Search results for "ground"
showing 10 items of 2432 documents
Renormalized Proton-Neutron Quasiparticle Random-Phase Approximation and Its Application to Double Beta Decay
1995
A self-consistent method of treating excitations of the proton-neutron quasiparticle random-phase approximation is presented. The non-self-consistent methods violate the Pauli exclusion principle and lead to an eventual collapse of the ground state. This behavior renders a reliable calculation of the nuclear matrix elements, relevant for the prediction of double-beta-decay half-lives, difficult. The present formalism promotes the Pauli exclusion principle and avoids the collapse of the double-beta-decay matrix elements. We have applied this formalism to the double beta decay of ${}^{100}$Mo.
Computing the dipole polarizability of 48Ca with increased precision
2018
We compute the electric dipole polarizability of 48Ca with an increased precision by including more correlations than in previous studies. Employing the coupled-cluster method we go beyond singles and doubles excitations and include leading-order three-particle-three-hole (3p-3h) excitations for the ground state, excited states, and the similarity transformed operator. We study electromagnetic sum rules, such as the bremsstrahlung sum rule m_0 and the polarizability sum rule alpha_D using interactions from chiral effective field theory. To gauge the quality of our coupled-cluster approximations we perform several benchmarks with the effective interaction hyperspherical harmonics approach in…
Proton Decay of an Intruder State inB185i
1996
The new proton radioactivity ${}^{185m}\mathrm{Bi}$ has been observed, produced via the ${}^{95}\mathrm{Mo}{(}^{92}\mathrm{Mo},pn{)}^{185}\mathrm{Bi}$ reaction. Its decay proceeds from the low-lying ${\frac{1}{2}}^{+}$ intruder state in ${}^{185}\mathrm{Bi}$ to the ${}^{184}\mathrm{Pb}$ ground state with the emission of a proton of energy $1.585\ifmmode\pm\else\textpm\fi{}0.009\mathrm{MeV}$ and a half-life of $44\ifmmode\pm\else\textpm\fi{}16\ensuremath{\mu}\mathrm{s}$. This marks the first observation of proton radioactivity above the $Z\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}82$ closed shell, and it has been used to obtain the admixture of a ${0}^{+}$ intruder state in ${}^{184…
High-quality variational wave functions for small4Heclusters
1999
We report a variational calculation of ground state energies and radii of ${}^{4}{\mathrm{He}}_{N}$ droplets $(3l~Nl~40),$ using the Aziz HFD-B (HE) atom-atom interaction. The trial wave function has a simple structure, combining two- and three-body correlation functions coming from a translationally invariant configuration-interaction description, and Jastrow-type short-range correlations. The calculated ground state energies differ by around 2% from the diffusion Monte Carlo results.
Analyzing the enforcement of a high-spin ground state for a metallacrown single-molecule magnet
2016
We have studied element-selective magnetic properties of the hetero- and homometallic metallacrowns $\mathrm{Cu}{(\mathrm{II})}_{2}[12\ensuremath{-}{\mathrm{MC}}_{YN(Shi)}\ensuremath{-}4]$ ($Y=\text{Cu}$, Fe, in short ${\mathrm{CuCu}}_{4}$ and ${\mathrm{CuFe}}_{4}$). These metallacrowns comprise four Fe or Cu ions surrounding a central Cu ion. Using x-ray magnetic circular dichroism we have probed local symmetries, electronic configuration, orbital and spin magnetic moments of the magnetic ions. The ratio between the Cu and Fe moment of $\ensuremath{-}0.11$ is independent of temperature in the range of 15 K to 90 K. The Cu moment shows antiparallel to the Fe moment. For ${\mathrm{CuCu}}_{4}…
Controlling Fast Transport of Cold Trapped Ions
2012
We realize fast transport of ions in a segmented micro-structured Paul trap. The ion is shuttled over a distance of more than 10^4 times its groundstate wavefunction size during only 5 motional cycles of the trap (280 micro meter in 3.6 micro seconds). Starting from a ground-state-cooled ion, we find an optimized transport such that the energy increase is as low as 0.10 $\pm$ 0.01 motional quanta. In addition, we demonstrate that quantum information stored in a spin-motion entangled state is preserved throughout the transport. Shuttling operations are concatenated, as a proof-of-principle for the shuttling-based architecture to scalable ion trap quantum computing.
Quantum synchronization as a local signature of super- and subradiance
2017
We study the relationship between the collective phenomena of super- and subradiance and spontaneous synchronization of quantum systems. To this aim we revisit the case of two detuned qubits interacting through a pure dissipative bosonic environment, which contains the minimal ingredients for our analysis. By using the Liouville formalism, we are able to find analytically the ultimate connection between these phenomena. We find that dynamical synchronization is due to the presence of longstanding coherence between the ground state of the system and the subradiant state. We finally show that, under pure dissipation, the emergence of spontaneous synchronization and of subradiant emission occu…
Generation of minimum energy entangled states
2020
Quantum technologies exploiting bipartite entanglement could be made more efficient by using states having the minimum amount of energy for a given entanglement degree. Here, we study how to generate these states in the case of a bipartite system of arbitrary finite dimension either by applying a unitary transformation to its ground state or through a zero-temperature thermalization protocol based on turning on and off a suitable interaction term between the subsystems. In particular, we explicitly identify three possible unitary operators and five possible interaction terms. On the one hand, two of the three unitary transformations turn out to be easily decomposable in terms of local eleme…
Resonance interaction energy between two accelerated identical atoms in a coaccelerated frame and the Unruh effect
2016
We investigate the resonance interaction energy between two uniformly accelerated identical atoms, interacting with the scalar field or the electromagnetic field in the vacuum state, in the reference frame coaccelerating with the atoms. We assume that one atom is excited and the other in the ground state, and that they are prepared in their correlated symmetric or antisymmetric state. Using perturbation theory, we separate, at the second order in the atom-field coupling, the contributions of vacuum fluctuations and radiation reaction field to the energy shift of the interacting system. We show that only the radiation reaction term contributes to the resonance interaction between the two ato…
Quench of symmetry broken ground states
2016
We analyze the problem of how different ground states associated to the same set of the Hamiltonian parameters evolve after a sudden quench. To realize our analysis we define a quantitative approach to the local distinguishability between different ground states of a magnetically ordered phase in terms of the trace distance between the reduced density matrices obtained projecting two ground states in the same subset. Before the quench, regardless the particular choice of the subset, any system in a magnetically ordered phase is characterized by ground states that are locally distinguishable. On the other hand, after the quench, the maximum of the distinguishability shows an exponential deca…