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Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Quantum random number generators employ the inherent randomness of quantum mechanics to generate truly unpredictable random numbers, which are essential in cryptographic applications. While a great variety of quantum random number generators have been realized using photonics, few exploit the high-field confinement offered by plasmonics, which enables device footprints an order of magnitude smaller in size. Here we integrate an on-chip nanowire plasmonic waveguide into an optical time-of-arrival based quantum random number generation setup. Despite loss, we achieve a random number generation rate of 14.4 Mbits s − 1 using low light intensity, with the generated bits passing industry standard tests without post-processing. By increasing the light intensity, we were then able to increase the generation rate to 41.4 Mbits s − 1 , with the resulting bits only requiring a shuffle to pass all tests. This is an order of magnitude increase in the generation rate and decrease in the device size compared to previous work. Our experiment demonstrates the successful integration of an on-chip nanoscale plasmonic component into a quantum random number generation setup. This may lead to new opportunities in compact and scalable quantum random number generation. [ABSTRACT FROM AUTHOR]

In this article, we propose a postprocessing variationally scheduled quantum algorithm (pVSQA) for solving constrained combinatorial optimization problems (COPs). COPs are typically transformed into ground-state search problems of the Ising model on a quantum annealer or gate-based quantum device. Variational methods are used to find an optimal schedule function that leads to high-quality solutions in a short amount of time. Postprocessing techniques convert the output solutions of the quantum devices to satisfy the constraints of the COPs. The pVSQA combines the variational methods and the postprocessing technique. We obtain a sufficient condition for constrained COPs to apply the pVSQA based on a greedy postprocessing algorithm. We apply the proposed method to two constrained NP-hard COPs: the graph partitioning problem and the quadratic knapsack problem. The pVSQA on a simulator shows that a small number of variational parameters is sufficient to achieve a (near-) optimal performance within a predetermined operation time. Then, building upon the simulator results, we implement the pVSQA on a quantum annealer and a gate-based quantum device. The experimental results demonstrate the effectiveness of our proposed method.

How to improve charging processes and suppress self-discharging processes has always been one of the key issues to achieve quantum batteries with high performance. Although a quantum battery is inevitably influenced by composite environments, this situation is still little understood, particularly regarding the influence of the memory effect of the composite environments and the coupling between composite environments. In this work, we investigate the effects of the composite environments, composed of two identical parts each containing a single cavity mode decaying to a reservoir, on the charging and self-discharging processes of a quantum battery. We show that increasing the two-mode coupling can effectively enhance the charging performance (i.e., the stored energy, the charging power, ergotropy) and restrain the self-discharging process (i.e., suppressing the process of dissipating the energy). However, different from the effect of two-mode coupling, we reveal that the memory effect of the reservoir in this composite environment is unfavorable to the charging process of the quantum battery, which is in sharp contrast to previous studies where the memory effect can significantly improve the charging performance of a quantum battery. Our results may benefit to the realization of quantum batteries with high performance under the actual complex environmental noise. [ABSTRACT FROM AUTHOR]

Quantum random number generators employ the inherent randomness of quantum mechanics to generate truly unpredictable random numbers, which are essential in cryptographic applications. While a great variety of quantum random number generators have been realized using photonics, few exploit the high-field confinement offered by plasmonics, which enables device footprints an order of magnitude smaller in size. Here we integrate an on-chip nanowire plasmonic waveguide into an optical time-of-arrival based quantum random number generation setup. Despite loss, we achieve a random number generation rate of $14.4\,\mathrm{Mbits}\,\mathrm{s}^{-1}$ using low light intensity, with the generated bits passing industry standard tests without post-processing. By increasing the light intensity, we were then able to increase the generation rate to $41.4\,\mathrm{Mbits}\,\mathrm{s}^{-1}$ , with the resulting bits only requiring a shuffle to pass all tests. This is an order of magnitude increase in the generation rate and decrease in the device size compared to previous work. Our experiment demonstrates the successful integration of an on-chip nanoscale plasmonic component into a quantum random number generation setup. This may lead to new opportunities in compact and scalable quantum random number generation.

Free Space Optic Communication (FSO) is one of the communication systems chosen for 5G + / 6G backhaul. Many works were done to improve signal quality either at emission, transmission channel or at reception through photodetector. The aim of this work is to design a new transimpedance amplifier (TIA) to improve Free Space Optic Communication (FSO) photodetector performance. To achieve our purpose, a negative electrical resistance was introduced into conventional TIA. SPICE software and Kirchhoff's laws were used to design and analyze the circuit. The obtained results show that the new TIA has a better amplitude gain response and lower equivalent noise than conventional TIAs. High bandwidth and flat amplitude response in the pass band characterize our TIA. This characteristic is one of the two criteria for a photodetector to be considered as a quantum device. A 3D gain representation highlights different regions of positive and negative feedback resistors and frequencies to be used or avoided in order to ensure TIA stability.

Organic semiconductors, characterized by their exceptionally long spin relaxation times (≈ms) and unique spinterface effects, are considered game-changers in spintronics. However, achieving high-performance and wide-range tunable magnetoresistance (MR) in organic spintronic devices remains challenging, severely limiting the development of organic spintronics. This work combines straintronic multiferroic heterostructures with organic spin valve (OSV) to develop a three-terminal OSV device with a gate structure. The device exhibits a record-high MR ratio of 281% which 10 times higher than the average in polymer systems. More importantly, this work can perform multilevel writing operations on the device using gate voltages and create at least 10 stable spin-dependent working states within a single device. Both experiments and theoretical calculations confirm such an extraordinary tunability range originates from the synergistic effects of strain and charge accumulation that amplified by the spinterface. This study demonstrates the potential of OSV systems for efficient spin manipulation and highlights the spinterface as an ideal platform for amplifying spin effects for next-generation spintronic devices., (© 2024 Wiley‐VCH GmbH.)

The alkali-metal vapor cell is the key sensitive element of quantum sensors such as atomic magnetometers, atomic gyroscopes, and atomic clocks. The alkali-metal vapor in the cell interacts with laser and magnetic field to achieve high-precision measurement of some physical quantities. A teaching experiment platform for parameter testing of alkali-metal vapor cells with high temperature and high pressure is constructed. According to the measured laser absorption spectrum, the pressure of the buffer gas and the density of alkali-metal atoms inside the vapor cell can be obtained. This experimental platform help students to directly observe the interaction between laser and atoms, which helps them to understand the alkali-metal vapor cell, cultivate their experimental hands-on ability and provides support for graduate and undergraduate related courses. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plasmons, the electromagnetic excitations coupled with electron waves, possess the intrinsic ability of manipulating light at subwavelength scales down to picometer. This ability not only helps uncovering the fascinating quantum behaviors that strengthen the basic understanding of quantum science, but also enables the inventions of various quantum optoelectronic devices, triggering the birth of quantum plasmonic technology. The past decade has witnessed the flourishing of this technology. In this review, we first focus on fundamental investigations into quantum behaviors for both "isolated" plasmonic nanostructures and "coupled" plasmon-emitter systems, emphasizing new theoretical frameworks and experimental advances. Leveraging on these fundamentals, the progress in exploring and applying quantum plasmonic devices is discussed, such as quantum plasmonic circuits, nanolasers, biochemistry, and spin-orbit interaction devices. Upon summarizing the past and present developments, the future research directions and promising applications are highlighted. [ABSTRACT FROM AUTHOR]

Quantum computation is often limited by environmentally-induced decoherence. We examine the loss of coherence for a two-branch quantum interference device in the presence of multiple witnesses, representing an idealized environment. Interference oscillations are visible in the output as the magnetic flux through the branches is varied. Quantum double-dot witnesses are field-coupled and symmetrically attached to each branch. The global system—device and witnesses—undergoes unitary time evolution with no increase in entropy. Witness states entangle with the device state, but for these blind witnesses, which-path information is not able to be transferred to the quantum state of witnesses—they cannot “see” or make a record of which branch is traversed. The system which-path information leaves no imprint on the environment. Yet, the presence of a multiplicity of witnesses rapidly quenches quantum interference.

Majorana fermions are particles identical to their antiparticles proposed theoretically in 1937 by Ettore Majorana as real solutions of the Dirac equation. Alexei Kitaev suggested that Majorana particles should emerge in condensed matter systems as zero mode excitations in one-dimensional (1-D) p-wave superconductors, with possible applications in quantum computation due to their non-abelian statistics. The search for Majorana zero modes in condensed matter systems led to one of the first realistic models based in a semiconductor nanowire with high spin-orbit coupling, induced superconducting s-wave pairing, and Zeeman splitting. Soon, it was realized that size-quantization effects should generate subbands in these systems that could even allow the emergence of more than one Majorana mode at each edge, resulting in a zero bias peak on the differential conductance with a different shape from the predicted by simplified theoretical models. In this paper, we provide a connection between a finite-size nanowire with two occupied subbands and a 2-band Kitaev chain, and discuss the advantage of a 1-D model to understand the phenomenology of the system, including the presence of a hidden chiral symmetry and its similarity with a spinfull Kitaev chain under a magnetic field. [ABSTRACT FROM AUTHOR]

We have developed a multi-scale model, consisting of an atomistic model in LAMMPS of an InSb nano-wire, and a continuum model in COMSOL of a so-called Majorana research device, to study the effects of thermo-mechanical deformations during the cool down from room temperature to the operating temperature of about 50 mK. For the simulation of the InSb nano-wire suitable potentials were implemented in LAMMPS. The simulation results of the nano-wire show size dependent Young's moduli and gradients in the radial lattice spacing during uniaxial straining. The material properties that were derived from the atomistic model, were introduced in the continuum model. Cool down of the device from room temperature to its operating temperature introduced significant deformation. However, the stresses in the system are moderate and no fracture or damage is expected. Still, deformation of the device will induce shifts in band gap behavior of the device. Band gap shifts using a simple approximation are estimated to be about 34%. [ABSTRACT FROM AUTHOR]

The article offers interview with William J. Munro, group leader of Japanese technology company Nippon Telegraph & Telephone Corporation (NTT) Laboratories, who discusses quantum physics in telecommunication, technical innovation in electronic devices, and plans for future.

An introduction to the journal is presented in which the author discusses various reports within the issue involving low-dimensional semiconductor devices including thermal noise in miniaturized electronic devices, emissive silicon light, and gallium arsenide (GaAs).

Addressable quantum states well isolated from the environment are of considerable interest for quantum information science and technology. Carbon nanotubes are an appealing system, since a perfect crystal can be grown without any missing atoms and its cylindrical structure prevents ill-defined atomic arrangement at the surface. Here, we develop a reliable process to fabricate compact multielectrode circuits that can sustain the harsh conditions of the nanotube growth. Nanotubes are suspended over multiple gate electrodes, which are themselves structured over narrow dielectric ridges to reduce the effect of the charge fluctuators of the substrate. We measure high-quality double- and triple-quantum dot charge stability diagrams. Transport measurements through the triple-quantum dot indicate long-range tunneling of single electrons between the left and right quantum dots. This work paves the way to the realization of a new generation of condensed-matter devices in an ultraclean environment, including spin qubits, mechanical qubits, and quantum simulators.

The article discusses the development of scanning near-field optical microscope which works under cryogenic temperature and strong magnetic field. This study has focused on the development of a cantilever-based scanning near-field optical microscope working in an extreme environment, at cryogenic temperature and under strong magnetic field. The researchers of the study have designed a new optical system based on an infinite conjugate microscope.

We propose and analyze a cellular nonlinear network (CNN) based on a semiconductor nanostructure consisting of multiple layers of two semiconductors along with an incorporated quantum dot layer. An elementary logic cell of the proposed CNN consists of two resonant tunneling diodes connected in series through a quantum dot. The cell may be realized with multiple layers of two semiconductor materials with an embedded dot layer in between. The local interconnections of nanocells are achieved via tunneling between the neighboring quantum dots. Cells may be biased by the common column contacts, and only edge cells have individual I/O ports. Using approximate tunneling characteristics, we simulated network dynamics and found procedures leading to useful logic functionality. In order to illustrate network capabilities for image processing, we present examples of filtering, erosion, dilation, and edge detection carried out on a test image on a 400 &time; 269 cell template. The realization of a number of logic functions in one module is possible due to the incorporation of nonlinear (tunneling) elements for cell interconnections. The proposed CNN architecture for nanostructures demonstrates powerful computing potential that will be beneficial for many practical applications. [ABSTRACT FROM AUTHOR]

A review of semiconductor-based schemes for the realization of quantum information processing devices is presented. After recalling the fundamentals of quantum information/computation theory, we shall discuss potential implementation schemes based on charge and/or spin degrees of freedom in semiconductor nanostructures. More specifically, we shall present an all-optical implementation scheme of quantum information processing with semiconductor macroatoms/molecules, where the computational degrees of freedom are interband optical transitions (excitonic states) manipulated/controlled by ultrafast sequences of multicolor laser pulses. We shall primarily focus on implementation schemes dealing with charge excitations in GaAs as well as GaN quasi-zero-dimensional structures. We shall finally discuss the possibility to combine charge and spin degrees of freedom, thus, allowing for fast-quantum gates, which do not translate into fast-decoherence times. [ABSTRACT FROM PUBLISHER]

In view of applications to hexagonal binary decision diagram (BDD) LSIs, a first attempt is made to form quantum BDD node switches on selectively grown (SG) embedded quantum wires (QWRs) by molecular beam epitaxy (MBE). SG branch switches controlled by a Schottky wrap gate (WPG) were successfully fabricated by MBE growth and subsequent device processing. Gate control characteristics were studied by gate-dependent Shubnikov–de-Haas measurements, and the behavior was found to be similar to that of devices fabricated on wires by etching. The switch exhibited clear conductance quantization at low temperature, and temperature dependence of the voltage slope of conductance jump was clarified. A Y-branch BDD node device using two SG branch switches was successfully fabricated, and realized clear path switching characteristics. [Copyright &y& Elsevier]

The paper describes the fabrication of single-electron transistors and circuits using silicon-on-insulators (SOIs). We first point out that control of the oxidation of Si is quite important and could be the key to the fabrication of quantum devices including single-electron devices. We then introduce our technique for making single-electron transistors, which uses special phenomena that occur during the oxidation of SOIs, and show that the technique enables us to realize primary single-electron circuits as a result of its high controllability, reproducibility and thermal stability. [Copyright &y& Elsevier]

The concept, the present status, key issues and future prospects of a novel hexagonal binary decision diagram (BDD) quantum circuit approach for III–V quantum large-scale integrated circuits (QLSIs) are presented and discussed. In this approach, the BDD logic circuits are implemented on III–V semiconductor-based hexagonal nanowire networks controlled by nanoscale Schottky gates. The hexagonal BDD QLSIs can operate at delay-power products near the quantum limit in the quantum regime as well as in the many-electron classical regime. To demonstrate the feasibility of the present approach, GaAs Schottky wrap gate (WPG)-based single-electron BDD node devices and their integrated circuits were fabricated and their proper operations were confirmed. Selectively grown InGaAs sub-10 nm quantum wires and their hexagonal networks have been investigated to form high-density hexagonal BDD QLSIs operating in the quantum regime at room temperature. [Copyright &y& Elsevier]