{"id":490733,"date":"2026-01-04T02:00:16","date_gmt":"2026-01-04T02:00:16","guid":{"rendered":"https:\/\/www.europesays.com\/us\/490733\/"},"modified":"2026-01-04T02:00:16","modified_gmt":"2026-01-04T02:00:16","slug":"what-breaks-quantum-monogamy-electron-crowding-delivers-a-surprise","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/us\/490733\/","title":{"rendered":"What breaks quantum monogamy? Electron crowding delivers a surprise"},"content":{"rendered":"

Are quantum particles polygamous? New experiments suggest some of them abandon long-standing partnerships when conditions get crowded.<\/p>\n

Quantum particles do not behave like isolated dots.<\/p>\n

They interact, form bonds, and follow strict social rules. One of the most fundamental divides separates fermions and bosons.<\/p>\n

Fermions refuse to share quantum states. Bosons happily pile together.<\/p>\n

Those opposing traits underpin everything from solid matter to superconductors.<\/p>\n

But new work shows that quantum relationships can break down in unexpected ways.<\/p>\n

Researchers found that under extreme conditions, particles once thought to be strictly \u201cmonogamous\u201d can suddenly change partners.<\/p>\n

The result flips long-held assumptions about how particles move through materials.<\/p>\n

When quantum norms fail<\/p>\n

Electrons sometimes bind tightly to atoms, locking a material into an insulating state.<\/p>\n

In other cases, they roam freely and carry electric current.<\/p>\n

Under special conditions, electrons even pair with each other into Cooper pairs, enabling superconductivity.<\/p>\n

Another important pairing involves electrons and holes. <\/p>\n

A hole forms when an atom in a material loses an electron, leaving behind a mobile positive charge.<\/p>\n

When an electron and hole bind, they create an exciton. Physicists often describe excitons as monogamous because breaking them apart requires energy.<\/p>\n

Excitons behave like bosons. Individual electrons remain fermions.<\/p>\n

That contrast makes them ideal for studying how fermions and bosons interact.<\/p>\n

JQI Fellow Mohammad Hafezi and his colleagues wanted to see how changing the balance between these particles affects motion inside a material. <\/p>\n

They predicted that packing a material with fermionic electrons would block excitons and slow them down.<\/p>\n

The experiment produced the opposite result.<\/p>\n

\u201cWe thought the experiment was done wrong,\u201d says Daniel Su\u00e1rez-Forero, a former JQI postdoctoral researcher who is now an assistant professor at the University of Maryland, Baltimore County. \u201cThat was the first reaction.\u201d<\/p>\n

The team built a carefully aligned layered material. Its structure forced electrons and excitons into a tidy grid of allowed positions. Electrons refused to share those sites. Excitons could hop between them.<\/p>\n

At low electron densities, excitons behaved normally. <\/p>\n

As more electrons entered the system, exciton motion slowed. Their paths became indirect as they navigated around occupied sites.<\/p>\n

Then the system crossed a threshold.<\/p>\n

When nearly every site filled with an electron<\/a>, exciton mobility jumped sharply. Instead of freezing, excitons suddenly traveled farther than before.<\/p>\n

\u201cNo one wanted to believe it,\u201d says Pranshoo Upadhyay, a JQI graduate student and lead author of the paper.<\/p>\n

\u2018It\u2019s like, can you repeat it? And for about a month, we performed measurements on different locations of the sample with different excitation powers and replicated it in several other samples.\u201d<\/p>\n

The team repeated the experiment across samples, setups, and even continents. The effect persisted.<\/p>\n

\u201cWe repeated the experiment in a different sample, in a different setup, and even in a different continent, and the result was exactly the same,\u201d Su\u00e1rez-Forero says.<\/p>\n

Beyond exciton monogamy<\/p>\n

Theory eventually caught up with experiment.<\/p>\n

The researchers realized that excitons did not sit in the same way as free electrons and holes.<\/p>\n

\u201cAt least this was what we thought,\u201d said Tsung-Sheng Huang, a former JQI graduate student of the group who is now a postdoctoral researcher at the Institute of Photonic Sciences in Spain.<\/p>\n

\"\"<\/a>Layered material shows electrons and excitons moving through a quantum landscape. Credit \u2013 Mahmoud Jalali Mehrabad\/JQI<\/p>\n

\u201cAny external fermion should not see the constituents of the exciton separately; but in reality, the story is a little bit different.\u201d<\/p>\n

At very high electron densities, holes inside excitons<\/a> began treating all nearby electrons as equivalent. The exclusive bond broke down.<\/p>\n

Holes effectively switched partners repeatedly, a process the team calls non-monogamous hole diffusion.<\/p>\n

That rapid partner-switching allowed excitons to move straight through the crowded system. <\/p>\n

Instead of weaving around obstacles, they traveled efficiently before recombining and emitting light.<\/p>\n

The researchers triggered the effect simply by adjusting the voltage<\/a>.<\/p>\n

That control makes the phenomenon attractive for future electronic and optical devices, including exciton-based solar technologies.<\/p>\n

The study is published in the journal Science<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"Are quantum particles polygamous? New experiments suggest some of them abandon long-standing partnerships when conditions get crowded. Quantum…\n","protected":false},"author":3,"featured_media":490734,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[25],"tags":[221281,221282,108528,221283,221284,492,59175,836,159,97305,67,132,68],"class_list":{"0":"post-490733","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physics","8":"tag-bosons","9":"tag-electron-hole-pairs","10":"tag-excitons","11":"tag-fermions","12":"tag-particle-interactions","13":"tag-physics","14":"tag-quantum-materials","15":"tag-quantum-physics","16":"tag-science","17":"tag-superconductivity","18":"tag-united-states","19":"tag-unitedstates","20":"tag-us"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@us\/115834363988122706","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/490733","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/comments?post=490733"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/490733\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media\/490734"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media?parent=490733"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/categories?post=490733"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/tags?post=490733"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}