Coherence measures with respect to general quantum measurements

Quantum coherence with respect to orthonormal bases has been studied extensively in the past few years. Recently, Bischof, et al. [Phys. Rev. Lett. 123, 110402 (2019)] generalized it to the case of general positive operator-valued measure (POVM) measurements. Such POVM-based coherence, including the block coherence as a special case, have significant operational interpretations in quantifying the advantage of quantum states in quantum information processing. In this work we first establish an alternative framework for quantifying the block coherence and provide several block coherence measures. We then present several coherence measures with respect to POVM measurements, and prove a conjecture on the $l_{1}$-norm related POVM coherence measure.Comment: 11 pages, no figure

trans-Tetra­aqua­bis(nicotinamide-κN)cadmium(II) biphenyl-4,4′-disulfonate

In the title compound, [Cd(C6H6N2O)2(H2O)4](C10H8O6S2), the CdII ion is located on a crystallographic inversion centre. An octa­hedral coordination geometry is defined by four water mol­ecules in one plane, and two trans N-atom donors of the nicotinamide ligands. The biphenyl-4,4′-disulfonate anion also lies on a crystallographic inversion centre. In the crystal structure, the complex cations are connected to the counter-anions via N—H⋯O and O—H⋯O hydrogen bonds, forming a three-dimensional network

Resonant two-photon ionization spectroscopy of jet-cooled PtSi

Journal ArticleJet-cooled diatomic PtSi, produced in a laser ablation supersonic expansion source, has been spectroscopically investigated between 17 400 and 24 000 cm-1 by resonant two-photon ionization spectroscopy. Two vibrational progressions are observed and identified as the [15.7]?'=1 ?X 1?+ and [18.5]?'=1 ?X 1?+ band systems. Three bands in the former system and six bands in the latter system were rotationally resolved and analyzed, leading to bond lengths of r'e=2.1905(13) ? and r'e=2.2354(3) ? for the [15.7]?'=1 and [18.5]?'=1 states, respectively. The ?"=0 ground state of PtSi is assigned as a 1?+ state, in agreement with previous work and with the assigned ground states of the isovalent NiC, PdC, PtC, and NiSi molecules. The ground state bond length of PtSi is given by r'o=2.0629(2) ?. A Rydberg?Klein?Rees analysis of the ground and excited state potential energy curves is presented, along with a discussion of the chemical bonding and a comparison to the isoelectronic molecule, AlAu. Evidence is presented for a double bond in PtSi, as opposed to a single bond in AlAu

Non-perturbative Dynamical Decoupling Control: A Spin Chain Model

This paper considers a spin chain model by numerically solving the exact model to explore the non-perturbative dynamical decoupling regime, where an important issue arises recently (J. Jing, L.-A. Wu, J. Q. You and T. Yu, arXiv:1202.5056.). Our study has revealed a few universal features of non-perturbative dynamical control irrespective of the types of environments and system-environment couplings. We have shown that, for the spin chain model, there is a threshold and a large pulse parameter region where the effective dynamical control can be implemented, in contrast to the perturbative decoupling schemes where the permissible parameters are represented by a point or converge to a very small subset in the large parameter region admitted by our non-perturbative approach. An important implication of the non-perturbative approach is its flexibility in implementing the dynamical control scheme in a experimental setup. Our findings have exhibited several interesting features of the non-perturbative regimes such as the chain-size independence, pulse strength upper-bound, noncontinuous valid parameter regions, etc. Furthermore, we find that our non-perturbative scheme is robust against randomness in model fabrication and time-dependent random noise