Quantum teleportation with additional a priori information about the input state achieves higher fidelity than teleportation of a completely unknown state. However, perfect teleporation of two nonorthogonal input states requires the same amount of entanglement as perfect teleportation of an unknown state, namely one ebit. We analyze how well two-state teleportation can be achieved using every degree of pure-state entanglement. We find the highest fidelity of ``teleportation'' that can be achieved with only classical communication but no shared entanglement. A two-state telecloning scheme is constructed.
Quantum teleportation with additional a priori information about the input state achieves higher fidelity than teleportation of a completely unknown state. However, perfect teleporation of two nonorthogonal input states requires the same amount of entanglement as perfect teleportation of an unknown state, namely one ebit. We analyze how well two-state teleportation can be achieved using every degree of pure-state entanglement. We find the highest fidelity of ``teleportation'' that can be achieved with only classical communication but no shared entanglement. A two-state telecloning scheme is constructed.
Quantum mechanics shows superiority than classical mechanics in many aspects and quantum entanglement plays an essential role in information processing and some computational tasks such as quantum teleportation (QT). QT was proposed to transmit the unknown states, in which EPR pairs, the entangled states, can be used as quantum channels. In this paper, we present two simple schemes for teleporting a product state of two arbitrary single-particle and an arbitrary two-particle pure entangled state respectively. Alice and Bob have shared an entangle state. Two Bell states are used as quantum channels. Then after Alice measuring her qubits and informing Bob her measurement results, Bob can perfectly reconstruct the original state by performing corresponding unitary operators on his qubits. It shown that a product state of two arbitrary single-particle and an arbitrary two-particle pure entangled state can be teleported perfectly, i.e. the success probabilities of our schemes are both 1.
FINDING: Quantum teleportation is a protocol for transferring an unknown quantum state via shared entanglement and classical communication — not instantaneous matter transport. | MATH: Bell state basis: |Φ⁺⟩ = (|00⟩ + |11⟩)/√2; teleportation requires 2 classical bits + 1 ebit (maximally entangled pair); state transfer fidelity F = 1 for ideal case; measurement in Bell basis yields 4 equiprobable outcomes (prob 1/4 each); Pauli corrections {I, X, Z, XZ} applied based on 2-bit classical message. | CONNECTION: The 4 Bell states form an orthonormal basis in ℂ²⊗ℂ² — isomorphic to the vertices of a tetrahedron (tetrahedral symmetry, 4-fold rotational symmetry in SO(3)); the √2 normalization is the same factor appearing in 45° rotations (π/4) — related to the ratio 1/√2 ≈ 0.7071, which is the geometric mean of 0.5 and 1.0, and appears in crystallographic root system A₁ (the only rank-1 simple Lie algebra). The 2 classical bits ↔ 4 outcomes ↔ 4 Pauli operators ↔ tetrahedral group T_d (order 24 Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com
Quantum teleportation is one of the essential primitives of quantum communication. We suggest that any quantum teleportation scheme can be characterized by its efficiency, i.e. how often it succeeds to teleport, its fidelity, i.e. how well the input state is reproduced at the output, and by its insensitivity to cross talk, i.e. how well it rejects an input state that is not intended to teleport. We discuss these criteria for the two teleportation experiments of independent qubits which have been performed thus far. In the first experiment (1997, Nature, 390, 575) where the qubit states were various different polarization states of photons, the fidelity of teleportation was as high as 0.80 ± 0.05 thus clearly surpassing the limit of 2/3 which can, in principle, be obtained by a direct measurement on the qubit and classical communication. This high fidelity is confirmed in our second experiment (1998, Phys. Rev. Lett., 80, 3891), demonstrating entanglement swapping, that is, realizing the teleportation of a qubit which itself is still entangled to another one. This experiment is the only one to date that demonstrates the teleportation of a genuine unknown quantum state.
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 is one of the essential primitives of quantum communication. We suggest that any quantum teleportation scheme can be characterized by its efficiency, i.e. how often it succeeds to teleport, its fidelity, i.e. how well the input state is reproduced at the output, and by its insensitivity to cross talk, i.e. how well it rejects an input state that is not intended to teleport. We discuss these criteria for the two teleportation experiments of independent qubits which have been performed thus far. In the first experiment (1997, Nature, 390, 575) where the qubit states were various different polarization states of photons, the fidelity of teleportation was as high as 0.80 ± 0.05 thus clearly surpassing the limit of 2/3 which can, in principle, be obtained by a direct measurement on the qubit and classical communication. This high fidelity is confirmed in our second experiment (1998, Phys. Rev. Lett., 80, 3891), demonstrating entanglement swapping, that is, realizing the teleportation of a qubit which itself is still entangled to another one. This experiment is the only one to date that demonstrates the teleportation of a genuine unknown quantum state.