Temporal loss boundary engineered photonic cavity

Losses are ubiquitous and unavoidable in nature inhibiting the performance of most optical processes. Manipulating losses to adjust the dissipation of photons is analogous to braking a running car that is as important as populating photons via a gain medium. Here, we introduce the transient loss boundary into a photon populated cavity that functions as a ‘photon brake’ and probe photon dynamics by engineering the ‘brake timing’ and ‘brake strength’. Coupled cavity photons can be distinguished by stripping one photonic mode through controlling the loss boundary, which enables the transition from a coupled to an uncoupled state. We interpret the transient boundary as a perturbation by considering both real and imaginary parts of permittivity, and the dynamic process is modeled with a temporal two-dipole oscillator: one with the natural resonant polarization and the other with a frequency-shift polarization. The model unravels the underlying mechanism of concomitant coherent spectral oscillations and generation of tone-tuning cavity photons in the braking process. By synthesizing the temporal loss boundary into a photon populated cavity, a plethora of interesting phenomena and applications are envisioned such as the observation of quantum squeezed states, low-loss nonreciprocal waveguides and ultrafast beam scanning devices.

Вакуумное двулучепреломление в поле плоской электромагнитной волны

We study the process of vacuum birefringence in a strong electromagnetic field: a probe photon changes its polarization while traversing a counterpropagating laser beam. To describe this phenomenon, we calculate the polarization tensor in the field of a plane monochromatic wave to leading order with respect to its amplitude. The main goal of the study is to compare the results with the data obtained within the locally constant field approximation (LCFA). Here we identify the domain of the LCFA applicability in the case of a plane-wave external background. It is shown that the frequency of the probe photon and that of the external field are symmetrically involved in the relative uncertainty. The exact treatment of the spatiotemporal dependence beyond the LCFA becomes necessary at the energy scale 0.1-1 MeV.

Pair production by Schwinger and Breit–Wheeler processes in bi-frequent fields

Counter-propagating and suitably polarized light (laser) beams can provide conditions for pair production. Here, we consider in more detail the following two situations: (i) in the homogeneity regions of anti-nodes of linearly polarized ultra-high intensity laser beams, the Schwinger process is dynamically assisted by a second high-frequency field, e.g. by an XFEL beam; and (ii) a high-energy probe photon beam colliding with a superposition of co-propagating intense laser and XFEL beams gives rise to the laser-assisted Breit–Wheeler process. The prospects of such bi-frequent field constellations with respect to the feasibility of conversion of light into matter are discussed.

QUANTUM CIRCUIT FOR ENTANGLING PROBE

The quantum circuit and design are given for an optimized entangling probe attacking the BB84 protocol of quantum key distribution and yielding maximum information to the probe. Probe photon polarization states become entangled with the signal states on their way between the legitimate transmitter and receiver.