49 research outputs found
Nuclear magnetic resonance implementation of the Deutsch-Jozsa algorithm using different initial states
The Deutsch-Jozsa algorithm distinguishes constant functions from balanced
functions with a single evaluation. In the first part of this work, we present
simulations of the nuclear magnetic resonance (NMR) application of the
Deutsch-Jozsa algorithm to a 3-spin system for all possible balanced functions.
Three different kinds of initial states are considered: a thermal state, a
pseudopure state, and a pair (difference) of pseudopure states. Then,
simulations of several balanced functions and the two constant functions of a
5-spin system are described. Finally, corresponding experimental spectra
obtained by using a 16-frequency pulse to create an input equivalent to either
a constant function or a balanced function are presented, and the results are
compared with those obtained from computer simulations.Comment: accepted for publication in the Journal of Chemical Physic
A simple method for the preparation of pseudopure states in NMR quantum information processing
The use of nuclear magnetic resonance (NMR) to carry out quantum information
processing (QIP) often requires the preparation, transformation, and detection
of pseudopure states. In our previous work, it was shown that the use of pairs
of pseudopure states (POPS) as a basis for QIP is very convenient because of
the simplicity in experimental execution. It is now further demonstrated that
the product of the NMR spectra corresponding to two sets of POPS that share a
common pseudopure state has the same peak frequencies as those of the common
(single) pseudopure state. Examples of applying two different quantum logic
gates to a 5-qubit system are given.Comment: Accepted by J.Chem.Phys., 12 pages, 3 figure
Invariant Measures and Convergence for Cellular Automaton 184 and Related Processes
For a class of one-dimensional cellular automata, we review and complete the
characterization of the invariant measures (in particular, all invariant phase
separation measures), the rate of convergence to equilibrium, and the
derivation of the hydrodynamic limit. The most widely known representatives of
this class of automata are: Automaton 184 from the classification of S.
Wolfram, an annihilating particle system and a surface growth model.Comment: 18 page
Experimental realization of a continuous version of the Grover algorithm
A continuous, analog version of the Grover algorithm is realized using NMR.
The system studied is 23Na in a liquid crystal medium. The presence of
quadrupolar coupling makes the spin I=3/2 nucleus a 2-qubit system. Applying a
specially designed pulse sequence, the time evolution of the spin density
operator is described in an interaction representation which has no external
time-dependent radio-frequency fields. This approach is used to implement one
instance of the continuous Grover search for the transform of a uniform state
to a target state, and the implementation provides a clear physical
interpretation of the algorithm. The experimental results are in good agreement
with the theory.Comment: 14 pages plus 2 figures, accepted for publication in Phys. Rev.
Mars’ plasma system. Scientific potential of coordinated multipoint missions: “The next generation”
The objective of this White Paper, submitted to ESA’s Voyage 2050 call, is to get a more holistic knowledge of the dynamics of the Martian plasma system, from its surface up to the undisturbed solar wind outside of the induced magnetosphere. This can only be achieved with coordinated multi-point observations with high temporal resolution as they have the scientific potential to track the whole dynamics of the system (from small to large scales), and they constitute the next generation of the exploration of Mars analogous to what happened at Earth a few decades ago. This White Paper discusses the key science questions that are still open at Mars and how they could be addressed with coordinated multipoint missions. The main science questions are: (i) How does solar wind driving impact the dynamics of the magnetosphere and ionosphere? (ii) What is the structure and nature of the tail of Mars’ magnetosphere at all scales? (iii) How does the lower atmosphere couple to the upper atmosphere? (iv) Why should we have a permanent in-situ Space Weather monitor at Mars? Each science question is devoted to a specific plasma region, and includes several specific scientific objectives to study in the coming decades. In addition, two mission concepts are also proposed based on coordinated multi-point science from a constellation of orbiting and ground-based platforms, which focus on understanding and solving the current science gaps
GrassPlot - a database of multi-scale plant diversity in Palaearctic grasslands
GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). GrassPlot collects plot records (releves) from grasslands and other open habitats of the Palaearctic biogeographic realm. It focuses on precisely delimited plots of eight standard grain sizes (0.0001; 0.001;... 1,000 m(2)) and on nested-plot series with at least four different grain sizes. The usage of GrassPlot is regulated through Bylaws that intend to balance the interests of data contributors and data users. The current version (v. 1.00) contains data for approximately 170,000 plots of different sizes and 2,800 nested-plot series. The key components are richness data and metadata. However, most included datasets also encompass compositional data. About 14,000 plots have near-complete records of terricolous bryophytes and lichens in addition to vascular plants. At present, GrassPlot contains data from 36 countries throughout the Palaearctic, spread across elevational gradients and major grassland types. GrassPlot with its multi-scale and multi-taxon focus complements the larger international vegetationplot databases, such as the European Vegetation Archive (EVA) and the global database " sPlot". Its main aim is to facilitate studies on the scale-and taxon-dependency of biodiversity patterns and drivers along macroecological gradients. GrassPlot is a dynamic database and will expand through new data collection coordinated by the elected Governing Board. We invite researchers with suitable data to join GrassPlot. Researchers with project ideas addressable with GrassPlot data are welcome to submit proposals to the Governing Board