8,153 research outputs found
Tunable disorder in a crystal of cold polar molecules
In the present work, we demonstrate the possibility of controlling by an
external field the dynamics of collective excitations (excitons) of molecules
on an optical lattice. We show that a suitably chosen two-species mixture of
ultracold polar molecules loaded on an optical lattice forms a phononless
crystal, where exciton-impurity interactions can be controlled by applying an
external electric field. This can be used for the controlled creation of
many-body entangled states of ultracold molecules and the time-domain quantum
simulation of disorder-induced localization and delocalization of quantum
particles
Emulating Molecular Orbitals and Electronic Dynamics with Ultracold Atoms
In recent years, ultracold atoms in optical lattices have proven their great
value as quantum simulators for studying strongly correlated phases and complex
phenomena in solid-state systems. Here we reveal their potential as quantum
simulators for molecular physics and propose a technique to image the
three-dimensional molecular orbitals with high resolution. The outstanding
tunability of ultracold atoms in terms of potential and interaction offer fully
adjustable model systems for gaining deep insight into the electronic structure
of molecules. We study the orbitals of an artificial benzene molecule and
discuss the effect of tunable interactions in its conjugated pi electron system
with special regard to localization and spin order. The dynamical time scales
of ultracold atom simulators are on the order of milliseconds, which allows for
the time-resolved monitoring of a broad range of dynamical processes. As an
example, we compute the hole dynamics in the conjugated pi system of the
artificial benzene molecule.Comment: 8 pages, 4 figure
Large-scale multilayer architecture of single-atom arrays with individual addressability
We report on the realization of large-scale 3D multilayer configurations of
planar arrays of individual neutral atoms with immediate applications in
quantum science and technology: a microlens-generated Talbot optical lattice In
this novel platform, the single-beam illumination of a microlens array
constitutes a structurally robust and wavelength-universal method for the
realization of 3D atom arrays with favourable scaling properties due to the
inherent self-imaging of the focal structure. Thus, 3D scaling comes without
the requirement of extra resources. We demonstrate the trapping and imaging of
individual rubidium atoms and the in-plane assembly of defect-free single-atom
arrays in several Talbot planes. We present interleaved lattices with dynamic
position control and parallelized sub-lattice addressing of spin states
Scalability of quantum computation with addressable optical lattices
We make a detailed analysis of error mechanisms, gate fidelity, and
scalability of proposals for quantum computation with neutral atoms in
addressable (large lattice constant) optical lattices. We have identified
possible limits to the size of quantum computations, arising in 3D optical
lattices from current limitations on the ability to perform single qubit gates
in parallel and in 2D lattices from constraints on laser power. Our results
suggest that 3D arrays as large as 100 x 100 x 100 sites (i.e.,
qubits) may be achievable, provided two-qubit gates can be performed with
sufficiently high precision and degree of parallelizability. Parallelizability
of long range interaction-based two-qubit gates is qualitatively compared to
that of collisional gates. Different methods of performing single qubit gates
are compared, and a lower bound of is determined on the
error rate for the error mechanisms affecting Cs in a blue-detuned
lattice with Raman transition-based single qubit gates, given reasonable limits
on experimental parameters.Comment: 17 pages, 5 figures. Accepted for publication in Physical Review
Designer quantum states of matter created atom-by-atom
With the advances in high resolution and spin-resolved scanning tunneling
microscopy as well as atomic-scale manipulation, it has become possible to
create and characterize quantum states of matter bottom-up, atom-by-atom. This
is largely based on controlling the particle- or wave-like nature of electrons,
as well as the interactions between spins, electrons, and orbitals and their
interplay with structure and dimensionality. We review the recent advances in
creating artificial electronic and spin lattices that lead to various exotic
quantum phases of matter, ranging from topological Dirac dispersion to complex
magnetic order. We also project future perspectives in non-equilibrium
dynamics, prototype technologies, engineered quantum phase transitions and
topology, as well as the evolution of complexity from simplicity in this newly
developing field
Quantum control of molecular rotation
The angular momentum of molecules, or, equivalently, their rotation in
three-dimensional space, is ideally suited for quantum control. Molecular
angular momentum is naturally quantized, time evolution is governed by a
well-known Hamiltonian with only a few accurately known parameters, and
transitions between rotational levels can be driven by external fields from
various parts of the electromagnetic spectrum. Control over the rotational
motion can be exerted in one-, two- and many-body scenarios, thereby allowing
to probe Anderson localization, target stereoselectivity of bimolecular
reactions, or encode quantum information, to name just a few examples. The
corresponding approaches to quantum control are pursued within separate, and
typically disjoint, subfields of physics, including ultrafast science, cold
collisions, ultracold gases, quantum information science, and condensed matter
physics. It is the purpose of this review to present the various control
phenomena, which all rely on the same underlying physics, within a unified
framework. To this end, we recall the Hamiltonian for free rotations, assuming
the rigid rotor approximation to be valid, and summarize the different ways for
a rotor to interact with external electromagnetic fields. These interactions
can be exploited for control --- from achieving alignment, orientation, or
laser cooling in a one-body framework, steering bimolecular collisions, or
realizing a quantum computer or quantum simulator in the many-body setting.Comment: 52 pages, 11 figures, 607 reference
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