Impact of electron–phonon coupling on electron transport through T-shaped arrangements of quantum dots in the Kondo regime

• Patryk Florków and
• Stanisław Lipiński

Beilstein J. Nanotechnol. 2021, 12, 1209–1225, doi:10.3762/bjnano.12.89

• the coherent superposition of cotunneling processes. The latter lead to effective spin flips, in consequence of which the bound singlet state of the dot spin with the electrons of the leads is formed. This resonance is characterized by SU(2) symmetry. In nanoscopic systems SU(2) Kondo effects have

• very weakly in the transmission through the open dot in the case when phonons couple to IQDs. However, they are reflected clearly in the density of states (DOS) of IQDs, but this is difficult to detect in transport experiments. The single T-shaped device decoupled from phonons is characterized by SU(2

• determined by the Fano parameter q = EO/Γ, which can be tuned by gate voltage. For q = 0 interference between the ballistic channel through the open dot and the Kondo resonant channel leads to the symmetric dip structure with vanishing transmission for SU(2) symmetry (destructive interference, Fano–Kondo

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

• close to perpendicular. When the field approaches a transverse orientation a crossover from SU(2) or SU(3) symmetry into SU(4) is observed. Keywords: carbon nanotubes; Kondo effect; mesoscopic transport; quantum dots; valleytronics; Introduction Due to their remarkable electronic, transport

• due to intershell mixing. We also announced in [26] the possibility of the occurrence of the SU(4) Kondo effect in narrow-bandgap nanotubes despite the presence of SO coupling. In the present paper, we show that the Kondo physics of narrow-bandgap nanotubes is much richer. Apart from SU(2) Kondo

• slanting magnetic fields. Based on this observation we anticipate the possible occurrence of Kondo effects in which both types of carriers take part. Apart from SU(2) Kondo lines, also SU(3) Kondo points and SU(4) may appear for orientations of the field close to perpendicular. Model and Formalism In our

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

• for concreteness, we here imagine the field B as independent local field coupled only to the QD spin. One could use, e.g., a ferromagnetic grain near the QD to generate it. This field here plays a crucial role because for B = 0, the S+QD part is spin rotation [SU(2)] invariant and the arguments of [31

Solid-state Stern–Gerlach spin splitter for magnetic field sensing, spintronics, and quantum computing

• Kristofer Björnson and
• Annica M. Black-Schaffer

Beilstein J. Nanotechnol. 2018, 9, 1558–1563, doi:10.3762/bjnano.9.147

• magnetic flux and as a spintronics switch. With normal metallic leads a switchable spintronics NOT-gate can be implemented. Furthermore, we show that a sequence of such devices can be used to construct a single-qubit SU(2)-gate, one of the two gates required for a universal quantum computer. The field

• sensitivity, or switching field, b, is related to the characteristic size of the device, r, through b = h/(2πqr2), with q being the unit of electric charge. Keywords: Aharanov–Bohm; quantum computing; spintronics; Stern–Gerlach; SU(2); topological insulator; Introduction Two famous examples of the

• already been noted in [14]. While the ordinary AB effect arises because of interference in a single complex number, the effects achieved here relies on modifying the relative phase between the up and down components of the spin. Thus, the effects we describe here can be classified as a SU(2)-AB effects