Fingerprinting Spin Qubits

Electrons not only have mass and charge, they also have magnetic properties directly related to their intrinsic spin. These spins can combine into quantum states of different spin parity, and such states may be useful as qubits in future quantum computers. As [Egues][1] discusses in his Perspective, [Engel and Loss][2] report in this issue a method for fingerprinting the spin states of electrons contained in quantum dot structures. By allowing the electrons to leak from one dot to another, and then using a nanowire to sense the presence of the spin states, the authors were able to perform a nondestructive spin-parity measurement. Such a spin-parity detector should permit the manipulation of quantum dot qubits for quantum computation. [1]: http://www.sciencemag.org/cgi/content/full/309/5734/565 [2]: http://www.sciencemag.org/cgi/content/short/309/5734/586