QDev Seminar: Giorgos Katsaros
Institute of Science and Technology Austria
Holes: a blessing or a curse?
In the past 10 years many groups have used electrons confined in silicon quantum dots in order to realize spin qubits . Impressive progress in the extension of spin lifetimes has been achieved and record coherence times of about 1 second were reported in 2014 for 31P electrons in isotopically engineered 28Si substrates . Holes on the other hand are much less studied . Theory predicts that holes can show similar spin lifetimes as electrons  and should be promising for creating long distance two qubit gates . However none of these predictions have been verified so far.
In this talk I will focus on holes confined in Ge self-assembled quantum dots. I will present our recent results which demonstrate the presence of purely heavy-hole states in ultra-thin Ge hut wires and discuss our progress in the realization of T-junction charge sensors and double quantum dot devices.References: F. A. Zwanenburg et al., Rev. Mod. Phys. 85, 961 (2013) J. T. Muhonen et al., Nature Nanotechnology 9, 986 (2014) Y. Hu et al., Nat. Nanotechn. 7, 47 (2012) ; A. P. Higginbotham et al., Nano Letters 14, 3582 (2014) D. V. Bulaev et al., Phys. Rev. Lett. 95, 076805 (2005) S. E. Nigg et al., Phys. Rev. Lett. 118, 147701 (2017) H. Watzinger et al. Nano Letters 16, 6879 (2016)