Controlled multi-photon subtraction with cascaded Rydberg superatoms as single-photon absorbers

Abstract

The preparation of light pulses with well-defined quantum properties requires precise control at the individual photon level. Here, we demonstrate exact and controlled multi-photon subtraction from incoming light pulses. We employ a cascaded system of tightly confined cold atom ensembles with strong, collectively enhanced coupling of photons to Rydberg states. The excitation blockade resulting from interactions between Rydberg atoms limits photon absorption to one per ensemble and rapid dephasing of the collective excitation suppresses stimulated re-emission of the photon. We experimentally demonstrate subtraction with up to three absorbers. Furthermore, we present a thorough theoretical analysis of our scheme where we identify weak Raman decay of the long-lived Rydberg state as the main source of infidelity in the subtracted photon number and investigate the performance of the multi-photon subtractor for increasing absorber numbers in the presence of Raman decay.

Nichtlineare Optik mit einzelnen Photonen

“…Beispielsweise kann aus einem Lichtstrahl mit mehreren Photonen durch Transmission durch ein Superatom gezielt genau ein Photon absorbiert werden (s. Physik in unserer Zeit 2017 , 48 , 2). Dieses Schema lässt sich kaskadieren: bei Transmission durch zwei, drei oder mehr Superatome können gezielt genau zwei, drei oder mehr Photonen absorbiert werden [14]. Alternativ kann man versuchen, mit einem Lichtstrahl mit vielen Photonen Anregungen in einem Superatom zu erzeugen.…”

Creation of non-classical states of light in a chiral waveguide

“…In recent years, quantum emitters coupled to chiral waveguides in which light propagates in a single, welldefined direction, have emerged as promising experimental tools for the manipulation of light [18,19]. For example, it has been shown that these systems can be used to implement atom-mediated photon-photon interactions, photon circulators, deterministic photon sources, and single to few photon subtractors [20][21][22][23][24][25]. They can be implemented in a variety of different platforms, ranging from circuit QED with superconducting qubits [26,27], to quantum dots coupled to photonic crystal waveguides [21,28,29], atoms coupled to optical nanofibres [20,22,30], or free space Rydberg superatoms [31].…”

Many-Body Radiative Decay in Strongly Interacting Rydberg Ensembles

“…This process can be controlled by the phase-coherence of the excitation laser and by the temperature of the Rydberg gas. It is also influenced by strong interactions among Rydberg atoms [15][16][17][18], which can be exploited for designing single photon absorbers and emitters [19][20][21][22][23]. Radiative decay, on the other hand, is an ubiquitous process which is caused by the coupling of the atomic dipole to the electromagnetic field.…”