Quantum teleportation provides a way to transfer unknown quantum states from one system to another via an entangled state as a quantum channel without physical transmission of the object itself. The entangled channel, measurement performed by the sender (Alice), and classical information sent to the receiver (Bob) are three key ingredients in the procedure, which need to cooperate with each other. To study the relationship among the three parts, we propose a scheme for perfect teleportation of a qubit through a high-dimensional quantum channel in a pure state with two equal largest Schmidt coefficients. The scheme requires less entanglement of Alice's measurement but more classical bits than the original scheme via a Bell state. The two quantities increase with the entanglement of the quantum channel when its dimension is fixed and thereby can be regard as Alice's necessary capabilities to use the quantum channel. And the two capabilities appear complementary to each other.
Quantum teleportation provides a way to transfer unknown quantum states from one system to another via an entangled state as a quantum channel without physical transmission of the object itself. The entangled channel, measurement performed by the sender (Alice), and classical information sent to the receiver (Bob) are three key ingredients in the procedure, which need to cooperate with each other. To study the relationship among the three parts, we propose a scheme for perfect teleportation of a qubit through a high-dimensional quantum channel in a pure state with two equal largest Schmidt coefficients. The scheme requires less entanglement of Alice's measurement but more classical bits than the original scheme via a Bell state. The two quantities increase with the entanglement of the quantum channel when its dimension is fixed and thereby can be regard as Alice's necessary capabilities to use the quantum channel. And the two capabilities appear complementary to each other.
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.
Abstract In this study, we propose an encrypted quantum teleportation broadcast scheme using a 6-qubit entangled channel and an encrypted quantum teleportation scheme with a controller via a 7-qubit entangled channel. The quantum state of Alice, to be transmitted, is first encrypted into two distinct states that satisfy certain conditions. As the main sender, Alice designates two agents to transmit encrypted states to two receivers. She shares a 6-qubit entangled state with each party and provides the receivers with a 1-bit classical information containing the chosen encryption. After the agents perform measurements on the corresponding orthogonal bases and send the results to the receivers, each receiver can reconstruct the original state sent by Alice. To enhance security for the receivers, the scheme introduces Alice as a controller. The receivers can reconstruct the original state only if Alice performs a measurement and shares her measurement outcome. The use of encryption ensures that even if an agent’s qubit is intercepted, the actual state remains secure. Alice, as the controller, can also terminate the transmission if a security threat is detected or she change her mind to finish the transmission. The teleportation performance depends on how the qubit is encrypted. For a specific input state used as an example, the protocol obtained a teleportation success probability of 0.9608.
A new scheme for short-distance quantum teleportation of an arbitrary unknown three-dimensional two-qutrit state is proposed, utilizing a three-dimensional Bell-state and a ground-state auxiliary qutrit as quantum channel. In this scheme, both the sender and receiver are required to pre-share an auxiliary qutrit in addition to sharing the three-dimensional Bell state. The sender performs joint measurements on their Bell qutrit and the unknown quantum system after performing quantum gate operations on the auxiliary qutrit, and sends the classical information of the measurement results to the receiver. Based on the measurement results, the receiver converts, with 100% probability, the quantum state of his/her own Bell qutrit and auxiliary qutrit into an exact replica of the unknown quantum state initially altered by the sender. This scheme exhibits advantages such as a short transmission distance, high information capacity, reduced consumption of entanglement resources, and promising applications in quantum teleportation for solid-state devices, such as on-chip implementations.
In this work, we consider two stages one qubit quantum teleportation protocol via an arbitrary entangled two qubits state. In the first stage, Alice use XOR gate and computational basis measurement, while for the second stage, Alice use Hadamard gate and another computational basis measurement. Alice sent measurement result to Bob via one classical bit each. As the result, we show that this teleportation can has unit fidelity if the channel used has non-zero two terms and maximally entangled. Then the protocol is applicable if the channel is one of four Bell's state.
In this paper, an asymmetric bidirectional controlled quantum teleportation via a six-qubit partially entangled state is given, in which Alice wants to transmit a two-qubit entangled state to Bob and Bob wants to transmit a single-qubit state to Alice on the same time. Although the six-qubit state as quantum channel is partially entangled, the teleportation is implemented deterministically. Furthermore, only Bell-state measurements, single-qubit measurements and some unitary operations are needed in the scheme.
We investigate whether it is possible to teleport the coherence of an unknown quantum state from Alice to Bob by communicating a smaller number of classical bits in comparison to what is required for teleporting an unknown quantum state. We find that we cannot achieve perfect teleportation of coherence with one bit of classical communication for an arbitrary qubit. However, we find that if the qubit is partially known, i.e., chosen from the equatorial and polar circles of the Bloch sphere, then teleportation of coherence is possible with the transfer of one cbit of information when we have maximally entangled states as a shared resource. In the case of the resource being a nonmaximally entangled state, we can teleport the coherence with a certain probability of success. In a general teleportation protocol for coherence, we derive a compact formula for the final state at Bob's laboratory in terms of the composition of the completely positive maps corresponding to the shared resource state and a joint positive operator-valued measure (POVM) performed by Alice on her qubit and the unknown state. Using this formula, we show that teleportation of the coherence of a partially known state with real matrix elements is perfectly possible with the help of a maximally entangled state as a resource. Furthermore, we explore the teleportation of coherence with Werner states and show that even when Werner states become separable, the amount of teleported coherence is nonzero, implying the possibility of teleportation of coherence without entanglement.