Energy spectrum and quantum phase transition of the coupled single spin and an infinitely coordinated Ising chain

• Seidali Seidov,
• Natalia Pugach and
• Anatolie Sidorenko

Beilstein J. Nanotechnol. 2025, 16, 1668–1676, doi:10.3762/bjnano.16.117

• layouts, if one considers spins as qubits. In particular, we have previously proposed a method for implementing a CCZ (control–control–Z) quantum gate on a system composed of three logical qubits, which are connected to another coupler qubit [10]. This approach allows to increase the fidelity of the

• operation, and it has technical benefits such as simplicity of calibration and suppression of the unwanted longitudinal ZZ interaction. One of the important quantities is the shift of the coupler qubits energy levels depending on the state of the logical qubits. In the present manuscript, we find the energy

• levels of such system in the limit of infinitely many logical qubits, and find the energy spectrum of the coupler qubit depending on the state of the logical qubits ensemble. We start our theoretical analysis by mapping the Ising chain Hamiltonian to a Lipkin– Meshkov–Glik (LMG) Hamiltonian [11][12][13

Few-photon microwave fields for superconducting transmon-based qudit control

• Irina A. Solovykh,
• Andrey V. Pashchenko,
• Natalya A. Maleeva,
• Nikolay V. Klenov,
• Olga V. Tikhonova and
• Igor I. Soloviev

Beilstein J. Nanotechnol. 2025, 16, 1580–1591, doi:10.3762/bjnano.16.112

• and Electronics of RAS, 125009 Moscow, Russia 10.3762/bjnano.16.112 Abstract Increasing the efficiency of quantum processors is possible by moving from two-level qubits to elements with a larger computational base. An example would be a transmon-based superconducting atom, but the new basic elements

• qubits; Introduction Currently, quantum computing is under active development, opening new horizons for solving a number of problems that are difficult for classical processors, including modeling the behavior of quantum systems, optimization problems, breaking cryptographic systems, solving large

• decomposition into n basis states. Today, the main focus is on processors based on qubits (a special case of qudits with n = 2) on a superconducting, ionic, or other platform. However, it is still not easy to create the necessary number of qubits and control channels to implement really useful quantum

Modeling magnetic properties of cobalt nanofilms used as a component of spin hybrid superconductor–ferromagnetic structures

• Aleksey Fedotov,
• Olesya Severyukhina,
• Anastasia Salomatina and
• Anatolie Sidorenko

Beilstein J. Nanotechnol. 2025, 16, 1557–1566, doi:10.3762/bjnano.16.110

• Josephson contacts [13]. These nanomaterials are widely used [17][18][19] in the creation of individual qubits and quantum computers in general, superconducting microcircuits and interferometers, single photon detectors [20] and other devices of quantum electronics and spintronics. Mathematical Model for

A bifunctional superconducting cell as flux qubit and neuron

• Dmitrii S. Pashin,
• Pavel V. Pikunov,
• Marina V. Bastrakova,
• Andrey E. Schegolev,
• Nikolay V. Klenov and
• Igor I. Soloviev

Beilstein J. Nanotechnol. 2023, 14, 1116–1126, doi:10.3762/bjnano.14.92

• , Russia 10.3762/bjnano.14.92 Abstract Josephson digital or analog ancillary circuits are an essential part of a large number of modern quantum processors. The natural candidate for the basis of tuning, coupling, and neromorphic co-processing elements for processors based on flux qubits is the adiabatic

• ; superconducting quantum interferometer; Introduction Superconducting interferometers are widely used both as flux qubits and as a part of the peripherals in various implementations of quantum computers [1][2][3][4][5][6][7][8][9][10]. In particular, the D-Wave 2000Q quantum computer, released in 2017, operates

• interconnects that allow for programmable interaction between qubits. The Pegasus P16 superconducting chip of the Advantage QA system, released in 2020, contained 1,030,000 Josephson junctions, of which only 40,484 were used for interconnects, and 5,640 Josephson structures were part of the qubits. In this

A superconducting adiabatic neuron in a quantum regime

• Marina V. Bastrakova,
• Dmitrii S. Pashin,
• Dmitriy A. Rybin,
• Andrey E. Schegolev,
• Nikolay V. Klenov,
• Igor I. Soloviev,
• Anastasiya A. Gorchavkina and
• Arkady M. Satanin

Beilstein J. Nanotechnol. 2022, 13, 653–665, doi:10.3762/bjnano.13.57

• from the utilization of a single technology suitable for superconducting qubits. In this case, the classical part can operate in an adiabatic mode ensuring minimal impact on quantum circuits. However, quantum effects, in turn, can significantly affect the operation of neuromorphic elements. In this

Tunable superconducting neurons for networks based on radial basis functions

• Andrey E. Schegolev,
• Nikolay V. Klenov,
• Sergey V. Bakurskiy,
• Igor I. Soloviev,
• Mikhail Yu. Kupriyanov,
• Maxim V. Tereshonok and
• Anatoli S. Sidorenko

Beilstein J. Nanotechnol. 2022, 13, 444–454, doi:10.3762/bjnano.13.37

• data [7][8][9][10][11][12][13]. Similar problems arise nowadays when reading data in superconducting noisy intermediate-scale quantum (NISQ) computers [14][15][16][17]. Here again, we need real-time identification and classification of varying signals from multiple sources (qubits) in a narrow

Kondo effects in small-bandgap carbon nanotube quantum dots

• Patryk Florków,
• Damian Krychowski and
• Stanisław Lipiński

Beilstein J. Nanotechnol. 2020, 11, 1873–1890, doi:10.3762/bjnano.11.169

• degeneracy points and the gate dependence of degeneracy lines are interesting for quantum computing because they open the possibility of electric switching between different types of qubits (spin, valley, or valley–spin) and their higher-dimensional equivalents (qutrits [51][52], qudits [53][54]) in the same

• for quantum computing by providing a method for electrically switching, in the same nanoscopic system, between spin, valley, or spin–valley qubits, as well as between qubits and qutrites (threefold degeneracy) or qudits (fourfold degeneracy) of various types. For the analyzed nanotube C(24,21

Functional nanostructures for electronics, spintronics and sensors

• Anatolie S. Sidorenko

Beilstein J. Nanotechnol. 2020, 11, 1704–1706, doi:10.3762/bjnano.11.152

• ” electronics for a superconducting computer where a low-noise cryogenic microwave amplifier as a read-out circuit of superconducting X-mon qubits is demonstrated. Also, in addition to the progress towards theoretical and experimental developments of a superconducting computer, this thematic issues also

A wideband cryogenic microwave low-noise amplifier

• Boris I. Ivanov,
• Dmitri I. Volkhin,
• Ilya L. Novikov,
• Dmitri K. Pitsun,
• Dmitri O. Moskalev,
• Ilya A. Rodionov,
• Evgeni Il’ichev and
• Aleksey G. Vostretsov

Beilstein J. Nanotechnol. 2020, 11, 1484–1491, doi:10.3762/bjnano.11.131

• processing circuits [4]. The latter include the most challenging and attractive topics such as quantum bits (qubits) [5], quantum dots [6], microwave single-photon detectors [7], high-quality resonators [8], superconducting microwave beam splitters [9], and other circuit quantum electrodynamics structures

• sensitivity and measurement speed of the full measurement setup is obviously defined by the signal-to-noise ratio and, thus, by the gain and the noise temperature of the cLNA. The sample under study contained superconducting X-mon qubits coupled to coplanar quarter wavelength resonators. Each resonator was

Superconductor–insulator transition in capacitively coupled superconducting nanowires

• Alex Latyshev,
• Andrew G. Semenov and
• Andrei D. Zaikin

Beilstein J. Nanotechnol. 2020, 11, 1402–1408, doi:10.3762/bjnano.11.124

• example, for possible realization of superconducting qubits [13]. Such effects were investigated theoretically [14] and observed experimentally [15][16]. Each quantum phase slip generates sound-like plasma modes [17] which propagate along the wire and interact with other QPSs. The exchange of such Mooij

Atomic defect classification of the H–Si(100) surface through multi-mode scanning probe microscopy

• Jeremiah Croshaw,
• Thomas Dienel,
• Taleana Huff and
• Robert Wolkow

Beilstein J. Nanotechnol. 2020, 11, 1346–1360, doi:10.3762/bjnano.11.119

• for the patterning and operation of atom scale devices including qubits [2][3] and single electron transistors [4][5] made from atomically precise implanted donor atoms near the H–Si surface, and logic structures using fabricated silicon dangling bonds [6][7][8]. In many cases the structures

Hexagonal boron nitride: a review of the emerging material platform for single-photon sources and the spin–photon interface

• Stefania Castelletto,
• Faraz A. Inam,
• Shin-ichiro Sato and
• Alberto Boretti

Beilstein J. Nanotechnol. 2020, 11, 740–769, doi:10.3762/bjnano.11.61

• ) with proven single-photon emission from the visible to infrared, a quantum spin–photon interface, and ancilla qubits, it is expected that other material platforms could emerge with similar characteristics in the near future. These two materials also naturally lead to monolithic integrated photonics as

• spin–photon interfaces for remote spin–photon entanglement with available nuclear spins as ancilla qubits for quantum memory [11][12]. These include the nitrogen-vacancy (NV) center in diamond [13], the silicon-vacancy center in diamond [14][15][16], the germanium-vacancy center in diamond [17], the

• nuclear spins and concentrations; however, suitable impurities have not yet been recognized. As such, ancilla qubits such as nuclear spins that can couple with the point defects for quantum memories in a future quantum network appear to be still an element under investigation among these emerging

Anomalous current–voltage characteristics of SFIFS Josephson junctions with weak ferromagnetic interlayers

• Tairzhan Karabassov,
• Anastasia V. Guravova,
• Aleksei Yu. Kuzin,
• Elena A. Kazakova,
• Shiro Kawabata,
• Boris G. Lvov and
• Andrey S. Vasenko

Beilstein J. Nanotechnol. 2020, 11, 252–262, doi:10.3762/bjnano.11.19

• , e.g., single-flux quantum circuits [46][47], spintronic devices [48], memory elements [49][50][51][52][53][54][55][56][57][58] and spin-valves [59][60][61][62][63][64][65], magnetoelectronics [66][67][68], qubits [69], artificial neural networks [70], microrefrigerators [71][72], and low-temperature

Nitrogen-vacancy centers in diamond for nanoscale magnetic resonance imaging applications

• Alberto Boretti,
• Lorenzo Rosa,
• Jonathan Blackledge and
• Stefania Castelletto

Beilstein J. Nanotechnol. 2019, 10, 2128–2151, doi:10.3762/bjnano.10.207

Unipolar magnetic field pulses as an advantageous tool for ultrafast operations in superconducting Josephson “atoms”

• Daria V. Popolitova,
• Nikolay V. Klenov,
• Igor I. Soloviev,
• Sergey V. Bakurskiy and
• Olga V. Tikhonova

Beilstein J. Nanotechnol. 2019, 10, 1548–1558, doi:10.3762/bjnano.10.152

• picosecond time scale. The experimental realization of a circuit-on-chip for the discussed ultrafast control is presented. Keywords: adiabatic superconducting logic; Josephson “atoms”; quantum-state-control; superconducting qubits; ultrafast quantum operations; Introduction One of the main problems of

• modern quantum physics is the transfer and storage of quantum information. This is why the development of quantum logic protocols using the fast state control of promising qubits and registers is of great importance. Superconducting artificial atoms based on Josephson junction circuits underlie a number

• state preparation and control, the characteristic Rabi-period appears to be in the nanosecond range, which is caused by the small energy separation and near-degeneracy of the atomic levels. For this reason an important task is to decrease the time of the operations with meta-atoms (qubits, qutrits

Transport signatures of an Andreev molecule in a quantum dot–superconductor–quantum dot setup

• Zoltán Scherübl,
• András Pályi and
• Szabolcs Csonka

Beilstein J. Nanotechnol. 2019, 10, 363–378, doi:10.3762/bjnano.10.36

• , nanodevices provide the confinement of electrons into 1D or 0D. The interplay of these properties is a key ingredient of novel promising qubit realizations, such as Majorana qubits [1][2] and Andreev qubits [3]. The basic physical mechanism behind these applications is the Andreev reflection, when a Cooper

Two-dimensional semiconductors pave the way towards dopant-based quantum computing

• José Carlos Abadillo-Uriel,
• Belita Koiller and
• María José Calderón

Beilstein J. Nanotechnol. 2018, 9, 2668–2673, doi:10.3762/bjnano.9.249

• 21941-972, Brazil 10.3762/bjnano.9.249 Abstract Since the proposal in 1998 to build a quantum computer using dopants in silicon as qubits, much progress has been made in the nanofabrication of semiconductors and the control of charge and spins in single dopants. However, an important problem remains

• (for two-qubit operations). Our results indicate that a wide variety of 2D materials may perform at least as well as, and possibly better, than the currently studied bulk host materials for donor qubits. Keywords: two-dimensional (2D) materials; dopants; qubits; quantum computing; Introduction

• compatible with the existing Si-based transistor industry. For spin qubits, Si has the additional advantage of sustaining very long spin-coherence times, up to seconds for isotopically purified Si [3]. The effort to understand single-donor behavior has led to significant raise of expertise on the

Tunable fractional Fourier transform implementation of electronic wave functions in atomically thin materials

• Daniela Dragoman

Beilstein J. Nanotechnol. 2018, 9, 1828–1833, doi:10.3762/bjnano.9.174

• even realized with superconducting qubits [4], but no affordable, room-temperature substitute to present-day desktop computers is available up to now. On the other hand, the development of enhanced computing architectures fabricated with the help of the current nanotechnology could alleviate at least

Josephson effect in junctions of conventional and topological superconductors

• Alex Zazunov,
• Albert Iks,
• Miguel Alvarado,
• Alfredo Levy Yeyati and
• Reinhold Egger

Beilstein J. Nanotechnol. 2018, 9, 1659–1676, doi:10.3762/bjnano.9.158

• devices allow for a Majorana-induced parity switch between Andreev state sectors with different parity in a superconducting atomic contact. This observation could be useful for future microwave spectroscopy experiments of Andreev qubits in such contacts. Schematic setups studied in this paper. a) S–QD–TS

Spatial Rabi oscillations between Majorana bound states and quantum dots

• Jun-Hui Zheng,
• Dao-Xin Yao and
• Zhi Wang

Beilstein J. Nanotechnol. 2018, 9, 1527–1535, doi:10.3762/bjnano.9.143

• ][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. The study of Majorana bound states has attracted tremendous interest recently because they constitute topological parity qubits. These qubits are defined by the degenerate ground states of topological superconductors, and therefore are

• protected by the superconducting energy gap [4][15]. They have a long coherence time and are resistant to local decoherence sources [15][2][18][19]. Most importantly, the topological qubits can be topologically manipulated by braiding the Majorana bound states [4][15][17]. These topological braiding

• qubits based on quantum dots [42]. Finally, we note that our results are based on the minimal models for the quantum dot, the Majorana bound state and the Andreev bound state. It is certainly helpful to consider more sophisticated models for the quantum dot by including the Zeeman energy and Coulomb

Robust topological phase in proximitized core–shell nanowires coupled to multiple superconductors

• Tudor D. Stanescu,
• Anna Sitek and
• Andrei Manolescu

Beilstein J. Nanotechnol. 2018, 9, 1512–1526, doi:10.3762/bjnano.9.142

• , = 3,5. We conclude that the presence of disorder induces low-energy localized states than can destroy the topological protection of the Majorana subspace. We note that within a topological quantum computation scheme based on qubits characterized by a finite charging energy [51][52], interaction-mediated

Interplay between pairing and correlations in spin-polarized bound states

• Szczepan Głodzik,
• Aksel Kobiałka,
• Anna Gorczyca-Goraj,
• Andrzej Ptok,
• Grzegorz Górski,
• Maciej M. Maśka and
• Tadeusz Domański

Beilstein J. Nanotechnol. 2018, 9, 1370–1380, doi:10.3762/bjnano.9.129

• (σ = ↓) section. This effect has to be taken into account, when designing nanostructures for a controllable spatial displacement of the Majorana modes (criticial for the realization of quantum computations with use of the Majorana-based qubits) either by electrostatic or magnetic means. Some

• an electrostatic potential. This would be important for future quantum computers using qubits based on topologically protected Majorana states. Finally, we have also confronted the Majorana quasiparticles with the subgap Kondo effect, revealing their complex relationship that can be hardly regarded

Beyond Moore’s technologies: operation principles of a superconductor alternative

• Igor I. Soloviev,
• Nikolay V. Klenov,
• Sergey V. Bakurskiy,
• Mikhail Yu. Kupriyanov,
• Alexander L. Gudkov and
• Anatoli S. Sidorenko

Beilstein J. Nanotechnol. 2017, 8, 2689–2710, doi:10.3762/bjnano.8.269

• quantum computers. QFPs are utilized as qubits and couplers in adiabatic quantum optimization systems of D-Wave Systems [60][61]. Another reason for the current rise of interest to ASL is the Japanese JST-ALCA project “Superconductor electronics system combined with optics and spintronics” [62]. The idea

• “flying qubits” transmitting quantum information [73][76]. Yet, this idea is not implemented experimentally. Discussion We considered non-adiabatic and adiabatic logics the implementations of which are different mainly in the type of power supply: ac or dc. Each type has its own advantages and

Tuning the spin coherence time of Cu(II)−(bis)oxamato and Cu(II)−(bis)oxamidato complexes by advanced ESR pulse protocols

• Ruslan Zaripov,
• Evgeniya Vavilova,
• Iskander Khairuzhdinov,
• Kev Salikhov,
• Violeta Voronkova,
• Mohammad A. Abdulmalic,
• Francois E. Meva,
• Saddam Weheabby,
• Tobias Rüffer,
• Bernd Büchner and
• Vladislav Kataev

Beilstein J. Nanotechnol. 2017, 8, 943–955, doi:10.3762/bjnano.8.96

• amounts to10τc. From the point of view of potential application of electron spins as qubits, the slowing down of the spin decoherence as compared to the primary echo is certainly an interesting effect. Furthermore, for a given time interval of the observation the slowing down of the spin decoherence

A terahertz-vibration to terahertz-radiation converter based on gold nanoobjects: a feasibility study

• Kamil Moldosanov and
• Andrei Postnikov

Beilstein J. Nanotechnol. 2016, 7, 983–989, doi:10.3762/bjnano.7.90

• processing systems. A working unit for quantum-information applications can be imagined in the spirit of a scheme described by Stannigel et al. [21][22], in which a nanomechanical resonator mediates interactions between the qubits and light. We suggest that gold nanobars and nanorings discussed in the