Unexpected physics breakthrough could lead to a new generation of supercomputers

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

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.

The work, carried out with collaborators at MIT and Japan’s National Institute for Materials Science, suggests a path toward computers that sip rather than guzzle power.

Graphene continues to surprise

Graphene is a single‑atom sheet of carbon arranged in a honeycomb, a lattice so flat and stiff that quantum behavior shows up at macroscopic scales.

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

A decade of experiments has shown that squeezing or twisting graphene can spawn superconductivity, magnetism, or insulating gaps on command.

The new study turns the spotlight on the quantum anomalous Hall effect, where current races along the edge without resistance, even when no external magnet is present.

Electron behavior in graphene

The surprise is that Lu’s device also enters a fractional version of that state, something theorists once thought impossible outside colossal magnetic fields.

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

This strange behavior means the electrons were strongly influencing each other instead of acting independently.

Such fractions mirror the older fractional quantum Hall effect discovered in gallium arsenide in 1982, yet the carbon system needs neither magnetic coils nor expensive semiconducting wafers.

Instead, it relies on the natural stacking order of rhombohedral graphite, a symmetry that keeps the electronic bands almost perfectly flat.

Edge currents to charged carriers

MIT researchers first reported fractionalization in pentalayer graphene in 2024, calling the observation “so exotic” and praising its simplicity, noted Long Ju, one of the study authors.

Lu’s 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.

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. 

“If 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,” said Lu.

Electron ice allows control

The coexistence matters because it offers a built‑in laboratory for swapping between liquid‑like and solid‑like behaviors without altering the crystal.

By nudging the displacement field, engineers can melt the electron ice into a conductive stream or refreeze it, a level of control long sought by condensed‑matter physicists.

Even the crystalline phase, dubbed “extended quantum anomalous Hall,” 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.

Twistronics in graphene

The magic ingredient is the moiré pattern formed when graphene meets hexagonal boron nitride at a slight rotational mismatch.

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.

This strategy has revolutionized two‑dimensional materials by letting experimenters “dial in” electronic phases with a protractor.

In Lu’s architecture the twist is small enough that the pattern repeats every few nanometers, carving the flat bands needed for fractionalization.

Because the moiré 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.

Scaling that pattern to wafer size, however, demands atomic‑level alignment tools that industry is only beginning to deploy.

Fault‑tolerant quantum computing

Quantum computers are limited today by errors that creep in every microsecond.

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.

Fractional quantum anomalous Hall states already satisfy key topological criteria, supporting anyon‑like quasiparticles whose braiding implements logic gates.

If paired with superconductivity, those anyons could become non‑Abelian, meaning exchanging two of them alters the quantum state permanently, which is the basis of fault‑tolerant operations.

Graphene stack with zero field edges

Lu’s zero‑field platform removes a longstanding roadblock: superconductors collapse under magnetic fields, so earlier schemes required unwieldy shielding.

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

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.

Teams are experimenting with substrate engineering and high‑κ dielectrics to lift the critical temperature into the range of pumped helium.

Another task is reproducibility, because fractional plateaus appear only when the moiré pattern is nearly perfect, so fabricators are refining dry‑transfer methods that leave fewer wrinkles and contamination pockets.

Progress in twisted bilayer photonics suggests that sub‑degree alignment across inches is feasible with robotically controlled rotation stages.

Graphene and future supercomputers

Theorists aim to pin down why electron ice coexists with fractional rivers, weighing explanations involving Wigner crystals, composite fermions, or Chern band instabilities.

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

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.

The study is published in Nature.

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