17,361 research outputs found
Creation of macroscopic superposition states from arrays of Bose-Einstein condensates
We consider how macroscopic quantum superpositions may be created from arrays
of Bose-Einstein condensates. We study a system of three condensates in Fock
states, all with the same number of atoms and show that this has the form of a
highly entangled superposition of different quasi-momenta. We then show how, by
partially releasing these condensates and detecting an interference pattern
where they overlap, it is possible to create a macroscopic superposition of
different relative phases for the remaining portions of the condensates. We
discuss methods for confirming these superpositions.Comment: 7 pages, 5 figure
Efficient preparation and detection of microwave dressed-state qubits and qutrits with trapped ions
We demonstrate a method for preparing and detecting all eigenstates of a three-level microwave dressed system with a single trapped ion. The method significantly reduces the experimental complexity of gate operations with dressed-state qubits, as well as allowing all three of the dressed states to be prepared and detected, thereby providing access to a qutrit that is well protected from magnetic field noise. In addition, we demonstrate individual addressing of the clock transitions in two ions using a strong static magnetic field gradient, showing that our method can be used to prepare and detect microwave dressed states in a string of ions when performing multi-ion quantum operations with microwave and radio frequency fields. The individual addressability of clock transitions could also allow for the control of pairwise interaction strengths between arbitrary ions in a string using lasers
Approximation algorithms for hard variants of the stable marriage and hospitals/residents problems
When ties and incomplete preference lists are permitted in the Stable Marriage and Hospitals/Residents problems, stable matchings can have different sizes. The problem of finding a maximum cardinality stable matching in this context is known to be NP-hard, even under very severe restrictions on the number, size and position of ties. In this paper, we describe polynomial-time 5/3-approximation algorithms for variants of these problems in which ties are on one side only and at the end of the preference lists. The particular variant is motivated by important applications in large scale centralised matching schemes
Optical trapping with "on-demand" two-photon luminescence using Cr:LiSAF laser with optically addressed saturable Bragg reflector
We demonstrate a diode-pumped Cr:LiSAF laser with controllable and reliable fast switching between its continuous-wave and mode-locked states of operation using an optically-addressed semiconductor Bragg reflector, permitting dyed microspheres to be continuously trapped and monitored using a standard microscope imaging and on-demand two-photon-excited luminescence techniques
Morphological Thermodynamics of Fluids: Shape Dependence of Free Energies
We examine the dependence of a thermodynamic potential of a fluid on the
geometry of its container. If motion invariance, continuity, and additivity of
the potential are fulfilled, only four morphometric measures are needed to
describe fully the influence of an arbitrarily shaped container on the fluid.
These three constraints can be understood as a more precise definition for the
conventional term "extensive" and have as a consequence that the surface
tension and other thermodynamic quantities contain, beside a constant term,
only contributions linear in the mean and Gaussian curvature of the container
and not an infinite number of curvatures as generally assumed before. We verify
this numerically in the entropic system of hard spheres bounded by a curved
wall.Comment: 4 pages, 3 figures, accepted for publication in PR
- …