TY - JOUR

T1 - Quantum Feedback Networks: Hamiltonian Formulation

AU - Gough, John Edward

AU - James, M. R.

N1 - Gough, J. E., James, M. R., Quantum Feedback Networks: Hamiltonian Formulation, Commun. Math. Phys., Volume 287, Number 3 / May, 2009, 1109-1132

PY - 2009/5/1

Y1 - 2009/5/1

N2 - A quantum network is an open system consisting of several component Markovian input-output subsystems interconnected by boson field channels carrying quantum stochastic signals. Generalizing the work of Chebotarev and Gregoratti, we formulate the model description by prescribing a candidate Hamiltonian for the network including details of the component systems, the field channels, their interconnections, interactions and any time delays arising from the geometry of the network. (We show that the candidate is a symmetric operator and proceed modulo the proof of selfadjointness.) The model is non-Markovian for finite time delays, but in the limit where these delays vanish we recover a Markov model and thereby deduce the rules for introducing feedback into arbitrary quantum networks. The type of feedback considered includes that mediated by the use of beam splitters. We are therefore able to give a system-theoretic approach to introducing connections between quantum mechanical state-based input-output systems, and give a unifying treatment using non-commutative fractional linear, or Möbius, transformations.

AB - A quantum network is an open system consisting of several component Markovian input-output subsystems interconnected by boson field channels carrying quantum stochastic signals. Generalizing the work of Chebotarev and Gregoratti, we formulate the model description by prescribing a candidate Hamiltonian for the network including details of the component systems, the field channels, their interconnections, interactions and any time delays arising from the geometry of the network. (We show that the candidate is a symmetric operator and proceed modulo the proof of selfadjointness.) The model is non-Markovian for finite time delays, but in the limit where these delays vanish we recover a Markov model and thereby deduce the rules for introducing feedback into arbitrary quantum networks. The type of feedback considered includes that mediated by the use of beam splitters. We are therefore able to give a system-theoretic approach to introducing connections between quantum mechanical state-based input-output systems, and give a unifying treatment using non-commutative fractional linear, or Möbius, transformations.

U2 - 10.1007/s00220-008-0698-8

DO - 10.1007/s00220-008-0698-8

M3 - Article

SN - 0010-3616

VL - 287

SP - 1109

EP - 1132

JO - Communications in Mathematical Physics

JF - Communications in Mathematical Physics

IS - 3

ER -