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Recent Advances in Nanowires and Superconductors

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A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Nanoelectronics, Nanosensors and Devices".

Deadline for manuscript submissions: closed (30 September 2023) | Viewed by 5153

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Dr. Fabio Cavaliere

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1. Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy
2. CNR-SPIN, Via Dodecaneso 33, 16146 Genova, Italy
Interests: quantum condensed matter theory; quantum thermodynamics; correlated electron systems
Special Issues, Collections and Topics in MDPI journals

Dr. Niccolò Traverso Ziani

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Dear Colleagues,

Advancements in the theoretical and experimental understanding of quantum wires (QWs), ranging from semiconductors and carbon nanotubes (CNTs) to topological insulators (TIs), have led to the proposal and observation of a plethora of novel physical phenomena. In view of this rich and exciting scenario, it is compelling to assess where the bleeding edge of research in this field lies. This is the goal of this Special Issue.

Very recently, the formation of elusive Wigner molecules has been proven in suspended CNT QWs, and it has finally been understood theoretically how such a phenomenon implies a quantum phase transition at zero temperature. At finite temperature, one of the most natural theoretical models to describe this molecule is the spin-incoherent Luttinger liquid, whose existence has been shown in trapped 1D cold atoms, and that yet remains to be confirmed in condensed matter. At weaker interactions, one of the frontiers represents harvesting non-linear effects which may even lead to unconventional nanophotonic devices.

Even in a weakly interacting context, interesting physics may arise in wires made of non-trivial materials such as TIs and in spin-orbit coupled ones. Such systems are interesting on their own, and even more so when proximized with superconductors. Indeed, Majorana and parafermionic modes may arise, which can be exploited to implement topologically protected quantum computation.

Connecting and possibly stacking several such QWs is a required goal in order to control and exploit the properties of Majorana and parafermionic modes, to build individual quantum gates and eventually to scale up towards complex quantum circuits. Beyond their usefulness in topological quantum computation, superlattices of QWs show novel collective phenomena leading, for instance, to new optical transitions and vibrational properties. In addition, the procedure of "wire construction" has been theoretically exploited to tackle the study of exotic states of matter such as the Fractional Quantum Hall Effect.

We hope that this Special Issue will contribute to the cross-fertilization of the different subfields mentioned above.

Dr. Fabio Cavaliere
Dr. Niccolò Traverso Ziani
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

quantum wires
superconductors
carbon nanotubes
topological insulators
spin-orbit
Majorana fermions
parafermions
superlattices
topologically protected quantum computation
Luttinger liquids

Related Special Issue

Recent Advances in Nanowires and Superconductors (Second Edition) in Nanomaterials

Published Papers (4 papers)

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Research

13 pages, 5134 KiB

Open AccessArticle

Silicon-Nanowire-Type Polarization-Diversified CWDM Demultiplexer for Low Polarization Crosstalk

by Seok-Hwan Jeong, Heuk Park and Joon Ki Lee

Nanomaterials 2023, 13(16), 2382; https://doi.org/10.3390/nano13162382 - 21 Aug 2023

Cited by 1 | Viewed by 763

Abstract

Coarse wavelength division multiplexing (CWDM)-targeted novel silicon (Si)-nanowire-type polarization-diversified optical demultiplexers were numerically analyzed and experimentally verified. The optical demultiplexer comprised a hybrid mode conversion-type polarization splitter rotator (PSR) and a delayed Mach–Zehnder interferometric demultiplexer. Si-nanowire-based devices were fabricated using a commercially available Si photonics foundry process, exhibiting nearly identical spectral responses regardless of the polarization states of the input signals under the PSR. The experiment demonstrated a low insertion loss of 1.0 dB and a polarization-dependent loss of 1.0 dB, effectively suppressing spectral crosstalk from other channels by less than −15 dB. Furthermore, a TM-mode rejection-filter-integrated optical demultiplexer was designed and experimentally validated to mitigate unwanted TM-mode-related polarization crosstalk that arose from the PSR. It exhibited an improved polarization crosstalk rejection efficiency of −25 dB to −50 dB within the whole CWDM spectral range. Full article

(This article belongs to the Special Issue Recent Advances in Nanowires and Superconductors)

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12 pages, 2756 KiB

Open AccessEditor’s ChoiceArticle

Atomic-Layer Engineering of La_2−xSr_xCuO₄—La_2−xSr_xZnO₄ Heterostructures

by Xiaotao Xu, Xi He, Anthony T. Bollinger, Xiaoyan Shi and Ivan Božović

Nanomaterials 2023, 13(15), 2207; https://doi.org/10.3390/nano13152207 - 29 Jul 2023

Viewed by 808

Abstract

The fabrication of trilayer superconductor-insulator-superconductor (SIS) Josephson junctions with high-temperature superconductor (HTS) electrodes requires atomically perfect interfaces. Therefore, despite great interest and efforts, this remained a challenge for over three decades. Here, we report the discovery of a new family of metastable materials, La_2−xSr_xZnO₄ (LSZO), synthesized by atomic-layer-by-layer molecular beam epitaxy (ALL-MBE). We show that LSZO is insulating and epitaxially compatible with an HTS compound, La_2−xSr_xCuO₄ (LSCO). Since the “parent” compound La₂ZnO₄ (LZO) is easier to grow, here we focus on this material as our insulating layer. Growing LZO at very low temperatures to reduce cation interdiffusion makes LSCO/LZO interfaces atomically sharp. We show that in LSCO/LZO/LSCO trilayers, the superconducting properties of the LSCO electrodes remain undiminished, unlike in previous attempts with insulator barriers made of other materials. This opens prospects to produce high-quality HTS tunnel junctions. Full article

(This article belongs to the Special Issue Recent Advances in Nanowires and Superconductors)

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15 pages, 4167 KiB

Open AccessArticle

Phonon-Assisted Tunneling through Quantum Dot Systems Connected to Majorana Bound States

by Levente Máthé, Zoltán Kovács-Krausz, Ioan Botiz, Ioan Grosu, Khadija El Anouz, Abderrahim El Allati and Liviu P. Zârbo

Nanomaterials 2023, 13(10), 1616; https://doi.org/10.3390/nano13101616 - 11 May 2023

Viewed by 1848

Abstract

We theoretically analyze phonon-assisted tunneling transport in a quantum dot side connected to a Majorana bound state in a topological superconducting nanowire. We investigate the behavior of the current through the dot, for a range of experimentally relevant parameters, in the presence of one long-wave optical phonon mode. We consider the current-gate voltage, the current-bias voltage and the current-dot–Majorana coupling characteristics under the influence of the electron–phonon coupling. In the absence of electron–phonon interaction, the Majorana bound states suppress the current when the gate voltage matches the Fermi level, but the increase in the bias voltage counteracts this effect. In the presence of electron–phonon coupling, the current behaves similarly as a function of the renormalized gate voltage. As an added feature at large bias voltages, it presents a dip or a plateau, depending on the size of the dot–Majorana coupling. Lastly, we show that the currents are most sensitive to, and depend non-trivially on the parameters of the Majorana circuit element, in the regime of low temperatures combined with low voltages. Our results provide insights into the complex physics of quantum dot devices used to probe Majorana bound states. Full article

(This article belongs to the Special Issue Recent Advances in Nanowires and Superconductors)

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13 pages, 4630 KiB

Open AccessEditor’s ChoiceArticle

Reconstruction-Induced φ₀ Josephson Effect in Quantum Spin Hall Constrictions

by Lucia Vigliotti, Fabio Cavaliere, Giacomo Passetti, Maura Sassetti and Niccolò Traverso Ziani

Nanomaterials 2023, 13(9), 1497; https://doi.org/10.3390/nano13091497 - 27 Apr 2023

Cited by 2 | Viewed by 1426

Abstract

The simultaneous breaking of time-reversal and inversion symmetry, in connection to superconductivity, leads to transport properties with disrupting scientific and technological potential. Indeed, the anomalous Josephson effect and the superconducting-diode effect hold promises to enlarge the technological applications of superconductors and nanostructures in general. In this context, the system we theoretically analyze is a Josephson junction (JJ) with coupled reconstructed topological channels as a link; such channels are at the edges of a two-dimensional topological insulator (2DTI). We find a robust

φ_{0}

Josephson effect without requiring the presence of external magnetic fields. Our results, which rely on a fully analytical analysis, are substantiated by means of symmetry arguments: Our system breaks both time-reversal symmetry and inversion symmetry. Moreover, the anomalous current increases as a function of temperature. We interpret this surprising temperature dependence by means of simple qualitative arguments based on Fermi’s golden rule. Full article

(This article belongs to the Special Issue Recent Advances in Nanowires and Superconductors)

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