Phase-dependent Andreev molecules and superconducting gap closing in coherently-coupled Josephson junctions

Abstract

The Josephson junction (JJ) is an essential element of superconducting (SC) devices for both fundamental and applied physics. The short-range coherent coupling of two adjacent JJs forms Andreev molecule states (AMSs), which provide a new ingredient to engineer exotic SC phenomena such as topological SC states and Andreev qubits. Here we provide tunneling spectroscopy measurements on a device consisting of two electrically controllable planar JJs sharing a single SC electrode. We discover that Andreev spectra in the coupled JJ are highly modulated from those in the single JJs and possess phase-dependent AMS features reproduced in our numerical calculation. Notably, the SC gap closing due to the AMS formation is experimentally observed. Our results help in understanding SC transport derived from the AMS and promoting the use of AMS physics to engineer topological SC states and quantum information devices.

Nonadiabatic molecular dynamics with subsystem density functional theory: application to crystalline pentacene

“…Quantum processes play a critical role in many natural systems such as light-harvesting and photosynthetic complexes [1][2][3][4], biological vision [5,6] and light sensing [7][8][9][10] systems as well as in artificial photocatalytic [11][12][13][14] and photovoltaic [15][16][17] materials, materials for quantum sensing applications [18][19][20], or qubits [21][22][23], to name a few. Quantum coherence facilitates efficient and directional excitation energy transfer in the light-harvesting complexes [24][25][26], coupled electron-proton transfer [27][28][29], quantum tunneling [30][31][32], is critical to biological systems [33], and nonradiative energy relaxation, which realizes mechanisms of protection from the photodamage [34][35][36][37][38].…”