Browsing Quantum Systems, Information and Control by Issue Date

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  • Gough, John E. (2004)
    We consider a Markovian approximation, of weak coupling type, to an open system perturbation involving emission, absorption and scattering by reservoir quanta. The result is the general form for a quantum stochastic flow ...
  • Gough, John E. (2004-03)
    We consider an atomic beam reservoir as a source of quantum noise. The atoms are modelled as two-state systems and interact one-at-a-time with the system. The Floquet operators are described in terms of the Fermionic ...
  • Sobolev, Andrei; Gough, John E. (2004-03-17)
    We derive the stochastic Schrödinger equation for the limit of continuous weak measurement where the observables monitored are canonical position and momentum. To this end we extend an argument due to Smolianov and Truman ...
  • Gough, John E. (2006)
    We extend the Ito -to- Stratonovich analysis or quantum stochastic differential equations, introduced by Gardiner and Collett for emission (creation), absorption (annihilation) processes, to include scattering (conservation) ...
  • Van Handel, R.; Gough, John E. (2007-02)
    We consider a physical system which is coupled indirectly to a Markovian resevoir through an oscillator mode. This is the case, for example, in the usual model of an atomic sample in a leaky optical cavity which is ubiquitous ...
  • Bayat, Abolfazl; Burgarth, Daniel Klaus; Mancini, Stefano; Bose, Sougato (2008-05-22)
    We investigate the multiple use of a ferromagnetic spin chain for quantum and classical communications without resetting. We find that the memory of the state transmitted during the first use makes the spin chain a ...
  • Gough, John E. (World Scientific, 2008-11-12)
    We consider the problem of optimal feedback control of a quantum system with linear dynamics undergoing continual non-demolition measurement of position and/or momentum, or both together. Specically, we show that a stable ...
  • Gough, John E.; James, Matthew R. (IEEE, 2008-12-09)
    The purpose of this paper is to discuss how Willems’ behavioral modeling might be applied to physical systems governed by the laws of quantum physics. A quantum behavior is simply defined in terms of the evolution of ...
  • Burgarth, Daniel Klaus; Bose, Sougato; Bruder, Christoph; Giovannetti, Vittorio (2009)
    We give a sufficient criterion that guarantees that a many-body quantum system can be controlled by properly manipulating the (local) Hamiltonian of one of its subsystems. The method can be applied to a wide range of ...
  • Giovannetti, Vittorio; Burgarth, Daniel Klaus; Mancini, Stefano (2009-01-13)
    A chain of interacting spin behaves like a quantum mediator (quantum link), which allows two distant parties that control the ends of the chain to exchange quantum messages. We show that over repeated uses without resetting ...
  • Zhang, Jingfu; Burgarth, Daniel; Ditty, Michael; Ryan, Colm A.; Chandrashekar, C. M.; Laforest, Martin; Moussa, Osama; Baugh, Jonathan; Laflamme, Raymond (2009-06-16)
    We implement an iterative quantum state transfer exploiting the natural dipolar couplings in a spin chain of a liquid-crystal NMR system. During each iteration, a finite part of the amplitude of the state is transferred ...
  • Burgarth, Daniel Klaus; Maruyama, Koji (2009-10-07)
    Identifying the many-body Hamiltonian of a large quantum system is essential in understanding many physical phenomena, yet extremely difficult in general. We show that coupling strengths in networks of spin-1/2 particles ...
  • Gough, John Edward; James, Matthew R. (2009-10-13)
    The purpose of this paper is to present simple and general algebraic methods for describing series connections in quantum networks. These methods build on and generalize existing methods for series (or cascade) connections ...
  • Gough, John Edward; Wildfeuer, Sebastian (2009-10-14)
    The theory of quantum feedback networks has recently been developed with the aim of showing how quantum input-output components may be connected together so as to control, stabilize, or enhance the performance of one of ...
  • Köstler, Claus; Speicher, Roland (2009-12-31)
    We showthat the classical de Finetti theorem has a canonical noncommutative counterpart if we strengthen 'exchangeability' (i.e., invariance of the joint distribution of the random variables under the action of the permutation ...
  • Heule, Rahel; Bruder, Christoph; Burgarth, Daniel; Stojanović, Vladimir M. (2010)
    Motivated by some recent results of quantum control theory, we discuss the feasibility of local operator control in arrays of interacting qubits modeled as isotropic Heisenberg spin chains. Acting on one of the end spins, ...
  • Gough, John Edward; Nurdin, Hendra; Wildfeuer, Sebastian (2010-01-01)
    We show that, for arbitrary quantum feedback networks consisting of several quantum mechanical components connected by quantum fields, the limit of adiabatic elimination of fast oscillator modes in the components and the ...
  • Gough, John Edward; Nurdin, Hendra; James, Matthew R. (2010-02-03)
    The aim of this article is to extend linear quantum dynamical network theory to include static Bogoliubov components (such as squeezers). Within this integrated quantum network theory, we provide general methods for cascade ...
  • Köstler, Claus (2010-02-15)
    The extended de Finetti theorem characterizes exchangeable infinite sequences of random variables as conditionally i.i.d. and shows that the apparently weaker distributional symmetry of spreadability is equivalent to ...
  • Burgarth, Daniel; Maryuama, Koji; Murphy, Michael; Montangero, Simone; Calarco, Tommaso; Nori, Franco; Plenio, Martin B. (2010-04-22)
    We apply quantum control techniques to a long spin chain by acting only on two qubits at one of its ends, thereby implementing universal quantum computation by a combination of quantum gates on these qubits and indirect ...

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