Related papers: Charge Relaxation in a Single Electron Si/SiGe Dou…
We developed transmon qubits based on epitaxial tunnel junctions and interdigitated capacitors. This multileveled qubit, patterned by use of all-optical lithography, is a step towards scalable qubits with a high integration density. The…
The temperature-dependent electron spin relaxation of positively charged excitons in a single InAs quantum dot (QD) was measured by time-resolved photoluminescence spectroscopy at zero applied magnetic fields. The experimental results show…
One of the biggest challenges impeding the progress of Metal-Oxide-Silicon (MOS) quantum dot devices is the presence of disorder at the Si/SiO$_2$ interface which interferes with controllably confining single and few electrons. In this work…
Engineered spin-electric coupling enables spin qubits in semiconductor nanostructures to be manipulated efficiently and addressed individually. While synthetic spin-orbit coupling using a micromagnet is widely used for driving qubits based…
Electric control of individual atoms or molecules in a solid-state system offers a promising way to bring quantum mechanical functionalities into electronics. This idea has recently come into the reach of the established domain of silicon…
The longitudinal spin relaxation time, T1, in a Si/SiGe quantum well is determined from the saturation of the ESR signal. We find values of a few microseconds. Investigations of T1 as a function of Fermi energy, concentration of scattering…
We present measurements of the capacitive coupling energy and the inter-dot capacitances in a linear quadruple quantum dot array in undoped Si/SiGe. With the device tuned to a regime of strong ($>$1 GHz) intra-double dot tunnel coupling, as…
We study theoretically phonon-induced spin dynamics of two electrons confined in a self-assembled double quantum dot. We calculate the transition rates and time evolution of occupations for the spin-triplet and spin-singlet states. We…
We investigate the energy and phase relaxation of a superconducting qubit caused by a single quasiparticle. In our model, the qubit is an isolated system consisting of a small island (Cooper-pair box) and a larger superconductor (reservoir)…
We present the experimental observation of a large exchange coupling $J \approx 300$ $\mu$eV between two $^{31}$P electron spin qubits in silicon. The singlet and triplet states of the coupled spins are monitored in real time by a…
Fast operations, an easily tunable Hamiltonian, and a straightforward two-qubit interaction make charge qubits a useful tool for benchmarking device performance and exploring two-qubit dynamics. Here, we tune a linear chain of four Si/SiGe…
To test the contribution of non-equilibrium quasiparticles to qubit relaxation, we have repeatedly measured the relaxation time T_1 in Al/AlOx/Al transmons with electrodes that have different superconducting gaps. In one device, the first…
Charge-based quantum computation can be attained through reliable control of single electrons in lead-less quantum systems. Single-charge transitions in electrically-isolated double quantum dots (DQD) realised in phosphorus-doped silicon…
We report on dual-gate reflectometry in a metal-oxide-semiconductor double-gate silicon transistor operating at low temperature as a double quantum dot device. The reflectometry setup consists of two radio-frequency resonators respectively…
We have engineered the bandgap profile of transmon qubits by combining oxygen-doped Al for tunnel junction electrodes and clean Al as quasiparticle traps to investigate energy relaxation due to quasiparticle tunneling. The relaxation time…
Dielectric constant and absorption measurements on boron doped silicon samples show that transitions between the acceptor energy levels can be induced by an applied resonant ac electric field and the Stark tuning of level spacing with an…
We study and compare two analytic models of graphene quantum dots for calculating charge relaxation times due to electron-phonon interaction. Recently, charge relaxation processes in graphene quantum dots have been probed experimentally and…
Silicon spin qubits are promising candidates for realising large scale quantum processors, benefitting from a magnetically quiet host material and the prospects of leveraging the mature silicon device fabrication industry. We report the…
Recent studies of silicon spin qubits at temperatures above 1 K are encouraging demonstrations that the cooling requirements for solid-state quantum computing can be considerably relaxed. However, qubit readout mechanisms that rely on…
We investigate the relaxation of a superconducting qubit for the case when its detector, the Josephson bifurcation amplifier, remains latched in one of its two (meta)stable states of forced vibrations. The qubit relaxation rates are…