Scientists discover way to make quantum states last 10,000 times longer

phys.org ^ | 08/13/2020

[BenLurkin]

University of Chicago's Pritzker School of Molecular Engineering announced the discovery of a simple modification that allows quantum systems to stay operational—or "coherent"—10,000 times longer than before. Though the scientists tested their technique on a particular class of quantum systems called solid-state qubits, they think it should be applicable to many other kinds of quantum systems and could thus revolutionize quantum communication, computing and sensing.

Quantum states need an extremely quiet, stable space to operate, as they are easily disturbed by background noise coming from vibrations, temperature changes or stray electromagnetic fields.

Thus, scientists try to find ways to keep the system coherent as long as possible. One common approach is physically isolating the system from the noisy surroundings, but this can be unwieldy and complex. Another technique involves making all of the materials as pure as possible, which can be costly

In tandem with the usual electromagnetic pulses used to control quantum systems, the team applied an additional continuous alternating magnetic field. By precisely tuning this field, the scientists could rapidly rotate the electron spins and allow the system to "tune out" the rest of the noise.

This small change allowed the system to stay coherent up to 22 milliseconds, four orders of magnitude higher than without the modification—and far longer than any previously reported electron spin system. (For comparison, a blink of an eye takes about 350 milliseconds).

[tet68]

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