Quantum Systems, Information and Control

 

Recent Submissions

  • Gough, John Edward; James, Matthew R.; Nurdin, Hendra I.; Combes, Joshua (2012-10-15)
    We derive the stochastic master equations, that is to say, quantum filters, and master equations for an arbitrary quantum system probed by a continuous-mode bosonic input field in two types of nonclassical states. Specifically, ...
  • Gough, John Edward; James, Matthew R.; Nurdin, Hendra I. (2012-11-28)
    We determine quantum master and filter equations for continuous measurement of systems coupled to input fields in certain non-classical continuous-mode states, specifically single photon states. The quantum filters are ...
  • Gough, John Edward; Nurdin, H. I. (2012-11-28)
    Two standard operations of model reduction for quantum feedback networks, elimination of internal connections under the instantaneous feedback limit and adiabatic elimination of fast degrees of freedom, are cast as ...
  • Burgarth, Daniel; Giovannetti, Vittorio (2011-09-27)
    We discuss an explicit protocol which allows one to externally cool and control a composite system by operating on a small subset of it. The scheme permits to transfer arbitrary and unknown quantum states from a memory on ...
  • Gough, John E.; James, Matthew R. (IEEE Press, 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 ...
  • Köstler, Claus (2011-01-31)
    Inspired by Lehner's results on exchangeability systems in [Leh06] we define `weak conditional freeness' and `conditional freeness' for stationary processes in an operator algebraic framework of noncommutative probability. ...
  • Evans, Dafydd Gwion; Gough, John Edward; James, Matthew (2012-11-07)
    We show that the series product, which serves as an algebraic rule for connecting state-based input/output systems, is intimately related to the Heisenberg group and the canonical commutation relations. The series product ...
  • James, Matthew R.; Gough, John E.; Nurdin, Hendra (2012-11-07)
    The purpose of this paper is to determine quantum master and filter equations for systems coupled to fields in certain non-classical continuous-mode states. Specifically, we consider two types of field states (i) single ...
  • Maruyama, Koji; Burgarth, Daniel; Ishizaki, Akihito; Takui, Takeji; Whaley, K. Birgitta (2012-10-15)
    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 ...
  • Gough, John Edward; Guta, Madalin I.; James, Matthew R.; Nurdin, Hendra I. (2011)
    Recent developments in quantum technology mean that is it now possible to manipulate systems and measure fermion elds (e.g. reservoirs of electrons) at the quantum level. This progress has motivated some recent work on ...
  • Genoni, Marco; Serafini, Alessio; Kim, Myungshik; Burgarth, Daniel Klaus (2012-04-09)
    Controllability - the possibility of performing any target dynamics by applying a set of available operations - is a fundamental requirement for the practical use of any physical system. For finite-dimensional systems, ...
  • Burgarth, Daniel Klaus; Yuasa, Kazuya (2012-02-23)
    The aim of quantum system identification is to estimate the ingredients inside a black box, in which some quantum-mechanical unitary process takes place, by just looking at its input-output behavior. Here we establish a ...
  • Lapasar, Elham Hosseini; Maruyama, Koji; Burgarth, Daniel Klaus; Takui, Takeji; Kondo, Yasushi; Nakahara, Mikio (2012-01-23)
    It has been shown that inter-spin interaction strengths in a spin-1/2 chain can be evaluated by accessing one of the edge spins only. We demonstrate this experimentally for the simplest case, a three-spin chain, with the ...
  • 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 ...
  • Yuasa, Kazuya; Burgarth, Daniel Klaus; Giovannetti, Vittorio; Nakazato, Hiromichi (2011-09-26)
    A scheme for preparing two fixed noninteracting qubits in a maximally entangled state is presented. By repeating on- and off-resonant scattering of ancilla qubits, the target qubits are driven from an arbitrary initial ...
  • 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 ...
  • 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 ...
  • 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 ...
  • Sinaysky, Ilya; Petruccione, Francesco; Burgarth, Daniel Klaus (2011-09-26)
    The dynamics of a simple spin chain (two spins) coupled to bosonic baths at different temperatures is studied. The analytical solution for the reduced density matrix of the system is found. The dynamics and temperature ...
  • Burgarth, Daniel Klaus; Giovannetti, Vittorio (2010-08-19)
    In this addendum to our paper [ D. Burgarth and V. Giovannetti Phys. Rev. Lett. 99 100501 (2007)] we prove that during the transformation that allows one to enforce control by relaxation on a quantum system, the ancillary ...

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