In recent years, exploration of the possible use of separable states as a resource to achieve quantum information processing (QIP) tasks has been gaining increasing significance. In this context, a particularly important demonstration has been that nonvanishing discord is the necessary condition for separable states to be used as a resource for remotely preparing any arbitrary pure target state [Nat. Phys. 8, 666 (2012)]. The present work stems from our observation that not only can resource states with the same discord imply different efficiencies (in terms of average fidelity) of the remote state preparation (RSP) protocol, but also states with higher discord can imply lower RSP efficiency. Therefore, this necessitates identification of the relevant feature of quantum correlations that can appropriately quantify the effectiveness of the resource state for the RSP protocol. To this end, for the two-qubit Bell-diagonal states, we show that an appropriate measure of simultaneous correlations in three mutually unbiased bases can serve to quantify the usefulness of the resource for the RSP task using entangled as well as separable states, including nondiscordant states as a resource. In particular, it is revealed that zero-discord states with such a nonvanishing measure can be useful for remotely preparing a subset of pure target states. Thus, this work shows that, using separable states, an effective resource for QIP tasks such as RSP can be provided by simultaneous correlations in mutually unbiased bases.
In recent years, exploration of the possible use of separable states as a resource to achieve quantum information processing (QIP) tasks has been gaining increasing significance. In this context, a particularly important demonstration has been that nonvanishing discord is the necessary condition for separable states to be used as a resource for remotely preparing any arbitrary pure target state [Nat. Phys. 8, 666 (2012)]. The present work stems from our observation that not only can resource states with the same discord imply different efficiencies (in terms of average fidelity) of the remote state preparation (RSP) protocol, but also states with higher discord can imply lower RSP efficiency. Therefore, this necessitates identification of the relevant feature of quantum correlations that can appropriately quantify the effectiveness of the resource state for the RSP protocol. To this end, for the two-qubit Bell-diagonal states, we show that an appropriate measure of simultaneous correlations in three mutually unbiased bases can serve to quantify the usefulness of the resource for the RSP task using entangled as well as separable states, including nondiscordant states as a resource. In particular, it is revealed that zero-discord states with such a nonvanishing measure can be useful for remotely preparing a subset of pure target states. Thus, this work shows that, using separable states, an effective resource for QIP tasks such as RSP can be provided by simultaneous correlations in mutually unbiased bases.
Quantum discord and quantum entanglement are resources in some quantum information processing (QIP) models. However, in recent years, the evidence that separable states or classically correlated states can also accomplish QIP is demonstrated. It provides a useful tool since such states are easier to prepare. Quantum coherence is a measure of non-classical correlation, containing entanglement and discord as a subset. Nowadays, it is of interest whether quantum coherence can act as a resource in QIP independently or not, without the help from quantum discord or entanglement. In this paper, we show that quantum correlated coherence(a measure of coherence with local parts removed) is also a kind of quantum resource. It is the sufficient and necessary resource for quantum remote state preparation and quantum teleportation.
In recent years, the evidence that separable states and classically correlated states can also accomplish quantum information process(QIP) is demonstrated. This evidence provides a useful tool since it is easier to generate coherence than entanglement and discord. Nowadays, it is of interest whether quantum coherence can act as a resource in QIP independently or not, without the help of quantum discord or entanglement. In this paper, we show that quantum correlated coherence induced by basis-independence and l2-norm is another kind of quantum resource. Correlated coherence can accurately quantify the effectiveness of the resource state in the Remote State Preparation(RSP) protocol. Tomographically reconstructed correlated coherent states can accomplish RSP protocol individually. We provide both the theoretical derivation and experimental scheme. In quantum teleportation, a resource state with non-zero correlated coherence is effective while a correlated incoherent state is not.
This article develops an expanded critical–propositional analysis of Borivoje Dakić et al.’s 2012 experimental study, “Quantum Discord as Resource for Remote State Preparation,” in systematic dialogue with the Theory of Objectivity (TO), developed by Vidamor Cabannas and Denivaldo Silva. Dakić et al. investigated whether nonclassical correlations beyond entanglement can function as operational resources in quantum information processing. Their theoretical and photonic experimental work established, for the class of states and remote-state-preparation protocol considered, a direct relation between geometric quantum discord and remote state preparation (RSP) fidelity. Particularly significant was their demon- stration that a separable state possessing nonzero discord could outperform a specific entangled state in RSP. The experiment employed polarization-encoded photonic qubits, compared two deliberately constructed mixed resource states, and remotely prepared fifty-eight states distributed over Bob’s Bloch sphere. The experimentally realized separable state exhibited zero concurrence but geometric discord of approximately 0.097 and RSP fidelity of approximately 0.098, whereas the entangled comparison state had concurrence of approximately 0.12, geometric discord of approximately 0.036, and RSP fidelity of approximately 0.036. The performance separation was reported at sixty-two standard deviations (Dakić et al. 2012). The present analysis distinguishes rigorously among three epistemological levels: first, independent empirical confirmation of physical phenomena; second, structural compatibility between those phenomena and categories of the Theory of Objectivity; and third, TO-specific empirical confirmation capable of discrim- inating the theory from established quantum mechanics. This distinction is necessary because TO assigns modal necessity to its foundational axioms, whereas experimental physics operates through contingent observations, models, measure- ments, and statistical inference. Accordingly, empirical results cannot generate the alleged modal necessity of the TO axioms, although they may instantiate, constrain, or operationalize physical structures compatible with them. The strongest points of dialogue concern TO’s categories of boundary/interface, relational observation, composition, and especially the transcendent element, which TO identifies with knowledge or information produced in atomic rela- tions and associates with atomic radiation. Dakić et al. provide experimentally controlled evidence that relational quantum structure can possess operational informational value not exhausted by entanglement and not reducible to the properties of isolated subsystems. This result is highly compatible with a general TO thesis according to which relations are physically productive and information- ally significant. Nevertheless, quantum discord cannot simply be equated with the TO transcendent element, nor does the experiment establish the TO-specific equivalence between information and atomic radiation. The article also does not test the TO cosmogonic theorem, its cosmological eras, or its complete set of modal axioms. Subsequent criticisms and refinements are incorporated. Piani’s criticism of Hilbert–Schmidt geometric discord, Giorgi’s demonstration that discord is not universally necessary and sufficient for useful RSP, and later work distinguishing mere discord from genuinely nonclassical RSP prevent an unrestricted ontological interpretation of the 2012 result (Piani 2012; Giorgi 2013; Chen et al. 2024). Rather than weakening the dialogue with TO, these developments clarify the appropriate bridge: the enduring lesson is not that one particular discord measure is a universal ontological substance, but that physically instantiated relations can encode operational resources not captured by simpler classifications such as entanglement alone. The study concludes that Dakić et al. provide meaningful indirect empirical corroboration of a relational-informational orientation compatible with TO, while providing no exclusive confirmation of TO. A research program is proposed in which TO would define quantitative informational variables, boundary-sensitive transformations, and experimentally discriminating predictions capable of being compared with quantum-information observables. On a zero-to-ten scale of substantive dialogue with TO, the analyzed article is assigned 7.6/10. Keywords: Theory of Objectivity; quantum discord; remote state prepara- tion; quantum information; relational information; modal necessity; geometric discord; photon polarization; nonclassical correlations; empirical corroboration; transcendent information; inductive effects.
This article develops an expanded critical–propositional analysis of Borivoje Dakić et al.’s 2012 experimental study, “Quantum Discord as Resource for Remote State Preparation,” in systematic dialogue with the Theory of Objectivity (TO), developed by Vidamor Cabannas and Denivaldo Silva. Dakić et al. investigated whether nonclassical correlations beyond entanglement can function as operational resources in quantum information processing. Their theoretical and photonic experimental work established, for the class of states and remote-state-preparation protocol considered, a direct relation between geometric quantum discord and remote state preparation (RSP) fidelity. Particularly significant was their demon- stration that a separable state possessing nonzero discord could outperform a specific entangled state in RSP. The experiment employed polarization-encoded photonic qubits, compared two deliberately constructed mixed resource states, and remotely prepared fifty-eight states distributed over Bob’s Bloch sphere. The experimentally realized separable state exhibited zero concurrence but geometric discord of approximately 0.097 and RSP fidelity of approximately 0.098, whereas the entangled comparison state had concurrence of approximately 0.12, geometric discord of approximately 0.036, and RSP fidelity of approximately 0.036. The performance separation was reported at sixty-two standard deviations (Dakić et al. 2012). The present analysis distinguishes rigorously among three epistemological levels: first, independent empirical confirmation of physical phenomena; second, structural compatibility between those phenomena and categories of the Theory of Objectivity; and third, TO-specific empirical confirmation capable of discrim- inating the theory from established quantum mechanics. This distinction is necessary because TO assigns modal necessity to its foundational axioms, whereas experimental physics operates through contingent observations, models, measure- ments, and statistical inference. Accordingly, empirical results cannot generate the alleged modal necessity of the TO axioms, although they may instantiate, constrain, or operationalize physical structures compatible with them. The strongest points of dialogue concern TO’s categories of boundary/interface, relational observation, composition, and especially the transcendent element, which TO identifies with knowledge or information produced in atomic rela- tions and associates with atomic radiation. Dakić et al. provide experimentally controlled evidence that relational quantum structure can possess operational informational value not exhausted by entanglement and not reducible to the properties of isolated subsystems. This result is highly compatible with a general TO thesis according to which relations are physically productive and information- ally significant. Nevertheless, quantum discord cannot simply be equated with the TO transcendent element, nor does the experiment establish the TO-specific equivalence between information and atomic radiation. The article also does not test the TO cosmogonic theorem, its cosmological eras, or its complete set of modal axioms. Subsequent criticisms and refinements are incorporated. Piani’s criticism of Hilbert–Schmidt geometric discord, Giorgi’s demonstration that discord is not universally necessary and sufficient for useful RSP, and later work distinguishing mere discord from genuinely nonclassical RSP prevent an unrestricted ontological interpretation of the 2012 result (Piani 2012; Giorgi 2013; Chen et al. 2024). Rather than weakening the dialogue with TO, these developments clarify the appropriate bridge: the enduring lesson is not that one particular discord measure is a universal ontological substance, but that physically instantiated relations can encode operational resources not captured by simpler classifications such as entanglement alone. The study concludes that Dakić et al. provide meaningful indirect empirical corroboration of a relational-informational orientation compatible with TO, while providing no exclusive confirmation of TO. A research program is proposed in which TO would define quantitative informational variables, boundary-sensitive transformations, and experimentally discriminating predictions capable of being compared with quantum-information observables. On a zero-to-ten scale of substantive dialogue with TO, the analyzed article is assigned 7.6/10. Keywords: Theory of Objectivity; quantum discord; remote state prepara- tion; quantum information; relational information; modal necessity; geometric discord; photon polarization; nonclassical correlations; empirical corroboration; transcendent information; inductive effects.
Quantum networks typically comprise quantum channels, repeaters, and end nodes. Remote state preparation (RSP) allows one end node to prepare the states of the other end nodes remotely. While quantum discord has recently been recognized as necessary for RSP, it does not guarantee the practical implementation of RSP in quantum networks surpasses any classical method. Herein, we theoretically introduce and experimentally study a quantum resource that we call the RSP capability. This resource validates all the static and dynamic elements required to enable genuine quantum networks where the RSP’s implementation can outperform any classical emulation of entanglement- and qubit-unitaries-free strategies, including the static resources of Einstein-Podolsky-Rosen pairs and the dynamic resources of quantum channels and repeaters. Our experiment measures the RSP capability to demonstrate the transition between classical and nonclassical RSP depending on the photon-pair qualities. It shows that quantum discord does not confirm a nonclassical RSP, but the RSP capability does. These results help reveal the quantum advantages that emerge when networking RSP is in play. The authors introduce and experimentally study a quantum resource called the remote state preparation capability. This resource validates all static and dynamic elements required to enable quantum networks where the implementation of remote state preparation can outperform any classical emulation of entanglement- and qubit-unitaries-free strategies.
Abstract Understanding how correlations can be used for quantum communication protocols is a central goal of quantum information science. While many authors have linked the global measures of correlations such as entanglement or discord to the performance of specific protocols, in general the latter may require only correlations between specific observables. In this work, we first introduce a general measure of correlations for two-qubit states, based on the classical mutual information between local observables. Our measure depends on the state’s purity and the symmetry in the correlation distribution, according to which we provide a classification of maximally mixed marginal states (MMMS). We discuss the complementarity relation between correlations and coherence. By focusing on a simple yet paradigmatic example, i.e. the remote state preparation protocol, we introduce a method to systematically define the proper protocol-tailored measures of the correlations. The method is based on the identification of those correlations that are relevant (useful) for the protocol. On the one hand, the approach allows the role of the symmetry of the correlation distribution to be discussed in determining the efficiency of the protocol, both for MMMS and general two-qubit quantum states, and on the other hand, it allows an optimized protocol for non-MMMS to be devised, which is more efficient with respect to the standard one. Overall, our findings clarify how the key resources in simple communication protocols are the purity of the state used and the symmetry of the correlation distribution.