Photon echo in vacuum

Игорь Сергеевич Осадько

Ashat M. Basharov, V. Popov

Kinetic equations describing atomic behavior in non-resonant classical and broadband squeezed fields are received. It is shown that the main parameters of squeezed field can be obtained from the decay of two-pulse photon echo.

Boris D. Fainberg

Wen-Te Liao, Sven Ahrens

Abstract Gravitational redshift, a striking prediction of Einstein’s theory of general relativity, has been experimentally confirmed on Earth. Yet, exploiting this effect as a controllable resource in coherent quantum systems remains challenging. Here, we theoretically demonstrate gravitationally induced γ -ray photon echoes in solid-state Thorium-229 targets using the 8.4 eV nuclear clock transition, which, owing to its nuclear origin, extends the definition of γ rays down into the vacuum ultraviolet regime. With its ultranarrow linewidth (1 mHz), exceptional quality factor (10 19 ), and long 1740 s isomeric half-life, this transition offers a compact solid-state platform sensitive to millimeter-scale gravitational variations. We further investigate the gravitational photon echo in a spinless crystal with a coherence time on the order of seconds. Controlled target rotations enable the generation, manipulation, and storage of γ -ray echoes, paving the way for a gravitationally driven γ -ray memory, a narrowband γ -ray source, and relativistic geodesy.

Galina A. Nemova

Hari Kumar Yadalam, Matthias Kizmann, Shaul Mukamel

In classical macroscopic ultrafast optical four-wave mixing signals, phase matching selects three classes of light–matter interaction pathways: double quantum coherence; non-rephasing; and photon-echo. Multiple pathways contribute to each of these signals. We show that a coincidence-double-heterodyne detection scheme that employs two classical and two vacuum fields can isolate a single pathway contribution to each of these signals. We further demonstrate the advantage of the proposed technique by comparing it with the classical photon-echo signal for a model Frenkel-exciton dimer.