We have investigated the effects of quantum fluctuations of quasiparticles on the operation of superconducting radio-frequency single-electron transistors (rf-SETs) for large values of the quasiparticle cotunneling parameter alpha = 8EJ/Ec, where EJ and Ec are the Josephson and charging energies. We find that, for alpha > 1, subgap rf-SET operation is still feasible despite quantum fluctuations that wash out quasiparticle tunneling thresholds. Surprisingly, such rf-SETs show linearity and signal-to-noise ratio superior to those obtained when quantum fluctuations are weak, while still demonstrating excellent charge sensitivity.
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http://dx.doi.org/10.1103/PhysRevLett.93.066804 | DOI Listing |
Nature
January 2025
Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea.
A particle current generated by pumping in the absence of gradients in potential energy, density or temperature is associated with non-trivial dynamics. A representative example is charge pumping that is associated with the quantum Hall effect and the quantum anomalous Hall effect. Spin pumping, the spin equivalent of charge pumping, refers to the emission of a spin current by magnetization dynamics.
View Article and Find Full Text PDFBioorg Chem
January 2025
Department of Chemistry, St Berchmans College (Autonomous), Changanassery, Kerala 686101, India; Centre for Theoretical and Computational Chemistry, St Berchmans College (Autonomous), Changanassery, Kerala 686101, India. Electronic address:
In this study, three novel derivatives of benzo[b]thiophene-2-carbaldehyde (BTAP1, BTAP2, and BTAP3) were successfully synthesized and comprehensively characterized using spectroscopic techniques including FTIR, UV-VIS, HNMR, and CNMR. Thermal analysis through TGA and DTA demonstrated remarkable thermal stability with a maximum threshold at 270 °C. Spectroscopic investigations revealed π → π* transitions in all compounds, attributed to the conjugated system comprising benzothiophene rings connected to bromophenyl/ aminophenyl/phenol rings via α, β-unsaturated ketone bridges.
View Article and Find Full Text PDFSci Adv
January 2025
Department of Physics, Princeton University, Princeton, NJ 08544, USA.
Introducing superconductivity in topological materials can lead to innovative electronic phases and device functionalities. Here, we present a unique strategy for quantum engineering of superconducting junctions in moiré materials through direct, on-chip, and fully encapsulated 2D crystal growth. We achieve robust and designable superconductivity in Pd-metalized twisted bilayer molybdenum ditelluride (MoTe) and observe anomalous superconducting effects in high-quality junctions across ~20 moiré cells.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Johns Hopkins University, Institute for Quantum Matter and Department of Physics and Astronomy, Baltimore, Maryland 21218, USA.
The tetragonal heavy-fermion superconductor CeRh_{2}As_{2} (T_{c}=0.3 K) exhibits an exceptionally high critical field of 14 T for B∥c. It undergoes a field-driven first-order phase transition between superconducting states, potentially transitioning from spin-singlet to spin-triplet superconductivity.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Ens de Lyon, Université Lyon, CNRS, Laboratoire de Physique, F-69342 Lyon, France.
We introduce a new paradigm for the preparation of deeply entangled states useful for quantum metrology. We show that, when the quantum state is an eigenstate of an operator A, observables G which are completely off diagonal with respect to A have purely quantum fluctuations, as quantified by the quantum Fisher information, namely, F_{Q}(G)=4⟨G^{2}⟩. This property holds regardless of the purity of the quantum state, and it implies that off-diagonal fluctuations represent a metrological resource for phase estimation.
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