Coherent and incoherent tunneling into YSR states revealed by atomic scale shot-noise spectroscopy

Abstract

The pair breaking potential of individual magnetic impurities in s-wave superconductors generates localized states inside the superconducting gap commonly referred to as Yu- Shiba-Rusinov (YSR) states whose isolated nature makes them ideal building blocks for artificial structures that may host Majorana fermions. One of the challenges in this endeavor is to understand their intrinsic lifetime, $\hslash /\Lambda$, which is expected to be limited by the inelastic coupling with the continuum thus leading to decoherence. Here we use shot-noise scanning tunneling microscopy to reveal that electron tunnelling into superconducting 2H-NbSe${}_2$ mediated by YSR states is ordered as function of time, as evidenced by a reduction of the noise. Moreover, our data show the concomitant transfer of charges e and 2e, indicating that incoherent single particle and coherent Andreev processes operate simultaneously. From the quantitative agreement between experiment and theory we obtain $\Lambda$ = 1 $\mu$eV $\ll$ $k_{B}T$ demonstrating that shot-noise can probe energy- and time scales inaccessible by conventional spectroscopy whose resolution is thermally limited.

arXiv comment6 pages, 4 figures, Supplementary Information included as ancillary file

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Cited by in corpus (17)

• Single-electron charge transfer into putative Majorana and trivial modes in individual vortices
• Differential current noise as an identifier of Andreev bound states that induce nearly quantized conductance plateaus
• Full Counting Statistics of Yu-Shiba-Rusinov Bound States
• Shot-noise measurements of single-atom junctions
• Nonequilibrium Fractional Josephson Effect
• Microwave Excitation of Atomic Scale Superconducting Bound States
• Andreev spin-noise detector
• Tunneling spectra of impurity states in unconventional superconductors
• Importance Sampling for counting statistics in one-dimensional systems
• Probing the dichotomy between Yu-Shiba-Rusinov and Majorana bound states via conductance, quantum noise and ${\Delta }_T$ noise
• Anisotropy of Yu-Shiba-Rusinov states in NbSe${}_2$
• $\Delta T$-noise in Multiterminal Hybrid Systems
• Effects of electron-electron interactions in the Yu-Shiba-Rusinov lattice model
• Underscreened Kondo Compensation in a Superconductor
• Thermodynamic and energetic constraints on transition probabilities of small-scale quantum systems
• Evidence for atomic-scale vibron-mediated electron bunching
• Non-Topological Edge-Localized Yu-Shiba-Rusinov States in CrBr${}_3$/NbSe${}_2$ Heterostructures