Combining macroscopicity and nonclassicality with mechanical oscillators by detection of single Raman-scattered photons: possibilities and limitations
Detection of a single Raman-scattered photon adds or removes an excitation to the scattering quantum system, e.g., a molecule, an ensemble of atoms, or even an engineered mechanical oscillator. This can be exploited to project the system into a desired quantum state or to generate remote entanglement between several such systems. In this talk, I will briefly review this quantum state preparation technique, with a particular emphasis on its application to engineered mechanical oscillators in optomechanical systems. I will then describe recent theoretical work aiming to further exploit this technique towards higher levels of macroscopicity. I will show how detection of a single photon can: a) render an oscillator that undergoes large-scale coherent oscillations nonclassical [1] and b) create multipartite entanglement between a large number of systems [2]. I will also explain how the induced nonclassicality in both cases can be verified by analyzing the statistics of subsequent Raman-scattered photons. Finally, I will discuss limitations to these proposals due to thermal noise.
[1] K. R. Bush & K. Børkje, Proposal for Observing Nonclassicality in Highly Excited Mechanical Oscillators by Single Photon Detection, Phys. Rev. A 109, 043505 (2024)
[2] K. R. Bush & K. Børkje, Witnesses of Genuine Multipartite Entanglement and Nonlocal Measurement Back-action for Raman-scattering Quantum Systems, Phys. Rev. A 113, 032436 (2026).
About the qGAP seminar series
We aim to have a biweekly research seminar, with various people presenting research results, or discussing papers in a journal club style.
Every other week, however, we will have Francesco Massel from USN leading a discussion-style journal club on theoretical quantum sensing.
You can find the approximate schedule for what will be discussed in the various weeks here: Lecture plan Sensing theory.xlsx
Ideally, everyone would have read the weekly reading before coming to the seminar, as they will be structured as a discussion rather than a lecture. We particularly encourage Master's students to come.
The seminars are at 14.15 in the CCSE seminar room (4th floor Physics building, East Wing), as per usual
If you have something you would like to present (whether own research or a journal-club style talk), please do not hesitate to get in touch!
A Zoom link for the seminar is available from:
Contact: Gunnar Lange - Postdoctoral Fellow, University of Oslo