55 research outputs found
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Broadband boundary effects on Brownian motion
Brownian motion of particles in confined fluids is important for many applications, yet the effects of the boundary over a wide range of time scales are still not well understood. We report high-bandwidth, comprehensive measurements of Brownian motion of an optically trapped micrometer-sized silica sphere in water near an approximately flat wall. At short distances we observe anisotropic Brownian motion with respect to the wall. We find that surface confinement not only occurs in the long time scale diffusive regime but also in the short time scale ballistic regime, and the velocity autocorrelation function of the Brownian particle decays faster than that of a particle in bulk fluid. Furthermore, at low frequencies the thermal force loses its color due to the reflected flow from the no-slip boundary. The power spectrum of the thermal force on the particle near a no-slip boundary becomes flat at low frequencies. This detailed understanding of boundary effects on Brownian motion opens a door to developing a 3D microscope using particles as remote sensors.Sid W. Richardson FoundationR. A. Welch Foundation F-1258Physic
Magneto-Optical Cooling of Atoms
We propose an alternative method to laser cooling. Our approach utilizes the
extreme brightness of a supersonic atomic beam, and the adiabatic atomic
coilgun to slow atoms in the beam or to bring them to rest. We show how
internal-state optical pumping and stimulated optical transitions, combined
with magnetic forces can be used to cool the translational motion of atoms.
This approach does not rely on momentum transfer from photons to atoms, as in
laser cooling. We predict that our method can surpass laser cooling in terms of
flux of ultra-cold atoms and phase-space density, with lower required laser
power and reduced complexity
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Device and method for squeezed state generation by a coupled system
Squeezed states of light having significant degrees of squeezing are achieved with modest values of atomic density and intracavity electromagnetic (EM) field by a device and method for coupling the EM field within the optical cavity. An oscillatory exchange of excitation then occurs between the atomic polarization and the EM field within the cavity.Board of Regents, University of Texas Syste
Ultra-high fidelity qubits for quantum computing
We analyze a system of fermionic Li atoms in an optical trap, and show
that an atom "on demand" can be prepared with ultra-high fidelity, exceeding
0.99998. This process can be scaled to many sites in parallel, providing a
realistic method to initialize N qubits at ultra-high fidelity for quantum
computing. We also show how efficient quantum gate operation can be implemented
in this system, and how spatially resolved single-atom detection can be
performed
Calculation of Atomic Number States: a Bethe Ansatz Approach
We analyze the conditions for producing atomic number states in a
one-dimensional optical box using the Bethe ansatz method. This approach
provides a general framework, enabling the study of number state production
over a wide range of realistic experimental parameters
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