Poster: Neutralising the dark side of quantum networks

More details on the work in the following poster (and more!) can be found at arXiv:1707.07482

Neutralising the dark side of quantum networks

T. P. Le*,‡ & S. Severini

* EPSRC Centre for Doctoral Training (CDT) in Delivering Quantum Technologies, University College London

Department of Computer Science, University College London


//dark subspace the vector subspace orthogonal to the target node (a.k.a. invariant1/ orthogonal2/ trapping-free2 subspace)

//identify spanned by all eigenvectors with a zero at the target-node position

//task neutralise the dark subspace to enhance quantum transport


  1. given an underlying network, there exists a Hamiltonian with node interactions such that there is no dark subspace
  2. very large graphs asymptotically almost surely have no dark subspace

//Tactic 01 - Avoid

//what initialise completely outside the dark subspace4

//why zero component stuck in the dark subspace; entire transfer possible

//requires initial superpositions/delocalised state

//Tactic 02 - Control

//what time-varying control fields change the dynamics on the network

//why disrupts the dark subspace and evolves the state towards the target

//see also controllability5

//Tactic 03 - Disrupt

//what local static noise, local dephasing, dissipation on the network1,2

//why changes eigenspectrum and decreases/destroys the dark subspace

//see also environment-assisted transport

  1. Caruso et al, J. Chem. Phys. 131, 105106 (2009)
  2. Wu et al, Phys. Rev. Lett. 110, (2013)
  3. Le & Severini, in preparation (2017)
  4. Schijven & Mülken, Phys. Rev. E 85, (2012)
  5. Pemberton-Ross & Schirmer, Phys. Rev. A 82, (2010)
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  • poster by TPLE 2017