Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1210.4645 · Physical Review Letters

Dispersive Readout of a Few-Electron Double Quantum Dot with Fast rf Gate Sensors

James Colless, Alice Mahoney, J. M. Hornibrook, Andrew C. Doherty, Hong Lü, Arthur C. Gossard, D. J. Reilly

Published Jan 25, 2013• 211 citations
arXivHTMLPDF

Abstract

We report the dispersive charge-state readout of a double quantum dot in the few-electron regime using the in situ gate electrodes as sensitive detectors. We benchmark this gate sensing technique against the well established quantum point contact charge detector and find comparable performance with a bandwidth of $\ensuremath{\sim}10\text{ }\text{ }\mathrm{MHz}$ and an equivalent charge sensitivity of $\ensuremath{\sim}6.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{ }e/\sqrt{\mathrm{Hz}}$. Dispersive gate sensing alleviates the burden of separate charge detectors for quantum dot systems and promises to enable readout of qubits in scaled-up arrays.

DOI
10.1103/physrevlett.110.046805

Related papers

Dispersive readout of a silicon quantum dot with an accumulation-mode gate sensor

A. Rossi, R. Zhao, Andrew S. Dzurak +1 more

Sensitive charge detection has enabled qubit readout in solid-state systems. Recently, an alternative to the well-established charge detection via on-chip electrometers has emerged, based on in situ gate detectors and radio-frequency dispersive readout techniques. This approach promises to facilitate scalability by removing the need for additional device components devoted to sensing. Here, we perform gate-based dispersive readout of an accumulation-mode silicon quantum dot. We observe that the response of an accumulation-mode gate detector is significantly affected by its bias voltage, particularly if this exceeds the threshold for electron accumulation. We discuss and explain these results in light of the competing capacitive contributions to the dispersive response.

arXiv:1610.00767•Applied Physics Letters•May 22, 2017•20 citations

Dispersive readout of a silicon quantum dot with an accumulation-mode gate sensor

Alessandro Rossi, Ruichen Zhao, Andrew S. Dzurak +1 more

Sensitive charge detection has enabled qubit readout in solid-state systems. Recently, an alternative to the well-established charge detection via on-chip electrometers has emerged, based on $\textit{in situ}$ gate detectors and radio-frequency dispersive readout techniques. This approach promises to facilitate scalability by removing the need for additional device components devoted to sensing. Here, we perform gate-based dispersive readout of an accumulation-mode silicon quantum dot. We observe that the response of an accumulation-mode gate detector is significantly affected by its bias voltage, particularly if this exceeds the threshold for electron accumulation. We discuss and explain these results in light of the competing capacitive contributions to the dispersive response.

•May 23, 2017•12 citations

Scalable Control and Measurement of Gate-Defined Quantum Dot Systems

James Colless

There is currently a worldwide effort towards the realisation of large-scale quantum computers that exploit quantum phenomena for information processing. While these computing systems could potentially redefine the technological landscape, harnessing quantum effects is challenging due to their inherently fragile nature and the experimentally demanding environments in which they arise. In order for quantum computation to be viable it is first necessary to demonstrate the operation of two-level quantum systems (qubits) which have long coherence times, can be quickly read out, and can be controlled with high fidelity. Focusing on these key requirements, this thesis presents four experiments towards scalable solid state quantum computing using gate-defined quantum dot devices based on gallium arsenide (GaAs) heterostructures. The first experiment investigates a phonon emission process that limits the charge coherence in GaAs and potentially complicates the microwave control of multi-qubit devices. We show that this microwave analogy to Raman spectroscopy can provide a means of detecting the unique phonon spectral density created by a nanoscale device. Experimental results are compared to a theoretical model based on a non-Markovian master equation and approaches to suppressing electron-phonon coupling are discussed. The second experiment demonstrates a technique involving in-situ gate electrodes coupled to lumped-element resonators to provide high-bandwidth dispersive read-out of the state of a double quantum dot. We characterise the charge sensitivity of this method in the few-electron regime and benchmark its performance against quantum point contact charge sensors. The third experiment implements a low-loss, chip-level frequency multiplexing scheme for the readout of scaled-up spin qubit arrays. Dispersive gate-sensing is realised in combination with charge detection based on two radio frequency quantum point contacts to perform multiplexed readout of a double quantum dot in the few-electron regime. Demonstration of a 10-channel multiplexing device is achieved and limitations in scaling spin qubit readout to large numbers using multiplexed channels discussed. The final experiment ties previously presented results together by realising a micro-architecture for controlling and reading out qubits during the execution of a quantum algorithm. The basic principles of this architecture are demonstrated via the manipulation of a semiconductor qubit using control pulses that are cryogenically routed using a high-electron mobility transistor switching matrix controlled by a field programmable gate array. Finally, several technical results are also presented including the development of printed circuit board solutions to allow the high-frequency measurement of nanoscale devices at cryogenic temperatures and the design of on-chip interconnects used to suppress electromagnetic crosstalk in high-density spin qubit device architectures.

•Oct 10, 2016•0 citations

Fast single-charge sensing with a rf quantum point contact

D. J. Reilly, Charles M. Marcus, Micah P. Hanson +1 more

We report high-bandwidth charge sensing measurements using a GaAs quantum point contact embedded in a radio frequency impedance matching circuit (rf-QPC). With the rf-QPC biased near pinch-off where it is most sensitive to charge, we demonstrate a conductance sensitivity of 5×10−6e2∕hHz−1∕2 with a bandwidth of 8MHz. Single-shot readout of a proximal few-electron double quantum dot is investigated in a mode where the rf-QPC back action is rapidly switched.

arXiv:0707.2946•Applied Physics Letters•Oct 15, 2007•295 citations

Frequency multiplexing for readout of spin qubits

J. M. Hornibrook, James Colless, Alice Mahoney +5 more

We demonstrate a low loss, chip-level frequency multiplexing scheme for readout of scaled-up spin qubit devices. By integrating separate bias tees and resonator circuits on-chip for each readout channel, we realise dispersive gate-sensing in combination with charge detection based on two radio frequency quantum point contacts. We apply this approach to perform multiplexed readout of a double quantum dot in the few-electron regime and further demonstrate operation of a 10-channel multiplexing device. Limitations for scaling spin qubit readout to large numbers of multiplexed channels are discussed.

arXiv:1312.5064•Applied Physics Letters•Mar 10, 2014•113 citations

Probing the limits of gate-based charge sensing

M. Fernando González-Zalba, Sylvain Barraud, Andrew J. Ferguson +1 more

Quantum computation requires a qubit-specific measurement capability to readout the final state of individual qubits. Promising solid-state architectures use external readout electrometers but these can be replaced by a more compact readout element, an in situ gate sensor. Gate-sensing couples the qubit to a resonant circuit via a gate and probes the qubit’s radiofrequency polarizability. Here we investigate the ultimate performance of such a resonant readout scheme and the noise sources that limit its operation. We find a charge sensitivity of 37 μe Hz−1/2, the best value reported for this technique, using the example of a gate sensor strongly coupled to a double quantum dot at the corner states of a silicon nanowire transistor. We discuss the experimental factors limiting gate detection and highlight ways to optimize its sensitivity. In total, resonant gate-based readout has advantages over external electrometers both in terms of reduction of circuit elements as well as absolute charge sensitivity. Reading out the state of quantum bits is an essential requirement that any quantum computer implementation must satisfy. Gonzalez-Zalba et al. now show that in situresonant gate-based detection can be a more sensitive approach than external electrometers while reducing the qubit architecture’s complexity.

arXiv:1405.2755•Nature Communications•Jan 20, 2015•173 citations
We report the dispersive charge-state readout of a double quantum dot in the few-electron regime using the in situ gate electrodes as sensitive detectors. We benchmark this gate sensing technique against the well established quantum point contact charge detector and find comparable performance with a bandwidth of \ensuremath∼10  MHz\ensuremath{\sim}10\text{ }\text{ }\mathrm{MHz}\ensuremath∼10  MHz and an equivalent charge sensitivity of \ensuremath∼6.3\ifmmode×\else\texttimes\fi10\ensuremath−3  e/Hz\ensuremath{\sim}6.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{ }e/\sqrt{\mathrm{Hz}}\ensuremath∼6.3\ifmmode×\else\texttimes\fi10\ensuremath−3  e/Hz​. Dispersive gate sensing alleviates the burden of separate charge detectors for quantum dot systems and promises to enable readout of qubits in scaled-up arrays.
Sensitive charge detection has enabled qubit readout in solid-state systems. Recently, an alternative to the well-established charge detection via on-chip electrometers has emerged, based on in situ gate detectors and radio-frequency dispersive readout techniques. This approach promises to facilitate scalability by removing the need for additional device components devoted to sensing. Here, we perform gate-based dispersive readout of an accumulation-mode silicon quantum dot. We observe that the response of an accumulation-mode gate detector is significantly affected by its bias voltage, particularly if this exceeds the threshold for electron accumulation. We discuss and explain these results in light of the competing capacitive contributions to the dispersive response.
Sensitive charge detection has enabled qubit readout in solid-state systems. Recently, an alternative to the well-established charge detection via on-chip electrometers has emerged, based on in situ\textit{in situ}in situ gate detectors and radio-frequency dispersive readout techniques. This approach promises to facilitate scalability by removing the need for additional device components devoted to sensing. Here, we perform gate-based dispersive readout of an accumulation-mode silicon quantum dot. We observe that the response of an accumulation-mode gate detector is significantly affected by its bias voltage, particularly if this exceeds the threshold for electron accumulation. We discuss and explain these results in light of the competing capacitive contributions to the dispersive response.
There is currently a worldwide effort towards the realisation of large-scale quantum computers that exploit quantum phenomena for information processing. While these computing systems could potentially redefine the technological landscape, harnessing quantum effects is challenging due to their inherently fragile nature and the experimentally demanding environments in which they arise. In order for quantum computation to be viable it is first necessary to demonstrate the operation of two-level quantum systems (qubits) which have long coherence times, can be quickly read out, and can be controlled with high fidelity. Focusing on these key requirements, this thesis presents four experiments towards scalable solid state quantum computing using gate-defined quantum dot devices based on gallium arsenide (GaAs) heterostructures. The first experiment investigates a phonon emission process that limits the charge coherence in GaAs and potentially complicates the microwave control of multi-qubit devices. We show that this microwave analogy to Raman spectroscopy can provide a means of detecting the unique phonon spectral density created by a nanoscale device. Experimental results are compared to a theoretical model based on a non-Markovian master equation and approaches to suppressing electron-phonon coupling are discussed. The second experiment demonstrates a technique involving in-situ gate electrodes coupled to lumped-element resonators to provide high-bandwidth dispersive read-out of the state of a double quantum dot. We characterise the charge sensitivity of this method in the few-electron regime and benchmark its performance against quantum point contact charge sensors. The third experiment implements a low-loss, chip-level frequency multiplexing scheme for the readout of scaled-up spin qubit arrays. Dispersive gate-sensing is realised in combination with charge detection based on two radio frequency quantum point contacts to perform multiplexed readout of a double quantum dot in the few-electron regime. Demonstration of a 10-channel multiplexing device is achieved and limitations in scaling spin qubit readout to large numbers using multiplexed channels discussed. The final experiment ties previously presented results together by realising a micro-architecture for controlling and reading out qubits during the execution of a quantum algorithm. The basic principles of this architecture are demonstrated via the manipulation of a semiconductor qubit using control pulses that are cryogenically routed using a high-electron mobility transistor switching matrix controlled by a field programmable gate array. Finally, several technical results are also presented including the development of printed circuit board solutions to allow the high-frequency measurement of nanoscale devices at cryogenic temperatures and the design of on-chip interconnects used to suppress electromagnetic crosstalk in high-density spin qubit device architectures.
We demonstrate a low loss, chip-level frequency multiplexing scheme for readout of scaled-up spin qubit devices. By integrating separate bias tees and resonator circuits on-chip for each readout channel, we realise dispersive gate-sensing in combination with charge detection based on two radio frequency quantum point contacts. We apply this approach to perform multiplexed readout of a double quantum dot in the few-electron regime and further demonstrate operation of a 10-channel multiplexing device. Limitations for scaling spin qubit readout to large numbers of multiplexed channels are discussed.
Quantum computation requires a qubit-specific measurement capability to readout the final state of individual qubits. Promising solid-state architectures use external readout electrometers but these can be replaced by a more compact readout element, an in situ gate sensor. Gate-sensing couples the qubit to a resonant circuit via a gate and probes the qubit’s radiofrequency polarizability. Here we investigate the ultimate performance of such a resonant readout scheme and the noise sources that limit its operation. We find a charge sensitivity of 37 μe Hz−1/2, the best value reported for this technique, using the example of a gate sensor strongly coupled to a double quantum dot at the corner states of a silicon nanowire transistor. We discuss the experimental factors limiting gate detection and highlight ways to optimize its sensitivity. In total, resonant gate-based readout has advantages over external electrometers both in terms of reduction of circuit elements as well as absolute charge sensitivity. Reading out the state of quantum bits is an essential requirement that any quantum computer implementation must satisfy. Gonzalez-Zalba et al. now show that in situresonant gate-based detection can be a more sensitive approach than external electrometers while reducing the qubit architecture’s complexity.