Entanglement of a 2-qubit system coupled to a bath of quantum spin glass

•Quantum entanglement (concurrence) of a 2-qubit system coupled to a spin glass bath of 2 to n≥4n≥4 qubits.•A general formula is obtained to describe the concurrence with J=0J=0 and h=0h=0 for nn bath sites.•The physics of a 2-qubit system coupled with nn bath sites for J=0J=0 is analytically described.•For small fluctuation in JJ, a mean steady state average concurrence of about 0.5 is obtained.

We study the quantum entanglement (concurrence) of a 2-qubit system coupled to a small spin glass bath of 2 to n≥n≥ 4 qubits. The bath is described by the quantum XXXX Heisenberg model with random JJ coupling and varying magnetic field hh. We look at the dynamics of the steady state average concurrence for the system and obtain a general formula to describe the concurrence with J=0J=0 and h=0h=0 for nn bath sites. The physics of 2-qubit system coupled with nn bath sites for J=0J=0 is analytically described for small nn. The result for large nn was numerically found to be qualitatively similar. For small fluctuation in JJ, a mean steady state average concurrence of about 0.5 is obtained.