- A team of University of Chicago scientists found links at the atomic level between photosynthesis and exciton condensates.
- The condensate allows energy to flow frictionlessly through a material.
- Researchers suggest the findings may one day offer new ways to design electronics.
PRESS RELEASE — Inside a lab, scientists marvel at a strange state that forms when they cool down atoms to nearly absolute zero. Outside their window, trees gather sunlight and turn them into new leaves. The two seem unrelated—but a new study from the University of Chicago suggests that these processes aren’t so different as they might appear on the surface.
The study, published in PRX Energy on April 28, found links at the atomic level between photosynthesis and exciton condensates—a strange state of physics that allows energy to flow frictionlessly through a material. The finding is scientifically intriguing and may suggest new ways to think about designing electronics, the authors said.
“As far as we know, these areas have never been connected before, so we found this very compelling and exciting,” said study co-author Prof. David Mazziotti.
Mazziotti’s lab specializes in modelling the complicated interactions of atoms and molecules as they display interesting properties. There’s no way to see these interactions with the naked eye, so computer modeling can give scientists a window into why the behavior happens—and can also provide a foundation for designing future technology.
In particular, Mazziotti and study co-authors Anna Schouten and LeeAnn Sager-Smith have been modelling what happens at the molecular level when photosynthesis occurs.
When a photon from the sun strikes a leaf, it sparks a change in a specially designed molecule. The energy knocks loose an electron. The electron, and the “hole” where it once was, can now travel around the leaf, carrying the energy of the sun to another area where it triggers a chemical reaction to make sugars for the plant.
Together, that traveling electron-and-hole-pair is referred to as an “exciton.” When the team took a birds-eye view and modeled how multiple excitons move around, they noticed something odd. They saw patterns in the paths of the excitons that looked remarkably familiar.
In fact, it looked very much like the behavior in a material that is known as a Bose-Einstein condensate, sometimes known as ‘the fifth state of matter.’ In this material, excitons can link up into the same quantum state—kind of like a set of bells all ringing perfectly in tune. This allows energy to move around the material with zero friction. (These sorts of strange behaviors intrigue scientists because they can be the seeds for remarkable technology—for example, a similar state called superconductivity is the basis for MRI machines).
According to the models created by Schouten, Sager-Smith and Mazziotti, the excitons in a leaf can sometimes link up in ways similar to exciton condensate behavior.
This was a huge surprise. Exciton condensates have only been seen when the material is cooled down significantly below room temperature. It’d be kind of like seeing ice cubes forming in a cup of hot coffee.
“Photosynthetic light harvesting is taking place in a system that is at room temperature and what’s more, its structure is disordered—very unlike the pristine crystallized materials and cold temperatures that you use to make exciton condensates,” explained Schouten.
This effect isn’t total—it’s more akin to “islands” of condensates forming, the scientists said. “But that’s still enough to enhance energy transfer in the system,” said Sager-Smith. In fact, their models suggest it can as much as double the efficiency.
This opens up some new possibilities for generating synthetic materials for future technology, Mazziotti said. “A perfect ideal exciton condensate is sensitive and requires a lot of special conditions, but for realistic applications, it’s exciting to see something that boosts efficiency but can happen in ambient conditions.”
Mazziotti said the finding also plays into a broader approach his team has been exploring for a decade.
The interactions between atoms and molecules in processes like photosynthesis are incredibly complex—difficult even for a supercomputer to handle—so scientists have traditionally had to simplify their models in order to get a handle on them. But Mazziotti thinks some parts need to be left in: “We think local correlation of electrons are essential to capturing how nature actually works.”
The study was partially supported by the National Science Foundation’s QuBBE Quantum Leap Challenge Institute.
Citation: “Exciton-Condensate-Like Amplification of Energy Transport in Light Harvesting.” Schouten, Sager-Smith, and Mazziotti, PRX Energy, April 28, 2023. .
Funding: U.S. National Science Foundation, U.S. Department of Energy.
Chuo Kikuu cha Chicago cha Marekani kimegundua uhusiano kati ya photosynthesis na condensates ya excitons. - Kondensati inaruhusu nishati kutiririka bila msuguano kupitia nyenzo. - Watafiti wanadokeza kwamba siku moja matokeo hayo yanaweza kutoa njia mpya za kubuni vifaa vya elektroniki. HARBORO: Katika maabara, wanasayansi wanashangazwa na hali ya ajabu inayotokezwa wanapopunguza joto la atomu hadi karibu na kiwango cha sifuri kabisa. Nje ya madirisha yao, miti hukusanya nuru ya jua na kuigeuza kuwa majani mapya. Hizi mbili zinaonekana kuwa hazihusiani - lakini utafiti mpya kutoka Chuo Kikuu cha Chicago unaonyesha kwamba michakato hii si tofauti sana kama inavyoweza kuonekana juu ya uso. Utafiti huo, uliochapishwa katika PRX Energy Aprili 28, uligundua uhusiano katika kiwango cha atomu kati ya photosynthesis na condensates ya excitons - hali ya ajabu ya fizikia ambayo inaruhusu nishati kutiririka bila msuguano kupitia nyenzo. Ugunduzi huo ni wa kuvutia kisayansi na unaweza kupendekeza njia mpya za kufikiri kuhusu kubuni vifaa vya elektroniki, waandishi walisema. "Kama tunavyojua, maeneo haya hayajawahi kuunganishwa hapo awali, kwa hivyo tulipata hii ya kuvutia sana na ya kuvutia", alisema mwandishi mwenza wa utafiti Profesa David Mazziotti. Maabara ya Mazziotti ni maalumu katika kuiga mwingiliano tata wa atomu na molekuli wakati zinaonyesha mali za kuvutia. Hakuna njia ya kuona maingiliano haya kwa jicho la kawaida, kwa hivyo muundo wa kompyuta unaweza kuwapa wanasayansi dirisha la kwa nini tabia hiyo hutokea na pia inaweza kutoa msingi wa kubuni teknolojia ya baadaye. Mazziotti na Anna Schouten na Lee Ann Sager-Smith, waandishi wa utafiti huo, wamekuwa wakifanya mfano wa kile kinachotokea katika kiwango cha molekuli wakati photosynthesis inapoanza. Picha ya jua inapopiga jani, huchochea mabadiliko katika molekuli iliyoundwa kwa njia ya pekee. Nishati hiyo huondoa elektroni. "Electron, na ""shimo"" ambapo ilikuwa wakati mmoja, sasa inaweza kusafiri kuzunguka jani, kubeba nishati ya jua kwa eneo jingine ambapo huchochea athari ya kemikali ya kufanya sukari kwa ajili ya mmea." Pamoja, kwamba kusafiri elektron-na-shimo-jozi ni inajulikana kama <unk>exciton.<unk> Wakati timu alichukua ndege-macho mtazamo na modeled jinsi excitons nyingi kusonga karibu, waligundua kitu ajabu. Waliona mifumo katika njia za excitons ambayo ilionekana ya kawaida sana. "Hiyo ni kwa sababu ya jinsi ya kuonekana kwa ""Bose-Einstein condensate"" - hali ya tano ya dutu - ambayo inaonyesha jinsi excitons zinavyoweza kuunganishwa katika hali moja ya quantum, na hivyo kuunda mfumo wa kuunganisha." Hilo huruhusu nishati kusonga kuzunguka nyenzo hiyo bila msuguano wowote. (Hizi aina ya tabia ya ajabu intrigue wanasayansi kwa sababu wanaweza kuwa mbegu kwa ajili ya teknolojia ya ajabu - kwa mfano, hali sawa aitwaye superconductivity ni msingi wa mashine MRI). Kulingana na mifano iliyoundwa na Schouten, Sager-Smith na Mazziotti, excitons katika jani wakati mwingine inaweza kuunganisha kwa njia sawa na tabia ya condensate ya exciton. Jambo hilo lilinishangaza sana. Exciton condensates wameonekana tu wakati nyenzo ni baridi chini kwa kiasi kikubwa chini ya joto la chumba. Ingekuwa kama kuona vipande vya barafu vikijitokeza katika kikombe cha kahawa moto. "Uchimbaji wa mwanga wa photosynthetic unafanyika katika mfumo ambao uko katika joto la chumba na nini zaidi, muundo wake haujasababishwa - tofauti sana na vifaa vya kioo vya asili na joto la baridi unayotumia kutengeneza condensates za exciton, "Schouten alielezea. Athari hii si kamili - ni zaidi kama "visiwa" vya condensates kuunda, wanasayansi alisema. "Lakini hiyo bado inatosha kuongeza uhamisho wa nishati katika mfumo", alisema Sager-Smith. Kwa kweli, mifano yao inadokeza kwamba inaweza hata maradufu ya ufanisi. Hii inafungua baadhi ya uwezekano mpya kwa ajili ya kuzalisha vifaa synthetic kwa ajili ya teknolojia ya baadaye, Mazziotti alisema. "Kufikia kiwango cha juu cha exciton, inahitaji hali maalum, lakini kwa matumizi halisi, ni ya kuvutia kuona kitu kinachoongeza ufanisi lakini kinaweza kutokea katika hali ya mazingira. ""Mazziotti alisema matokeo pia yanacheza katika mbinu pana ambayo timu yake imekuwa ikichunguza kwa miaka kumi." Maingiliano kati ya atomu na molekuli katika michakato kama vile photosynthesis ni ngumu sana - ngumu hata kwa supercomputer kushughulikia - hivyo wanasayansi wamekuwa kwa kawaida kurahisisha mifano yao ili kupata kushughulikia yao. "Mazziotti anasema: ""Tunafikiri kwamba uhusiano wa ndani wa elektroni ni muhimu kwa kukamata jinsi asili inafanya kazi,"" na ""Utafiti huo uliungwa mkono kwa sehemu na Taasisi ya Changamoto ya Quantum Leap ya Quantum Leap ya Shirika la Sayansi la Kitaifa." "Kutoka kwa ""Exciton-Condensate-Like Amplification of Energy Transport in Light Harvesting"" na ""Schouten, Sager-Smith, na Mazziotti,"" PRX Energy, Aprili 28, 2023." Ufadhili: Shirika la Sayansi la Kitaifa la Marekani, Idara ya Nishati ya Marekani.