Three-Qubit Correlations and Purity in Local Mixed Gaussian and Non-Gaussian Channels

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

Atta Ur Rahman, Youssef Khedif, Muhammad Javed +2 more

Abstract The dephasing effects of two independent local mixed static‐Ornstein Uhlenbeck (STC‐OUK) noisy channels on the dynamics of two‐qubit non‐classical correlations, non‐locality, and entanglement are addressed. Here, i) local quantum Fisher information; ii) local quantum uncertainty; iii) uncertainty‐induced non‐locality; iv) Bell non‐locality; and v) negativity to quantify two‐qubit non‐classical correlations, non‐locality and entanglement, respectively, and their loss under the influence of mixed noise are used. The findings show that measure (i) compared to measure (ii) remains more effective in demonstrating non‐classical correlations. For the two‐qubit state with maximum purity, measure (iii) remains less fragile to the mixed STC‐OUK noise than measure (iv) but gets more vulnerable as the initial purity of the two‐qubit state falls. It is intriguing that measures (i), (ii), and (v) completely freeze after a particular interval, yet measures (iii) and (iv) remains partially preserved indefinitely. When compared to other two‐qubit correlation quantifiers, measure (v) exhibits non‐Markovian behavior and the phenomenon of sudden death and birth. Markovian and non‐Markovian dynamical maps, and extended two‐qubit correlations, can be induced by optimizing the current configuration. Finally, under the influence of mixed dephasing effects, robust and strengthened quantum correlations beyond entanglement in the two‐qubit Werner state is shown.

Jianwei Xu

Javed, Muhammad, Rahman, Atta Ur, Lionel Tenemeza Kenfack +1 more

The dynamical map of entanglement and mixedness in four-qubit maximally entangled GHZ state paired with classical channels driven by fractional Gaussian noise is investigated. The qubit-channel coupling is assumed in four distinct ways: common, bipartite, tripartite, and independent local channel-qubit configurations comprising single, double, triple, or independent noisy sources. Using entanglement witness, negativity, purity and von Neumann entropy, except for the independent configuration, we show that indefinite entanglement and purity preservation may be simulated in multipartite GHZ-like states. Quantum correlations and purity decrease exponentially in four qubits, and exact fluctuating local field behaviour, as well as entanglement sudden death and birth revivals, are completely suppressed. Entanglement and purity preservation are affected by noise and the number of independent channels utilised. The Hurst parameter of fractional Gaussian noise was discovered in the four qubits to improve entanglement and avoid mixedness. Different entanglement and mixedness criteria yield different results, emphasizing the need to investigate various approaches in order to uncover multipartite correlations.

Muhammad Noman, Aqsa Mushtaq, Wei Cui

Abstract We investigate the dynamical maps of coherence, entanglement, and purity in two distinct three-qubit class states: the Werner (W-like) and Greeneberger–Horne–Zeillinger (GHZ-like) states. Utilizing a classical channel affected by Ornstein Uhlenbeck (OU) and Random Telegraph (RT) noise, we explore two scenarios: coupling two qubits with RT noise and one with OU noise, and vice versa . The preservation of coherence, entanglement, and purity is analyzed using the ℓ 1 norm of coherence, entanglement witness operation, and purity measures. Our results reveal that the considered dephasing channels lead to a decrease in initially encoded quantum correlations, even in the presence of Gaussian OU noise, which typically induces monotonic decay. The non-monotonic behavior and decay are primarily governed by the parameters of OU and RT noises, with the configuration where OU noise affects two qubits and RT noise affects the third being optimal for quantum correlation preservation. Comparing the two states, the GHZ-like state exhibits superior preservation under RT noise influencing two local fields and qubits, while the W-like state performs better when OU noise affects two qubits. Overall, the GHZ-like state shows enhanced revival characteristics compared to the W-like state.

Y. Lahlou, Bakmou Lahcen, Bouchra Maroufi +1 more