Quantum-Enhanced Two-Photon Spectroscopy Using Two-mode Squeezed Light

Abstract

We investigate the prospects of using two-mode intensity squeezed twin-beams, generated in Rb vapor, to improve the sensitivity of spectroscopic measurements by engaging two-photon Raman transitions. As a proof of principle demonstration, we demonstrated the quantum-enhanced measurements of the Rb 5D 3/2 hyperfine structure with reduced requirements for the Raman pump laser power and Rb vapor number density.

Engineering two-mode squeezed vacuum-like states by using the Bohm potential

“…The levels curves of both potentials are conics sections. Using elementary techniques of analytic geometry, we find that the discriminant of the level curves of the Bohm potential is D = − e −10rν(t) cosh[2ν(t)] 4m 3 which is always different from zero, so the level curves are always non-degenerated conics, and the minor of the element 33 of the matrix of the corresponding quadratic form is e −8rν(t)…”

“…Non-classical states are of interest as they show less fluctuations in a given canonical variable (at the expense of the other) than that of coherent states that have fluctuations referred to as the standard quantum limit. In coupled harmonic oscillators, one of the most studied non-classical states that most labs try to generate are the socalled two-mode squeezed vacuum states [2] because of their several applications; among them, the enhancement of two-photon spectroscopy [3]. Generation of two mode squeezed vacuum states and in particular of the superposition of two-mode squeezed states [4][5][6] may be used for quantum information processing and quantum sensing [7].…”

Quantum metrology of two-photon absorption

“…These studies concern linear spectroscopy, i.e. the absorption of single photons, or the combination of classical lasers with quantum light sources in two-photon Raman transitions [37,38]. First theoretical works also started to investigate the role of quantum correlations in TPA of entangled photon pairs [39,40], or of photon statistics in coherent control [41].…”