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.
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.
Remote state preparation (RSP) enables a sender to remotely prepare the quantum state of a receiver without sending the state itself. Recently, it has been recognized that quantum discord is a necessary resource for RSP. Here, we theoretically and experimentally investigate whether RSP can outperform dynamic classical remote state preparation processes. We show that such classical processes can describe certain RSPs powered by quantum discord. Rather, we argue that a new kind of Einstein-Podolsky-Rosen steering for dynamical processes, called quantum process steering, is the resource required for performing nonclassical RSP. We show how to measure quantum process steering by experimentally realizing nonclassical RSP of photonic quantum systems. Moreover, we demonstrate the transition from classical to quantum RSP. Our results also have applications in realizing genuine quantum RSP for quantum-enabled engineering.
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.
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.
A sender can prepare a quantum state for a remote receiver using preshared entangled pairs, only the sender's single-qubit measurement, and the receiver's simple correction informed by the sender. It provides resource-efficient advantages over quantum teleportation for quantum information. Here, we propose the most efficient approach to detect the remote state preparation (RSP) based on the quantum benefits powered by quantum coherence's static resources of the shared pairs and the dynamic resources both the RSP participants input. It requires only the receiver's minimum of one additional coherence creation operation to verify RSP. Experimentally, we implement the introduced RSP assessment using different photon pair states generated from a high-quality polarization Sagnac interferometer, confirming the necessary and sufficient role played by the static and dynamic quantum coherence resources and demonstrating efficient RSP verification. Our results provide a route to efficiently assess RSP in practical scenarios such as quantum information in quantum networks.
Remote state preparation (RSP) is the act of preparing a quantum state at a remote location without actually transmitting the state itself. Using at most two classical bits and a single shared maximally entangled state, one can in theory remotely prepare any qubit state with certainty and with perfect fidelity. However, in any experimental implementation the average fidelity between the target and output states cannot be perfect. In order for an RSP experiment to demonstrate genuine quantum advantages, it must surpass the optimal threshold of a comparable classical protocol. Here we study the fidelity achievable by RSP protocols lacking shared entanglement and determine the optimal value for the average fidelity in several different cases. We implement an experimental scheme for deterministic remote preparation of arbitrary photon polarization qubits, preparing 178 different pure and mixed qubit states with an average fidelity of 0.995. Our experimentally achieved average fidelities surpass our derived classical thresholds whenever the classical protocol does not trivially allow for perfect RSP.