Abstract In this paper, we present a theoretical framework for bidirectional quantum teleportation through pulsed two-qubit entangled channels. The protocol enables simultaneous reciprocal state exchange between spatially separated parties via deterministic quantum circuit operations on a ten-qubit system. We derive the complete time-evolved density matrix for independently pulsed qubits using Heisenberg picture dynamics, characterizing the quantum channel through correlation matrix formalism. Protocol success requires three synergistic conditions: maximal initial entanglement, symmetric pulse application to both channel qubits, and antipodal Bloch sphere initialization. Comprehensive analysis of fidelity and quantum Fisher information reveals that symmetric strong pulsing combined with appropriately structured correlations achieves near-unit fidelity and maximal parameter estimation precision across extensive parameter ranges. This optimal configuration exhibits remarkable robustness against pulse timing uncertainties and state preparation errors, essential attributes for experimental implementations. The quantum Fisher information analysis establishes that pulsed channels preserve both quantum states and parametric information, enabling applications in distributed quantum metrology. Our results demonstrate that engineered pulsed dynamics generate robust bidirectional communication channels, providing optimization principles for practical quantum networks.
Abstract In this paper, we present a theoretical framework for bidirectional quantum teleportation through pulsed two-qubit entangled channels. The protocol enables simultaneous reciprocal state exchange between spatially separated parties via deterministic quantum circuit operations on a ten-qubit system. We derive the complete time-evolved density matrix for independently pulsed qubits using Heisenberg picture dynamics, characterizing the quantum channel through correlation matrix formalism. Protocol success requires three synergistic conditions: maximal initial entanglement, symmetric pulse application to both channel qubits, and antipodal Bloch sphere initialization. Comprehensive analysis of fidelity and quantum Fisher information reveals that symmetric strong pulsing combined with appropriately structured correlations achieves near-unit fidelity and maximal parameter estimation precision across extensive parameter ranges. This optimal configuration exhibits remarkable robustness against pulse timing uncertainties and state preparation errors, essential attributes for experimental implementations. The quantum Fisher information analysis establishes that pulsed channels preserve both quantum states and parametric information, enabling applications in distributed quantum metrology. Our results demonstrate that engineered pulsed dynamics generate robust bidirectional communication channels, providing optimization principles for practical quantum networks.
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.
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.
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.
Abstract We propose two novel protocols for bidirectional quantum teleportation (BQT) of qutrit states in multi-party settings: a cyclic BQT protocol enabling simultaneous state exchange among three or more users, and a controlled BQT protocol incorporating a supervisory authorization mechanism. Both protocols leverage optimized multi-qutrit entangled channels and deterministic measurement-based correction schemes. We derive exact analytical expressions for the state-independent average fidelities under all four types of three-dimensional Pauli-like noise channels: trit-flip, t-phase-flip, trit-phase-flip, and t-depolarizing. Our results demonstrate a linear fidelity degradation with noise parameter p , yet both protocols maintain superior resource efficiency and security compared to conventional two-party BQT. The cyclic protocol achieves a 33% reduction in entanglement resource consumption compared to sequential two-party implementations, while the controlled protocol ensures unconditional security against unauthorized access. These advances establish a practical framework for high-dimensional quantum networks and secure distributed quantum applications.
Abstract A bidirectional quantum teleportation protocol is proposed for the transfer of two-qubit entangled states between two parties utilizing a six-qubit cluster state quantum channel. The protocol enhances the resource efficiency by allowing the reconstruction of teleported states without the use of CNOT operations or auxiliary qubits at the receiver’s end. Comparative analysis with existing schemes highlights the higher intrinsic efficiency of the proposed approach for bidirectional quantum teleportation. The protocol is further generalized to enable the bidirectional teleportation of arbitrary n-qubit entangled states using the same six-qubit quantum resource, demonstrating scalability. The protocol is simulated under various noise models to evaluate its robustness, with fidelity assessments carried out using the IBM Qiskit SDK. A complete teleportation circuit implementing the protocol is designed using standard quantum gates.
In practical quantum communication, quantum channels are inevitably affected by noise and decoherence, leading to their degradation into non-maximally entangled or even mixed states. As a result, conventional quantum teleportation schemes based on non-maximally entangled channels are inherently probabilistic and cannot simultaneously achieve unit fidelity and unit success probability. To address this issue, we exploit the structural degrees of freedom of high-dimensional partially entangled channels and construct an asymmetric joint measurement basis matched to the Schmidt-coefficient distribution of the channel, thereby proposing a controlled multi-output perfect quantum teleportation scheme. First, based on a three-dimensional partially entangled five-qutrit channel, a controlled two-output teleportation model for unknown single-qubit states is established. Perfect transmission with both unit fidelity and unit success probability is achieved through the controller’s projective measurement, the sender’s asymmetric joint measurement, and the receivers’ corresponding local recovery operations. On this basis, the scheme is generalized to arbitrary d-dimensional partially entangled channels and further extended from the two-output configuration to the multi-output scenario. Our analysis shows that, when the two largest Schmidt coefficients of the channel are equal, deterministic perfect teleportation with both unit fidelity and unit success probability can still be achieved using non-maximally entangled resources. The proposed scheme is more consistent with realistic quantum communication environments and provides a theoretical foundation for efficient and controllable quantum information distribution in complex quantum networks.