Browsing Quantum Systems, Information and Control by Author "Burgarth, Daniel"

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Browsing Quantum Systems, Information and Control by Author "Burgarth, Daniel"

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  • Application of indirect Hamiltonian tomography to complex systems with short decoherence times 
    Burgarth, Daniel; Takui, Takeji; Whaley, K. Birgitta; Maruyama, Koji; Ishizaki, Akihito (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 ...
  • Communication through a quantum link 
    Giovannetti, Vittorio; Mancini, Stefano; Burgarth, Daniel (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 ...
  • Controlling qubit arrays with anisotropic XXZ Heisenberg interaction by acting on a single qubit 
    Heule, Rahel; Bruder, Christoph; Stojanović, Vladimir M.; Burgarth, Daniel (2011-08-31)
    We investigate anisotropic XXZ Heisenberg spin-1/2 chains with control fields acting on one of the end spins, with the aim of exploring local quantum control in arrays of interacting qubits. In this work, which uses a recent ...
  • Coupling strength estimation for spin chains despite restricted access 
    Nori, Franco; Maruyama, Koji; Burgarth, Daniel (2011-09-26)
    Quantum control requires full knowledge of the system many-body Hamiltonian. In many cases this information is not directly available due to restricted access to the system. Here we show how to indirectly estimate all the ...
  • Dynamical Recurrence and the Quantum Control of Coupled Oscillators 
    Genoni, Marco; Serafini, Alessio; Kim, Myungshik; Burgarth, Daniel (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, ...
  • Dynamics of nonequilibrium thermal entanglement 
    Burgarth, Daniel; Sinaysky, Ilya; Petruccione, Francesco (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 ...
  • Efficient generation of a maximally entangled state by repeated on- and off-resonant scattering of ancilla qubits 
    Burgarth, Daniel; Yuasa, Kazuya; Nakazato, Hiromichi; Giovannetti, Vittorio (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 ...
  • Estimation of coupling constants of a three-spin chain: a case study of Hamiltonian tomography with nuclear magnetic resonance 
    Lapasar, Elham Hosseini; Maruyama, Koji; Burgarth, Daniel; Takui, Takeji; Nakahara, Mikio; Kondo, Yasushi (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 ...
  • Indirect Hamiltonian Identification through a small gateway 
    Burgarth, Daniel; 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 ...
  • Indirect quantum tomography of quadratic Hamiltonians 
    Burgarth, Daniel; Maruyama, Koji; Nori, Franco (2011-01-14)
    A number of many-body problems can be formulated using Hamiltonians that are quadratic in the creation and annihilation operators. Here, we show how such quadratic Hamiltonians can be efficiently estimated indirectly, ...
  • Local controllability of quantum networks 
    Burgarth, Daniel; 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 ...
  • Local quantum control of Heisenberg spin chains 
    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, ...
  • Memory Effects in spin-chain channels for information transmission 
    Bayat, Abolfazl; Burgarth, Daniel; Mancini, Stefano; Bose, Sougato (2008)
    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 ...
  • A Protocol For Cooling and Controlling Composite Systems by Local Interactions 
    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 ...
  • Quantum data bus in dipolar coupled nuclear spin qubits 
    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 ...
  • Quantum defragmentation algorithm 
    Giovannetti, Vittorio; Burgarth, Daniel (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 ...
  • Scalable quantum computation via local control of only two qubits 
    Montangero, Simone; Murphy, Michael; Burgarth, Daniel; Maryuama, Koji; Nori, Franco; Plenio, Martin B.; Calarco, Tommaso (2011-09-26)
    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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