A Quantum Leap Opens New Avenues to Very Fast Quantum Processes

Simulated Spin Dynamics

A quantum leap silently occurred in studies of quantum spin systems that lead to many exciting discoveries and new possible applications towards building quantum computers to develop ultra-precise magnetometers to improve quantum communications across fiber-optics networks. Scientists developed new ways of manipulating quantum systems on very short timescales, before quantum properties are degraded, due to decoherence. These investigations discovered the fast rotation of an isolated quantum system—spin of a nitrogen-vacancy (NV) color center in diamond. The state "up" was driven to the state "down," using magnetic field oscillating with the spin's Larmor frequency—when a magnetic moment is placed in a magnetic field, it tend to align with the field. Applying very strong fields, with the amplitude comparable to the frequency, sub-nanosecond coherent rotation of a single quantum spin was achieved. At such a strong driving, the motion of the spin is not a smooth nutation, but exhibits fast jumps and stallings. Seemingly random, this unusual pattern is totally reproducible and is caused by interference between two components of the driving field (one rotating together with the spin, the other rotating opposite). Studies showed field pulses with smoothened edges made the rotation more robust. Such pulses can be used for quantum control in a wide range of spin systems.

Contact: Viatcheslav Dobrovitski, slava@ameslab.gov

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