1,132 research outputs found
Hamiltonian tomography of dissipative systems under limited access: A biomimetic case study
The identification of parameters in the Hamiltonian that describes complex
many-body quantum systems is generally a very hard task. Recent attention has
focused on such problems of Hamiltonian tomography for networks constructed
with two-level systems. For open quantum systems, the fact that injected
signals are likely to decay before they accumulate sufficient information for
parameter estimation poses additional challenges. In this paper, we consider
use of the gateway approach to Hamiltonian tomography
\cite{Burgarth2009,Burgarth2009a} to complex quantum systems with a limited set
of state preparation and measurement probes. We classify graph properties of
networks for which the Hamiltonian may be estimated under equivalent conditions
on state preparation and measurement. We then examine the extent to which the
gateway approach may be applied to estimation of Hamiltonian parameters for
network graphs with non-trivial topologies mimicking biomolecular systems.Comment: 6 page
NMR Techniques for Quantum Control and Computation
Fifty years of developments in nuclear magnetic resonance (NMR) have resulted
in an unrivaled degree of control of the dynamics of coupled two-level quantum
systems. This coherent control of nuclear spin dynamics has recently been taken
to a new level, motivated by the interest in quantum information processing.
NMR has been the workhorse for the experimental implementation of quantum
protocols, allowing exquisite control of systems up to seven qubits in size.
Here, we survey and summarize a broad variety of pulse control and tomographic
techniques which have been developed for and used in NMR quantum computation.
Many of these will be useful in other quantum systems now being considered for
implementation of quantum information processing tasks.Comment: 33 pages, accepted for publication in Rev. Mod. Phys., added
subsection on T_{1,\rho} (V.A.6) and on time-optimal pulse sequences
(III.A.6), redid some figures, made many small changes, expanded reference
Continuous matrix product state tomography of quantum transport experiments
In recent years, a close connection between the description of open quantum
systems, the input-output formalism of quantum optics, and continuous matrix
product states in quantum field theory has been established. So far, however,
this connection has not been extended to the condensed-matter context. In this
work, we substantially develop further and apply a machinery of continuous
matrix product states (cMPS) to perform tomography of transport experiments. We
first present an extension of the tomographic possibilities of cMPS by showing
that reconstruction schemes do not need to be based on low-order correlation
functions only, but also on low-order counting probabilities. We show that
fermionic quantum transport settings can be formulated within the cMPS
framework. This allows us to present a reconstruction scheme based on the
measurement of low-order correlation functions that provides access to
quantities that are not directly measurable with present technology. Emblematic
examples are high-order correlations functions and waiting times distributions
(WTD). The latter are of particular interest since they offer insights into
short-time scale physics. We demonstrate the functioning of the method with
actual data, opening up the way to accessing WTD within the quantum regime.Comment: 11 pages, 4 figure
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