8,251 research outputs found
Dynamical resurrection of the visibility in a Mach-Zehnder interferometer
We study a single-electron pulse injected into the chiral edge-state of a
quantum Hall device and subject to a capacitive Coulomb interaction. We find
that the scattered multi-particle state remains unentangled and hence can be
created itself by a suitable classical voltage-pulse . The application of
the inverse pulse corrects for the shake-up due to the interaction and
resurrects the original injected wave packet. We suggest an experiment with an
asymmetric Mach-Zehnder interferometer where the application of such pulses
manifests itself in an improved visibility.Comment: 4 pages, 1 figur
Sequential quantum-enhanced measurement with an atomic ensemble
We propose a quantum-enhanced iterative (with steps) measurement scheme
based on an ensemble of two-level probes which asymptotically approaches
the Heisenberg limit , the number of quantum
resources. The protocol is inspired by Kitaev's phase estimation algorithm and
involves only collective manipulation and measurement of the ensemble. The
iterative procedure takes the shot-noise limited primary measurement with
precision to increasingly precise results
. A straightforward implementation of the algorithm
makes use of a two-component atomic cloud of Bosons in the precision
measurement of a magnetic field.Comment: 5 pages, 1 figur
Recovery of a quarkonium system from experimental data
For confining potentials of the form q(r)=r+p(r), where p(r) decays rapidly
and is smooth for r>0, it is proved that q(r) can be uniquely recovered from
the data {E_j,s_j}, where E_j are the bound states energies and s_j are the
values of u'_j(0), and u_j(r) are the normalized eigenfunctions of the problem
-u_j" +q(r)u_j=E_ju_j, r>0, u_j(0)=0, ||u_j||=1, where the norm is L^2(0,
\infty) norm. An algorithm is given for recovery of p(r) from few experimental
data
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