catena-Poly[[(2,2′-bipyridine)copper(II)]-μ-5-tert-butyl­isophthalato]

In the crystal structure of the title polymeric compound, [Cu(C12H12O4)(C10H8N2)]n, the asymmetric unit consists of one CuII ion, one 5-tert-butyl­isophthalate (tbip) and one 2,2′-bipyridine (bpy) ligand. The copper(II) ion is four-coordin­ated by two N atoms from bipy and two O atoms from two tbip ligands, leading to a distorted tetrahedral coordination. Each tbip ligand adopts a bis-monodentate coordination mode to connect two symmetry-related copper(II) ions, so forming a zigzag polymer chain parallel to [001]. The tert-butyl methyl groups are disordered over two positions with occupancies of 0.506 (6)/0.494 (6

Enhanced quantum teleportation in the background of Schwarzschild spacetime by weak measurements

It is commonly believed that the fidelity of quantum teleportation in the gravitational field would be degraded due to the heat up by the Hawking radiation. In this paper, we point out that the Hawking effect could be eliminated by the combined action of pre- and post-weak measurements, and thus the teleportation fidelity is almost completely protected. It is intriguing to notice that the enhancement of fidelity could not be attributed to the improvement of entanglement, but rather to the probabilistic nature of weak measurements. Our work extends the ability of weak measurements as a quantum technique to battle against gravitational decoherence in relativistic quantum information.Comment: 9 pages, 5 figures, comments are welcom

Robust Spin Squeezing Preservation in Photonic Crystal Cavities

We show that the robust spin squeezing preservation can be achieved by utilizing detuning modification for an ensemble of N separate two-level atoms embedded in photonic crystal cavities (PCC). In particular, we explore the different dynamical behaviors of spin squeezing between isotropic and anisotropic PCC cases when the atomic frequency is inside the band gap. In both cases, it is shown that the robust preservation of spin squeezing is completely determined by the formation of bound states. Intriguingly, we find that unlike the isotropic case where steady-state spin squeezing varies smoothly when the atomic frequency moves from the inside to the outside band edge, a sudden transition occurs for the anisotropic case. The present results may be of direct importance for, e.g., quantum metrology in open quantum systems.Comment: 6 pages, 4 figures, accepted by Laser Physics Letter