SISQ · Silicon Spin Quantum Bits
FP7 — People (Marie Curie Actions)
- Duration
- 2011-08-01 → 2015-07-31
- EU contribution
- €100,000
- Participants
- 1
- Scheme
- MC-CIG
Lines connect the coordinator with its partners.
Results in brief
Silicon Spin Quantum Bits
Spin qubits in coupled quantum dots (QDs) are promising for future quantum information processing (QIP). A quantum bit (qubit) is the quantum mechanical analogon of a classical bit. In general, each quantum mechanical two-level system can represent a qubit. For the spin of a single charge carrier e.g., which is a natural two-level system, the basis quantum states are given by the spin-up and the spin-down state. QIP based on the spin degree of freedom requires long spin coherence times. Silicon provides an environment where spins can be controlled with minimal decoherence because of the weak hyperfine and spin-orbit interaction. So far, most experiments have focused on electron spins, but hole spins offer great potential for spin-based QIP as well. A hole-spin qubit in silicon can benefit from its finite spin-orbit coupling, because it allows efficient electric-field driven spin resonance applicable via local gate electrodes. However, it is still unclear whether the electron spin or the hole spin is most suitable as a qubit. We have developed an ambipolar MOSFET-based device that allows the electron and the hole transport regime to be compared in one and the same nanostructure. A top gate overlaps n++ and p++ implanted regions on the source and the drain side. Depending on the applied top gate voltage VL, a two-dimensional electron or hole gas is formed at the Si/SiO2 interface. We locally control the charge density by an additional bottom gate. Non-linear transport measurements show single-charge transport through a QD created underneath the bottom gate. The same charging energy and capacitances of the last charge transition in both regimes indicate that we load the same QD with either an electron or a hole. Ambipolar QDs with single-charge occupancy can break new ground in spin-based QIP, since they have the potential to act as a qubit comparator where the suitability of electron-spin and hole-spin qubits can be evaluated in the same crystalline environment. Taking the advantages of either qubit one could think of future “quantum CMOS” technology based on ambipolar QDs.
Data: CORDIS, © European Union
Project objective
The objective is realising the first silicon single-electron spin quantum bits, which will be a significant step towards the realization of the first generation quantum computers. Quantum computers are expected to dramatically outperform the largest classical supercomputers in solving specific important problems. Applications involve data encryption (for intrinsically secure communication), the efficient simulation of quantum systems (such as chemical reactions), and support in many emerging forms of artificial nanotechnology, and in our understanding of the nanomachinery of biological molecules.In this proposal CMOS-compatible silicon quantum dots (QDs) are used as hosts for electron spin quantum bits for future solid-state quantum information processing. We will use a unique design which incorporates a large number of independently controllable gates, resulting in an unprecedented degree of tunability in Si QDs. This architecture has allowed for single-electron QDs in silicon. Here, we aim at establishing Pauli spin blockade in the few-electron regime in double QD (DQD) systems, which will be used as detector for single-electron spin resonance. This will enable us to determine the single electron spin coherence time T2, which holds the promise to be extremely long in Si QDs.
Original text from CORDIS.
Participants
- UNIVERSITEIT TWENTE · EnschedeCoordinatorNetherlands
Links
Data: CORDIS, © European Union