This article introduces an innovative four-qubit GHZ state protocol for superdense quantum coding, aimed at maximizing the capacities of quantum systems.The coding capacity was theoretically compared to the Holevo bound, which defines the limit of extractable information from a quantum system.Simulations were performed using quantum computing software, followed by implementation on the IBM Quantum Computer to assess both theoretical and practical outcomes.Experimental findings revealed a slight deviation from theoretical predictions: while theory assigned a 50% probability to each state, practical results indicated 50.19531% and 49.80469%.These differences are attributed to environmental noise and qubit interactions, which pose challenges in quantum computing.The study highlights the need for strategies to mitigate noise and enhance measurement precision.Results were presented using bar charts, facilitating clear data analysis and revealing patterns better.Overall, this research provides a new protocol and addresses key challenges in quantum technology, contributing significantly to the field of quantum computing and paving the way for future advancements.
This article introduces an innovative four-qubit GHZ state protocol for superdense quantum coding, aimed at maximizing the capacities of quantum systems.The coding capacity was theoretically compared to the Holevo bound, which defines the limit of extractable information from a quantum system.Simulations were performed using quantum computing software, followed by implementation on the IBM Quantum Computer to assess both theoretical and practical outcomes.Experimental findings revealed a slight deviation from theoretical predictions: while theory assigned a 50% probability to each state, practical results indicated 50.19531% and 49.80469%.These differences are attributed to environmental noise and qubit interactions, which pose challenges in quantum computing.The study highlights the need for strategies to mitigate noise and enhance measurement precision.Results were presented using bar charts, facilitating clear data analysis and revealing patterns better.Overall, this research provides a new protocol and addresses key challenges in quantum technology, contributing significantly to the field of quantum computing and paving the way for future advancements.
Abstract The superdense coding protocol is essential for quantum communication, allowing more efficient data transmission. This protocol facilitates the transfer of two bits of classical information using just one qubit by leveraging a pre-existing pair of Bell states. To achieve this capability, traditional implementations of superdense coding depend on entangled states, such as Bell states. This paper introduces a novel circuit that utilizes Bell diagonal states to implement the superdense coding protocol. We provide detailed instructions for the procedure using IBM’s Quantum Computing Lab, enabling practical applications in real-world contexts. Furthermore, the paper highlights the security features of this protocol, emphasizing its significance for secure communication in quantum networks. The combination of efficiency and security represents a notable advancement in quantum information science. We implemented and tested the proposed superdense coding circuit on the IBM Q quantum computing platform using Qiskit. Through extensive simulations on IBM’s Statevector and QASM simulators, we assessed the performance of the circuit based on Bell diagonal states (BDS)in terms of accuracy, noise resilience, and resource efficiency. Our findings indicate that, while Bell diagonal states pose challenges related to noise and decoherence, they also provide potential advantages in reducing qubit usage and enhancing error correction. This research contributes to the exploration of alternative techniques for superdense coding, which may have applications in quantum communication and future quantum networks. However, additional theoretical and experimental investigations are necessary to fully evaluate the scalability and practicality of this approach.
This study presents a generalized n--bit superdense coding protocol that enables the transmission of n classical bits of information using an entangled n--qubit quantum system and the transmission of n−1 qubits. The protocol involves creating a maximally entangled n--qubit GHZ 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 is an explicit, scalable n--bit encoding routine, realized on the GHZ channel with a low--depth encoding layer using only single--qubit Pauli--X and Pauli--Z operations.
The protocol was tested on real quantum hardware using Qiskit 2.0 and the IBM--Fez quantum computer for message lengths of 4, 6, 8, and 10 bits, as a circuit--level proof of concept on a single processor; the physical transmission of qubits between the parties was not implemented. Results show that success rates decrease as message length, transpiled circuit depth and gate count increase; the latter two are set mainly by transpilation rather than by the encoding itself. A mutual information analysis shows that the transmitted information exceeds the classical bound of n−1 bits only for short messages. Strategies to improve performance include sending messages in shorter segments and advances in qubit coherence and gate fidelity. This work offers a practical and easily scalable quantum communication protocol with potential applications in quantum networks and communication systems.
The aim of the research is the mathematical analysis of quantum superdense coding based on quantum entanglement to increase the efficiency and reliability of information transmission in quantum communication systems. The essence of quantum superdense coding is the ability to transmit two classical bits of information using one qubit, which is part of an entangled pair. The fundamental principles of the superdense quantum coding method are considered. The relevance of the research in the context of the development of secure quantum communications and optimization of information transmission in quantum networks is substantiated. A review of modern scientific publications devoted to the theoretical principles of superdense coding is conducted, which indicate the development potential and practical prospects of this direction of quantum informatics. The analysis of mathematical modeling of quantum superdense encoding and decoding is performed using two alternative approaches – projective measurement in the Bell basis and the inverse Bell transform. It is shown that both approaches allow for the complete recovery of classical information transmitted using entangled quantum states. The advantage of the inverse Bell transform is the simplicity of implementation on quantum devices, the flexibility and accuracy of information processing, and the possibility of scaling, which makes it a reasonable choice in many practical applications. The influence of noise and decoherence on the efficiency of superdense coding has been studied, which is a critical factor in the practical implementation of this method in real quantum systems. A mathematical model of data transmission through a quantum channel under the action of additive white noise has been constructed. An analytical dependence of the probability of correct information recovery on the noise level has been established, which allows us to estimate the limits of reliability of superdense coding in noisy environments. Based on the research, the prospects for the practical application of superdense coding in quantum communication networks, in particular the quantum Internet, as well as in quantum computing and information security systems, have been outlined. The results obtained contribute to the further development of quantum technologies and can be used to create new protocols for highly efficient quantum data transmission.
Quantum superdense coding provides a compelling solution to enhance the channel capacity compared with classical coding, which plays a vital role in quantum networks. However, the realization of a degenerate high-dimensional entangled state with high fidelity has remained an elusive challenge, limiting improvement in channel capacity. Here, we have demonstrated a 16-mode quantum process photonic chip and experimentally validated a degenerate eight-dimensional quDit entangled state with a fidelity of 0.973±0.002 . Moreover, we propose an efficient Bell state measurement method to distinguish eleven orthogonal Bell states in eight-dimensional quantum superdense coding. Leveraging the high-quality features of our quantum photonic chip, we have achieved an unprecedented channel capacity of 3.021±0.003 bits, highlighting the largest channel capacity to date. Furthermore, our method presents a remarkable quantum advantage over classical schemes, the latter of which can only transmit a maximum of 3 bits in the environment without any noise. Our findings not only open up a new avenue for integrated quantum information processing, but also contribute significantly to the advancement of multidimensional technologies, facilitating the establishment of practical, high-capacity quantum networks.
Abstract Superdense coding uses entanglement as a resource to communicate classical information efficiently through quantum channels. A superdense coding method is optimal when its capacity reaches Holevo bound. We show that for optimality, maximal entanglement is a necessity across the bipartition of Alice and Bob, but neither absolute nor genuine multipartite entanglement is required. Unlike the previous schemes, which can transmit either even or odd bits of information, we demonstrate a generalized dense coding protocol using the genuine multipartite entangled GHZ state to send arbitrary information bits. Expressed in the eigenbasis of different Pauli operators, GHZ state is characterized by a unique parity pattern which enables us to formulate a security checking technique to ensure absolute security of the protocol. We show this method is better applicable in a scenario, where the initial information is distributed among spatially separated parties. Finally, optimizing the number of qubit(s) sent to Bob, we construct a distributed dense coding method, which completely depicts absolutely secure quantum communication between many to one party.
Abstract This study focuses on the challenges posed by quantum noise to communication protocols, with a particular emphasis on the vulnerabilities of current quantum broadcast protocols. The research employs the generalized GHZ state, known for its multipartite entangled cluster state with real-value coefficients, as a diagnostic tool to understand and address the impact of quantum noise on transmitted information. Implementing two novel controlled quantum broadcast schemes on the IBM Quantum (IBMQ) Experience platform, using the Qiskit library and the QASM simulator, the investigation evaluates the effects of four different types of quantum noise through Kraus operator models. A notable aspect of the study is the pioneering use of quantum state tomography for a comprehensive analysis of quantum noise effects, providing novel insights into the resilience of quantum communication protocols.