10,345 research outputs found
Optimal State Discrimination Using Particle Statistics
We present an application of particle statistics to the problem of optimal
ambiguous discrimination of quantum states. The states to be discriminated are
encoded in the internal degrees of freedom of identical particles, and we use
the bunching and antibunching of the external degrees of freedom to
discriminate between various internal states. We show that we can achieve the
optimal single-shot discrimination probability using only the effects of
particle statistics. We discuss interesting applications of our method to
detecting entanglement and purifying mixed states. Our scheme can easily be
implemented with the current technology
Lower bounds on the dilation of plane spanners
(I) We exhibit a set of 23 points in the plane that has dilation at least
, improving the previously best lower bound of for the
worst-case dilation of plane spanners.
(II) For every integer , there exists an -element point set
such that the degree 3 dilation of denoted by in the domain of plane geometric spanners. In the
same domain, we show that for every integer , there exists a an
-element point set such that the degree 4 dilation of denoted by
The
previous best lower bound of holds for any degree.
(III) For every integer , there exists an -element point set
such that the stretch factor of the greedy triangulation of is at least
.Comment: Revised definitions in the introduction; 23 pages, 15 figures; 2
table
A Processor Core Model for Quantum Computing
We describe an architecture based on a processing 'core' where multiple
qubits interact perpetually, and a separate 'store' where qubits exist in
isolation. Computation consists of single qubit operations, swaps between the
store and the core, and free evolution of the core. This enables computation
using physical systems where the entangling interactions are 'always on'.
Alternatively, for switchable systems our model constitutes a prescription for
optimizing many-qubit gates. We discuss implementations of the quantum Fourier
transform, Hamiltonian simulation, and quantum error correction.Comment: 5 pages, 2 figures; improved some arguments as suggested by a refere
Growth and optical properties of nanowires
The present paper reviews the growth mechanism, processes and optical properties of nanowires with special reference to ZnO. A brief description of free standing vertical nanowires of ZnO grown in our lab is also included
Multi-level, multi-party singlets as ground states and their role in entanglement distribution
We show that a singlet of many multi-level quantum systems arises naturally
as the ground state of a physically-motivated Hamiltonian. The Hamiltonian
simply exchanges the states of nearest-neighbours in some network of qudits
(d-level systems); the results are independent of the strength of the couplings
or the network's topology. We show that local measurements on some of these
qudits project the unmeasured qudits onto a smaller singlet, regardless of the
choice of measurement basis at each measurement. It follows that the
entanglement is highly persistent, and that through local measurements, a large
amount of entanglement may be established between spatially-separated parties
for subsequent use in distributed quantum computation.Comment: Corrected method for physical preparatio
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