Unconventional photon blockade

Abstract

We review the unconventional photon blockade mechanism. This quantum effect remarkably enables a strongly sub-Poissonian light statistics, even from a system characterized by a weak single-photon nonlinearity. We revisit the past results, which can be interpreted in terms of quantum interferences or optimal squeezing, and show how recent developments on input-output field mixing can overcome the limitations of the original schemes towards passive and integrable single-photon sources. We finally present some valuable alternative schemes for which the unconventional blockade can be directly adapted.

Observation of the Unconventional Photon Blockade

“…4(a) is suppressed. By the same mechanism that suppresses the two photon state one also expects to see an increase of the three-photon component [18]. The increase of P 3 is not observed here because of the low mean photon number.…”

“…By moving from the region of arrow C to D in Fig. 3(d), the observed state switches from a phase squeezed to an amplitude squeezed state, which is a clear signature of the unconventional photon blockade effect [18].…”

“…More specifically, we rely here on the input-output tuning scheme described in detail in Refs. [18,19], here realized via the polarization degree of freedom, which is an extension of the original UPB proposal [17,21]. As a result the interference of different excitation pathways with and without involvement of the photon-number sensitive quantum dot transition can be tuned such that the two-photon component is suppressed.…”

“…However, moving further into the weak coupling regime (g < κ), which is much easier to achieve [10,11] (in particular if one aims for a small polarization mode splitting), the conventional photon blockade is no longer possible because the energy gap between the polariton states vanishes. Nevertheless, also in the weak coupling regime, the two-level system enables photon number sensitivity, which has recently enabled high-quality single photon sources using polarization postselection [12][13][14] or optimized cavity in-coupling [15,16].In 2010, Liew and Savona introduced the concept of the unconventional photon blockade (UPB) [17,18] …”

“…In 2010, Liew and Savona introduced the concept of the unconventional photon blockade (UPB) [17,18] which operates with arbitrarily weak nonlinearities. It was first investigated for Kerr non-linearities [17,19], then for χ ð2Þ nonlinearities [20] and the Jaynes Cummings [21,22] system which we focus on here.…”