Entangled Qubit States Enable Scalable Superdense Coding for N-bit Messages

The secure transmission of information remains a fundamental challenge, and quantum communication offers a potential solution, leveraging the unique properties of quantum mechanics.

Saba Arife Bozpolat from Marmara University and colleagues demonstrate a new method for encoding and transmitting data using entangled qubits, achieving what is known as superdense coding.

This research introduces a generalized protocol capable of sending multiple classical bits of information with a single transmission of qubits, representing a significant step towards more efficient quantum communication networks.

The team’s approach, tested on actual quantum hardware, establishes a practical and scalable instruction for quantum communication, paving the way for advancements in secure data transfer and potentially revolutionising future communication systems. N-bit Superdense Coding with GHZ States The study pioneers a generalized n-bit superdense coding protocol, enabling the transmission of n classical bits of information using an entangled n-qubit system and the transmission of qubits. Researchers began by creating a maximally entangled n-qubit state, specifically utilizing a Greenberger-Horne-Zeilinger (GHZ) state, to establish the foundational quantum resource for communication. This entangled state was designed to be shared between the sender and receiver, potentially generated at a quantum hub and then distributed for use in subsequent stages of the protocol. The core innovation of this work lies in a novel n-bit encoding routine, which encodes a classical message into n-1 qubits using Pauli-Z and Pauli-X gates, adding at most 2(n-1) single-qubit gates determined by the message content, minimizing potential errors as scaling progresses. Following encoding, the study involved transmitting these qubits via a suitable quantum communication channel to the receiver, who de-entangles the qubits and performs Bell State Measurements to extract the original classical message. Experiments were conducted using Qiskit 2. 0 and the IBM-Torino computer, testing message lengths of 4, 6, 8, and 10 bits, and demonstrated that success rates decreased with increasing message length, circuit depth, and gate count, largely due to the increased usage of Pauli-X gates for messages containing more “1” bits. This detailed experimental validation demonstrates the feasibility of the protocol and identifies key areas for optimization, such as sending messages in shorter segments and improving qubit coherence and gate fidelity.,. N-bit Superdense Coding Achieved Experimentally Scientists have achieved a generalized n-bit superdense coding protocol, demonstrating the transmission of n classical bits of information using an entangled n-qubit system and qubit transmission. This protocol involves creating a maximally entangled n-qubit state, followed by encoding the classical message using Pauli-Z and Pauli-X gates, and finally transmitting and decoding the message via quantum communication and measurements. The core of this work lies in a novel n-bit encoding routine, which constructs quantum circuits for n-bit superdense coding while minimizing errors through a streamlined design. Experiments were conducted using Qiskit 2. 0 on the IBM-Torino quantum computer for message lengths of 4, 6, 8, and 10 bits, demonstrating that success rates decrease as message length, circuit depth, and gate count increase, largely due to the increased usage of Pauli-X gates when messages contain more “1” bits. The encoding routine adds a variable number of single-qubit quantum gates to n-1 qubits, depending on the message content, with the best-case scenario requiring no additional gates when all message bits are “0”. Researchers observed that the protocol’s performance is sensitive to message length and gate complexity, highlighting the need for advancements in qubit coherence and gate fidelity to further improve success rates.,.

Scalable Superdense Coding on Quantum Hardware The research team has developed a generalized protocol for superdense coding, a quantum communication technique that transmits classical information using entangled qubits. This new approach enables the transmission of any number of classical bits using an entangled system of qubits and the transmission of qubits themselves. Crucially, the team designed an explicit and scalable circuit for implementing this n-bit superdense coding, minimizing errors through a streamlined design. The protocol’s performance was successfully tested on real quantum hardware, demonstrating its feasibility with message lengths up to ten bits.

Results demonstrate that the success rate of transmitting messages decreases as message length, circuit depth, and the number of gates in the quantum circuit increase, primarily due to the increased use of Pauli-X gates when messages contain more ‘1’ bits. While circuit optimization techniques offer limited improvement, the team found that dividing longer messages into shorter segments holds promise for increasing transmission accuracy, and future research will focus on determining the optimal chunk size for these shorter segments. Overall, this work presents a practical and scalable communication method with potential applications in future quantum networks, while also highlighting the trade-offs between circuit complexity and communication reliability on current quantum hardware., The secure transmission of information remains a fundamental challenge, and quantum communication offers a potential solution, leveraging the unique properties of quantum mechanics.

The team’s approach, tested on actual quantum hardware, establishes a practical and scalable instruction for quantum communication, paving the way for advancements in secure data transfer and potentially revolutionising future communication systems. Scientists generate a maximally entangled n-qubit state, encoding the classical message with Pauli-Z and Pauli-X gates, and then transmitting and decoding the message via quantum communication, quantum operations, and measurements. The key novelty of this work lies in the proposed n-bit encoding routine, which, to the best of their knowledge, is the first explicit and scalable recipe for constructing quantum circuits for n-bit Superdense Coding, minimizing errors through a simple circuit design. 👉 More information 🗞 General Quantum Instruction for Communication via Maximally Entangled -Qubit States 🧠 ArXiv: https://arxiv.org/abs/2512.14280 Tags: