85 research outputs found
Slow Mass Transport and Statistical Evolution of An Atomic Gas Across the Superfluid-Mott Insulator Transition
We study transport dynamics of ultracold cesium atoms in a two-dimensional
optical lattice across the superfluid-Mott insulator transition based on in
situ imaging. Inducing the phase transition with a lattice ramping routine
expected to be locally adiabatic, we observe a global mass redistribution which
requires a very long time to equilibrate, more than 100 times longer than the
microscopic time scales for on-site interaction and tunneling. When the sample
enters the Mott insulator regime, mass transport significantly slows down. By
employing fast recombination pulses to analyze the occupancy distribution, we
observe similarly slow-evolving dynamics, and a lower effective temperature at
the center of the sample
Nuclear-spin-independent short-range three-body physics in ultracold atoms
We investigate three-body recombination loss across a Feshbach resonance in a
gas of ultracold 7Li atoms prepared in the absolute ground state and perform a
comparison with previously reported results of a different nuclear-spin state
[N. Gross et.al., Phys. Rev. Lett. 103 163202, (2009)]. We extend the
previously reported universality in three-body recombination loss across a
Feshbach resonance to the absolute ground state. We show that the positions and
widths of recombination minima and Efimov resonances are identical for both
states which indicates that the short-range physics is nuclear-spin
independent.Comment: 4 pages, 2 figure
Topological Phase Separation In Trapped Ultracold Fermionic Gases
We investigate the harmonically trapped 2D fermionic systems with a effective
spin-orbit coupling and intrinsic s-wave superfluidity under the local density
approximation, and find that there is a critical value for Zeeman field. When
the Zeeman field larger than the critical value, the topological superfluid
phases emerge and coexist with the normal superfluid phase, topological phase
separation, in the trapped region. Otherwise, the superfluid phase is
topologically trivial.Comment: 6 pages, 3 figure
Exploring Universality of Few-Body Physics Based on Ultracold Atoms Near Feshbach Resonances
A universal characterization of interactions in few- and many-body quantum
systems is often possible without detailed description of the interaction
potential, and has become a defacto assumption for cold atom research.
Universality in this context is defined as the validity to fully characterize
the system in terms of two-body scattering length. We discuss universality in
the following three contexts: closed-channel dominated Feshbach resonance,
Efimov physics near Feshbach resonances, and corrections to the mean field
energy of Bose-Einstein condensates with large scattering lengths. Novel
experimental tools and strategies are discussed to study universality in
ultracold atomic gases: dynamic control of interactions, run-away evaporative
cooling in optical traps, and preparation of few-body systems in optical
lattices.Comment: ICAP 2008 Proceedin
Engineering entanglement for metrology with rotating matter waves
Entangled states of rotating, trapped ultracold bosons form a very promising scenario for quantum metrology. In order to employ such states for metrology, it is vital to understand their detailed form and the enhanced accuracy with which they could measure phase, in this case generated through rotation. In this work, we study the rotation of ultracold bosons in an asymmetric trapping potential beyond the lowest Landau level (LLL) approximation. We demonstrate that while the LLL can identify reasonably the critical frequency for a quantum phase transition and entangled state generation, it is vital to go beyond the LLL to identify the details of the state and quantify the quantum Fisher information (which bounds the accuracy of the phase measurement). We thus identify a new parameter regime for useful entangled state generation, amenable to experimental investigation
Ultracold molecules: vehicles to scalable quantum information processing
We describe a novel scheme to implement scalable quantum information
processing using Li-Cs molecular state to entangle Li and Cs
ultracold atoms held in independent optical lattices. The Li atoms will
act as quantum bits to store information, and Cs atoms will serve as
messenger bits that aid in quantum gate operations and mediate entanglement
between distant qubit atoms. Each atomic species is held in a separate optical
lattice and the atoms can be overlapped by translating the lattices with
respect to each other. When the messenger and qubit atoms are overlapped,
targeted single spin operations and entangling operations can be performed by
coupling the atomic states to a molecular state with radio-frequency pulses. By
controlling the frequency and duration of the radio-frequency pulses,
entanglement can either be created or swapped between a qubit messenger pair.
We estimate operation fidelities for entangling two distant qubits and discuss
scalability of this scheme and constraints on the optical lattice lasers
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