Experimental Hamiltonian identification for controlled two-level systems

We present a strategy to empirically determine the internal and control Hamiltonians for an unknown two-level system (black box) subject to various (piecewise constant) control fields when direct readout by measurement is limited to a single, fixed observable

Controlled phase gate for solid-state charge qubits

We describe a mechanism for realizing a controlled phase gate for solid-state charge qubits. By augmenting the positionally defined qubit with an auxiliary state, and changing the charge distribution in the three-dot system, we are able to effectively switch the Coulombic interaction, effecting an entangling gate. We consider two architectures, and numerically investigate their robustness to gate noise.Comment: 14 pages, 11 figures, 2 tables, RevTeX

Fidelity and coherence measures from interference

By utilizing single particle interferometry, the fidelity or coherence of a pair of quantum states is identified with their capacity for interference. We consider processes acting on the internal degree of freedom (e.g., spin or polarization) of the interfering particle, preparing it in states ρA or ρB in the respective path of the interferometer. The maximal visibility depends on the choice of interferometer, as well as the locality or nonlocality of the preparations, but otherwise depends only on the states ρA and ρB and not the individual preparation processes themselves. This allows us to define interferometric measures which probe locality and correlation properties of spatially or temporally separated processes, and can be used to differentiate between processes that cannot be distinguished by direct process tomography using only the internal state of the particle

Description of superdeformed bands in light N=Z nuclei using the cranked HFB method

Superdeformed states in light $N=Z$ nuclei are studied by means of the self-consistent cranking calculation (i.e., the P + QQ model based on the cranked Hartree-Fock-Bogoliubov method). Analyses are given for two typical cases of superdeformed bands in the $A \simeq 40$ mass region, that is, bands where backbending is absent ($^{40}$Ca) and present ($^{36}$Ar). Investigations are carried out, particularly for the following points: cross-shell excitations in the sd and pf shells; the role of the g$_{9/2}$ and d$_{5/2}$ orbitals; the effect of the nuclear pairing; and the interplay between triaxiality and band termination.Comment: 17 pages, 18 figures, accepted in Phys. Rev.

Fundamental Speed Limits on Quantum Coherence and Correlation Decay

The study and control of coherence in quantum systems is one of the most exciting recent developments in physics. Quantum coherence plays a crucial role in emerging quantum technologies as well as fundamental experiments. A major obstacle to the utilization of quantum effects is decoherence, primarily in the form of dephasing that destroys quantum coherence, and leads to effective classical behaviour. We show that there are universal relationships governing dephasing, which constrain the relative rates at which quantum correlations can disappear. These effectively lead to speed limits which become especially important in multi-partite systems

Systematic analyses of the t t clustering effect in He isotopes

A systematic study on the ground state structure of He isotopes including 10He is presented through a new method developed on the basis of antisymmetrized molecular dynamics AMD , the generator coordinate method GCM , and the stochastic variational method SVM . In this approach, variational calculations are carried out by means of the GCM with the AMD wave functions produced by means of the SVM. A role of the t t cluster component is examined with the present method, allowing the wider configuration space containing simultaneously the t t valence neutrons structure and 4He valence neutrons strucutur

Interference of Quantum Channels

We show how interferometry can be used to characterise certain aspects of general quantum processes, in particular, the coherence of completely positive maps. We derive a measure of coherent fidelity, maximum interference visibility and the closest unitary operator to a given physical process under this measure.Comment: 4 pages, 5 figures, REVTeX 4, typographical corrections and added acknowledgemen

Geometric phases for mixed states in interferometry

We provide a physical prescription based on interferometry for introducing the total phase of a mixed state undergoing unitary evolution, which has been an elusive concept in the past. We define the parallel transport condition that provides a connection-form for obtaining the geometric phase for mixed states. The expression for the geometric phase for mixed state reduces to well known formulas in the pure state case when a system undergoes noncyclic and unitary quantum evolution.Comment: Two column, 4 pages, Latex file, No figures, Few change

Changes in Serum Electrolytes and Lipid Profile in Diabetes Subjects in Freetown Sierra Leone

Background: Measurement of blood electrolytes level and lipid profile usually give good indications of the disease progression in a number of non communicable diseases. Objective: To investigate the effect of diabetes on electrolyte and lipid status of male and female diabetics in Freetown, Sierra Leone. Subjects and Methods: Serum concentrations of electrolytes and lipids in one hundred and twenty (120) adult diabetics attending some diagnostic centers in Freetown Sierra Leone were measured and compared with those of one hundred and twenty (120) non-diabetic individuals. Results: Total cholesterol, LDL-cholesterol, triglycerides and coronary heart disease (CHD) risk ratio in diabetic patients were significantly higher (