Principles of noise assisted transport in networks
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Imperial College London. Principles of Noise Assisted Transport in Networks. Martin B Plenio. Institute for Mathematical Sciences & Quantum Optics and Laser Science Group Blackett Laboratory Imperial College London http://www.imperial.ac.uk/quantuminformation.

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Principles of Noise Assisted Transport in Networks

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Imperial College London

Principles of Noise Assisted Transport in Networks

Martin B Plenio

Institute for Mathematical Sciences

&

Quantum Optics and Laser Science Group

Blackett Laboratory

Imperial College London

http://www.imperial.ac.uk/quantuminformation

In collaboration with: Animesh Datta & Filippo Caruso (Imperial College London, UK)

Alex Chin and Susana Huelga (Univ. Hertfordshire, UK)


Noise seems a problem here as it destroys quantum coherence


Weak coherent driving

Weak response


Weak coherent driving + weak noise give a strong coherent response.

Noise

Stochastic resonance


Biological systems can use noise to improve their sensitivity to weak coherent signals

Can we use this in quantum mechanics ?

Noise can be good for you in quantum mechanics too for entanglement generation and preservation !

Huelga & Plenio, PRA 1999, PRA 2000 & PRL 2002 & PRL 2007

See also overview talk by Susana Huelga Friday


A Fundamental Experiment

Clicks

Time

Clicks

Time


A Fundamental Experiment


A Fundamental Experiment

Clicks

Time

Clicks

Time


Photosynthesis

Green sulphur Bacteria

A black smoker in the Atlantic Ocean ~ 2000m deep

Y.C. Cheng and G.R. Fleming, Annu. Rev. Phys. Chem. 60, 241 (2009)


Exciton Transport in Photosynthesis

Green sulphur Bacteria

Reaction Centre

CO

+ 2 H S

2

2

+ energy

CH O

+ H O

+ 2 S

2

2


Exciton Transport in Photosynthesis

Green sulphur Bacteria

Reaction Centre

CO

+ 2 H S

2

2

+ energy

CH O

+ H O

+ 2 S

2

2


Exciton Transport in Photosynthesis

Green sulphur Bacteria

Reaction Centre

Transfer to reaction centre

CO

+ 2 H S

2

2

+ energy

CH O

+ H O

+ 2 S

2

2


Dephasing

Exchange of excitation

Transfer to reaction centre

Loss of excitation

Reaction Centre

CO

+ 2 H S

2

2

+ energy

CH O

+ H O

+ 2 S

2

2

M.B. Plenio and S.F. Huelga, New J. Phys. 10, 113019 (2008)


Noise Assisted Transport and Photosynthesis

More dephasing

Some dephasing

No dephasing

Plenio & Huelga, New J. Phys. 2008

Mohseni, Rebentrost, Lloyd, Aspuru-Guzik, J. Phys. Chem. 2008


Physical Origin of Noise Assisted Transport


Exciton Transport in Photosynthesis

Show Movie 1: No dephasing Initial excitation in site 1


Exciton Transport in Photosynthesis

Two differenttime scales !


Destructive Interference and Invariant States

Clicks

Time

Clicks

Time


Destructive Interference and Invariant States

=

J

J

Reactioncenter


Destructive Interference and Invariant States

=

J

J

Reactioncenter

Transfer efficiency


Noise Inhibits Destructive Interference

=

Decoherence inhibits destructive interference !

J

J

Reactionscenter

Transfer efficiency

Reactioncenter

Reduction ofdestructive interference


Destructive Interference and Invariant States

Two atoms in the same location:

Invariant state:


Dephasing on site 1 only

Show Movie1a: Small dephasing on site 1 only


Dephasing on site 1 only


Destructive Interference and Invariant States

Different energy splitting:

not invariant under Hamiltonian evolution !


Disorder Inhibits Destructive Interference

Static disorder inhibits destructive interference !

J

J

Destructiveinterference

Reactioncenter

J

J

Reactioncenter

Reduction ofdestructive interference


Disorder Inhibits Destructive Interference


The Hamiltonian of the FMO complex

Quite strong static disorder compared to coupling strengths !


Bridging the gap: Enhanced transport via line broadening


Dephasing Noise on Site 3 only

Play Movie1ab: Same amount of dephasing noise now only on site 3

Play Movie1b: Dephasing noise only on site 3


Dephasing Noise on Site 3 only


Line broadening does enhance transfer!

No line broadening, No transfer!


Spatially Correlated Noise

J

J

J

J

destructive

interference

destructive

interference

+J

-J

-J

-J

effect ofnoise enhanced

effect ofnoise reduced


Spatially Correlated Noise

dephasing with non-local correlations

T=5 ps

local dephasing without correlations

Therefore, correlated noise does not lead to decisive improvements in this setting!


Loss Enhanced Transport

J

J

destructive

interference

J

J

J

J

excitationlost

destructive interferencereduced


Noise Assisted Transport and Photosynthesis

More dephasing

Some dephasing

No dephasing


Dependence on Noise Strength

Inhibition of coupling

through dephasing

Reduction of destructive interference


Robustness of Noise Assisted Transport

optimal dephasing

Two differenttime scales !

no dephasing

Robustness against strong static disorder compared to coupling strengths (i.e. 20%)!


Entanglement Dynamics

F.Caruso., A.W. Chin, A. Datta, S.F. Huelga, M.B. Plenio, to be submitted


|01>-|10>

J

J

J

destructive interference

reduced destructive interference

  • Each process open additional pathways for propagation

F.C., A.W. Chin, A. Datta, S.F. Huelga, M.B. Plenio, arxiv:0901.4454 (2009)


The Fundamental Mechanisms

  • Dephasing can reduce destructive interference

  • Energy mismatch can reduce destructive interference

  • Dephasing noise increases overlap of energy levels

  • Each process open additional pathways for propagation

Plenio & Huelga, New J. Phys. 10, 113019 (2008)

Caruso, Chin, Datta, Huelga, Plenio, arxiv:0901.4454 [quant-ph]


Can we improve solar cellsbased on this idea ?

More generally: Adding the right kind of noise, to the right kind of nano-structure can improve its performance.

Engineer system to generate constructive interplay between quantum dynamics and noise


This talk was based on

Plenio & Huelga, New J. Phys. 10, 113019 (2008)

Caruso, Chin, Datta, Huelga, Plenio, E-Print arXiv:0901.4454

Caruso, Chin, Datta, Huelga, Plenio, to be submitted


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