Quantum teleportation is a very helpful information-theoretic protocol that allows to transfer an unknown arbitrary quantum state from one location to another without having to transmit the quantum system through the intermediate region. Quantum states, quantum channels, and indefinite causal structures are all examples of quantum causal structures that not only enable advanced quantum information processing functions, but can also model causal structures in nonclassical spacetimes. In this letter, we develop quantum teleportation of arbitrary quantum causal structures, as formalized by the process matrix framework. Instead of teleporting all the physical degrees of freedom that implement the causal structure, the central idea is to just teleport the inputs to and outputs from the operations of agents. The communication of outcomes of Bell state measurements, which is necessary for deterministic quantum teleportation, is not possible for all causal structures that one might wish to investigate. To avoid this problem, we propose partially and fully post-selected teleportation protocols. We prove that our partially post-selected teleportation protocol is compatible with all quantum causal structures, including those that involve indefinite causal order.
Quantum teleportation is a very helpful information-theoretic protocol that allows to transfer an unknown arbitrary quantum state from one location to another without having to transmit the quantum system through the intermediate region. Quantum states, quantum channels, and indefinite causal structures are all examples of quantum causal structures that not only enable advanced quantum information processing functions, but can also model causal structures in nonclassical spacetimes. In this letter, we develop quantum teleportation of arbitrary quantum causal structures, as formalized by the process matrix framework. Instead of teleporting all the physical degrees of freedom that implement the causal structure, the central idea is to just teleport the inputs to and outputs from the operations of agents. The communication of outcomes of Bell state measurements, which is necessary for deterministic quantum teleportation, is not possible for all causal structures that one might wish to investigate. To avoid this problem, we propose partially and fully post-selected teleportation protocols. We prove that our partially post-selected teleportation protocol is compatible with all quantum causal structures, including those that involve indefinite causal order.
This work develops a process-based interpretation of quantum teleportation, quantum switching, and time, grounded in discrete process graphs rather than continuous space–time dynamics. We introduce a formal framework in which the fundamental unit of physical evolution is not the quantum state itself, but a discrete process step (process tact), represented as a unitary transformation acting on a structured process graph. Quantum teleportation is reinterpreted as a transition between isomorphic index layers of the same process graph, rather than as a transmission of a quantum state through space–time. In this framework, entanglement establishes a shared structural constraint, measurement performs index selection, and classical communication transfers index information only. The quantum state remains invariant under graph isomorphism, and teleportation is formalized as reindexation without a physical carrier. Time is shown to emerge as an ordering relation between process steps and index layers, not as a fundamental parameter. Changes in temporal ordering correspond to transitions between equivalent graph embeddings, enabling a natural interpretation of temporal displacement as index reassignment within a recursive process structure. Geometrically, these ideas are represented using recursive pentagon–pentagram embeddings, which serve as an exact structural analogy for quantum switching. The pentagram functions as a universal quantum switch, mediating transitions between distinct but isomorphic orderings. This construction provides an intuitive and mathematically consistent representation of indefinite causal order. The framework is directly connected to EPR correlations, quantum teleportation protocols, and the quantum switch, and is shown to be naturally compatible with the Everett (many-worlds) interpretation of quantum mechanics. Within this ontology, the wave function is treated as an objective process structure, and no collapse postulate is required. This work builds upon and extends previously published results on graph-based quantum key switching and emergent space–time structure, unifying them into a single process-theoretic description of quantum information transfer, causal order, and temporal indexing. Reference to previous foundational work: DOI 10.5281/zenodo.18498181. Reference to previous foundational work: DOI 10.5281/zenodo.18504244.
This paper proposes a novel quantum teleportation protocol leveraging multi-variable quantum entanglement. The core of the protocol relies on the strong correlations inherent in multi-dimensional entangled states to achieve high-efficiency and secure quantum teleportation. We demonstrate a framework for constructing such a protocol and analyze its potential advantages over traditional approaches. The key contribution lies in expanding the theoretical foundation of quantum teleportation, offering a new strategy for quantum communication and information processing. The protocol utilizes a series of Bell state measurements and classical communication to transfer the quantum state from one location to another, relying heavily on pre-shared multi-variable entangled pairs. We outline the mathematical formalism underpinning the protocol, including the description of the entangled states, the Bell state measurements, and the necessary classical information exchange. The protocol aims to enhance the transmission efficiency and bolster the security of quantum teleportation by exploiting the complexity and robustness afforded by multi-variable entanglement.
Quantum teleportation is a quintessential quantum communication protocol that enables the transmission of an arbitrary quantum state between two distant parties without physically transmitting the state with the help of shared entanglement and limited classical communication. We show that it is possible to relax the entanglement requirement in quantum teleportation if we have access to a certain strain of superposition of quantum processes. Two types of superposition of quantum processes are generally considered in the literature: superposition of paths identified with quantum maps and superposition of indefinite causal orders of the maps. We find that when superposition of paths is incorporated in the protocol, quantum teleportation with unit fidelity becomes possible with nonzero probability of 1/4 even when the two parties share certain classes of separable states, including pure product states. In contrast, the assistance of superposition of indefinite causal order of quantum maps in teleportation protocol does not enable any quantum advantage for shared pure product states. Furthermore, we show that separable Werner states can also yield quantum advantage in quantum teleportation assisted by the superposition of paths. Finally, we establish that the presence of quantum coherence in the control qubit is both necessary and sufficient to achieve quantum advantage in quantum teleportation assisted with superposition of paths. The results potentially uncover yet another role of quantum superposition, in general, in teleportation versus entanglement.
Spatial separation restricts the set of locally implementable quantum operations on distributed multipartite quantum systems. We propose that indefinite causal structure arising due to quantum superposition of different space-time geometries can be used as an independent universal resource for local implementation of any quantum operation on spatially distributed quantum systems. Consequently, all such quantum tasks that are not accomplishable by local operations and classical communication (LOCC) only also become locally accomplishable. We show that exploiting indefinite causal structure as the sole resource, it is possible to perfectly teleport the state of one agent's subsystem to the other distant laboratory in such a way that the agent at the distant laboratory can have access to the whole initially shared state in his or her laboratory and can perform any global quantum operation on the joint state locally. We further find that, after the teleportation process, the resource---indefinite causal structure of the space-time does not get consumed. Hence, after implementing the desired quantum operation the state of the first agent's subsystem can be teleported back to its previous laboratory using the same resource. We show that this two-way teleportation is not always necessary for locally executing all nonlocal quantum tasks that are not realizable by LOCC only. Without invoking any kind of teleportation, we present a protocol for perfect local discrimination of the set of four Bell states that exploits indefinite causal structure as the sole resource. As immediate upshots, we present some more examples of such nonlocal tasks as local discrimination of the set of states exhibiting ``quantum nonlocality without entanglement'' and activation of bound entangled states that are also achievable by our proposed protocol incorporating indefinite causal structure as a resource.
Quantum teleportation is a cornerstone of quantum information processing, enabling the nonlocal transmission of quantum states across arbitrary distances using shared entanglement and classical communication. While the standard protocol typically employs Z-basis Bell-state measurements, this fixed-basis approach limits flexibility in practical quantum networks, where dynamic operations, hardware variability, and advanced communications demand alternative measurement bases.
In this work, we introduce a multi-axis quantum teleportation protocol that generalizes the measurement process by allowing arbitrary basis choices. We provide a formal derivation and self-contained mathematical proof demonstrating that the input quantum state can be faithfully reconstructed under basis-adaptive restoration operations. By establishing a rigorous algorithmic and analytical foundation, this work validates the generalized teleportation protocol and paves the way toward advanced strategies for quantum communication. The demonstrations of the proposed protocol are available at: https://github.com/JJJayyyy/Multi-Axis-Quantum-Teleportation.
In this paper we provide a genuine relativistic quantum teleportation protocol the classical communication component of which makes use of relativistic causal propagation of a quantum field. Consequently, the quantum teleportation is fully relativistic by construction. Our scheme is based on the Unruh-DeWitt qubit detector model, where the quantum state being teleported is associated to an actual qubit rather than the field mode considered by Alsing and Milburn [P. M. Alsing and G. J. Milburn, Phys. Rev. Lett. 91, 180404 (2003)]. We show that the existing works in (relativistic) quantum information, including good definitions of one-shot and asymptotic channel capacities, as well as algebraic formulation of quantum field theory, already provide us with all the necessary ingredients to construct a fundamentally relativistic teleportation protocol in a relatively straightforward manner.