Group seminar at MPQ and Zoom: Quantum Computing Enhanced Sensing
 

Francisco Machado, TU Delft, Netherlands
Group seminar at MPQ lecture hall and Zoom
Tuesday, 27 January, 09:00am (MEZ)

Sensing provides one example where the ability to prepare and control an entangled state provides a scalable advantage over an entirely classical approach. Such advantage is often termed the Heisenberg limit and it arises from the ability to imbue a quantum state with global correlations that reduce the size of fluctuations. However, the control of quantum systems offers an opportunity to not only engineer quantum correlations, but also process information in a quantum coherent manner. Developing practical and useful sensing protocols that leverage both these aspects remains an important opportunity for understanding the limits and opportunities of quantum machines.
In this talk, I will present a concrete example of such an opportunity, where a novel form of quantum sensing improvement arises when a quantum sensor is coherently controlled by a quantum computer. Focusing on "broadband AC sensing" — the detection of a weak oscillating signal across a large frequency bandwidth — I will describe a quantum computer-assisted sensing protocol that solves this broadband AC sensing faster than any conventional quantum sensing approach. This construction is optimal, saturating (up to polylogarithmic factors) a new fundamental limit set by quantum mechanics — the Grover-Heisenberg limit. I will conclude by discussing the requirements for the implementation of our protocol in near-term experiments, using a solid state defect platform (a Nitrogen-Vacancy center coupled to nearby nuclear spins) as a specific example.