Coherent spin-exchange via a quantum mediator

Nature Nanotechnology 12, 26 (2017).
doi:10.1038/nnano.2016.188

Authors: Timothy Alexander Baart, Takafumi Fujita, Christian Reichl, Werner Wegscheider & Lieven Mark Koenraad Vandersypen
Coherent interactions at a distance provide a powerful tool for quantum simulation and computation. The most common approach to realize an effective long-distance coupling ‘on-chip’ is to use a quantum mediator, as has been demonstrated for superconducting qubits and trapped ions. For quantum dot arrays, which combine a high degree of tunability with extremely long coherence times, the experimental demonstration of the time evolution of coherent spin–spin coupling via an intermediary system remains an important outstanding goal. Here, we use a linear triple-quantum-dot array to demonstrate a coherent time evolution of two interacting distant spins via a quantum mediator. The two outer dots are occupied with a single electron spin each, and the spins experience a superexchange interaction through the empty middle dot, which acts as mediator. Using single-shot spin readout, we measure the coherent time evolution of the spin states on the outer dots and observe a characteristic dependence of the exchange frequency as a function of the detuning between the middle and outer dots. This approach may provide a new route for scaling up spin qubit circuits using quantum dots, and aid in the simulation of materials and molecules with non-nearest-neighbour couplings such as MnO (ref. 2...

Source: Nature Nanotechnology - October 9, 2016 Category: Nanotechnology Authors: Timothy Alexander Baart Takafumi Fujita Christian Reichl Werner Wegscheider Lieven Mark Koenraad Vandersypen Tags: Letter Source Type: research