Speaker: Ken DeRose (Northwestern University)
Title: A Surprise in the Lab from the Interplay of Dynamical Decoupling and Dissipation
Abstract: Dynamical decoupling (DD) sequences are widely used in quantum sensing to extend and enhance qubit sensitivity to oscillating signals in the presence of dephasing. By applying DD in the form of echo pulses, the effects of detuning are reversed and allow a refocusing of the qubit phase, suppressing sensitivity to constant detuning offsets. While extending such sequences into the qubit’s dissipative regime, we uncovered an unexpected form of coherence that is insensitive to oscillating signals yet highly sensitive to detuning, opposite to the intended behavior. This effect arises from the interplay between decay and the periodic coherent driving of the DD sequence. In this talk, I will present our investigation of this phenomenon and strategies to mitigate its impact on quantum sensors. I will further show how decay, rather than being purely detrimental, can be harnessed to enable detuning-sensitive measurements that remain robust against frequency noise in the qubit transition or driving field above the qubit decay rate.
Erin Sazy
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