60 research outputs found
Quantum filtering for multiple input multiple output systems driven by arbitrary zero-mean jointly Gaussian input fields
In this paper, we treat the quantum filtering problem for multiple input
multiple output (MIMO) Markovian open quantum systems coupled to multiple boson
fields in an arbitrary zero-mean jointly Gaussian state, using the reference
probability approach formulated by Bouten and van Handel as a quantum version
of a well-known method of the same name from classical nonlinear filtering
theory, and exploiting the generalized Araki-Woods representation of Gough.
This includes Gaussian field states such as vacuum, squeezed vacuum, thermal,
and squeezed thermal states as special cases. The contribution is a derivation
of the general quantum filtering equation (or stochastic master equation as
they are known in the quantum optics community) in the full MIMO setup for any
zero-mean jointy Gaussian input field states, up to some mild rank assumptions
on certain matrices relating to the measurement vector.Comment: 19 pages, no figures. Published in a special issue of the Russian
Journal of Mathematical Physics dedicated to the memory of Slava Belavki
Reduced-dimension linear transform coding of distributed correlated signals with incomplete observations
We study the problem of optimal reduced-dimension linear transform coding and reconstruction of a signal based on distributed correlated observations of the signal. In the mean square estimation context this involves finding he optimal signal representation based on multiple incomplete or only partial observations that are correlated. In particular this leads to the study of finding the optimal Karhunen-Loeve basis based on the censored observations. The problem has been considered previously by Gestpar, Dragotti and Vitterli in the context of jointly Gaussian random variables based on using conditional covariances. In this paper, we derive the estimation results in the more general setting of second-order random variables with arbitrary distributions, using entirely different techniques based on the idea of innovations. We explicitly solve the single transform coder case, give a characterization of optimality in the multiple distributed transform coders scenario and provide additional insights into the structure of the problm
Quantum state transfer for multi-input linear quantum systems
Effective state transfer is one of the most important problems in quantum
information processing. Typically, a quantum information device is composed of
many subsystems with multi-input ports. In this paper, we develop a general
theory describing the condition for perfect state transfer from the multi-input
ports to the internal system components, for general passive linear quantum
systems. The key notion used is the zero of the transfer function matrix.
Application to entanglement generation and distribution in a quantum network is
also discussed.Comment: 6 pages, 3 figures. A preliminary condensed version of this work will
appear in Proceedings of the 55th IEEE Conference on Decision and Contro
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