Quantum computation and quantum information
Quantum computation and quantum information
A centralized quantum switch network based on probabilistic channels
Quantum Information Processing
| Hi-index | 0.00 |
In this paper we have tried to interpret the physical role of three-tangle and π-tangle inreal physical information processes. For the model calculation we adopt the tripartiteteleportation scheme through various noisy channels. The three parties consist of sender,accomplice and receiver. It is shown that the π-tangles for the X- and Z-noisy channelsvanish at the limit kt → ∞, where kt is a decoherence parameter introduced in the masterequation in the Lindblad form. At this limit the maximum fidelity of the receiver'sstate reduces to the classical limit 2/3. However, this nice feature is not maintainedfor the Y- and isotropy-noise channels. For the Y-noise channel the π-tangle vanisheswhen 0.61 ≤ kt. At kt = 0.61 the maximum fidelity becomes 0.57, which is muchless than the classical limit. Similar phenomenon occurs for the isotropic noise channel.We also compute analytically the three-tangles for the X- and Z-noise channels. Theremarkable fact is that the three-tangle for the Z-noise channel coincides exactly with thecorresponding π-tangle. In the X-noise channel the three-tangle vanishes when 0.10 ≤ kt.At kt = 0.10 the fidelity of the receiver's state can reduce to the classical limit providedthat the accomplice performs the measurement appropriately. However, the maximumfidelity becomes 8/9, which is much larger than the classical limit. Since the Y- andisotropy-noise channels are rank-8 mixed states, their three-tangles are not computedexplicitly in this paper. Instead, their upper bounds are derived by making use of theanalytic formulas of the three-tangle for other noisy channels. Our analysis stronglysuggests that different tripartite entanglement measure is needed whose value is betweenthree-tangle and π-tangle.