Resonant regeneration in the sub-quantum regime – A demonstration of fractional quantum interference

• Published in: Physics letters. B Vol. 698; no. 5; pp. 346 - 352
• Main Authors: Hartnett, John G., Jaeckel, Joerg, Povey, Rhys G., Tobar, Michael E.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 25-04-2011; Elsevier
• Subjects: Elementary particles; Exact sciences and technology; Holes; Interference; Light shining through walls experiments; Low energy particle physics; Microwave cavities; Microwaves; Nuclear physics; Photons; Physics; Quantum mechanics; Regeneration; Tests of quantum interference; The physics of elementary particles and fields; Walls; Tests of quantum interference; Low energy particle physics; Microwave cavities; Light shining through walls experiments; Amplification; Weak coupling; Axions; Quantum interference phenomena; Quantum mechanics
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2011.03.022

Light shining through wall experiments (in the optical as well as in the microwave regime) are a powerful tool to search for light particles coupled very weakly to photons such as axions or extra hidden sector photons. Resonant regeneration, where a resonant cavity is employed to enhance the regeneration rate of photons, is one of the most promising techniques to improve the sensitivity of the next generation of experiments. However, doubts have been voiced if such methods work at very low regeneration rates where on average the cavity contains less than one photon. In this Letter we report on a demonstration experiment using a microwave cavity driven with extremely low power, to show that resonant amplification works also in this regime. In accordance with standard quantum mechanics this is a demonstration that interference also works at the level of less than one quantum. As an additional benefit this experiment shows that thermal photons inside the cavity cause no adverse effects.