118 research outputs found
Remote capacitive sensing in two-dimension quantum-dot arrays
We investigate gate-defined quantum dots in silicon on insulator nanowire
field-effect transistors fabricated using a foundry-compatible fully-depleted
silicon-on-insulator (FD-SOI) process. A series of split gates wrapped over the
silicon nanowire naturally produces a bilinear array of quantum
dots along a single nanowire. We begin by studying the capacitive coupling of
quantum dots within such a 22 array, and then show how such couplings
can be extended across two parallel silicon nanowires coupled together by
shared, electrically isolated, 'floating' electrodes. With one quantum dot
operating as a single-electron-box sensor, the floating gate serves to enhance
the charge sensitivity range, enabling it to detect charge state transitions in
a separate silicon nanowire. By comparing measurements from multiple devices we
illustrate the impact of the floating gate by quantifying both the charge
sensitivity decay as a function of dot-sensor separation and configuration
within the dual-nanowire structure.Comment: 9 pages, 3 figures, 35 cites and supplementar
Single-electron control in a foundry-fabricated two-dimensional qubit array
Silicon spin qubits have achieved high-fidelity one- and two-qubit gates,
above error correction thresholds, promising an industrial route to
fault-tolerant quantum computation. A significant next step for the development
of scalable multi-qubit processors is the operation of foundry-fabricated,
extendable two-dimensional (2D) arrays. In gallium arsenide, 2D quantum-dot
arrays recently allowed coherent spin operations and quantum simulations. In
silicon, 2D arrays have been limited to transport measurements in the
many-electron regime. Here, we operate a foundry-fabricated silicon 2x2 array
in the few-electron regime, achieving single-electron occupation in each of the
four gate-defined quantum dots, as well as reconfigurable single, double, and
triple dots with tunable tunnel couplings. Pulsed-gate and gate-reflectometry
techniques permit single-electron manipulation and single-shot charge readout,
while the two-dimensionality allows the spatial exchange of electron pairs. The
compact form factor of such arrays, whose foundry fabrication can be extended
to larger 2xN arrays, along with the recent demonstration of coherent spin
control and readout, paves the way for dense qubit arrays for quantum
computation and simulation.Comment: 9 pages (including supplementary information and 5 figures
Pauli Blockade in a Few-Hole PMOS Double Quantum Dot limited by Spin-Orbit Interaction
We report on hole compact double quantum dots fabricated using conventional
CMOS technology. We provide evidence of Pauli spin blockade in the few hole
regime which is relevant to spin qubit implementations.
A current dip is observed around zero magnetic field, in agreement with the
expected behavior for the case of strong spin-orbit. We deduce an intradot spin
relaxation rate 120\,kHz for the first holes, an important step
towards a robust hole spin-orbit qubit
Reflectometry of charge transitions in a silicon quadruple dot
Gate-controlled silicon quantum devices are currently moving from academic
proof-of-principle studies to industrial fabrication, while increasing their
complexity from single- or double-dot devices to larger arrays. We perform
gate-based high-frequency reflectometry measurements on a 2x2 array of silicon
quantum dots fabricated entirely using 300 mm foundry processes. Utilizing the
capacitive couplings within the dot array, it is sufficient to connect only one
gate electrode to one reflectometry resonator and still establish
single-electron occupation in each of the four dots and detect single-electron
movements with high bandwidth. A global top-gate electrode adjusts the overall
tunneling times, while linear combinations of side-gate voltages yield detailed
charge stability diagrams. We support our findings with
modeling and electrostatic simulations based on a
constant interaction model, and experimentally demonstrate single-shot
detection of interdot charge transitions with unity signal-to-noise ratios at
bandwidths exceeding 30 kHz. Our techniques may find use in the scaling of
few-dot spin-qubit devices to large-scale quantum processors.Comment: 10 pages including appendices and 7 figure
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