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Detectors
Published in C. R. Kitchin, Astrophysical Techniques, 2020
A possible replacement for the CCD in a few years, at least at well-equipped major observatories, is the STJ. The STJ can operate from the UV to long-wave IR and also in the X-ray and radio regions, can detect individual photons, has a very rapid response, and perhaps most importantly, provides an intrinsic spectral resolution (Sections 1.1.8 and 4.1) of around 500 or 1000 in the visible. Its operating principle is based upon a Josephson junction. This has two superconducting layers separated by a thin insulating layer. Electrons are able to tunnel across the junction because they have a wave-like behaviour as well as a particle-like behaviour and so a current may flow across the junction despite the presence of the insulating layer. Within the superconductor, the lowest energy state for the electrons occurs when they link together to form Cooper pairs. The current flowing across the junction because of the paired electrons can be suppressed by a magnetic field.
Nanoelectronic devices
Published in David Crawley, Konstantin Nikolić, Michael Forshaw, 3D Nanoelectronic Computer Architecture and Implementation, 2020
Josephson junction persistent current bit (JJPCB) devices also use a superconducting loop, with three Josephson junctions around its perimeter. This can support two opposite circulating currents, whose relative magnitude can be controlled by external magnetic fields, figure 4.11(c). A micrometre-sized working device has been built [124, 125]. It was originally proposed (and demonstrated) as being capable of storing a quantum bit (qubit) but it has also been proposed for use as a ‘classical’ binary logic device (‘classical qubit’ or ‘cubit’) [128]. Nanoscale superconducting quantum bits based on Josephson junctions could be the building blocks for future quantum computers, because they combine the coherence of the superconducting state with the control possibilities of conventional electronic circuits.
Polyimides as Langmuir-Blodgett Films
Published in Malay K. Ghosh, K. L. Mittal, Polyimides Fundamentals and Applications, 2018
Mitsumasa Iwamoto, Masa-aki Kakimoto
(a) As a Tunneling Barrier in Josephson Junctions. One of the potential applications of LB films might be as electrically insulating spacers in the manufacture of Josephson junctions with a structure of superconductor-insulating spacer-superconductor [79–81]. Miles and McMahon were the first to produce Josephson junctions using LB films [82]. They fabricated junctions that consisted of a barium stearate LB film sandwiched between (Pb-Sn) and (Pb-In) superconducting electrodes. Larkins et al. fabricated junctions consisting of a poly (vinyl stearate) LB film sandwiched between Pb and In alloys [83]. Hao et al. also fabricated junctions consisting of a 20,21-oxiranhenecosanoic acid LB film sandwiched between Pb and In alloys [53]. They then observed typical I-V characteristics of the ideal Josephson junction at a temperature of 4.2 Κ. However, we anticipate that an inherent oxide layer was formed on the base electrodes in their junctions and the oxide layer functioned as a tunneling barrier, and that conducting defects originating in LB films existed in their junctions [32,33]. Thus it is very important to prepare pinhole-free LB films sandwiched between superconducting electrodes without the presence of any inherent oxide layers on the electrodes.
Leveraging the power of quantum computing for breaking RSA encryption
Published in Cyber-Physical Systems, 2021
Moolchand Sharma, Vikas Choudhary, R. S. Bhatia, Sahil Malik, Anshuman Raina, Harshit Khandelwal
We here use the D-Wave quantum computer that houses the 2000 quantum bit (qubit) commonly known as D wave 2000Q. The configuration of this quantum computer roughly covers: Inside the Quantum computer processor: Building blocks of QC – Classical CMOS transistors, The SQUID – a quantum transistorThe qubits are connected using elements known as couplersA framework of switches (formed from Josephson junctions) is used for addressing each qubit (routes pulses of magnetic information to the correct places on-chip) and storing the information in a magnetic memory element local to each deviceAn output unitOutside the Quantum Processing Unit (QPU) The QPU wrapping – One of the CPUs is selected from the wafer to build the QC, and is placed in the centre of the QPU packaging systemComputer cooling–Since the QC works at an optimum temperature and the processing process gets the heat high, thus reducing this heat, the cooling unit is used.Computer shielding and wiring- To protect the QC from outside interference and interference caused by its components.