Ik Kyeong Jin

Silicon hole quantum dot qubits offer several advantages over conventional electron quantum dot qubits. The strong spin-orbit interaction in holes allows fast all-electric spin control [1, 2]. Recent calculations also suggest it is possible to engineer “sweet spots” for holes, where environmental decoherence is minimised, while simultaneously allowing rapid spin control [3, 4]. It has been found that electron devices are more stable and exhibit less charge noise than hole devices. This has made it difficult to isolate a single hole in a planar silicon quantum dot, which was demonstrated only recently [5].

Ambipolar CMOS devices combine both electron and hole devices within the same chip to offer a route to integrate a high performance, stable electron charge sensor with a hole qubit device. Ambipolar CMOS charge sensing was recently demonstrated [6] - but this approach has not been applied to optimised qubit devices. Here, we fabricate a fully controllable ambipolar CMOS device, consists of an electron charge sensor adjacent to a double hole quantum dot. We show that this geometry allows sensing of the double hole quantum dot system down to the last hole. We show that we can electrically control the spin state of the double dot via electric dipole spin resonance (EDSR). We also demonstrate control of the reservoir tunnel rates which can allow latched spin readout [7], as well as control of the interdot coupling rate which is essential for exchange qubit operation. These results show the feasibility of ambipolar CMOS charge sensing qubits.