Search

Recent developments on the detector and the cryogenics for the terahertz photon detector system are discussed. The detector has been redesigned for improved performance, which exhibited optical efficiency of 6% at 530 GHz. Cryogenics for the detector system has been newly developed which employs a pulse-tube cooler with two originally developed compact 4He sorption fridges. Initial experiments demonstrated continuous cooling by altering operation of two sorption fridges, supported by a pulse-tube cooler with cooling power of 0.4 W. [ABSTRACT FROM AUTHOR]

Abstract The superconducting tunneling effect in heterostructures, describing the process where single electrons or Cooper pairs tunnel through the barrier, can always play a significant role in understanding the phase coherence and pairing mechanisms in superconductors. Taking advantage of the easy cleavage to atomically-thin monolayer structure of layered superconductors and resulting quantum confinement of electrons or Cooper pairs at two-dimensional limit, van der Waals superconducting materials hosting superconducting order in monolayers or heterostructures can exhibit extensive emergent phenomena associated with quantum phase transitions of vortex and anti-vortex pairs. Examples of superconducting tunnel junctions (STJs) based on layered superconductors have been demonstrated to achieve novel phenomena, including Andreev bound states, Majorana bound states and 0/π-phase junctions. Since the characteristic parameters of quasiparticle tunneling through the barrier are directly associated with the energy gap values of superconductors, such critical parameter can be obtained within the STJ device geometry, which helps us understand and control the pairing states and emerging phenomena in superconductors. In this review, from the perspective of STJs with single electron tunneling and Cooper pair tunneling, we discuss Andreev reflection, Majorana bound states, photon-induced tunneling effects, non-reciprocal transport and superconducting diode phenomena, as well as prospects for layered-superconductor-based STJs.

The superconducting tunneling effect in heterostructures, describing the process where single electrons or Cooper pairs tunnel through the barrier, can always play a significant role in understanding the phase coherence and pairing mechanisms in superconductors. Taking advantage of the easy cleavage to atomically-thin monolayer structure of layered superconductors and resulting quantum confinement of electrons or Cooper pairs at two-dimensional limit, van der Waals superconducting materials hosting superconducting order in monolayers or heterostructures can exhibit extensive emergent phenomena associated with quantum phase transitions of vortex and anti-vortex pairs. Examples of superconducting tunnel junctions (STJs) based on layered superconductors have been demonstrated to achieve novel phenomena, including Andreev bound states, Majorana bound states and 0/π-phase junctions. Since the characteristic parameters of quasiparticle tunneling through the barrier are directly associated with the energy gap values of superconductors, such critical parameter can be obtained within the STJ device geometry, which helps us understand and control the pairing states and emerging phenomena in superconductors. In this review, from the perspective of STJs with single electron tunneling and Cooper pair tunneling, we discuss Andreev reflection, Majorana bound states, photon-induced tunneling effects, non-reciprocal transport and superconducting diode phenomena, as well as prospects for layered-superconductor-based STJs. [ABSTRACT FROM AUTHOR]

Precision measurements of nuclear β decay are among the most sensitive methods to probe beyond standard model (BSM) physics in the neutrino sector. In particular, momentum conservation between the emitted decay products in the final state is sensitive to any new physics that couples to the neutrino mass. One way to observe these momentum recoil effects experimentally is through high-precision measurements of nuclear electron capture (EC) decay where the final state only contains the neutrino and a recoiling atom. The Beryllium Electron capture in Superconducting Tunnel junctions (BeEST) experiment precisely measures the eV-scale radiation that follows the radioactive decay of 7 Be implanted into sensitive superconducting tunnel junction (STJ) quantum sensors. STJs are ideally suited for measurements of this type due to their high resolution at the low recoil energies in EC decay, and their high-rate counting capabilities. We present the motivation for the BeEST experiment and describe the various phases of the project. [ABSTRACT FROM AUTHOR]

Particle induced X-ray emission with the use of focused ion beam (µ-PIXE) utilizing a superconducting tunnel junction (STJ) X-ray spectrometer has been developed to realize light element mapping in the soft X-ray region. A five hundred pixels array of STJ detector has been installed in the µ-PIXE beamline at the accelerator facility in the University of Tsukuba. Performance of a single-pixel STJ detector is tested. The K-lines of light elements C to Al have been separately detected in the pulse height spectra with a broad background, which is attributed substrate-hit events caused by scattered protons and high-energy characteristic X-ray lines. The background is rejected by using the anticoincidence technique or rise-time discrimination. [ABSTRACT FROM AUTHOR]

Cryodetection mass spectrometry (MS) was used to study the Au 10 (TBBT) 10 (TBBT = 4- tert- butylbenzenethiolate) catenane nanocluster. The matrix-assisted laser desorption ionization (MALDI) process generates distinct fragments that can be arranged into two distinct regimes: (i) in-source fragmentation, which occurs rapidly in a relatively short (<170 ns) time frame, and (ii) metastable fragmentation, which occurs postacceleration during a time-of-flight (TOF) mass analysis over a longer time frame (>170 ns-250 μs). Using MALDI-TOF MS with superconducting tunnel junction (STJ) cryodetection, distinct metastable nanocluster fragments were resolved at lower energies deposited into the detector. The results also demonstrated that STJ cryodetection MS can be used to acquire multiple (>10), simultaneous tandem mass spectra in a single experiment. Simulated fragmentation of the Au 10 nanocluster using ab initio molecular dynamics (AIMD) revealed the different fragmentation processes and confirmed the MS results. Using both the empirical MS data and AIMD calculations, fragmentation pathways are proposed for Au 10 (TBBT) 10 , which terminate with two small, stable ringed species.