Current news

New publication in Phys. Rev. X and Highlight in this weeks Physics Magazine: Frequency comb from a single driven nonlinear nanomechanical mode

Phononic frequency combs have attracted increasing attention both as a qualitatively new type of nonlinear phenomena in vibrational systems and from the point of view of applications. It is commonly believed that at least two modes must be involved in generating a comb. We demonstrate that a comb can be generated by a single nanomechanical mode driven by a resonant monochromatic drive. The comb emerges where the drive is still weak, so the anharmonic part of the mode potential energy remains…

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New Publication: Signature of resonant modes in radiative heat current noise spectrum

Radiative heat transfer between bodies is often dominated by a narrow resonance in the transmission, e.g., due to a cavity mode or a surface excitation. However, this resonant character is not visible in the average heat current. Here, we show that the noise spectrum of heat current can serve as a direct probe of the heat-carrying excitations. Namely, the resonant mode produces a sharp peak in the noise spectrum with a width related to the mode lifetime. We demonstrate that heat transfer in…

Non-reciprocity of vortex-limited critical current in conventional superconducting micro-bridges

Non-reciprocity in the critical current has been observed in a variety of superconducting systems and has been called the superconducting diode effect. The origin underlying the effect depends on the symmetry breaking mechanisms at play. We investigate superconducting micro-bridges of NbN and also NbN/magnetic insulator (MI) hybrids. We observe a large diode efficiency of ~30% when an out-of-plane magnetic field as small as 25 mT is applied. In both NbN and NbN/MI hybrid, we find that the diode…

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