Acceleration-Induced Effects in Stimulated Light-Matter Interactions

We show that, in addition to the Unruh effect, there exist two new phenomena that are due to acceleration in the quantum theory of the light-matter interaction. The first is the phenomenon of acceleration-induced transparency which arises since acceleration impacts not only the counter-rotating terms in the light-matter interaction (the cause of the conventional Unruh effect) but also the rotating wave terms. The second new phenomenon is that the Unruh effect can be stimulated, a phenomenon that arises since not only rotating-wave terms can be stimulated (as in conventional stimulated emission) but also counter-rotating terms. The new phenomena are potentially strong enough to be experimentally observable.

Figure 1

Comparison between conventional first order processes in light-matter interaction that happens in inertial motion (gray, green, blue), and those that happen only in the presence of non-inertial motion (black, orange, red). Shown here are the pairs of states $\{|g⟩\otimes |n_k⟩,|e⟩\otimes |n_k⟩\}$ as the field photon number $n_k$ increases, and the transitions between them due to the various processes together with the terms that describe the processes.

Figure 2

The two curves display $|I_{\pm }(\mathrm{\Omega })|$ for an example of a trajectory of the form given in Eq. (12). The red curve is the resonant contribution $|I_{-}|$ which shows the strength of conventional absorption while the green curve is the nonresonant contribution $|I_{+}|$ which shows the strength of Unruh-type counter-rotating effects. Importantly, we see that the resonant contribution dips below that of the latter (here $|I_{-}/I_{+}|\approx {10}^{-3}$), so that at that frequency, the probability of resonant absorption is $\sim {10}^{-6}$ of the stimulated Unruh process. The frequency at which the resonant contribution dips is designed to be the detector gap frequency. The two peaks in $I_{-}$ correspond to absorption at the Doppler shifted frequencies ${\omega }_0=k^0{s}_0$, ${\omega }_2=k^0{s}_2$ that are due to the initial and final inertial velocities of the trajectory.