102 research outputs found
Superfluid qubit systems with ring shaped optical lattices
We study an experimentally feasible qubit system employing neutral atomic
currents. Our system is based on bosonic cold atoms trapped in ring-shaped
optical lattice potentials. The lattice makes the system strictly one
dimensional and it provides the infrastructure to realize a tunable ring-ring
interaction. Our implementation combines the low decoherence rates of of
neutral cold atoms systems, overcoming single site addressing, with the
robustness of topologically protected solid state Josephson flux qubits.
Characteristic fluctuations in the magnetic fields affecting Josephson junction
based flux qubits are expected to be minimized employing neutral atoms as flux
carriers. By breaking the Galilean invariance we demonstrate how atomic
currents through the lattice provide a implementation of a qubit. This is
realized either by artificially creating a phase slip in a single ring, or by
tunnel coupling of two homogeneous ring lattices. The single qubit
infrastructure is experimentally investigated with tailored optical potentials.
Indeed, we have experimentally realized scaled ring-lattice potentials that
could host, in principle, of such ring-qubits, arranged in a stack
configuration, along the laser beam propagation axis.
An experimentally viable scheme of the two-ring-qubit is discussed, as well.
Based on our analysis, we provide protocols to initialize, address, and
read-out the qubit.Comment: 14 revtex4-1 pages, 7 figs; to be published in Scientific Report
ATOMTRONICS: QUANTUM TECHNOLOGY WITH COLD ATOMS IN RING SHAPED OPTICAL LATTICES
Ph.DDOCTOR OF PHILOSOPH
Rapid generation of high fidelity, dissipation-stabilized dimerized chain
Despite the many proposals to use dissipation as a resource to prepare
long-lived entangled states, the speed of such entanglement generation is
usually limited by the requirement of perturbatively small driving strengths.
We propose a new scheme to rapidly generate many-body entanglement between
multiple spins coupled to a 1D bath stabilized by the dissipation into the
bath. Our work stands in contrast to the current well known steady state
protocols for entanglement generation in spins coupled to 1D baths that take a
prohibitively long time, and exhibits a speedup over state-of-the-art protocols
by several orders of magnitude. Importantly, the protocol works even with a
local control Hamiltonian, and the timescale is independent of the system size.
Our scheme can be applied to simultaneously generate a large number of spin
dimer pairs, which can serve as a valuable resource for quantum metrology and
teleportation-based information processing.Comment: 11 pages, 7 figure
Annealing Effect on the Structural, Electrical and Optical Properties of Er, Li-Codoped ZnO Films
The effect of post deposition annealing in air on structural, electrical and optical properties of Er,Licodoped
ZnO films deposited on sapphire substrate by an e-beam evaporation technique in vacuum are investigated.
The structural, optical and electrical features of these films before and after short-time annealing
were studied by XRD, UV-VIS-IR absorption and reflection spectroscopy, photoluminescence and resistivity
measurements. Experimental results showed that there is wide absorption band in IR range, connected
with defect centers, presumably OH-complex, in as-deposited films, and after annealing it is disappeared.
Green and NIR photoluminescence of Er3+ ions in annealed films excited under nitrogen laser was
observed. The intensity of photoluminescence is much stronger for sample with Li (0.8 %) than that with Li
(0.6 %).
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3499
Coherent superposition of current flows in an Atomtronic Quantum Interference Device
We consider a correlated Bose gas tightly confined into a ring shaped
lattice, in the presence of an artificial gauge potential inducing a persistent
current through it. A weak link painted on the ring acts as a source of
coherent back-scattering for the propagating gas, interfering with the forward
scattered current. This system defines an atomic counterpart of the rf-SQUID:
the atomtronics quantum interference device (AQUID). The goal of the present
study is to corroborate the emergence of an effective two-level system in such
a setup and to assess its quality, in terms of its inner resolution and its
separation from the rest of the many-body spectrum, across the different
physical regimes. In order to achieve this aim, we examine the dependence of
the qubit energy gap on the bosonic density, the interaction strength, and the
barrier depth, and we show how the superposition between current states appears
in the momentum distribution (time-of-flight) images. A mesoscopic ring lattice
with intermediate-to-strong interactions and weak barrier depth is found to be
a favorable candidate for setting up, manipulating and probing a qubit in the
next generation of atomic experiments.Comment: 17 pages, 10 figure
Generation and optimization of entanglement between giant atoms chirally coupled to spin cavities
We explore a scheme for entanglement generation and optimization in giant
atoms by coupling them to finite one-dimensional arrays of spins that behave as
cavities. We find that high values for the concurrence can be achieved in
small-sized cavities, being the generation time very short. When exciting the
system by external means, optimal concurrence is obtained for very weak
drivings. We also analyze the effect of disorder in these systems, showing that
although the average concurrence decreases with disorder, high concurrences can
still be obtained even in scenarios presenting strong disorder. This result
leads us to propose an optimization procedure in which by engineering the
on-site energies or hoppings in the cavity, concurrences close to 1 can be
reached within an extremely short period of time
- …