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What role does Quantum
Mechanics play in Biology?
K. Birgitta Whaley, UC Berkeley
Exploring	
  the	
  Quantum	
  in	
  Biology	
  	
  	
  
plants,	
  bacteria:	
  
photosynthesis	
  
bird	
  naviga5on	
  ...
Quantum vs Classical ?
W.	
  H.	
  Zurek,	
  Physics	
  Today,	
  Oct.	
  1991	
  
• QM should apply to biology (life)
Bohr, Jordan,… 1929 onwards
•  1935
probed genetic structure and
mutations with X-rays...
Developing tools for
studying biological
structure and
function at
unprecedented
spatial and temporal
resolution
Can quant...
• First Era: 1930 ‒ 1950s (b.L.)
molecular structure and pathways,
energetics, kinetics, stability ‒ quantum
nature of mol...
•  Microscopic probes of living cells,
cellular response, biochemical &
electrical monitoring, biomolecule
delivery…
•  Ul...
Photosynthesis	
  
The	
  “light”	
  reac5ons	
  are	
  rapid	
  and	
  
efficient,	
  >95%	
  conversion	
  of	
  photons	
...
Photosystem	
  II	
  is	
  the	
  most	
  sophis6cated	
  nano	
  machine	
  on	
  earth	
  
Pablo Picasso – House and Tre...
Photosynthe5c	
  membrane	
  of	
  purple	
  bacteria	
  
Energy	
  travels	
  over	
  15-­‐30	
  nm	
  paths	
  in	
  1	
...
Does excitation hop or travel like a wave?
What	
  is	
  coherence?	
  
Incoherent	
  waves	
  
All	
  together	
  now!	
  	
  
Pedalling	
  in	
  step	
  
Coherent	...
Coherent	
  addi5on	
  of	
  waves	
  of	
  
different	
  frequencies	
  gives	
  beats	
  	
  
interference	
  phenomenon	...
τ T
Emission
Frequency
Excitation Frequency
Fourier Transform
with Respect to τ
2D Electronic Correlation Spectrum
A 2D sp...
FMO (green sulfur bacteria): 2D fsec spectra
Measured
Points:
0, 10, 20, 30,
40, 50, 65, 80,
95, 110, 125,
140, 155, 170,
...
Electronic	
  entanglement	
  	
  
| ⇥ |g⇥1|e⇥2 + |e⇥1|g⇥2
Site	
  1	
   Site	
  2	
  
Non-­‐local	
  quantum	
  correla5o...
17
Entanglement analog with ambiguous cube:
perceive orientational correlations between boxes
All coherence
experiments to date show
quantum beating in a
single complex –
Is quantum coherence relevant to long
range e...
Photosynthesis: what next?
•  fundamental understanding of quantum effects in
efficient energy conversion for life, role i...
Elysia chlorotica
captures chloroplasts from algae and store these in body, never need to
eat again (for 9-11 months of li...
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Birgitta Whaley (Berkeley Quantum Computation) at a LASER http://www.scaruffi.com/leonardo/feb2015b.html

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Birgitta Whaley (Berkeley Quantum Computation) at a LASER http://www.scaruffi.com/leonardo/feb2015b.html

  1. 1. What role does Quantum Mechanics play in Biology? K. Birgitta Whaley, UC Berkeley
  2. 2. Exploring  the  Quantum  in  Biology       plants,  bacteria:   photosynthesis   bird  naviga5on   animal  smell     ion  channels   brain…  
  3. 3. Quantum vs Classical ? W.  H.  Zurek,  Physics  Today,  Oct.  1991  
  4. 4. • QM should apply to biology (life) Bohr, Jordan,… 1929 onwards •  1935 probed genetic structure and mutations with X-rays Quantum Biology has long roots: first quantum probe of biological structures and function, acknowledgement of need to understand detailed molecular structure of functional biological entities N. Timofeev-Resovsky (genetics) K. Zimmer (photobiology) M. Delbrück (quantum physics)
  5. 5. Developing tools for studying biological structure and function at unprecedented spatial and temporal resolution Can quantum coherence be relevant for biological function? Biological  func5on  across  all  5me  and     size  scales   A.  Vaziri B.  HHMI/U. Vienna
  6. 6. • First Era: 1930 ‒ 1950s (b.L.) molecular structure and pathways, energetics, kinetics, stability ‒ quantum nature of molecular energy levels, energy barriers... (Schrödinger What is Life? 1943) • Second Era:1960s onward (a.L.) Quantum dynamical effects ‒ new generations of dynamical probes, new tools and innovation via quantum science and technology... DNA 1953
  7. 7. •  Microscopic probes of living cells, cellular response, biochemical & electrical monitoring, biomolecule delivery… •  Ultrafast spectroscopy, e.g., for quantum dynamics of electronic energy transfer in photosynthesis Quantum Biology: tools of quantum science and nanotechnology give new probes of structure and dynamics of biological systems NV centers: R. Walsworth, J. Wrachtrup, M. Lukin, H. Park, A. Jacoby.... Si nanorods offer cellular access: H. Park G. Fleming, G. Scholes, G. Engel, R. van Grondelle, N. van Hulst....
  8. 8. Photosynthesis   The  “light”  reac5ons  are  rapid  and   efficient,  >95%  conversion  of  photons   …Secondary  electron  transfer  reac5ons,    Water   spliMng,  Proton  transport  across  thylakoid  membrane,   Reduc5on  of  NADP+,  ATP  synthesis…     Charge  separa5on  Reac6on Center   Blue-­‐absorbing  pigments   Red-­‐absorbing     pigments   Orange-­‐absorbing     pigments   “Antenna”   Light-­‐harves5ng           bacteria   green     plants  
  9. 9. Photosystem  II  is  the  most  sophis6cated  nano  machine  on  earth   Pablo Picasso – House and Trees Paris, Winter 1908 140g  of  chlorophyll  per  tree   Reac5on     Center   Light     Harvester   How  many  chlorophylls  are  there  in  Picasso’s  Tree?   500  mg  of  primary  electron  donor  chlorophylls  
  10. 10. Photosynthe5c  membrane  of  purple  bacteria   Energy  travels  over  15-­‐30  nm  paths  in  1  ns     excita5on  energy  is   spread  out  over  rough   energy  landscape   Quantum  effects  in  photosynthesis   5  nm   Light  Harvester   Reac5on  Center   light  harves5ng  has  near  perfect  efficiency    experiments  reveal  wave-­‐like      ‘quantum  coherent’  energy  transfer     Absorp5on   Energy     Conversion   -­‐   +   Energy     Storage   ATP   NADPH   Sucrose   •  quantum  coherence  contributes  ~10%  to  efficiency   •  natural  systems  are  op5mal  with  respect  to  all   parameters,  no  ar5ficial  system  is  compete5ve   •  coherence  enables  robust  uphill  and  long  range   transport  
  11. 11. Does excitation hop or travel like a wave?
  12. 12. What  is  coherence?   Incoherent  waves   All  together  now!     Pedalling  in  step   Coherent  waves   Rela%ve  phases  are  stable  in  %me,  space  
  13. 13. Coherent  addi5on  of  waves  of   different  frequencies  gives  beats     interference  phenomenon  
  14. 14. τ T Emission Frequency Excitation Frequency Fourier Transform with Respect to τ 2D Electronic Correlation Spectrum A 2D spectrum is a correlation map between the initial and final excitations and coherences The correlation depends on the processes occurring during time T Spectrally resolved, heterodyne detected photon echo
  15. 15. FMO (green sulfur bacteria): 2D fsec spectra Measured Points: 0, 10, 20, 30, 40, 50, 65, 80, 95, 110, 125, 140, 155, 170, 185, 200, 220, 240, 260, 280, 300, 330, 360, 390, 420, 450, 480, 510, 540, 570, 600, 630, 660fs Fleming et al. 2007
  16. 16. Electronic  entanglement     | ⇥ |g⇥1|e⇥2 + |e⇥1|g⇥2 Site  1   Site  2   Non-­‐local  quantum  correla5ons  between  molecular   electronic  states   Schrödinger  1935:  entanglement  (Verschränkung)  is     “the  characteris6c  trait  of  quantum  mechanics”  
  17. 17. 17 Entanglement analog with ambiguous cube: perceive orientational correlations between boxes
  18. 18. All coherence experiments to date show quantum beating in a single complex – Is quantum coherence relevant to long range energy transfer? Photosystem II super-complex, courtesy of Roberta Croce •  Is coherence transmitted between complexes? •  If so, why? How might it help photosynthetic function? Hoyer et al. PRE (2012) •  coherence is transmitted •  enables unidirectional transport •  enables uphill transport
  19. 19. Photosynthesis: what next? •  fundamental understanding of quantum effects in efficient energy conversion for life, role in biology •  reengineer photosynthesis - design of artificial devices for effective ‘quantum’ conversion of sunlight into chemical energy without competing biological constraints •  lessons for design of robust and sensitive quantum devices an “evolved” natural quantum processor? design rules for robust quantum devices and efficient transduction of solar energy?
  20. 20. Elysia chlorotica captures chloroplasts from algae and store these in body, never need to eat again (for 9-11 months of life)…. Green sea slug

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