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Scientific Reports

Bidirectional multi-nodes quantum teleportation using discrete-time quantum walk

Nada Ikken, Pankaj Kumar, Abdallah Slaoui, Binayak Kar, R. Ahl Laamara, Mariam Zomorodi Moghadam, Ahmed A. Abd El‐Latif

Published Dec 29, 2025• 1 citation

Abstract

We suggest a new technique for bidirectional quantum teleportation (BQT) that combines coherent-state encoding with discrete-time quantum walks to allow two users to communicate quantum information simultaneously. Our method enables Alice and Bob to simultaneously teleport quantum states to one another within a single protocol, as compared to unidirectional teleportation, which only transmits quantum states in one direction. To allow for a qubit-like representation and fidelity analysis using Bloch vector formalism, the quantum information is encoded using non-orthogonal coherent states that are converted into an orthonormal basis of even and odd Schrödinger cat states. Four different quantum walk steps, each acting on a three-part quantum system made up of position and coin spaces, drive the teleportation process. We use density matrix overlaps in the even-odd basis to derive closed-form formulas for teleportation fidelity in both directions analytically. Using the SeQUeNCe discrete-event simulator, we simulate large-scale quantum network settings with realistic limitations, including photon loss, memory decoherence, entanglement swapping degradation, and various channel capacities in order to evaluate the potential of our approach. We evaluate quantum memory utilization, throughput, and end-to-end fidelity in various network topologies and scenarios. Our findings demonstrate that BQT allows symmetric communication with strong fidelity, particularly in high-capacity and large-scale network situations, but requires a greater resource overhead than unidirectional protocols. The hybrid framework developed in this study offers a scalable and analytically simple solution for next-generation quantum communication systems by combining discrete-time quantum evolution with continuous-variable state encoding.

DOI: 10.1038/s41598-025-28524-2

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We suggest a new technique for bidirectional quantum teleportation (BQT) that combines coherent-state encoding with discrete-time quantum walks to allow two users to communicate quantum information simultaneously. Our method enables Alice and Bob to simultaneously teleport quantum states to one another within a single protocol, as compared to unidirectional teleportation, which only transmits quantum states in one direction. To allow for a qubit-like representation and fidelity analysis using Bloch vector formalism, the quantum information is encoded using non-orthogonal coherent states that are converted into an orthonormal basis of even and odd Schrödinger cat states. Four different quantum walk steps, each acting on a three-part quantum system made up of position and coin spaces, drive the teleportation process. We use density matrix overlaps in the even-odd basis to derive closed-form formulas for teleportation fidelity in both directions analytically. Using the SeQUeNCe discrete-event simulator, we simulate large-scale quantum network settings with realistic limitations, including photon loss, memory decoherence, entanglement swapping degradation, and various channel capacities in order to evaluate the potential of our approach. We evaluate quantum memory utilization, throughput, and end-to-end fidelity in various network topologies and scenarios. Our findings demonstrate that BQT allows symmetric communication with strong fidelity, particularly in high-capacity and large-scale network situations, but requires a greater resource overhead than unidirectional protocols. The hybrid framework developed in this study offers a scalable and analytically simple solution for next-generation quantum communication systems by combining discrete-time quantum evolution with continuous-variable state encoding.

This paper presents BQT-MDQW, a hybrid quantum-classical framework for routing in multihop quantum communication networks. The framework combines fidelity-aware edge costs, quantum-walkassisted exploration, and resource-adaptive bidirectional quantum teleportation (BQT). Three composite entangled resources—W-Bell, GHZ-Bell, and Cluster-Bell—are formulated as candidate channels and compared under a common simulation model. The protocol estimates link-level channel-quality parameters and selects resource states and conditional Pauli recovery operations according to the estimated channel conditions. Routing is performed by a modified Dijkstra layer that minimizes a fidelity-derived edge cost, while a coined quantum walk supplies candidate high-fidelity regions of the network graph; the final route is reconstructed and verified classically. Circuit-level simulations are carried out on the Qiskit Aer simulator, and network-level evaluations are reported for graphs of 50-200 nodes under depolarizing noise and independent link-failure models.Within this simulated regime,W-Bell-based routing preserves comparatively higher end-to-end fidelity than GHZ-Bell- and Cluster-Bell-based routing, and the bidirectional scheme is presented as a trade-off against unidirectional teleportation rather than as a uniform performance gain. TheO(log2N) scaling reported here is an assumption-dependent estimate for the idealized quantum-walk search subroutine only, excluding state preparation, link-fidelity estimation, output extraction, classical path reconstruction, and hop-by-hop teleportation; it is not a complexity bound for the full routing protocol, and unconditional quantum speedup over classical shortest-path routing is not established. The contribution is a proof-of-concept hybrid framework that integrates fidelity-aware routing, quantum-walkassisted exploration, and bidirectional teleportation for multi-hop quantum networks.

Abstract In this paper, we propose a new scheme for faithful bidirectional quantum teleportation (BQT) of special type of two-qubit entangled states by using single G state as a quantum channel. In 2016, by using five-qubit and six-qubit entangled states as the quantum channels, two different BQT schemes were proposed by Sang ((2016) Int. J. Theor. Phys . 55 , 1333) and Hassanpour et al ((2016) Quantum Inf. Process. 15 , 905) respectively. In first scheme, Alice teleports a special type of two-qubit entangled state to Bob and at the same time Bob teleports a single qubit state to Alice. In later scheme, Alice and Bob teleport special type of two-qubit entangled state to each other simultaneously. In contrast to these schemes, in our proposed scheme Alice and Bob can teleport special type of two-qubit entangled states to each other simultaneously while the quantum channel is a four-qubit entangled state. Our proposed BQT scheme requires minimum consumption of quantum and classical resources and it has maximum intrinsic efficiency as compared with previous BQT schemes. We also generalize our scheme for bidirectional quantum teleportation of N-qubit entangled states.

Abstract This paper proposes a hybrid bidirectional quantum communication protocol, in which two parties simultaneously transmit two-qubit states: one via quantum teleportation (QT) and the other via remote state preparation (RSP). This approach establishes a more flexible model for bidirectional quantum communication. The protocol utilizes a specially designed maximally entangled quantum channel to enable hybrid bidirectional communication. By performing Bell measurements, joint projective measurements, and corresponding unitary operations, quantum teleportation from Alice to Bob and remote state preparation from Bob to Alice can be accomplished synchronously. Furthermore, the robustness of the proposed protocol is evaluated under three typical noisy environments, namely the amplitude damping (AD) channel, phase damping(PD) channel and the depolarizing (DP) channel. The proposed protocol provides a novel framework for effcient bidirectional quantum communication, with potential advantages in enhancing interactivity and optimizing resource utilization in future quantum networks.

In this paper, different from the other existing methods that only the special and limited numbers of qubits transmit between Alice and Bob, a general method is proposed to implement Bidirectional Quantum Controlled/uncontrolled Teleportation (BQCT/BQT) that Alice and Bob can transmit each type of arbitrary n and m-qubits to each other, simultaneously. This protocol is based on Controlled-NOT (CNOT) operation, appropriate single-qubit unitary operations and single-qubit measurement in the Z-basis and X-basis. Also, the quantum channel can be created by using Hadamard and CNOT operations. One of the advantages of this method is using the single-qubit measurements which are more efficient than two-qubit measurements.

Optical coherent states are experimentally realizable continuous variable quantum states of which preparation by lasers, as well as its manipulation and monitoring by linear optical gadgets are well established. We propose a strategy to send an arbitrary superposition of four-component bimodal entangled coherent states from a sender to a receiver who, simultaneously, tries to transmit an unknown Schrodinger Cat coherent state to sender via employing a cluster consisting of three superposition of two component bimodal entangled coherent states as the quantum channel and utilizing linear optical gadgets. Heralded detection of photons in laboratories of sender and receiver followed by classical communications of even and odd number of photons and local unitary operations, impeccably, accomplishes simultaneous faithful asymmetric bidirectional quantum teleportation with one eighth of probability of success. It is seen that not all detection events implement the protocol and, therefore, one has to locally apply displacement operator, a necessary evil. We analyze near faithful partial asymmetric bidirectional quantum teleportation and associated probability of success therein. We demonstrated that, for an intense coherent optical field, fidelity approach unity.

Quantum teleportation has evolved from single-qubit, unidirectional communication to multi-qubit and multidirectional protocols. However, most existing schemes rely on protocol-specific entangled resources, motivating the development of universal quantum channels capable of supporting multiple communication tasks simultaneously. In this work, we demonstrate that a single twelve-qubit entangled channel exhibits such versatility by enabling the bidirectional teleportation of arbitrary three-qubit states and the cyclic teleportation of arbitrary two-qubit states through local Bell-state measurements and single-qubit operations. Both protocols are further generalized to multi-qubit and multi-party configurations, establishing the scalability of the proposed framework. To assess its practical applicability, the protocols are analyzed under amplitude-damping, phase-damping, bit-flip, phase-flip, and depolarizing noise channels by plotting the teleportation fidelity as a function of both the input-state parameters and noise strength. The analysis reveals distinct noise sensitivities, with the bidirectional protocol remaining perfectly faithful under bit-flip noise for all input states and noise strengths, while the cyclic protocol is consistently more vulnerable to environmental disturbances. The proposed schemes achieve an intrinsic efficiency of

25\%

, which is compared with several existing protocols. The framework therefore provides a scalable and resource-efficient approach to unified quantum communication in realistic noisy quantum networks.