Physicists discover how fundamental particles lose track of quantum mechanical ...(affiliated with the California NanoSyste...)

Recently the issue of how fundamental particles lose track of quantum mechanical properties through interaction with the environment has gained crucial importance in the field of quantum information. In this area, robust manipulation of quantum states promises enormous speedups over classical computation. Keeping track of the quantum phase is essential for keeping the quantum information, and insight into loss of the phase will greatly help to mitigate this process.

Experimental work on this subject has thus far been hindered by the lack of high-fidelity coherent control of a single spin in nature and our inability to directly influence the bath dynamics.

In a collaboration between physicists in Awschaloms research group at UCSB and Slava Dobrovitski, a visiting scientist from Ames Laboratory in Iowa, a series of experiments were undertaken that utilized electron spins in diamond to investigate different regimes of spin-bath interactions, and provide much information about the decoherence dynamics.

The scientists use diamond crystals to study a single electron spin tied to an adjustable collection of nearby spins. Two features of diamond that make this system viable for unprecedented investigations into the coherent dynamics are the precise optical control of a single spin that is unique to diamond, and the magnetic tunability of the spin-bath and intrabath dynamics with small permanent magnets. Their teams observations contain a number of extraordinary discoveries, such as the time-dependent disappearance and reappearance of quantum oscillations of the spins in the diamond lattice.

To our surprise, when looking at longer times, the oscillations disappeared then re-appeared, said co-author Ronald Hanson, a postdoctoral student at UCSB during this period who is now a professor at th
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