Enhancing qubit noise spectroscopy using a quantum quench*

Understanding in detail the dissipative environment of a qubit or quantum processor is crucial for the design of optimal dynamical decoupling protocols and high-fidelity operations. Qubit-based quantum noise spectroscopy seeks to use a probe qubit and tailored control pulses as a tool for reconstructing environmental noise spectra [1]. While standard approaches treat the environment as a fixed noise source, true quantum environments have a dynamical nature that can play an important role in dissipative effects. Here, we discuss modifications of standard Ramsey-based noise spectroscopy protocols that incorporate an effective quantum quench of the bath. These techniques allow one to extract bath properties that are not accessible via standard methods (e.g., parameter-free measurements of bath temperature, or evidence that the bath is not in thermal equilibrium). We discuss how our approaches are readily compatible with standard diamond NV-center based quantum sensing platforms.

[1] Degen et al., Quantum sensing, Rev. Mod. Phys. 89, 035002 (2017)