Search results for "Coulomb"

Coulomb blockade nanothermometer

1998

Reliable thermometry is normally based on commercial secondary sensors which are factory calibrated. Primary thermometers exist, too, but their use is limited because of intrinsic slowness, complex instrumentation, or inconvenient installation at the desired location. We have found that arrays of nanoscale tunnel junctions exhibit properties which are very suitable for primary and secondary cryogenic thermometry. Temperature range of this Coulomb blockade thermometer (CBT) extends over about two decades for one sensor and the mean temperature is lithographically adjustable. We have studied the performance of the CBT sensors at very low temperatures where the minimum temperature is limited b…

Memory effects in single-electron nanostructures

2001

We investigate the memory function at room temperature in devices based on quantum dots. By Low Pressure Chemical Vapour Deposition (LPCVD) we deposited Si dots embedded in SiO2. On these devices flat band voltage shifts were well detected at low write voltages for write times of the order of milliseconds, and furthermore, a plateau in the flat band voltage shift, maybe consequence of Coulomb blockdale, was observed.

Structure of low-lying states in 140Sm studied by Coulomb excitation

2016

The electromagnetic structure of 140Sm was studied in a low-energy Coulomb excitation experiment with a radioactive ion beam from the REX-ISOLDE facility at CERN. The 2+ and 4+ states of the ground-state band and a second 2+ state were populated by multistep excitation. The analysis of the differential Coulomb excitation cross sections yielded reduced transition probabilities between all observed states and the spectroscopic quadrupole moment for the 2+ 1 state. The experimental results are compared to large-scale shell model calculations and beyond-mean-field calculations based on the Gogny D1S interaction with a five-dimensional collective Hamiltonian formalism. Simpler geometric and alge…

Effect of Confinement and Coulomb Interactions on the Electronic Structure of the (111) LaAlO3/SrTiO3 Interface

2023

A tight binding supercell approach is used for the calculation of the electronic structure of the (111) LaAlO3/SrTiO3 interface. The confinement potential at the interface is evaluated solving a discrete Poisson equation by means of an iterative method. In addition to the effect of the confinement, local Hubbard electron–electron terms are included at the mean-field level within a fully self-consistent procedure. The calculation carefully describes how the two-dimensional electron gas arises from the quantum confinement of electrons near the interface due to the band bending potential. The resulting electronic sub-bands and Fermi surfaces show full agreement with the electronic structure de…

Non-analog decay of 74Rb

2001

The magnitude of the Coulomb mixing parameter δ1 IM has been experimentally deduced, for the first time, for the β decay of 74Rb. The estimated magnitude is derived from the feeding of the non-analog first excited 0+ state in 74Kr. The inferred upper limit of 0.07% is small compared to theoretical predictions. The half-life was measured to be 64.90(9) ms. peerReviewed

Exact Coulomb cutoff technique for supercell calculations in two dimensions

2009

We present a reciprocal space technique for the calculation of the Coulomb integral in two dimensions in systems with reduced periodicity, i.e., finite systems, or systems that are periodic only in one dimension. The technique consists in cutting off the long-range part of the interaction by modifying the expression for the Coulomb operator in reciprocal space. The physical result amounts in an effective screening of the spurious interactions originated by the presence of ghost periodic replicas of the system. This work extends a previous report [C. A. Rozzi et al., Phys. Rev. B 73, 205119 (2006)], where three-dimensional systems were considered. We show that the use of the cutoffs dramatic…

Signorini problem with Coulomb's law of friction. Shape optimization in contact problems

1992

Absence of structure in the $^{20,22}$Ne + $^{118}$Sn quasi-elastic barrier distribution

2005

Abstract Motivated by the extreme deformation parameters of the projectile, we have measured quasi-elastic scattering for 20 Ne +  118 Sn. In contrast to calculations based on known collective states, the experimental barrier distribution is structureless. A comparison with the system 22 Ne +  118 Sn shows that this smoothing is unlikely to be due to nucleon- or α -transfer channels, and is more likely to be due to coupling to many other weak channels.

Anomalous Coulomb matrix elements in thef7/2shell

2003

γ decays from high-spin states in the N=Z-1 nucleus 2753Co26 have been identified for the first time. Level energies and Coulomb energy differences between these states and their analogs in its mirror nucleus 53Fe have been compared with large-scale pf shell-model calculations, which offer excellent agreement. New information has been obtained on two-proton Coulomb matrix elements needed in the interpretation. These have been extracted from the data via a number of methods and are shown to exhibit an anomalous behavior for the J=2 coupling.

Shuttling of Rydberg ions for fast entangling operations

2019

We introduce a scheme to entangle Rydberg ions in a linear ion crystal, using the high electric polarizability of the Rydberg electronic states in combination with mutual Coulomb coupling of ions that establishes common modes of motion. After laser-initialization of ions to a superposition of ground- and Rydberg-state, the entanglement operation is driven purely by applying a voltage pulse that shuttles the ion crystal back and forth. This operation can achieve entanglement on a sub-$\mu$s timescale, more than two orders of magnitude faster than typical gate operations driven by continuous-wave lasers. Our analysis shows that the fidelity achieved with this protocol can exceed $99.9\%$ with…