{"id":14043,"date":"2025-07-21T23:27:11","date_gmt":"2025-07-21T23:27:11","guid":{"rendered":"https:\/\/www.newsbeep.com\/ca\/14043\/"},"modified":"2025-07-21T23:27:11","modified_gmt":"2025-07-21T23:27:11","slug":"unexpected-behavior-of-graphene-could-power-supercomputers","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ca\/14043\/","title":{"rendered":"Unexpected behavior of graphene could power supercomputers"},"content":{"rendered":"

Five layers of carbon can still surprise physics. When researchers cooled a precisely stacked film of graphene to near absolute zero, they watched electrons<\/a> glide around its perimeter as if they carried only fragments of their usual charge.<\/p>\n

That curious flow sits at the heart of a fresh report from Assistant Professor Zhengguang Lu of Florida State University, whose team found previously unseen electronic phases that ignore energy loss and laugh at stray magnetic fields. <\/p>\n


\n \"EarthSnap\"\/
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The work, carried out with collaborators at MIT<\/a> and Japan\u2019s National Institute for Materials Science<\/a>, suggests a path toward computers that sip rather than guzzle power.<\/p>\n

Graphene continues to surprise<\/p>\n

Graphene is a single\u2011atom sheet of carbon arranged in a honeycomb, a lattice so flat and stiff that quantum behavior shows up at macroscopic scales. <\/p>\n

Because electrons cannot hop out of the plane, their wave functions spread sideways, amplifying subtle interactions that are washed out in bulk materials.<\/p>\n

A decade of experiments has shown that squeezing or twisting graphene can spawn superconductivity, magnetism, or insulating gaps on command. <\/p>\n

The new study turns the spotlight on the quantum anomalous Hall effect<\/a>, where current races along the edge without resistance, even when no external magnet is present.<\/p>\n

Electron behavior in graphene<\/p>\n

The surprise is that Lu\u2019s device also enters a fractional version of that state, something theorists once thought impossible outside colossal magnetic fields. <\/p>\n

Electricity flowed in unusual ways, with measurements showing that sometimes five electrons acted as if they shared nine or 11 units of charge. <\/p>\n

This strange behavior means the electrons were strongly influencing each other instead of acting independently.<\/p>\n

Such fractions mirror the older fractional quantum<\/a> Hall effect discovered in gallium arsenide in 1982, yet the carbon system needs neither magnetic coils nor expensive semiconducting wafers. <\/p>\n

Instead, it relies on the natural stacking order of rhombohedral graphite, a symmetry that keeps the electronic bands almost perfectly flat.<\/p>\n

Edge currents to charged carriers<\/p>\n

MIT researchers first reported<\/a> fractionalization in pentalayer graphene in 2024, calling the observation \u201cso exotic\u201d and praising its simplicity, noted Long Ju, one of the study authors. <\/p>\n

Lu\u2019s group has now shown that the exotic state sits right next to an electron crystal in the same device, separated only by a narrow range of gate voltage.<\/p>\n

Picture a river of fractional charges meandering between frozen banks of integer charges; that is the coexistence Lu detects through vanishing longitudinal resistance and sharp plateaus in the Hall signal.\u00a0<\/p>\n

\u201cIf the fractional quantum anomalous Hall effect is combined with a superconductor, the resulting quantum computer will be more efficient than current quantum computers and free of error,\u201d said\u202fLu.<\/p>\n

Electron ice allows control<\/p>\n

The coexistence matters because it offers a built\u2011in laboratory for swapping between liquid\u2011like and solid\u2011like behaviors without altering the crystal. <\/p>\n

By nudging the displacement field, engineers can melt the electron<\/a> ice into a conductive stream or refreeze it, a level of control long sought by condensed\u2011matter physicists.<\/p>\n

Even the crystalline phase, dubbed \u201cextended quantum<\/a> anomalous Hall,\u201d shows zero resistance across a broad density window, hinting at hidden orders that theory is only starting to chart. Turning that window into a switch could enable lossless interconnects inside future chips.<\/p>\n

Twistronics in graphene<\/p>\n

The magic ingredient is the moir\u00e9 pattern<\/a> formed when graphene meets hexagonal boron nitride at a slight rotational mismatch. <\/p>\n

That nanoscale beat note reshapes the electronic landscape and slows carriers until their mutual repulsion dominates, a strategy broadly known as twistronics, where changing the twist angle controls conductivity like a dial.<\/p>\n

This strategy has revolutionized two\u2011dimensional materials by letting experimenters \u201cdial in\u201d electronic phases with a protractor. <\/p>\n

In Lu\u2019s architecture the twist is small enough that the pattern repeats every few nanometers, carving the flat bands needed for fractionalization.<\/p>\n

Because the moir\u00e9 potential is robust against bending or stretching, devices can be integrated onto flexible substrates, opening possibilities for curved sensors or cryogenic wiring that cannot tolerate magnetic fields. <\/p>\n

Scaling that pattern to wafer size, however, demands atomic\u2011level alignment tools that industry is only beginning to deploy.<\/p>\n

Fault\u2011tolerant quantum computing<\/p>\n

Quantum computers<\/a> are limited today by errors that creep in every microsecond. <\/p>\n

One proposed remedy is the topological qubit, which stores information in collective excitations that are immune to local noise. Technology firms hope that this concept will slash overhead for error correction.<\/p>\n

Fractional quantum anomalous Hall states already satisfy key topological criteria, supporting anyon\u2011like quasiparticles<\/a> whose braiding implements logic gates.<\/p>\n

If paired with superconductivity, those anyons could become non\u2011Abelian, meaning exchanging two of them alters the quantum<\/a> state permanently, which is the basis of fault\u2011tolerant operations.<\/p>\n

Graphene stack with zero field edges<\/p>\n

Lu\u2019s zero\u2011field platform removes a longstanding roadblock: superconductors collapse under magnetic fields, so earlier schemes required unwieldy shielding. <\/p>\n

A graphene stack that hosts both superconductivity and fractional edges at zero field would let engineers pattern Josephson junctions<\/a> directly on top, bringing the hardware footprint closer to classical chips.<\/p>\n

The immediate challenge is temperature. Present devices operate below 40 millikelvin, reachable only with dilution refrigerators that cost millions of dollars and fit in a room. <\/p>\n

Teams are experimenting with substrate engineering and high\u2011\u03ba dielectrics<\/a> to lift the critical temperature into the range of pumped helium. <\/p>\n

Another task is reproducibility, because fractional plateaus appear only when the moir\u00e9 pattern is nearly perfect, so fabricators are refining dry\u2011transfer methods that leave fewer wrinkles and contamination pockets.<\/p>\n

Progress in twisted bilayer photonics suggests that sub\u2011degree alignment across inches is feasible with robotically controlled rotation stages. <\/p>\n

Graphene and future supercomputers<\/p>\n

Theorists aim to pin down why electron ice coexists with fractional rivers, weighing explanations involving Wigner crystals<\/a>, composite fermions, or Chern band instabilities.<\/p>\n

Systematic deformation studies, possibly inside diamond anvil cells, could settle the debate and guide engineers to the most stable phase for qubit wiring. <\/p>\n

No single breakthrough will turn these films into laptops overnight, yet history shows how quickly materials science can leap, once a knob for tuning interactions appears.<\/p>\n

The study is published in Nature<\/a>.<\/p>\n

\u2014\u2013<\/p>\n

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Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n

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