Stishovite forms at pressures above 10 gigapascals — roughly 100,000 times atmospheric pressure — where the silicon in quartz switches from fourfold to sixfold oxygen coordination, creating one of the densest known forms of silica. Seifertite requires even higher pressures, above 120 gigapascals, found naturally only in meteorite impact sites and Earth's deep mantle. Synthesizing these phases in the laboratory traditionally requires a diamond anvil cell: two gem-quality diamonds squeezing a microscopic sample to millions of atmospheres, held at pressure long enough for the crystal structure to transform. The process is slow, the sample is tiny, and the equipment is expensive.
Noor, Yedigaryan, Calderon, and collaborators (arXiv 2602.22460, February 2026) produce stishovite, seifertite, and pyrite-type silica using a femtosecond laser pulse at ambient conditions, without a diamond anvil cell.
The mechanism has two stages. The femtosecond pulse — a flash of light lasting less than a trillionth of a second — deposits energy into the electrons of a silica-hafnia multilayer faster than the atoms can respond. The electronic excitation creates a transient pressure pulse through electronic stress: the excited electron distribution exerts forces on the lattice that compress it to gigapascal pressures. This first stage is non-thermal — the atoms haven't had time to move, but the electronic pressure is real and sufficient to initiate densification.
The second stage follows within picoseconds as the electronic energy transfers to the lattice. The atoms, now compressed into high-density configurations by the electronic pressure, experience rapid heating followed by ultrafast cooling as the energy dissipates into the surrounding material. This thermal quench freezes the high-pressure phases in place. The cooling is fast enough that the metastable structures cannot relax back to ambient-pressure quartz — they are kinetically trapped.
The result is a thin subsurface layer containing crystalline high-pressure silica polymorphs, mapped with transmission electron microscopy and confirmed by molecular dynamics simulations. The phases are the same ones found in Earth's deep interior and in hypervelocity impact sites, produced by a tabletop laser in a fraction of a nanosecond.
The approach inverts the conventional logic of high-pressure synthesis. A diamond anvil cell creates sustained equilibrium at high pressure — the sample transforms because it has time to find the thermodynamically stable phase at that pressure. The femtosecond laser creates a transient far-from-equilibrium state where pressure and temperature follow different timescales. The pressure arrives electronically, before the lattice responds. The temperature arrives later, and the cooling outruns the relaxation. The phase that forms is not the equilibrium phase at the peak conditions but the structure that the kinetics select during the quench.
Earth's core conditions — millions of atmospheres, thousands of degrees — reproduced on a desktop for a femtosecond. The flash is brief enough that the laboratory doesn't notice. The sample does.