This paper illustrates various aspects of the ER=EPR conjecture. It begins with a brief heuristic argument, using the Ryu‐Takayanagi correspondence, for why entanglement between black holes implies the existence of Einstein‐Rosen bridges. The main part of the paper addresses a fundamental question: Is ER=EPR consistent with the standard postulates of quantum mechanics? Naively it seems to lead to an inconsistency between observations made on entangled systems by different observers. The resolution of the paradox lies in the properties of multiple black holes, entangled in the Greenberger‐Horne‐Zeilinger pattern. The last part of the paper is about entanglement as a resource for quantum communication. ER=EPR provides a way to visualize protocols like quantum teleportation. In some sense teleportation takes place through the wormhole, but as usual, classical communication is necessary to complete the protocol.
This paper illustrates various aspects of the ER=EPR conjecture. It begins with a brief heuristic argument, using the Ryu‐Takayanagi correspondence, for why entanglement between black holes implies the existence of Einstein‐Rosen bridges. The main part of the paper addresses a fundamental question: Is ER=EPR consistent with the standard postulates of quantum mechanics? Naively it seems to lead to an inconsistency between observations made on entangled systems by different observers. The resolution of the paradox lies in the properties of multiple black holes, entangled in the Greenberger‐Horne‐Zeilinger pattern. The last part of the paper is about entanglement as a resource for quantum communication. ER=EPR provides a way to visualize protocols like quantum teleportation. In some sense teleportation takes place through the wormhole, but as usual, classical communication is necessary to complete the protocol.
If spacetime is built out of quantum bits, does the shape of space depend on how the bits are entangled? The ER=EPR conjecture relates the entanglement entropy of a collection of black holes to the cross sectional area of Einstein-Rosen (ER) bridges (or wormholes) connecting them. We show that the geometrical entropy of classical ER bridges satisfies the subadditivity, triangle, strong subadditivity, and Cadney-Linden-Winter inequalities. These are nontrivial properties of entanglement entropy, so this is evidence for ER=EPR. We further show that the entanglement entropy associated with classical ER bridges has nonpositive tripartite information. This is not a property of entanglement entropy, in general. For example, the entangled four qubit pure state ∣GHZ4⟩=(∣0000⟩+∣1111⟩)/2 has positive tripartite information, so this state cannot be described by a classical ER bridge. Large black holes with massive amounts of entanglement between them can fail to have a classical ER bridge if they are built out of ∣GHZ4⟩ states. States with nonpositive tripartite information are called monogamous. We conclude that classical ER bridges require monogamous EPR correlations.
The Greenberger-Horne-Zeilinger version of the Einstein-Podolsky-Rosen (EPR) paradox is widely regarded as a conclusive logical argument that rules out the possibility of reproducing the predictions of Quantum Mechanics within the framework of any physical theory sharing the notions of reality and relativistic causality that we acknowledge as a given in our classical descriptions of the macroscopic world. Thus, this renowned argument stands as a seemingly insurmountable roadblock on the path to a very desired, physically intuitive understanding of quantum phenomena and, in particular, quantum entanglement. In this paper, we notice, however, that the GHZ argument involves unaccounted spurious gauge degrees of freedom and that it can be overcome once these degrees are properly taken into account. It is then possible to explicitly build a successful statistical model for the GHZ experiment based on the usual notions of relativistic causality and physical reality. This model, thus, completes—in the EPR sense—the quantum description of the GHZ state and paves the way to a novel intuitive interpretation of the quantum formalism and a deeper understanding of the physical reality that it describes.
This preprint offers a minimal, background-independent logical re-reading of the ER=EPR conjecture using the Logical Language (LL) of standard quantum mechanics. ER=EPR links quantum entanglement to geometric connections (Einstein–Rosen bridges) in emergent spacetime, with standard arguments relying on AdS/CFT and the Ryu–Takayanagi formula. LL strictly follows textbook QM and classical logic, defining physical existence solely by in-principle distinguishability (a detector). Undefined classical local spacetime variables across regions thus lack independent reality. Consistency then requires stronger-than-classical correlations to maintain connectivity, yielding the simple relation: the closer two points, the stronger the correlation. This captures ER=EPR’s core intuition (entanglement as geometric proximity) with far fewer assumptions—no duality, no holographic background, no new postulates—using only standard QM. The note recaps LL (definitional existence, operating setups), illustrates via double-slit and EPR examples, and derives the correlation–distance link from two premises (Consistency and Definitional Existence).
An accumulation of theoretical evidence contribute to the picture of gravity as a manifestation of quantum entanglement in a certain many-body quantum system. This is in particular expresses in the ER=EPR conjecture, which relates gravitational Einstein-Rosen (ER) bridge with the Einstein-Podolsky-Rosen (EPR) quantum entangled pairs or, more generally, with the so-called Thermofield Double State. In this letter, the ER=EPR conjecture is employed to introduce unitary quantum teleportation protocol, which \emph{recycles} the entanglement forming traversable generalization of the Einstein-Rosen bridge. In consequence, the wormhole remains unaffected by the quantum teleportation. Furthermore, it is shown that the protocol guarantees the unconditional security of the quantum communication. Performance of the protocol is demonstrated in a simple setting with the use of 5-qubit Santiago IBM quantum computer, giving fidelities above the 2/3 classical limit for a representative set of teleported states. Security of the protocol has been supported by experimental studies performed with the use of the noisy quantum processor. Possible generalization of the protocol, which may have relevance in the context of macroscopic gravitational configurations, is also considered.
Quantum entanglement was once a subject of intense philosophical debate and regarded as a puzzling theoretical anomaly. However, it has now been empirically validated and is widely recognized as a fundamental feature of quantum mechanics. This review traces its development in chronological order, beginning with the Einstein–Podolsky–Rosen (EPR) paradox, which raised profound questions about the completeness of quantum theory, and John Stewart Bell’s subsequent theorem, which established a measurable framework to verify entanglement’s non-local nature. The discussion then turns to contemporary experimental and applied domains where entanglement serves as a critical resource. Notable examples include quantum teleportation, entanglement-enhanced metrology, quantum radar, and emerging quantum energy devices such as quantum batteries. The transition from theoretical dispute to practical application underscores how entanglement now enables tangible technologies—ranging from ultra-secure communication networks to highly precise sensors. Furthermore, potential interdisciplinary applications in fields such as quantum biology are also explored, suggesting new pathways for innovation. This review aims to bridge foundational concepts with current technological advances, illustrating the continuing impact of quantum entanglement on both scientific understanding and real-world engineering.
This paper explores the ER bridges theory and its relationship with quantum phenomena. An argument can be made that the ER bridges theory does not explicitly address quantum phenomena and implies that Einstein intended to differentiate between individual particles within the ER bridges theory and the systems involved in the EPR paradox. However, this paper contends that Einstein held a distinct viewpoint. He endeavored to elucidate quantum characteristics by modifying general relativity, aiming to incorporate concepts such as local realism, separability, causality, and determinism, without relying on the principles of quantum mechanics. He proposed representing elementary particles using parallel ER bridges connecting two flat sheets to achieve this.