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In semiconductor hole spin qubits, low magnetic field ($B$) operation extends the coherence time ($T_\mathrm{2}^*$) but proportionally reduces the gate speed. In contrast, singlet-triplet (ST) qubits are primarily controlled by the exchange…

We calculate the electronic structure of germanium-tin (Ge$_{1-x}$Sn$_{x}$) binary alloys for $0 \leq x \leq 1$ using density functional theory (DFT). Relaxed alloys with semiconducting or semimetallic behaviour as a function of Sn…

Materials Science · Physics 2021-05-26 Conor O'Donnell , Alfonso Sanchez-Soares , Christopher A. Broderick , James C. Greer

We demonstrate dynamical spin injection into p-type germanium (Ge) at room temperature (RT) using spin pumping. The generated pure spin current is converted to a charge current by the inverse spin-Hall effect (ISHE) arising in the p-type Ge…

A novel spintronic nanodevice is proposed that is capable to manipulate the single heavy hole spin state in a coherent manner. It can act as a single quantum logic gate. The heavy hole spin transformations are realized by transporting the…

Mesoscale and Nanoscale Physics · Physics 2015-06-04 P. Szumniak , S. Bednarek , B. Partoens , F. M. Peeters

First-principles calculations were performed to investigate the electronic structure of two-dimensional (2-D) Ge, Sn, and Pb without and with the presence of an external electric field in combination with spin-orbit coupling. Tight-binding…

In superconductor-semiconductor hybrid structures, superconductivity and spin polarization are competing effects because magnetic fields break Cooper pairs. They can be combined using thin films and in-plane magnetic fields, an approach…

Electrically defined semiconductor quantum dots are attractive systems for spin manipulation and quantum information processing. Heavy-holes in both Si and GaAs are promising candidates for all-electrical spin manipulation, owing to the…

Mesoscale and Nanoscale Physics · Physics 2016-12-06 Daisy Q. Wang , Oleh Klochan , Jo-Tzu Hung , Dimitrie Culcer , Ian Farrer , David A. Ritchie , Alexander R. Hamilton

The phonon modes of self-assembled Ge/Si quantum dots grown by molecular-beam epitaxy in an apparatus integrated with a chamber of the scanning tunneling microscope into a single high-vacuum system are investigated using Raman spectroscopy.…

We study the formation and characteristics of "spin droplets",i.e., compact spin-polarized configurations in the highest occupied Landau level, in an etched quantum Hall device at filling factors $2\leq\nu\leq3$. The confining potential for…

Mesoscale and Nanoscale Physics · Physics 2015-06-12 H. Atci , U. Erkarslan , A. Siddiki , E. Rasanen

Holes confined in semiconductor nanostructures realize qubits where the quantum mechanical spin is strongly mixed with the quantum orbital angular momentum. The remarkable spin-orbit coupling allows for fast all electrical manipulation of…

Mesoscale and Nanoscale Physics · Physics 2021-01-22 Vincent P. Michal , Benjamin Venitucci , Yann-Michel Niquet

Optical spin orientation and depolarization phenomena in semiconductors are of overwhelming importance for the development of spin-optoelectronics. In this paper we employ Ge-based spin-photodiodes to investigate the room temperature…

Mesoscale and Nanoscale Physics · Physics 2021-03-16 C. Rinaldi , M. Cantoni , R. Bertacco

In recent years, hole-spin qubits based on semiconductor quantum dots have advanced at a rapid pace. We first review the main potential advantages of these hole-spin qubits with respect to their electron-spin counterparts, and give a…

Mesoscale and Nanoscale Physics · Physics 2023-02-07 Yinan Fang , Pericles Philippopoulos , Dimitrie Culcer , W. A. Coish , Stefano Chesi

Spins based in silicon provide one of the most promising architectures for quantum computing. Quantum dots are an inherently scalable technology. Here, we combine these two concepts into a workable design for a silicon-germanium quantum…

Group IV alloys of GeSn have gained significant attention for electronic and optoelectronic applications on a Si platform due to their compatibility with existing CMOS technology, tunable band structure, and potential for a direct bandgap…

In this work, we probe the sensitivity of hole-spin properties to hole occupation number in a planar silicon double-quantum dot device fabricated on a 300 mm integrated platform. Using DC transport measurements, we investigate the g-tensor…

In this paper, several nanodevices which realize basic single heavy hole qubit operations are proposed and supported by time dependent self consistent Poisson-Schr\"{o}dinger calculations using a four band heavy hole-light hole model. In…

Mesoscale and Nanoscale Physics · Physics 2015-06-15 P. Szumniak , S. Bednarek , J. Pawłowski , B. Partoens

We report high resolution coherent population trapping on a single hole spin in a semiconductor quantum dot. The absorption dip signifying the formation of a dark state exhibits an atomic physics-like dip width of just 10 MHz. We observe…

The electron-hole states of semiconductor quantum dots are investigated within the framework of empirical tight-binding descriptions for Si, as an example of an indirect gap material, and InAs and CdSe as examples of typical III-V and II-VI…

Condensed Matter · Physics 2009-10-31 Seungwon Lee , Lars Jonsson , John W. Wilkins , Garnett W. Bryant , Gerhard Klimeck

We report measurements of spin susceptibility of a two-dimensional hole gas confined at an GaAs/AlGaAs interface in density range from 2.8 x 10^10 to 6.5 x 10^10 cm-2. We used the method of spin polarization of carriers in parallel magnetic…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Mukesh Kumar , Giorgio Mori , Flavio Capotondi , Giorgio Biasiol , Lucia Sorba

Low-dimensional germanium hole devices are promising systems with many potential applications such as hole spin qubits, Andreev spin qubits, and Josephson junctions, and can serve as a basis for the realization of topological…

Mesoscale and Nanoscale Physics · Physics 2023-10-27 Christoph Adelsberger , Henry F. Legg , Daniel Loss , Jelena Klinovaja