Thursday, August 4, 2011
A new Science paper explores an advance in spin-based quantum computing by a team in the Netherlands including Martin Laforest, now the Institute for Quantum Computing's (IQC) manager of scientific outreach.
The paper summarizes research conducted at the Delft University of Technology, where Martin Laforest did postdoctoral research before joining IQC to head scientific outreach last year.
The researchers demonstrated, for the first time, a “single-shot readout” of two electron spins in a double quantum dot (the spins are confined next to each other at the interface of two semiconductor materials).
Previously, this technique has been demonstrated in single quantum dots, but its generalization to multiple quantum dots is experimentally challenging due to cross-talk and interaction between spins.
In addition to this result, the Delft team — Laforest, Katja Nowack, Mohammad Shafiei, Guenevere Prawiroatmodjo, Lars Schreiber, Christian Reichl, Werner Wegscheider and leader Lieven Vandersypen — demonstrated exchange interactions between two spins. Thanks to the single-shot readout, the team could investigate the resulting correlation given multiple initial states.
Their results demonstrate two important factors needed for scalable quantum computing — namely, readout and exchange — working in a single experiment.
"Our work brings together two important requirements for the implementation of quantum computing in the solid state and is paving the way to the realization of proof-of-principle quantum algorithms and quantum error correction,” said Laforest. “All in all, this demonstrates the viability of the spin qubit in quantum dots as a scalable quantum processor."
The paper was published online Aug. 4 in Science Express prior to its release in the print edition of Science.