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Science 22 July 2005:
Vol. 309. no. 5734, pp. 586 - 588
DOI: 10.1126/science.1113203
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Reports

Fermionic Bell-State Analyzer for Spin Qubits

Hans-Andreas Engel1,2 and Daniel Loss2

We propose a protocol and physical implementation for partial Bell-state measurements of Fermionic qubits, allowing for deterministic quantum computing in solid-state systems without the need for two-qubit gates. Our scheme consists of two spin qubits in a double quantum dot where the two dots have different Zeeman splittings and resonant tunneling between the dots is only allowed when the spins are antiparallel. This converts spin parity into charge information by means of a projective measurement and can be implemented with established technologies. This measurement-based qubit scheme greatly simplifies the experimental realization of scalable quantum computers in electronic nanostructures.

1 Lyman Laboratory, Department of Physics, Harvard University, Cambridge, MA 02138, USA.
2 Department of Physics and Astronomy, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.

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Science. ISSN 0036-8075 (print), 1095-9203 (online)