Radio-Frequency Capacitive Gate-Based Sensing

Ahmed, Imtiaz; Haigh, J. A.; Schaal, Simon; Barraud, S.; Zhu, Yi; Lee, Chang-Min; Amado, M.; Robinson, Jason W. A.; Rossi, Alessandro; Morton, John J. L.; González-Zalba, M. Fernando

doi:10.1103/physrevapplied.10.014018

Cited by 71 publications

(71 citation statements)

References 47 publications

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“…The detection of electron tunnelling using radiofrequency (rf) reflectometry has been demonstrated in a variety of quantum dot architectures [9][10][11][12][13][14][15]. By detecting shifts in the phase of the reflected signal, this technique can approach the sensitivity of state of the art charge sensors.…”

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confidence: 99%

“…This would increase the observed phase shift eight-fold, resulting in an average gate-based spin readout fidelity exceeding 99% (Methods). Further improvements can be obtained using optimised external matching techniques [15] or parametric amplification. Moreover, we emphasise that even if an on-chip electrometer outperforms a gate-based solution in terms of readout sensitivity, its benefits must be weighed against the added complexity as the number of qubits is increased.…”

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confidence: 99%

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Gate-based single-shot readout of spins in silicon

et al. 2019

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Electron spins in silicon quantum dots provide a promising route towards realising the large number of coupled qubits required for a useful quantum processor [1][2][3][4][5][6][7][8]. At present, the requisite single-shot spin qubit measurements are performed using on-chip charge sensors, capacitively coupled to the quantum dots. However, as the number of qubits is increased, this approach becomes impractical due to the footprint and complexity of the charge sensors, combined with the required proximity to the quantum dots [5]. Alternatively, the spin state can be measured directly by detecting the complex impedance of spin-dependent electron tunnelling between quantum dots [9][10][11]. This can be achieved using radio-frequency reflectometry on a single gate electrode defining the quantum dot itself [11][12][13][14][15], significantly reducing gate count and architectural complexity, but thus far it has not been possible to achieve single-shot spin readout using this technique. Here, we detect single electron tunnelling in a double quantum dot and demonstrate that gate-based sensing can be used to read out the electron spin state in a single shot, with an average readout fidelity of 73%. The result demonstrates a key step towards the readout of many spin qubits in parallel, using a compact gate design that will be needed for a large-scale semiconductor quantum processor.

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Gate-based single-shot readout of spins in silicon

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“…To measure the parametric capacitance of the DQD, we employ radiofrequency (RF) reflectometry by interfacing the transistor with an electrical LC resonator with a resonance frequency ω r /2π = 313 MHz and a loaded quality factor Q ∼ 40. The resonator is coupled to the DQD via the top gate for high-sensitivity dispersive readout [43][44][45][46][47] and consists of a surface mount inductor, L = 390 nH, and the parasitic capacitance to ground of the device, C p = 660 fF. Changes in device capacitance manifest as changes in resonant frequency (ω r = 1/ L(C p + C pm )) that we detect using lownoise cryogenic and room-temperature amplification, combined with homodyne detection.…”

Section: Resultsmentioning

confidence: 99%

Quantum interference capacitor based on double-passage Landau-Zener-Stückelberg-Majorana interferometry

et al. 2019

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The implementation of quantum technologies in electronics leads naturally to the concept of coherent singleelectron circuits, in which a single charge is used coherently to provide enhanced performance. In this work, we propose a coherent single-electron device that operates as an electrically-tunable capacitor. This system exhibits a sinusoidal dependence of the capacitance with voltage, in which the amplitude of the capacitance changes and the voltage period can be tuned by electric means. The device concept is based on double-passage Landau-Zener-Stückelberg-Majorana interferometry of a coupled two-level system that is further tunnel-coupled to an electron reservoir. We test this model experimentally by performing Landau-Zener-Stückelberg-Majorana interferometry in a single-electron double quantum dot coupled to an electron reservoir and show that the voltage period of the capacitance oscillations is directly proportional to the excitation frequency and that the amplitude of the oscillations depends on the dynamical parameters of the system: intrinsic relaxation and coherence time, as well as the tunneling rate to the reservoir. Our work opens up an opportunity to use the non-linear capacitance of double quantum dots to obtain enhanced device functionalities.

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“…Moreover, we note when applying this proposed architecture to particular qubit implementations, where small voltage drifts may induce undesired effects such as unwanted decoherence, further optimization could be necessary to find an optimal trade off between voltage noise, retention time and power dissipation depending on the cell's capacitance. Finally, we note that the signal-to-noise of gate-based readout -limited by the quality factor of the resonant circuit -could be improved by using superconducting spiral inductors [39]. There is a potential for such inductors to be made CMOS compatible using TiN allowing on-chip integration.…”

Section: Discussion: Scaling Up the Architecturementioning

confidence: 98%

A CMOS dynamic random access architecture for radio-frequency readout of quantum devices

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Quantum computing technology is maturing at a relentless pace, yet individual quantum bits are wired one by one. As quantum processors become more complex, they require efficient interfaces to deliver signals for control and readout while keeping the number of inputs manageable. Digital electronics offers solutions to the scaling challenge by leveraging established industrial infrastructure and applying it to integrate silicon-based quantum devices with conventional CMOS circuits. Here, we combine both technologies at milikelvin temperatures and demonstrate the building blocks of a dynamic random access architecture for efficient readout of complex quantum circuits. Our circuit is divided into cells, each containing a CMOS quantum dot (QD) and a field-effect transistor that enables selective readout of the QD, as well as charge storage on the QD gate similar to 1T-1C DRAM technology. We show dynamic readout of two cells by interfacing them with a single radiofrequency resonator. Our results demonstrate a path to reducing the number of input lines per qubit and enable addressing of large-scale device arrays. * simon.schaal.15@ucl.ac.uk

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Radio-Frequency Capacitive Gate-Based Sensing

Cited by 71 publications

References 47 publications

Gate-based single-shot readout of spins in silicon

Gate-based single-shot readout of spins in silicon

Quantum interference capacitor based on double-passage Landau-Zener-Stückelberg-Majorana interferometry

A CMOS dynamic random access architecture for radio-frequency readout of quantum devices

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