We present several examples where prominent quantum properties are transferred from a microscopic superposition to thermal states at high temperatures. Our work is motivated by an analogy of Schrödinger's cat paradox, where the state corresponding to the virtual cat is a mixed thermal state with a large average photon number. Remarkably, quantum entanglement can be produced between thermal stat...

The entanglement between a ?-type three-level atom and its spontaneous emission fields is investigated. The effect of spontaneously generated coherence (SGC) on entanglement between the atom and its spontaneous emission fields is then discussed. We find that in the presence of SGC the entanglement between the atom and its spontaneous emission fields is completely phase dependent, while in absen...

The time evaluation of quantum entropy in a four-level double- type atomic system is theoretically investigated. Quantum entanglement of the atom and its spontaneous emission fields is then discussed via quantum entropy. It is found that the degree of entanglement can be increased by the quantum interference induced by spontaneous emission. The phase dependence of the atom-field entanglement is...

In the present work we use the negativity to study the effect of Rashba parameter on the thermal entanglement of electronic spin and subband states inside a quasi-one-dimensional Rashba nanowire, in a perpendicular uniform magnetic field. We assume that the nanowire is held at a temperature T, so that both spin and subband states, with definite probabilities, are present. The partially transpos...

For a 3-qubit Heisenberg model in a uniform magnetic field, the pairwise thermal entanglement of any two sites is identical due to the exchange symmetry of sites. In this paper we consider the effect of a non-uniform magnetic field on the Heisenberg model, modeling a magnetic impurity on one site. Since pairwise entanglement is calculated by tracing out one of the three sites, the entanglement ...

We explore the role of entanglement in adiabatic quantum optimization by performing approximate simulations of the real-time evolution of a quantum system while limiting the amount of entanglement. To classically simulate the time evolution of the system with a limited amount of entanglement, we represent the quantum state using matrix-product states and projected entangledpair states. We show ...

We describe an entanglement witness for N -qubit mixed states based on the properties of N -point correlation functions. As the degree of violation increases beyond different threshold values, or strata, this witness can guarantee that no more than M qubits are separable from the rest of the state for any M 6 N , or that there is some genuine M-party or greater multipartite entanglement present...

We analyze the entanglement between two matter modes in a hybrid quantum system consists of a microcavity, a quantum well, and a mechanical oscillator. Although the exciton mode in the quantum well and the mechanical oscillator are initially uncoupled, their interaction through the microcavity field results in an indirect exciton-mechanical mode coupling. We show that this coupling is a Fano-Ag...