1,487 research outputs found
Conditional preparation of arbitrary atomic Dicke states
We propose an experimentally accessible procedure for conditional preparation
of highly non-classical states of collective spin of an atomic ensemble. The
quantum state engineering is based on a combination of QND interaction between
atoms and light previously prepared in a non-Gaussian state using photon
subtraction from squeezed vacuum beam, homodyne detection on the output light
beam, and a coherent displacement of atomic state. The procedure is capable of
non-deterministic preparation of a wide class of superpositions of atomic Dicke
states. We present several techniques to optimize the performance of the
protocol and maximize the trade-off between fidelity of prepared state and
success probability of the scheme.Comment: 10 pages, 7 figures, RevTeX
Deterministic Dicke state preparation with continuous measurement and control
We characterize the long-time projective behavior of the stochastic master
equation describing a continuous, collective spin measurement of an atomic
ensemble both analytically and numerically. By adding state based feedback, we
show that it is possible to prepare highly entangled Dicke states
deterministically.Comment: Additional information is available at
http://minty.caltech.edu/Ensemble
Deterministic preparation of Dicke states of donor nuclear spins in silicon by cooperative pumping
For donor nuclear spins in silicon, we show how to deterministically prepare
various symmetric and asymmetric Dicke states which span a complete basis of
the many-body Hilbert space. The state preparation is realized by cooperative
pumping of nuclear spins by coupled donor electrons, and the required controls
are in situ to the prototype Kane proposal for quantum computation. This scheme
only requires a sub-gigahertz donor exchange coupling which can be readily
achieved without atomically precise donor placement, hence it offers a
practical way to prepare multipartite entanglement of spins in silicon with
current technology. All desired Dicke states appear as the steady state under
various pumping scenarios and therefore the preparation is robust and does not
require accurate temporal controls. Numerical simulations with realistic
parameters show that Dicke states of 10-20 qubits can be prepared with high
fidelity in presence of decoherence and unwanted dynamics.Comment: published versio
An efficient scheme for the deterministic maximal entanglement of N trapped ions
We propose a method for generating maximally entangled states of N two-level
trapped ions. The method is deterministic and independent of the number of ions
in the trap. It involves a controlled-NOT acting simultaneously on all the ions
through a dispersive interaction. We explore the potential application of our
scheme for high precision frequency standards.Comment: 4 pages, no figures, submitted to PRL, under review, Revised Version:
Incorporated referee comment
Deterministically entangling distant nitrogen-vacancy centers by a nanomechanical cantilever
We present a practical scheme by global addressing to deterministically
entangle negatively charged nitrogen-vacancy (N-V) centers in distant diamonds
using a nano-mechanical cantilever with the magnetic tips strongly coupled to
the N-V electron spins. Symmetric Dicke states are generated as an example, and
the experimental feasibility and challenge of our scheme are discussed.Comment: 5 pages, 4 figure
Quantum-state synthesis of multi-mode bosonic fields: Preparation of arbitrary states of 2-D vibrational motion of trapped ions
We present a universal algorithm for an efficient deterministic preparation
of an arbitrary two--mode bosonic state. In particular, we discuss in detail
preparation of entangled states of a two-dimensional vibrational motion of a
trapped ion via a sequence of laser stimulated Raman transitions. Our formalism
can be generalized for multi-mode bosonic fields. We examine stability of our
algorithm with respect to a technical noise.Comment: 8 pages, revtex, including 2 ps-figures, section about physical
implementation added, references updated, submitted to Phys. Rev. A, computer
program available at http://www.savba.sk/sav/inst/fyzi/qo
Performance of a deterministic source of entangled photonic qubits
We study the possible limitations and sources of decoherence in the scheme
for the deterministic generation of polarization-entangled photons, recently
proposed by Gheri et al. [K. M. Gheri et al., Phys. Rev. A 58, R2627 (1998)],
based on an appropriately driven single atom trapped within an optical cavity.
We consider in particular the effects of laser intensity fluctuations, photon
losses, and atomic motion.Comment: 10 pages, 6 figure
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