Семинар международной лаборатории физики конденсированного состояния: Vladimir Manucharyan (University of Maryland) "Quantum electrodynamics of a superconductor-insulator transition in one dimension"

A 1D chain of Josephson junctions undergoes a BKT-type superconductor to insulator transition (SIT) driven by quantum fluctuations of the phase of the superconducting order parameter. Away from the transition a superconducting chain experiences two types of fluctuations. The first type corresponds to small vibrations of the phase and gives rise to propagating 1D plasmon waves. The second type corresponds to a slip of the phase by 2\pi. Theory predicts that phase slips induce the insulating state once the wave impedance of plasmons exceeds the value of Rq/4 ~ 2 kOhm, where Rq = 6.5 kOhm is the superconducting resistance quantum. We report microwave spectroscopy of nanofabricated 1D chains of Al/AlOx/Al tunnel junctions, containing 30,000+ junctions. Remarkably, we find that plasmons propagate along the entire chain even when the wave impedance exceeds 20kOhm, suggesting that the insulating chain behaves as superconductor to finite-frequency currents. This new experimental insight can help to clarify the nature of the insulating phase and the bosonic SIT transition. The high wave impedance of plasmons translates to an effective fine structure constant near unity which opens up a path to studying extreme regimes of light-matter coupling.

Семинар пройдет в помещении факультета физики и лаборатории по адресу:

ул.Ст. Басманная, 21/4, стр. 5, ауд. Б-312.

При необходимости заказа пропуска в НИУ ВШЭ обращайтесь к Ирине Аванесовой, iavanesova@hse.ru

Начало в 12:00.