Hensen, Bas

Date:   Friday, Sept. 14, 2018
Time:   11:00
Place:   ETH Zurich, Hönggerberg, HPF G 6
Host:   David van Woerkom

Gate-based single-shot readout of spins in silicon

Bas Hensen
The University of New South Wales, Sydney, Australia

A scalable error-corrected quantum processor will require repeated error detection across its constituent qubits [1]. At present, the requisite single-shot spin qubit measurements are performed using on-chip electrometers [2,3], capacitively coupled to the quantum dots. However, as the number of qubits is increased, this approach becomes impractical due to the complexity of the electrometers, combined with the required proximity to the quantum dots [4]. Gate-based dispersive sensing allows detection of single electron tunnelling in semiconductor quantum dots without the need for an external charge sensor [5]. Moreover, dispersive sensing of inter-dot charge transitions in tunnel coupled quantum dots combined with Pauli spin-blockade can be used to readout the electronic spin state without the need for a nearby electron reservoir [6-8] These properties can significantly reduce gate count and architectural complexity of extended one- or two- dimensional arrays of quantum dots [9-11]. At present, it has not been possible to achieve single-shot spin readout using a gate-based technique. Here [12], we detect single electron tunnelling in a double quantum dot and demonstrate that gate-based sensing can be used to read out the electronic 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.


1 - A. G. Fowler, M. Mariantoni, J. M. Martinis, A. N. Cleland, Physical Review A 86, 032324 (2012).
2 -M. A. Kastner, Reviews of Modern Physics 64, 849 (1992).
3 - B. J. van Wees, et al., Physical Review Letters 60, 848 (1988).
4 - D. Zajac, T. Hazard, X. Mi, E. Nielsen, J. Petta, Physical Review Applied 6, 054013 (2016).
5 - J. I. Colless, et al., Physical Review Letters 110, 046805 (2013)
6 - K. D. Petersson, et al., Nano Letters 10, 2789 (2010).
7 - M. G. House, et al., Nature Communications 6, 8848 (2015).
8 - A. C. Betz, et al., Nano Letters 15, 4622 (2015).
9 - M. Veldhorst, H. G. J. Eenink, C. H. Yang, A. S. Dzurak, Nature Communications 8, 1766 (2017).
10 - C. Jones, et al., Physical Review X 8, 021058 (2018).
11 - R. Li, et al., Science Advances 4, eaar3960 (2018).
12 - A. West, et al., arXiv:1809.01864 [cond-mat, physics:quant-ph] (2018). ArXiv: 1809.01864.