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

^‡ thao.le.16@ucl.ac.uk

//Brief

//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

//results³

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 network^1,2

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

//see also environment-assisted transport

References

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)

Other

• DQT Logo
• poster by TPLE 2017