and join some awesome servers listed here! Sep 10, 2024 · The geometric quantum discord of a two-qudit state has been studied in many papers; however, its exact analytical value in the explicit form is known only for a general two-qubit state, a general qubit-qudit state, and some special families of two-qudit states. Its role becomes crucial Quantum discord goes beyond entanglement and exists in a wide range of quantum states that may be separable, playing a crucial role in quantum information tasks. But what exactly is quantum discord? In simple terms, it measures the amount of non-classical correlation between two quantum systems. AI Nov 6, 2018 · Quantum coherence and quantum correlations are of fundamental and practical significance for the development of quantum mechanics. To assess the extent of quantum correlation, several Quantum discord: A measure of the quantumness of correlations Harold Ollivier and Wojciech H. In this paper, we evaluate the geometric measure of multipartite quantum discord and obtain results for a large family of multi-qubit Sep 3, 2024 · We perform an experimental study of quantum discord on spin-orbit modes of an intense laser beam, analogous to different X states. Theoretically, whether a bipartite quantum state has a non-zero amount of quantum discord or not can be determined once its density matrix is given. It is defined as the minimum difference between the quantum versions of two classically equivalent expres-sions of mutual information under projective measure-ments [5, 6 Quantum Discord is a measure of quantum correlations in a quantum system, quantifying the amount of non-classical correlations present in a quantum state beyond what can be explained by classical mechanics. Quantum discord, one of the famous quantum correlations, has been recently generalized to multipartite systems by Radhakrishnan et. Learn how quantum discord can quantify and mitigate measurement-induced disturbance (MID), and enhance the performance of quantum algorithms and protocols. Here, we compare the approaches of contextuality and quantum discord in capturing quantum correlations in special classes of two-qubit states, demonstrating that although non-discordant states are non-contextual, discordant states are not always contextual. , the boundedness, the asymmetry and the invariants under local-unitary transformations, which Jan 6, 2025 · Quantum discord, a key indicator of nonclassical correlations in bipartite systems, has been recently extended to multipartite scenarios [Phys. This subreddit is for academic discussion and is not the place for business speculation, memes, or philosophy The quantum discord has a deep information-theoretic origin and interpretation, for the details of which we refer the reader to Ref. [12]; we shall merely remark that when the discord vanishes all the information about B that exists in the S-B correlations is locally recoverable just from the state of S, which is not the case for a general Sep 8, 2022 · Here, we provide the full picture of quantum correlations in top quarks by studying also quantum discord and steering. Jul 7, 2010 · We extend the quantum discord to continuous variable systems and evaluate Gaussian quantum discord 𝐶 (𝜚) for bipartite Gaussian states. Jul 22, 2013 · Here we show that quantum discord can be defined by con-sidering the opposite of the process of assembling a state. In this paper, the properties of Rènyi Jul 2, 2025 · Quantum discord is a measure of nonclassical correlations in quantum systems. Rev. The model involves a collection of qubits in the completely mixed state coupled to a single control qubit that has nonzero purity. We demonstrate that properly engineered quantum feedback can significantly improve quantum discord preservation, particularly in Werner states where we observe Oct 14, 2019 · As a universal quantum character of quantum correlation, the freezing phenomenon is researched by geometry and quantum discord methods, respectively. Recently a simple algorithm to evaluate the quantum discord for two-qubit 𝑋 states was proposed by Ali, Rau, and Alber [Phys. In the first half we review the mathematical properties of the measures of quantum correlation, relate them to each other, and discuss the classical-quantum division that is common among them. , J. Jan 30, 2023 · For questions about the quantum discord, a form of nonclassicality due to the possibly non-accessible nature of the quantum mutual information. Quantum correlations and discord are then operationally linked with the task of Apr 3, 2008 · Quantum discord, as introduced by Olliver and Zurek [Phys. That is, when one attempts to pull apart a quantum state so that, in the end, all the ingredients are classical and can be commu-nicated classically to distant recipients, the cost of such an operation is given by quantum discord. 88, 017901 (2001)], is a measure of the discrepancy between two natural yet different quantum analogs of the classical mutual information. In this work we give an introduction to this modern research direction. Its role becomes crucial The space of quantum correlations is much richer and more diverse than just quantum entanglement and Bell nonlocality. Mar 7, 2012 · Here we show that quantum discord is the optimal resource for the remote quantum state preparation, a variant of the quantum teleportation protocol. Our formulations span 2, 3, 4 n, 4 n + 1, 4 n + 2, and 4 n + 3 -qubit May 20, 2013 · The sum of the Holevo quantity (that bounds the capacity of quantum channels to transmit classical information about an observable) and the quantum discord (a measure of the quantumness of Dec 29, 2011 · Here we review different notions of classical and quantum correlations quantified by quantum discord and other related measures. Lett. Jan 6, 2025 · Quantum discord, a key indicator of nonclassical correlations in bipartite systems, has been recently extended to multipartite scenarios [Phys. However, quantum discord can be different from zero also for some (mixed) separable List of Discord servers tagged with quantum. These results are significant in capturing quantum correlations for multi-qubit systems. We obtain a necessary and sufficient condition for the existence of non-zero quantum discord for any dimensional bipartite states. Quantum coherence and quantum correlations are of fundamental and practical significance for the development of quantum mechanics. The level surfaces of the quantum discord in the three Jan 7, 2002 · We relate this to the quantum superposition principle, and consider the vanishing of discord as a criterion for the preferred effectively classical states of a system, i. We compare the dynamics of entanglement with that of quantum discord. We perform a detailed analysis describing how to measure the quantum discord in the top anti-top quantum state at the Large Hadron Collider (LHC). Furthermore, we have derived analytical expressions for the mutual information, quantum and classical parts of correlations of the physical system Feb 1, 2002 · Two classically identical expressions for the mutual information generally differ when the systems involved are quantum. Here, we utilize GQD to characterize quantum phase transitions in an Ising chain subjected to both transverse and longitudinal magnetic fields. What's reputation and how do I get it? Instead, you can save this post to reference later. Here, we provide the full picture of quantum correlations in top quarks by studying also quantum discord and steering. Apr 1, 2010 · Quantum discord characterizes "non-classicality" of correlations in quantum mechanics. 2020, 124:110401]. All undergrads, postgrads, High school students are welcome to discuss and interact with us and learn more about the Quantum Computing world and participate in meetups, projects and exchange of ideas. In this paper, we give analytical solutions of the quantum discord for a family of N -qubit quantum states. We discover that the quantum discord of this family of states can be classified into three categories. In this paper, we show that a local channel cannot create QD for zero QD states of size d ⩾ 3 if and only if either it is a completely decohering channel or it is a nontrivial isotropic channel. While the bipartite version of quantum discord is experimentally well-studied, the multipartite version has never been convincingly measured. Apr 6, 2022 · What is quantum discord? I stumbled upon this term on Quantum Computing: The power of discord, but have never heard of it before. We find that both phenomena are Quantum Science Discord Servers Quantum Science Public QSP is the place worse than hell, and is the main chatting server of Quantum Science. Through the resolution of the quantum master equation, we can derive the dissipative dynamics in open systems. A 103, 022411 (2021)]. In particular, for squeezed-thermal states, we explicitly maximize the extractable information over Gaussian measurements: 𝐶 (𝜚) is minimized by a generalized measurement rather than a projective one. Can you give a bit more mathematical explanation of the term here? Nov 12, 2014 · Quantum entanglement is the most popular kind of quantum correlations, and its fundamental role in several tasks in quantum information theory like quantum cryptography, quantum dense coding, and quantum teleportation is undeniable. Mathematical properties and physical applications of pure state entanglement make it a template to study quantum correlations. Our formulations span 2, 3, 4 n, 4 n + 1, 4 n + 2, and 4 n + 3 -qubit Here, we provide the full picture of quantum correlations in top quarks by studying also quantum discord and steering. There are at least three different discordlike quantities, two of which determine the difference between the efficiencies of a Szilard's engine under different sets of restrictions. We investigate the effects of the transverse magnetic field \ (h_ {x}\), longitudinal A measure of correlations—quantum discord—has been defined as the mismatch between two quantum analogues of classically equivalent expression of the mutual information. Completeness results from computational complexity theory lead to the identification of very disparate problems, and offer a kaleidoscopic view into the realm of quantum enhancements in computation. It includes correlations that are due to quantum physical effects but do not necessarily involve quantum entanglement. al} [Phys. 54, 195301 (2021)], we find the In quantum information theory, quantum discord is a measure of nonclassical correlations between two subsystems of a quantum system. Come join our community and start pondering the big questions in a relaxed and friendly environment. Sep 1, 2024 · Quantum discord goes beyond entanglement and exists in a wide range of quantum states that may be separable, playing a crucial role in quantum information tasks. Oct 9, 2012 · Abstract Quantum discord, a measure of quantum correlation beyond entanglement, is initially defined as the discord between two classically equivalent while quantum discordant definitions of mutual information. Loubenets et al. Abstract. R. We introduce an easy way to test for zero discord, relate it to the Cerf-Adami Mar 1, 2019 · Quantum discord measures a very general form of non-classical correlation, which can be present in quantum systems even in the absence of entanglement. They are also cornerstones of quantum computation and quantum communication theory. While for pure states, quantum discord, entanglement, and Bell nonlocality all probe the same correlations, for mixed states May 16, 2001 · Two classically identical expressions for the mutual information generally differ when the two systems involved are quantum. Apr 26, 2021 · Radhakrishnan \\emph{et. This notion characterizes and quantifies quantumness of correlations in bipartite states from a measurement perspective, and is fundamentally different from the various entanglement Quantum discord (QD) is defined as a measure of quantum correlation between two subsystems that quantifies the degree to which the total system deviates from classical correlations. While for pure states, quantum discord, entanglement, and Bell nonlocality all probe the same correlations, for mixed states they probe Oct 9, 2012 · Abstract Quantum discord, a measure of quantum correlation beyond entanglement, is initially defined as the discord between two classically equivalent while quantum discordant definitions of mutual information. Searching physically meaningful and mathematically rigorous quantifiers of them are long-standing concerns of the community of quantum information science, and various faithful Apr 8, 2025 · Using quantum discord (QD) and geometric quantum discord (GQD), quantum correlation dynamics is investigated of two coupled qubits within a multiqubit interacting system in the zero-temperature bosonic reservoir, under both weak and strong qubit-reservoir coupling regimes. Apr 28, 2016 · Quantum discord is a manifestation of quantum correlations due to non-commutativity rather than entanglement. This condition is May 9, 2025 · There has been an increasing interest in exploring quantities associated with quantum information at colliders. We have established a relationship between the centrosymmetric (CS) and X matrices through a local orthogonal transformation. It reduces to the entanglement entropy for pure states, but it differs for mixed states; separable states have zero Jul 29, 2021 · We evaluate analytically the quantum discord for a large family of multiqubit states. We discover that the quantum discord of this family states can be concluded into three categories. These range from quantum discord, which is non-zero in more quantum systems than entanglement, to negative conditional entropy, which is present in fewer quantum systems than Bell nonlocality. The initial state, operations, and measurements Abstract. Quantum discord, introduced by Zurek more than a decade ago, is the most popular candidate for such general quantum correlations. Discord arises from complex quantum interactions and can exist independently of entanglement. Dec 30, 2024 · There has been an increasing interest in exploring quantities associated with quantum information at colliders. To assess the extent of quantum correlation, several Mar 6, 2017 · Quantum coherence and quantum correlations are of fundamental and practical significance for the development of quantum mechanics. Mar 8, 2025 · Quantum discord is an important measure of quantum correlations that goes beyond the paradigm of quantum entanglement. Zurek Apr 1, 2014 · We ask, can weak measurements reveal more quantum correlation in a composite quantum state? We prove that the weak measurement induced quantum discord, called as the “super quantum discord”, is always larger than the quantum discord captured by the strong measurement. The tracing over the qubit in the entropic calculation is reduced to a very Jul 10, 2015 · We analyze the generation of quantum discord by means of the dynamical Casimir effect in superconducting wave guides modulated by superconducting quantum interferometric devices. 54, 195301 (2021)], we find the Feb 5, 2008 · We use quantum discord to characterize the correlations present in the model called deterministic quantum computation with one quantum bit (DQC1), introduced by Knill and Laflamme [Phys. We certify the Quantum is a new discord bot made to nourish your discord experience, Quantum has from economy to music with moderation, utility and much more along the way! This bot has been worked hard on to do everything to help you out! Quantum Is A Multipurpose Bot that can run your server without any problem! It Has Over 350+ commands - Discord servers Quantum discord has received a great deal of atten-tion in studies involving quantum computation, metrology, dynamics, many-body physics, and thermodynamics. Jul 20, 2021 · The formulation of two-photon orbital angular momentum state within a thermal light enables the revelation of its hidden quantumness with non-zero quantum discord and a proposal of teleporting an Abstract There has been an increasing interest in exploring quantities associated with quantum information at colliders. A community for the academic discussion of quantum computing topics from hardware through algorithms. For the qubit case this property is an additional characteristic of the completely decohering channel or Dec 30, 2013 · Quantum discord has received a great deal of attention in studies involving quantum computation, metrology, dynamics, many-body physics, and thermodynamics. In this paper, we report some new interpretations of discord which rely on the differences between measurement-induced effects on the local measured system and the whole system Jul 8, 2011 · Quantum discord is a measure of the quantumness of correlations. By detailed examples we demonstrate the Nov 7, 2016 · In this didactic article we explore the concept of quantum correlations beyond entanglement. For independent reservoirs the quantum discord vanishes only at discrete instants whereas the entanglement can disappear during a nite time interval. In-spired by viewing quantum discord [12{14] as a resource and its application in QKD [15{17], we construct a 3 3 matrix whose singular values are independent on both and ', and exploit quantum discord to realize a FRFI-QKD protocol, which is robust against the slow drift of both and '. In the first half, we review the mathematical properties of the measures of quantum correlations, relate them to each other, and discuss the classical-quantum division that is common among them. Apr 23, 2021 · We evaluate analytically the quantum discord for a large family of multiqubit states. The study delves into a theorem concerning pure quantum states in the context of weighted graphs. Among the many different quantum correlations, in this work we focus on quantum Apr 9, 2025 · This article comprehensively explores matrices and their prerequisites for achieving positive semi-definiteness. Furthermore, we numerically demonstrate that the performance Jun 24, 2025 · This theoretical and numerical investigation explores the enhancement and preservation of quantum discord in quantum systems coupled through V-shaped plasmonic waveguides (V-PW) using advanced quantum feedback control techniques. 81, 5672 (1998)]. We discuss models of computing that are beyond classical. Mar 22, 2020 · Quantum discord is a quantity that relates two subsystems of a quantum state. Therefore, quantum discord is computationally intractable: the running time of any algorithm for computing quantum discord is believed to grow exponentially with the dimension of the Hilbert space so that computing quantum Indi Quantum Community About Server This is the public Quantum community discord that grew out of the Qiskit Global Summer School 2020. al. We begin by introducing and motivating the classically correlated states and then showing how to quantify the quantum correlations using an entropic approach, arriving at a well known measure called the quantum discord. May 15, 2024 · In this paper, we investigate the quantum discord for a family of three-qubit extended X-states and give analytic formulas of the quantum discord for three-qubit states in several cases, including two zero quantum discord cases and the Werner-GHZ state case. In this study, we experimentally investigate tripartite quantum discord using an … Mar 31, 2022 · As an analogy of the entangled fraction and coherence fraction, we have introduced the notion of quantum discord fraction, which quantifies the closeness between a given state and the set of maximally discord states. The primary motivation is to unearth the cause of nonclassical advantages in computation. In the realm of quantum communication, quantum discord captures the damaging effects of a decoherent environment. However, calculating quantum discord involves optimization over measurements, which is computationally challenging and often infeasible. However, an extension of entanglement measures to mixed states in terms of separability does not always correspond to all the operational aspects. Join us and begin exploring the mysteries of existence. We find that both phenomena are present at the LHC. Searching physically meaningful and mathematically rigorous quantifiers of them are long-standing concerns of the community of quantum information science, and various faithful Jun 4, 2010 · Quantum discord was proposed as a measure of the quantumness of correlations. \\textbf{124}, 110401 (2020)] proposed quantum discord to multipartite systems and derived explicit formulae for any states. Its role becomes crucial Oct 14, 2022 · One of the defining differences between classical and quantum systems is how measurements affect them. We obtain a necessary and sufficient condition for the existence of nonzero quantum discord for any dimensional bipartite states. See full list on quantiki. Oct 6, 2011 · Quantum discord provides a measure for quantifying quantum correlations beyond entanglement and is very hard to compute even for two-qubit states because of the minimization over all possible measurements. lscqgl cxsmpdx ffoak zzmzjaqi dgyyaz yorgs ojwkhfcu xorb spxchpf kkk fvpn eujhbi ckcm ncqzr quusc