Correlations in a multi-qubit state

Shunlong Luo, Qiang Zhang

Zixuan Hu, Sabre Kais

Abstract A “qubit information logic” (QIL) theory is developed that uses the “qubit information equation” (QIE) and logic to describe the correlation behaviors of multi‐qubit entanglement. Introducing the “global information status” and “local information availability”, the QIL gives an alternative and natural interpretation of the “spooky action” and the quantum no‐communication theorem. Compared to the conventional entropy‐based entanglement theories, the QIL directly describes the correlation of each possible pair of qubits and how the correlation changes when other qubits are measured. This makes the QIL more advantageous in describing the correlation properties of multi‐qubit entanglement, which is illustrated by studying the dormant entanglement phenomenon. The QIL theory's usefulness is further demonstrated by understanding and designing an exotic quantum state where two qubits can be entangled but not correlated in any arbitrary basis. Overall the QIL provides an alternative and intuitive understanding of multi‐qubit entanglement that is, compared to the conventional theories, directly focused on the correlation behaviors between qubits and thus more suitable for designing exotic quantum states that may be used in quantum computing and information processing.

Sodeif Ahadpour, And F. Mirmasoudi

We study the pairwise quantum correlations for teleported state via a symmetric multi-qubitsystem. In the other words, the proposed model is considered as a quantum channel. Using thequantum discord, super quantum discord and concurrence to quantify quantum correlations forteleported state, some analytical and numerical results are presented. Moreover, we compare thedynamical evolutions of quantum correlations and fidelity versus measurement strength and thenumber of qubit channel for teleported state via symmetric multi-qubit model. Our main goalnow is to study how we can increase the quantum correlations and the fidelity of the teleportedstate in the presence of decoherence. The results show that, measurement strength and thenumber of qubit can control the quantum information obtained through the quantum channel.Therefore, measurement strength can be a good option for measuring exchanged information inthe teleportation process. In addition to, quantum correlations can provide an effective role inquantum teleportation

Fulin Zhang, Jing‐Ling Chen, Changliang Ren +1 more

Jean-Louis Basdevant, Jean Dalibard

Xin-Wei Zha, Yanpeng Zhang

We propose a method to detect genuine quantum correlation for multi-qubit pure states. We then derive a complementarity relations for pure quantum states of N qubits. We prove that in all many-qubit systems there exist strict monogamy laws for quantum correlations. On the other hand, it is known that the entanglement monogamy equality proposed by Coffman, Kundu, and Wootters is in general not true for multiqubit states. Inducing from the CKW equality, we find a proper form of entanglement monogamy equality for arbitrary quantum states. The total quantum correlation of qubit k with the remaining qubits Rk can be characterizes. Furthermore, the quantum correlation of qubit mn with the remaining qubits Rmn can also be obtained. Furthermore, some monogamy relations have been obtained.