Radio-Frequency Reflectometry in Silicon-Based Quantum Dots

Liu, Y. Y.; Philips, Stephan G. J.; Orona, Lucas; Samkharadze, Nodar; McJunkin, Thomas; MacQuarrie, E. R.; Eriksson, M. A.; Vandersypen, L. M. K.; Yacoby, Amir

doi:10.1103/physrevapplied.16.014057

Cited by 17 publications

(7 citation statements)

References 25 publications

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“…The impedance of the sensing dot is measured using RF reflectometry. The background of the measured signal depends on the inductance of the surface-mount inductor, the capacitance to ground 29 , 56 , 57 and the resistance to ground of the RF readout circuit. Extended Data Figure 6 f shows the response of the readout circuit under different microwave powers (the RF power is kept fixed).…”

Section: Methodsmentioning

confidence: 99%

Universal control of a six-qubit quantum processor in silicon

Philips

Mądzik

Amitonov

et al. 2022

Nature

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177

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Future quantum computers capable of solving relevant problems will require a large number of qubits that can be operated reliably1. However, the requirements of having a large qubit count and operating with high fidelity are typically conflicting. Spins in semiconductor quantum dots show long-term promise2,3 but demonstrations so far use between one and four qubits and typically optimize the fidelity of either single- or two-qubit operations, or initialization and readout4–11. Here, we increase the number of qubits and simultaneously achieve respectable fidelities for universal operation, state preparation and measurement. We design, fabricate and operate a six-qubit processor with a focus on careful Hamiltonian engineering, on a high level of abstraction to program the quantum circuits, and on efficient background calibration, all of which are essential to achieve high fidelities on this extended system. State preparation combines initialization by measurement and real-time feedback with quantum-non-demolition measurements. These advances will enable testing of increasingly meaningful quantum protocols and constitute a major stepping stone towards large-scale quantum computers.

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Section: Methodsmentioning

confidence: 99%

Universal control of a six-qubit quantum processor in silicon

Philips

Mądzik

Amitonov

et al. 2022

Nature

Self Cite

177

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“…We demonstrate the TIA's performance by measuring 2-nA peak-to-peak square-wave signals, which mimic the output of a standard charge sensing for qubit readout. The signal-to-noise ratio (SNR) for RFB = 200 k is 12.7, with a time resolution of 48 ns, which is comparable to the state-of-the-art RF reflectometry technique readout [13][14][15]. Thus, our TIA has excellent potential for industrial and fundamental research applications requiring broadband and low-noise cryogenic amplification.…”

mentioning

confidence: 88%

“…It is worth comparing the performance of our TIA-based readout electronics with that reported for RF reflectometry techniques. Our setup's bandwidth is much broader than the state-of-the-art reflectometry readout technique, which ranges from a few hundred kilohertz to ten megahertz at an SNR ≥ 1 [13][14][15]. Concerning the current sensitivity, the fastest reported reflectometry setup (f−3dB = 10 MHz set by an auxiliary LPF) has an SNR of at 60 mK using the input power corresponding to excitation of approximately 2 nArms [13].…”

mentioning

confidence: 99%

Fast time-domain current measurement for quantum dot charge sensing using a homemade cryogenic transimpedance amplifier

Bohuslavskyi

Hashisaka

Shimizu

et al. 2022

Applied Physics Letters

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We developed a high-speed and low-noise time-domain current measurement scheme using a homemade GaAs high-electron-mobility-transistor-based cryogenic transimpedance amplifier (TIA). The scheme is versatile for broad cryogenic current measurements, including semiconductor spin-qubit readout, owing to the TIA's having low input impedance comparable to that of commercial room-temperature TIAs. The TIA has a broad frequency bandwidth and a low noise floor, with a trade-off between them governed by the feedback resistance RFB. A lower RFB of 50 kΩ enables high-speed current measurement with a −3 dB cutoff frequency f−3dB = 28 MHz and noise-floor NF = 8.5 × 10−27 A2/Hz, while a larger RFB of 400 kΩ provides low-noise measurement with NF = 1.0 × 10−27 A2/Hz and f−3dB = 4.5 MHz. Time-domain measurement of a 2-nA peak-to-peak square wave, which mimics the output of the standard spin-qubit readout technique via charge sensing, demonstrates a signal-to-noise ratio (SNR) of 12.7, with the time resolution of 48 ns, for RFB = 200 kΩ, which compares favorably with the best-reported values for the radio frequency reflectometry technique. The time resolution can be further improved at the cost of the SNR (or vice versa) by using an even smaller (larger) RFB, with a further reduction in the noise figure possible by limiting the frequency band with a low-pass filter. Our scheme is best suited for readout electronics for cryogenic sensors that require a high time resolution and current sensitivity and, thus, provides a solution for various fundamental research and industrial applications.

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“…This lack of tuning flexibility is often problematic. The problem is solved by an accumulation-mode layout: This is a device with multiple pattern gate-layers, for which positive and negative voltages for accumulation and depletion are chosen within layers [2,[37][38][39][40].…”

Section: Gate Layoutsmentioning

confidence: 99%