Demonstration of Weak Measurement Based on Atomic Spontaneous Emission

TL;DR

This paper introduces a novel weak measurement technique utilizing atomic spontaneous emission, enabling quantum regime applications with single emitters and expanding the scope of weak measurement methods beyond Gaussian-based systems.

Contribution

It demonstrates a new weak measurement scheme based on spontaneous emission, bridging the gap between traditional Gaussian pointers and atomic quantum systems.

Findings

Successful demonstration of weak measurement with atomic spontaneous emission.

Observation of large shifts in photon arrival times due to imaginary weak values.

Potential applications in sensitive atomic probes like optical magnetometry.

Abstract

We demonstrate a new type of weak measurement based on the dynamics of spontaneous emission. The pointer in our scheme is given by the Lorentzian distribution characterizing atomic exponential decay via emission of a single photon. We thus introduce weak measurement, so far demonstrated nearly exclusively with laser beams and Gaussian statistics, into the quantum regime of single emitters and single quanta, enabling the exploitation of a wide class of sources that are abundant in nature. We describe a complete analogy between our scheme and weak measurement with conventional Gaussian pointers. Instead of a shift in the mean of a Gaussian distribution, an imaginary weak value is exhibited in our scheme by a significantly slower-than-natural exponential distribution of emitted photons at the postselected polarization, leading to a large shift in their mean arrival time. The dynamics of spontaneous emission offer a broader view of the measurement process than is usually considered within the weak measurement formalism. Our scheme opens the path for the use of atoms and atomlike systems as sensitive probes in weak measurements, one example being optical magnetometry.