Electron spin qubit measurement without demolishing it

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Scientists from the RIKEN Center in Japan has succeeded in taking repeated measurements of the spin of an electron in a silicon quantum dot (QD) without changing its spin in the process.

This type of “non-demolition” measurement is important for creating quantum computers that are fault-tolerant. So far, researchers have succeeded in developing single electron spins in silicon QDs with a long information retention time and high-precision quantum operation, but quantum non-demolition measurement has proven elusive. The conventional method for reading out single electron spins in silicon is to convert the spins into charges that can be rapidly detected, but unfortunately, the electron spin is affected by the detection process.

The RIKEN team has achieved such non-demolition measurement. Essentially, they were able to transfer the spin information of an electron in a QD to another electron in the neighboring QD using the Ising type interaction model in a magnetic field, and then could measure the spin of the neighbor using the conventional method, so that they could leave the original spin unaffected.

The research has been published in Nature Communications. (Phys.org)